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Title Question Date Posted
Use of the Inflection Point as a Brace Point

I was told that the use of an inflection point to brace the compression flange of a beam is no longer allowed. Is this true?

01-01-2012
Weld Access Hole Height In ANSI/AISC 360-05 Section J1.6, the height of a weld access hole is required to be at least 1 in. (25 mm). The commentary to this section states, “The height of the weld access hole must provide sufficient clearance for ease
of welding and inspection and must be large enough to allow the welder to deposit sound weld metal through and beyond the web.” It seems one could satisfy this intent using an access hole with a height less than 1 in. Is there any provision that would allow use of a lesser access hole height?
01-01-2012
Beveled Gusset Corners What are the benefits of “snipping” or bevel cutting the edge of a vertical bracing gusset where it lies under the bracing member? 01-01-2012
Moment Connection to HSS Column I am working on the design of a moment connection between a wide-flange beam and an HSS column. The beam flange is wider than the HSS column it connects to. According to ANSI/AISC 360-10 Section K1.3b, Bp/B must be less than or equal to 1. Do we need to taper the flanges of the beam to be
the same width of the column at the joint or can we keep the normal flange width with no taper and use Bp/B = 1.0?
01-01-2012
Fillet Weld Design Per ANSI/AISC 360 Table J2.5, the base metal shear strength for a fillet weld is governed by Section J4. Is the gross area of the base metal subject to shear based on the thickness of the base metal at the weld or the size of the weld leg? In other words, does the failure occur through the thickness of the base metal or at the fusion zone between the fillet weld leg and the base metal? 01-01-2012
CJP Groove Weld for Round HSS I need to make a CJP butt-welded splice in a round HSS. I had planned on using a smaller pipe as a backing bar but cannot find any guidance concerning an allowable gap for the backing bar. How much gap is allowed between base metal and the backing bar for a CJP butt weld? 01-01-2012
Built-Up Shape Tolerances Does AISC specify fabrication tolerances for welded built-up I shapes? 01-01-2012
SCBF Brace Slenderness I noticed that AISC 341-10 Section F2.5b specifies that the slenderness of diagonal braces in SCBF must be less than or equal to 200. Section 13.2a of the 2005 edition has an upper limit of 4 y E F, with an exception that allowed an upper limit of 200 if additional criteria are met. Can you provide an explanation for this change? 01-01-2012
Strength of a Tapped Hole

We have a unique connection configuration where we would prefer to fasten an ASTM A325 bolt into a threaded hole in a plate in lieu of using a nut. Is there a way to calculate the capacity of a threaded plate used as a nut?

12-01-2011
Fracture Critical Members

Is the bottom flange of a plate girder fracture critical if it is connected to the web using all-bolted double angles?

12-01-2011
Prying Action

When attaching a hanger connection to the bottom flange of a beam, is it appropriate to use the procedures in Part 9 of the 14th Edition AISC Steel Construction Manual to evaluate prying action of the continuous beam bottom flange?

12-01-2011
Stitch Plate Design

When adding stitch plates between back-to-back angles used for bracing, what criteria are used to design the stitch plate and its connection to the angles?

12-01-2011
Eccentricity in Axially Loaded WT-Sections

Is it necessary to account for the eccentricity on a WT section used as a compression or tension member? That is, can AISC Steel Construction Manual Table 4-7 be used for a WT compression member connected at the flange only?

12-01-2011
Minimum Edge Distance In the 2005 AISC Specification, Table J3.4 lists different

edge distance values for bolt holes at sheared edges and rolled edges or thermally cut edges. I understand that the provisions of sections J3.10 and J4 must still be met, but what is the reasoning behind the different values in the table for different edge conditions?

12-01-2011
K-Factor for Gusset Buckling

The AISC Design Examples use K = 0.5 for compression buckling of some gusset plate connections. The commentary to Appendix 7 of AISC 360-10 lists the theoretical K-factor equal to 0.5 for these support conditions, but recommends using K = 0.65 for design. Is it correct to use K = 0.5 for compression buckling of gusset plates?

12-01-2011
Welding in the k-area

Is welding not permitted in the k-area of beams, or is it just not recommended?

12-01-2011
Stiffened Seated Connection Strength

I am designing a stiffened seated connection to a wide-flange column web where the horizontal seat plate is welded to the column web and to both column flanges. The stiffener plate is also welded to the column web. Is the strength of this connection equal to the value in AISC Steel Construction Manual Table 10-8 plus the value of the welds connecting the seat plate to the column flanges on each side?

11-01-2011
Base Plate Shear Transfer

AISC Steel Design Guide No. 1, Base Plate and Anchor Rod Design, 2nd Edition, discusses three methods of transferring shear to the concrete at a base plate: friction, shear lugs and anchor rods. However, I do not see a discussion on whether any of these methods can be used in combination with one another. Can the strengths from these mechanisms be combined?

11-01-2011
Shape Properties

Where can I find the AISC steel shapes properties and dimensions?

11-01-2011
Welder Identification

Is there an AISC requirement that welders, welding operators or tack welders place a unique, hard-stenciled identification mark near the welds they have produced?

11-01-2011
Welding Electrode Storage

On one of our projects, the welding electrodes are not being stored in an oven. Our structural drawings specify the use of E7018 electrodes. Is it acceptable not to store the electrodes in an oven?

11-01-2011
Fire Design of Concrete-Filled HSS Columns

On page 28 of AISC Steel Design Guide No. 19, Fire Resistance of Structural Steel Framing, it states that two vent holes in opposite directions are needed at the top and bottom of concrete-filled HSS columns. Are these vent holes required by AISC or is this simply a recommendation?

11-01-2011
Eccentrically Loaded Bolt Groups

In the AISC 14th Edition Steel Construction Manual, formulas are provided for the analysis of eccentrically loaded bolt groups based on the instantaneous center of rotation method. In this analysis, the actual eccentricity is used; in earlier editions, the eccentricity was allowed to be reduced based on the number of fasteners in a vertical row using the equation,

 

 

Was that method unsafe? I have designed many connections using this method and am wondering why it was changed.

11-01-2011
Eccentrically Loaded Bolts

I am analyzing an eccentric bolt group and cannot use the eccentrically loaded bolt group tables in the AISC Manual due to a non-standard spacing. How can I calculate the coefficient C?

10-01-2011
Use of Lock Washers

A customer has asked that lock washers be provided at all pretensioned and slip-critical bolted connections. I cannot find lock washers mentioned in the AISC or RCSC

specifications. Are lock washers permitted to be used in pretensioned or slip-critical connections?

10-01-2011
Established Finish Line

In the AISC Code of Standard Practice, Section 7.13.1.3(b) on adjustable items refers to the “established finish line.” What is the definition of an established finish line?

10-01-2011
Material Availability

I’m looking for a supplier of several structural shapes. How do I find information on availability and where to purchase structural steel?

10-01-2011
Fixed Connection to HSS Columns

Which AISC publications address the design of wideflange beams moment connected to HSS columns? Will the connection design have an impact on the axial capacity of

the column?

10-01-2011
NDT per AISC 360 Chapter N The 2010 AISC Specification requires UT inspection for some CJP groove welds with a transversely applied tension load (Section N5.5b). This would seem to apply to most

bolted end-plate moment connections. In light of the very good results seen historically with this type of connection and the recent push to tout the advantages of visual weld

inspection and the weak points of relying on NDT as the sole arbiter of weld quality, how are we justifying this seeming discrepancy?

10-01-2011
OMF Connection Design

AISC Seismic Design Manual Example 4.4 calculates the required shear strength, Vu, of an OMF connection equal to 3(1.1RyMp)/(2L). However, AISC 341-05 Equation 11-1 specifies Vu equal to 2(1.1RyMp)/Lh. Which is correct?

10-01-2011
Monorail Runway Design

I am designing a monorail crane runway with loads on the bottom flange of the runway beam. What resources are available to aid me in this design?

10-01-2011
Flexural Strength of a Box Section

When calculating Se for a box section with slender flanges, should the full Sx of each web be included?

09-01-2011
Double-Angle Connections

Can you please provide some recommendations on whether

or not to use double-angle connections, bolted to a beam

and welded to an HSS column when the connection is

subject to axial tension?

09-01-2011
Joists in SMF Protected Zone

We are designing a building with special moment frames as the seismic force resisting system. Are open-web joists allowed to bear on the beam in the protected zone?

09-01-2011
Workable Gage

The AISC Steel Construction Manual Table 1-1 lists the workable gage for a W14×145 as 3-7½-3. These large W14 sections are the only members in this table that have the gage listed as such. Can you please explain this gage designation?

09-01-2011
AESS and Stiffener Corner Clips

Does AISC Code of Standard Practice Section 10.2.4 regarding AESS fabrication tolerances apply to stiffener clips at the radius on a wide flange?

09-01-2011
Detailing for Steel Construction

Does AISC’s Detailing for Steel Construction, 3rd Edition, have connection design examples similar to those contained in the 1st Edition?

09-01-2011
OCBF Unbalanced Load

In a two-story “X” type OCBF, must the beam and braces above resist the unbalanced forces as specified in AISC 341 Section 14.3(1)?

09-01-2011
Multiple Washers

Is there a maximum number of washers that can be used in a

high-strength bolted connection?

09-01-2011
Long-Slotted Holes

In a slip critical connection, can one member have long slots parallel to the direction of the load and the other have long slots perpendicular to the load?

09-01-2011
Protected Storage of Bolts

Section 2.2 of the 2009 RCSC Specification states that bolts cannot be used in the work that have become dirty or rusty and that these bolts must be qualified to Section 7. If individual bolts are cleaned and lubricated on an “as needed” schedule, do bolts need to be requalifed if they have already been qualifed in the as-received condition?

09-01-2011
Design of Bracing Connections

 

Is the variation of the Uniform Force Method found in the 14th Edition AISC Steel Construction Manual section titled "Analysis of Existing Diagonal Bracing Connections" applicable to new construction?

08-01-2011
Shear Lag

 

 

Reinforcement may be required due to shear lag in heavily loaded HSS tension member connections. Does AISC have a published approach for the design of reinforcement for square HSS at slotted HSS-to-gusset connections?

08-01-2011
Galvanized Anchor Rods

 

Can an ASTM F1554 Grade 105 anchor rod be hot dip galvanized?

08-01-2011
Welding Historic Steels

 

I would like to make some welded modifications to an existing steel structure that was constructed with ASTM A7 steel. Is welding to A7 steel acceptable?

08-01-2011
Single-Angle Shear Strength

 

AISC 360-05 Section G4, Single Angles, states, "The nominal shear strength of a single angle leg shall be determined using Equation G2-1 with Cv=1.0, …, and kv=1.2." If Cv=1.0, what is kv used for?

08-01-2011
Beam Bracing

 

Does AISC have requirements regarding the required strength of beam lateral braces? I have not been able to find any information on this in the 9th Edition AISC Manual of Steel Construction.

08-01-2011
Preinstallation Verification Testing

 

RCSC Specification Section 7 requires the use of a tension calibrator for preinstallation verification testing. Who is to provide the tension calibrator on a project when job site preinstallation verification testing is required?

08-01-2011
Fillet Weld Design

How should I design the fillet weld for the load condition shown below?

08-01-2011
Composite Beam Design

 

Can composite beams in negative flexure be designed to include any contribution of the concrete slab to the strength of the composite section?

08-01-2011
Proper Nut Orientation

 

I have seen nuts for structural fasteners that have a flat face on one side while the other side has chamfered corners. Common sense would indicate that the flat surface of the nut would face the washer. Is there a specified orientation for the nut?

08-01-2011
Silicon Steel I am analyzing a structure that was built in the late 1920s. The structure consists of steel space frame arches. The existing drawings nore the steel typically as structural grade steel, except for the chords of the main arches, which are noted to be silicon steel. What is silicon steel and why would it be singled out for use in the chords of a truss? Is it recommended to test coupons of steel from this era or was steel fairly standardized by then where I could just use typical specification properties? 07-01-2011
PJP Groove Weld Strength

 

AISC Specification Table J2.5, Available Strength of Welded Joints, lists different PJP groove weld strengths in compression for "connections of members designed to bear other than columns" and "connections not finished-to-bear." Please explain what is meant by that and why the "connections not finished-to-bear" have a higher strength.

07-01-2011
Coatings for Faying Surfaces

 

I have not been able to find information on which manufacturers make an appropriate paint for either a Class A or a Class B faying surface for slip-critical bolted connections. Where can I find this information?

07-01-2011
OMF Connection Design

 

I am trying to determine the design moment for an FR beam-to-column moment connection in an ordinary moment frame. AISC 341-05 Section 11.2a specifies the required flexural strength as the lesser of 1.1RyMp or the maximum moment that can be developed by the system. How do I determine the maximum moment that can be developed by the system?

07-01-2011
Round HSS Biaxial Bending

 

The 3rd Edition AISC LRFD Manual contained the Design Specification for Steel Hollow Structural Sections. This HSS Specification had an equation indicating that, for biaxial flexure of round HSS, the required flexural strength, Mu, can be calculated as the square root of (Mux2 + Muy2). Since the 13th Edition AISC Steel Construction Manual does not contain the HSS Specification, is this condition now governed by equation H1-1b and is a linear combination required?

07-01-2011
HSS Connection Design

 

I am trying to design a fully restrained moment connection for a structure consisting of rectangular HSS. My situation involves a Cross-Connection as described in Chapter K3 of the AISC Specification. AISC Specification Section K3.3a contains a limit on the aspect ratio of the member, but doesn’t say to which member it is referring—the branch or the chord. Please explain why the aspect ratio is a limiting factor and to which member it applies.

07-01-2011
Impact Loading

 

The 9th Edition AISC Steel Construction Manual contained information on impact loads for elevators. Where can I find this information in the AISC Manual?

07-01-2011
Single Angle LTB

 

I am trying to calculate the capacity of a L6×6×¾ bent about its z-axis. The provisions in AISC Specification Section F10 do not seem to cover lateral-torsional buckling about the minor principal axis. Why is this?

07-01-2011
Double Angle Connections

 

What angle leg sizes are valid for use with Table 10-1 in the 14th Edition AISC Steel Construction Manual?

07-01-2011
Changes to Delegated Connection Designs

     I have a contract in which the connections have been specified as Option 3 connections per the 2010 AISC Code of Standard Practice. That is, the connections are to be designed by our engineer with sealed calculations provided as the substaining connection information. Shears and moments (formoment connections) were provided in the design drawings.

     We submitted representative samples of the substaining connection information, which showed the typed of connections (shear tabs and bolted flange-plate moment connections) and teh calculations we planned to submit to justify our connections. The final substaining connection information was consistent with the representative samples, and we submitted it to the Structural Engineer of Record (SER) with the shop nd erection drawings as a part of the approval process as given in Section 4.

     The returned shop drawings were marked up to require one additional row of bolts in each moment connection flange plate, even though the claculations we submitted demonstrate compliance with the requirements on the design drawings and in the AISC Specification, and recommendations in the AISC Manual.

     When we asked why the additional bolts were necessary, the SER responded that they wanted more strength in the connections. We objected because of the additional costs of revising uor shop drawings and changing the connections. the SER responded that the 2010 AISC Code of Standard Practice gives them final authority to require this, per Section 4, and additional compensation is not required. Is this option consistent with the intent of the Code?

06-01-2011
Fillet Weld to Skewed Plate I am trying to determine the equivalent fillet weld size for a skewed shear plate connection. AWS D1.1 Table B.1 only lists dihedral angles over 60. In my case the dihebral angle is 54. How is the equivalent fillet weld leg size determined for angles other than those listed in the table? 06-01-2011
Bolting Cost Comparison Article There was a Modern Steel Construction article that discussed the relative costs of snug tight, pretensioned and slip-critical connections. In which issue of MSC did it appear? 06-01-2011
Maximum Fillet Weld Size AISC Specification Section J2.2b has a requirement that the maximum size of a fillet weld on material 1/4 in. or more in thickness chall be 1/16 in. less than the material thickness. Would this requirement apply to the case of a column-to-base-plate connection?      06-01-2011
IMF Panel Zone Strength AISC 341 Section 9.3a requires that, as a minimum, the panel zones is special moment frames be designed based on the expected moments at the column faces due to plastic hinge formation in the beam. However, Section 10.3 does not have a similar requirement for intermediate moment frames. Why is the same capacity design philosophy not noted for the special and intermediate resisting frame? 06-01-2011
Evaluation of Existing Structures Do you have any publication for evaluation of existing steel structures? 06-01-2011
Existing Column Out-of-Plumb We have been asking to evaluate an existing structure where a number of the columns exceed the AISC Code of Standard Partice out-of-plumb tolerance limit. Does AISC have design recommendations for when columns exceed the erection tolerances established by the Code? 06-01-2011
Seismic End-Plate Width

 

I am designing a Four-Bolt Stiffened (4ES) Extended End-Plate Moment Connection in a Special Moment Frame. I have been designing according to AISC 358 Chapter 6. Table 6.1 has a limitation for the width of the end-plate of 10¾ in. maximum to 10¾ in. minimum. Am I only allowed to use a 10¾ in. wide end-plate?

06-01-2011
Bracing Connection Design

 

The 13th Edition AISC Steel Construction Manual discusses the analysis of existing diagonal bracing connections using the Uniform Force Method. How is objective function given on pages 13-10 and 13-11 used in distributing the moment in the bracing connection and how is the Lagrange multiplier calculated?

06-01-2011
Strength of PJP Groove Welds Is it possible to use the 13th Edition AISC Steel Construction Manual Tables 8-4 through 8-11 to determine the capacity of a PJP groove weld group by converting the groove weld size to an equivalent fillet weld size? 05-01-2011
Weld Intersection Fatigue Category We have welded plate girder that has a bottom flange with a groove welded splice. The web-to-flange welds are fillet welds that pass over the flange splice. Does this intersection of two welds, the fillet weld passing over the groove weld, fit into a stress category of AISC Specification Appendix 3 Table A-3.1? 05-01-2011
Elliptical Hollow Sections AISC 360-05 currently does not address the design of elliptical hollow sections. I was wondering if there are any other resources that can be used to design with these shapes. 05-01-2011
High-Strength Bolts Are high-strength bolts, nuts and washers required to be produced by the same manufacturer? 05-01-2011
Ceramic Weld Backing Can I use a ceramic backing material for complete-joint-penetration groove welds? 05-01-2011
Web Sideway Buckling

 

I noticed that there is a tw3 term in the numerator and denominator of AISC Specification Equation J10-7 for the web sidesway buckling case where the compression flange is not restrained against rotation. Since these terms cancel out, why are they included in the equation? Is it true that the web sidesway buckling strength is independent of web thickness?

04-01-2011
Weld Strength Calculation

 

On page 3-28 of the AISC Seismic Design Manual, the gusset-to-beam force was calculated assuming only a single line of weld. Is this a conservative assumption? Figure 3-7 on page 3-34 indicates a double-sided weld.

04-01-2011
Composite Beam Design

 

 

AISC 360-05 Section I3-2a seems to imply that if h/tw is less than or equal to 3.76√(E/Fy), then the condition of the stresses under construction loading need not be combined with stresses induced on the post-composite section. The 1989 AISC Specification required a check of MDL/Sbeam+MLL/Seff Fa. Is it correct that when using AISC 360-05 Section I3-2a, the superposition of construction stresses in the beam and post-composite stresses on the transformed section need not be checked?

04-01-2011
Combined Loading

 

I am designing a beam subject to combined strong-axis bending, weak-axis bending, axial compression and torsion. The shear is very small. What design guidance is available on this subject?

04-01-2011
Stairs and Handrails Where can I find information on the design of stairways and handrails? 04-01-2011
Anchor Rods I am trying to find the specific code section that requires a minimum of four anchor rods in a column base plate, buy could not find anything in AISC 360. Where can I find this requirement? 04-01-2011
Identifying Old Bolts I am modifying a steel structur erected in 1968. The typical bolt assembles include square bolt heads and hex nuts. There are no bolt head markings. Is it reasonable to assume that these bolts are ASTM A307? 04-01-2011
Attaching Fill Plates The 13th Edition of AISC Steel Construction Manual Table 4-3 Case 1-C shows fill plates shop bolted to the upper shaft. Can fill plates be shop tack welded in lieu of bolting? 04-01-2011
Continuing Education Do you have any recommendations on classes or seminars that would be useful for me to update my skills from ASD to LRFD? 04-01-2011
Column Plumbness Requirements What is the maximum plumbness tolerance for an interior column? 04-01-2011
Width-Thickness Limits

 

When reviewing the width-thickness ratios of elements in a custom shape, I found the term "NA" under λp in ANSI/AISC 360-05 Table B4.1. Does that signify that for this case, the shape having this element may be considered compact until the width-thickness ratio of that element reaches the limit defined by λr?

03-01-2011
Shear Strength of Round HSS

The 1989 AISC ASD Specification, Section F4 specifies the allowable shear stress for round HSS as Fv = 0.4Fy. The 2005 AISC Specification, Section G6 specifies Vn = Fcr Ag /2 and Fcr ≤ 0.6Fy for round HSS. Considering that Ωv = 1.67, the 2005 Specification results in a maximum allowable stress, Fv = 0.18Fy. Why does the current steel code penalize the shear capacity of the round HSS by a factor of 2 from the previous code?

03-01-2011
Prying Action

 

When evaluating prying action using the 13th Edition AISC Steel Construction Manual, the equation for tc has changed from the previous editions. The equation in the 13th Edition uses Fu whereas the equation in the previous editions is based on Fy. Why did the 13th Edition change to base the calculation of tc on Fu?

03-01-2011
Snug-Tight TC Bolts Is it acceptable to use twist-off type tension control bolts (TC bolts) in a connection specified as snug tight? If TC bolts are used in a connection specified as snug-tight, are the procedures for pre-installation verification, installation (snug tight joints, then pretension by starting with most rigid part of joint) and inspection required? 03-01-2011
Production Lots for Bolts How many high-strength bolts comprise a typical lot? 03-01-2011
Plastic Design What does plastic design of steel mean? 03-01-2011
Connection Design What is the standard of practice for connection design by the Structural Engineer of Record (SER)? Is it sufficient for the SER to provide connection loads and require an engineer working for the fabricator to provide the connection design? Is the delegation of connection design appropriate for connections related to lateral force resisting systems? What about "special" seismic systems in moderate-high Seismic Design Categories? 03-01-2011
Static Loads on Bolts

Section 4 of the 2009 RCSC Specification allows snug-tight shear bearing joints with tension as long as the tension load is "static." What is the definition of a "static" load? Are wind or seismic loads considered to be static loads?

03-01-2011
Nuts and Washers for Anchor Rods What is the proper material specification for anchor rod nuts and washers? 02-01-2011
Conflicting Requirements Between Contract Documents The project specification calls for shop-primed steel, but the drawings say in the notes section to not prime the steel that is concealed. Which directive governs? 02-01-2011
Paint Under Bolt Heads I have a field issue where paint is on the outer plies (under the bolt head and under the washer) in new pretensioned joints in an existing structure. The inspector is rejecting the bolts because the paint exists and it is squeezing out under the bolt head and washer. Can the paint remain? Is it a problem that it is squeezing out? 02-01-2011
Finding an AISC Member Fabricator or Erector I'm trying to find an AISC member fabricator. Does AISC provide such a list? 02-01-2011
Plate Bending A debate is raging in our office. For years, the allowable bending stress in base plates was 0.75Fy. The 13th Edition AISC Steel Construction Manual appears to stipulate 0.60Fy for ASD design methodology. Is this an error? If not, can you explain why the change is necessary?
02-01-2011
Protected Zones in SMF During shop drawing review, we noticed that we had located a gravity beam such that it fell in the reduced beam section (RBS) protected zone in the moment frame beam. The connection is a single-plate shear connection with bolts to the gravity beam and fillet welds to the moment frame beam. Is this acceptable? 01-01-2011
Secondary Moments in Truss Design Is it permissible to analyze a truss for member forces with the center line distance of the members, but then design the web members with the actual length of the web members between the top and bottom chords, not the center line length, taking advantage of the connection restraint? 01-01-2011
Drain Holes for HSS A tower fabricated with HSS has leg splices that are made with bolted butt plates. There are no drainage or venting holes at the butt plates, but I observed water weeping out of a connection and there has been a history of corrosion in the HSS just above the butt plates. Are there any recommendations in AISC literature for sealing or venting such a condition? 01-01-2011
Steel Plate Thickness Is there an AISC table that gives available steel plate thicknesses by material grade? 01-01-2011
Firm Contact Where can I find specific tolerances for gaps created when I have a double angle clip bolted to a beam web? When the bolts are tightened, a gap still exists between the angle face and the beam web, though I do have “firm contact” as described by RCSC. 01-01-2011
Vent Hole for Galvanizing Steel fabrication for a steel pipe column dictates that a steel base plate and steel cap plate be shop welded to each end of the pipe column. The steel pipe column is to be hot-dip galvanized after the welding operations have been performed, and the hot-dip galvanizer is requiring vent holes. Is there any guidance you can give or any references you can cite that would be helpful? 01-01-2011
Heat Cambering I’m trying to put a 2-in. camber in a 54-ft-long ASTM A992 W27×114 beam using heat not exceeding 1,200 °F. It’s a rather large beam size, and I’m wondering what size rosebud to use, what pattern to heat, and any other info that might help me camber this beast. Any suggestions for where to apply heat (flange or web), a good geometric pattern to follow, etc.? 01-01-2011
End-loaded Bolted Joints Chapter J in the AISC Specification covers reduction factors for long bolted joints and discusses an end-loaded configuration. what is an end-loaded joint and when do these reduction factors apply?
12-01-2010
Sealing Fabrication Drawings A contract we are considering states that we are to have our fabrication drawings sealed by an engineer other than the EOR. To do this, we would have to hire an engineer to review them. What does AISC think of this requirement?  12-01-2010
Accounting for Existing Web Openings I am analyzing an existing structure for some new, increased floor loading. One of the impacted beams has two existing web openings with a clear distance between them less than recommended in AISC Steel Design Guide No. 2. How can I analyze this existing condition to account for any interaction that may occur between the two openings? 12-01-2010
Checking Combined Loads For a built-up "C" section in compression and major-axis bending, what criteria from Table B4.1 in the AISC Specification need to be used to check the flanges and webs for width-thickness ratios? 12-01-2010
Bolted Joints in Seismic Applications According to AISC 341-05, Part I, Section 7., all bolts shall be pretensioned high-strength bolts and shall meet the requirements for slip-critical faying surfaces in accordance with AISC 360-05 Specification Section J3.8. The last sentence of the first paragraph in Section 7.2 says that "the available shear strength of bolted joints using standard holes shall be calculated as that for bearing-type joints in accordance with Specification Sections J3.7 and J3.10..." Must we design the bolted connections to be slip-critical or is using J3.7 and J3.10 the appropriate design? 12-01-2010
Drilling Through a Weld We are fabricating members for steel buildings as per AWS D1.1. Please advise if drilling holes through a CJP butt weld is allowable. 12-01-2010
SteelFacts Someone showed me a copy of a document called Facts for Steel Buildings, Earthquakes and Seismic Design. Is this an AISC publication? How can I get it? 12-01-2010
Plates as Beams I'm used to the old ASD approach. How do I design a plate in strong-axis bending using the 2005 AISC Specification?
11-01-2010
Weld Metal Chioce in Seismic Applications Are my choices of electrode strength level more limited in high-seismic applications? Specifically, where could I choose to use E60 electrode for welding ASTM A36 material? 11-01-2010
Minimum Percentage for Composite Design The Commentary to the AISC Specification recommends that small levels of partial composite design (low percentages) should not be used. I like that it is left to my engineering judgment, but what guidance can you give me? 11-01-2010
Fire Protection for HSS

Can I fill an HSS or steel pipe with concrete to serve as fire protection?

11-01-2010
Sawing Inside Corners Can I use a band saw to cut an inside corner square or do I have to form a radius at the intersection of the sides of the cut?
11-01-2010
Tee Stem in Compression Due to Bending I'm comparing the 2005 AISC Specification (Chapter F, Section F9 as well as F6 and F11) and an "ancient" article that was published in the 1965 AISC Engineering Journal titled "One Engineer's Opinion," by William A. Milek. There are some differences between these references; does the 2005 information agree with the Milek paper? 11-01-2010
Balancing Welds for Snow Load? AISC Specification Section J1.8 requires weld balancing for unsymmetric members subjected to cyclic loading. Should the designer consider snow load as a cyclic load?
11-01-2010
Strength Increase for PJP Groove Welds? I know that you can take up to a 50% increase on the strength of fillet welds loaded other than longitudinally. I'm wondering whether this is also applicable to PJP welds. Does the reasoning behind the increase for the fillet weld also apply for PJP groove welds? 11-01-2010
Cracking in Composite Slabs Over Girders We have a building with large cracks over the girders. I know these are not structurally of concern, but why did they occur and what can I do to prevent them? 11-01-2010
Paint on Faying Surfaces Was there a recent changes in the AISC Specification that now allows paint on the faying surfaces of slip-critical joints? 11-01-2010
Finding an AISC Member Fabricator or Erector I'm trying to find an AISC member fabricator. Does AISC provide such a list? 11-01-2010
Axial Force and Rotational Ductility in Shear Connections I am designing a beam end connection for combined axial force and shear force where the axial force is large compare to shear force. A double angle connection is not workable, but I can use a shear end-plate connection detail with a thickness of 3/4 in. How can I do this when for flexibility the maximum thickness is limited to 5/8 in.? 11-01-2010
Beveled Transitions A ½-in. steel plate transitions from 10 in. wide to 18 in. wide over a length of 6 in. (a transition slope of 1.5 to 1 along each side of the plate). Is this transition acceptable? 10-01-2010
AESS Expectations We had architecturally exposed structural steel on a previous project, and a difference in paint appearance resulted at parts where welding or grinding occurred - the steel "looked" different. Are there guidelines or standards as to the finishes where grinding and/or welding has occurred, so that we can avoid the problems of differing expectations in the future? 10-01-2010
Reinforcing an Existing Beam I'm designing for additional load in an existing structure and plan to reinforce the floor framing. Do I have to account for the existing stresses in the unreinforced shapes as I design the reinforced cross-section? 10-01-2010
Windows Compatability I just upgraded to Windows 7 and am trying to use the CD companion that came with my 13th Edition AISC Manual. It doesn't seem to work. How can I make it run? 10-01-2010
Shear Stud Spacing in Composite Design For the design of composite flexural members, Section I3.2d(6) in the 2005 AISC Specification limits the maximum center-to-center spacing of shear connectors to eight times the total slab thickness or 36 in. Does “total slab thickness” refer to the total thickness of slab and deck (for composite steel deck) or the concrete thickness above the deck? 10-01-2010
Proprietary Connection? I have been told by a provider of one proprietary seismic moment connection that they have a patent on the WUF-W connection. Is this connection subject to a patent? 10-01-2010
Flexural Stregnth at Bolt Holes When using Equation F13-1 to determine the flexural strength, φMn, of a W-shape beam with holes in the flange, is Sx simply the value in the property tables from Part 1 of the AISC Manual or do I have to calculate it considering the holes that are present in the tension flange? 10-01-2010
Axial Loads in Shear Connections I would like to have clarifications from AISC regarding the use of double-angle connections and single-plate connections. Is it true that a double-angle connection provides little resistance to axial loads? If so, should I use a single-plate connection in this case? 10-01-2010
Concentrically Braced Frame Design

Our office practice for concentrically braced frames is to include a redundant moment frame within the braced bay. We typically ask for the following with respect to the lateral system connections:

  • Braced connections to be designed for the full tensile capacity of the brace (0.6AgFy)
  • That the beam-to-column connection to be designed for the full elastic capacity of the beam (0.66SxFy)
  • That the scheduled beam shear be increased by (0.66SxFy) ×2/(length of girder)

Can you please comment on this practice?

09-01-2010
R = 3 System We are designing a four-story building. Our understanding is that using an R of 3 with no special detailing is the minimum required by the code. Can you please confirm this for us? 09-01-2010
Fillet Welding of Studs I am reinforcing an existing composite steel beam with additional ¾-in. diameter steel shear studs. Typically, I specify that the shear stud welding must be done with a stud welding gun. On this small project, the contractor would prefer to use fillet welding instead. Is a fillet weld a recommended equivalent substitute for stud gun welding? If yes, is reference to AWS D1.1 adequate to ensure quality, or are there some other specific recommendations which should be specified? 09-01-2010
Unbalanced Loads on OCBF I have a project where we are using V-type Ordinary Concentrically Braced Frames. We are using Section 14.3 of AISC 341 for the design. Section 14.3 (1) discusses the requirements for the design of the beam in an OCBF. These requirements include a check of the unbalanced force that will occur due to a tension brace force of RyFyAg and a compression brace force of 0.3Pn. Does that requirement apply to OCBFs even if they meet the slenderness limits of Section 14.2? 09-01-2010
Washers for Anchor Rods What type of nuts and washers are required for ASTM F1554 anchor rods? Table 14-2 in the 13th Edition AISC Steel Construction Manual states that ASTM F844 washers may be used if the base plate is less than 1.25 in. thick, using a reduced hole size, with no limits on tension. Section 2.6 of AISC Steel Design Guide 1 says to use ASTM F844 washers only for compression with a reduced diameter hole. 09-01-2010
Continuity Plate Welds I recently designed a special moment frame using a prequailified RBS moment connection in accordance with AISC 358. The steel fabricator proposed to use an electroslag welding system for the moment frame continuity plates and submit a PQR for AWS D1.1 Electroslag Welding Process (ESW). Are the complete joint penetration groove welds of continuity plates to column flanges considered demand critical welds in accordance with AISC 341? If the welding of the continuity plates is not a demand critical weld, should ESW be permitted? If the weld of continuity plates is demand critical, what documents should be submitted by the steel fabricator to meet the criteria in accordance with AISC 341 Appendix W6?
09-01-2010
Structural Steel Utilization I am trying to determine amount of steel used in the various construction sectors. I have the overall number of tons for construction, but am interested in getting the information at the sector level (lodging, commercial, bridge, etc.). Does your organization track this? 09-01-2010
Tension Control Bolts Per AISC 358-05 Section 4.1, “Bolts shall be pretensioned high-strength bolts conforming to ASTM A325 or A490. Twist-off type tension control bolt assemblies of equivalent mechanical properties and chemical composition may be substituted for A325 or A490 fastener assemblies.” Do ASTM F1852 bolts have mechanical properties and chemical compositions comparable to A325 and A490 bolts?

08-01-2010
Beam-to-Column Orientation Does the AISC Specification require that moment-connected beams can only frame orthogonally to column flanges in moment frames? 08-01-2010
Moment Splice We have a W36 beam that requires a full moment splice. We're planning to use CJP groove welds at the top and bottom flanges with a joint designation of B-U2a. Is there a thickness limit when utilizing this detail due to the 15/16-in.-thick flanges? 08-01-2010
Historic Shape I am trying to find section properties of a floor beam from a building built in 1931. The designation for the beam is BI 30x137. I tried using the AISC shapes search and had no luck in finding that particular shape. Can you help me identify the shape? 08-01-2010
What is a snug-tightened connection? What is a snug-tightened connection? 08-01-2010
BF in Table B3.2 I cannot find the definition for the column labeled "BF" in Table B3.2. What is this tabulated value? 08-01-2010
1987 Moment Frame I have an existing moment frame building built in 1987. I need to know if this could be a special moment-frame building. What year was the special moment frame added to the code? 08-01-2010
Member Splices What are the AISC requirements for floor beams and columns splice locations? What is the minimum distance that can be used between member splices? 08-01-2010
Flexure of Z-Shape I would like to design a "Zee" shaped member.  A "Zee" has no axis of symmetry, though the principal axis does pass through the center of the vertical web. Therefore, I believe this should be treated as a solid symmetric shape, like a rectangular bar, bent about major axis. Is this appropriate? The Zee is not bent about its major principal axis. 08-01-2010
Flare Groove Weld Is a flare groove weld prequalified, and if so, how should the effective throat be calculated? 08-01-2010
Window Washing Davits Do you have any info on the design of davits for window washing equipment? I understand there is a required factor of safety of 4. How does this work when using the LRFD load combinations? 08-01-2010
Partially Engaged Nuts Is there any guidance or wisdom on quantifying the strength of a bolted connection when the nut is not fully engaged on the bolt?
08-01-2010
Torch Cutting We often must torch cut steel in the field to correct errors. Does torch cutting have an effect on the properties of steel? Is the type of steel a factor? 08-01-2010
CB Section I am working on a rehabilitation project. Per the drawings, the steel dates from the late 1920s. There are members identified on the drawings as 12" CB 120#. Would it be reasonable to consider this beam section to be similar to a W12 X 120? 08-01-2010
Restrained Beam What constitutes a “restrained beam” for fire-rating purposes? 07-01-2010
Double-Angle Compression Member The term rib in Equation E6-2 of the AISC 360-05 Specification is defined as “radius of gyration of individual component relative to its centroidal axis parallel to member axis of buckling.” Does this mean that rib will be equal to rx of individual angle for LLBB angles, while it is equal to ry of the individual angle for SLBB angles? 07-01-2010
Peak Stress Does the AISC Specification define acceptance criteria for steel when using finite-element modeling to assess the stress distribution? 07-01-2010
ASTM A307 Bolts Why are ASTM A307 bolts not recommended for slip critical connections? Can they be used in low demand slip-critical connections? 07-01-2010
Weld for Single-Plate Shear Connection On page 10-101 of the 13th edition AISC Steel Construction Manual, it is indicated that the leg size of the double fillet welds for a single-plate shear connection is required to be 5/8tp. Is there a check required for the support base metal to which the weld is applied? 07-01-2010
Flexure of Flat Plate How can I determine the strength of a flat plate bent about the strong axis? 07-01-2010
Historic Beam Designation I am investigating a building designed in 1967, with the plans dated February 1, 1968. The plans indicate some roof beams as being 18B35. I have a 6th edition AISC Manual dated 1967 and this shape is not indicated. Can you tell me where I might find the properties of this shape? 07-01-2010
Rivet Replacement When removal of existing corroded rivets is required, what is the appropriate nomenclature and tightening method for high strength bolts being used as a replacement? Should slip-critical or pretensioned connections be considered? What are the differences in installation and inspection methods between the slip-critical and pretensioned options? 07-01-2010
Table B4.1 - Compression or Flexure? Table B4.1, Case 1 description says “Flexure in flanges of rolled I-shaped sections and channels.” For bending about the major axis, the stress distribution on the top flange (for a simply supported beam subject to gravity loads) is uniform compression. Therefore, should Case 3 be used for the flange classification?
07-01-2010
Maximum Bolt Tension We are installing ASTM A325 galvanized bolts by the turn-of-nut method. We are following the preinstallation verification procedure using a tension calibration (Skidmore) unit and making sure that we meet the extra 5% over the 70% minimum tensile strength. I understand there is not an upper limit of the applied pretension on the bolt, with the upper limit in effect resulting in the bolt breaking, or threads stripped during installation. The question has come up if this is true, then why can’t we reuse a bolt (A325 galvanized) if it has been previously pretensioned by the turn-of-nut method. 07-01-2010
Block Shear Should block shear failure be considered for the connection elements loaded in compression? 07-01-2010
Built-Up Compression Member How do I determine the required strength in shear for an intermediate connector in a built-up double-angle compression member? 06-01-2010
Historic Shape I want to check the strength of a shape called out on the plans as a “12B19” The plans are dated 1971, but have many revisions and an as-built date of 1976. I’ve looked in AISC Design Guide 15, but I can’t find this particular shape.
06-01-2010
S-shapes in Grade 50 Are S-shapes available in both ASTM A36 and ASTM A992 material? Is one grade more common? 06-01-2010
Beam Framing Over Column What are the requirements for splicing a beam when it is framing over a column; rather than into the side of the column?
06-01-2010
Weld Electrodes I am doing work on a building constructed in 1963, for which many of the connections are welded. I understand that ASTM A36 steel was used on the project, and need to determine what electrode strength level was used. Did the AISC Specification of that era permit the use of E70 electrodes?
06-01-2010
Drift Index - H/400 Would you please explain the background of the origin of the commonly used criterion of a building drift index of H/400? 06-01-2010
Ry for Seismic Design The Ry factor is applied to the loads for which to design connections in many seismic applications. However, the Ry factor is not considered in the capacity of the connection material. Is this not an overly conservative approach?

06-01-2010
Second-Order Analysis for Braced Frames When accounting for second order effects using the B1-B2 method, Section C2.1b of the AISC Specification lists two options for Rm under Equation C2-6b. The first option lists Rm as 1.0 for braced-frame systems and the second option lists Rm as 0.85 for moment-frame systems. Why does the Specification include a condition for braced-frame systems when determining B2? My understanding is that braced-frame systems are not supposed to experience lateral translation and, henceforth, no lateral-translational moments or forces need be amplified.

06-01-2010
CJP Groove Weld for HSS When installing a backing bar on HSS that require an all-around complete-joint-penetration groove weld, should the backing bar be curved to follow the inside corner profile of the shape, or can four individual straight pieces be used? 06-01-2010
Open Parking Garages What is the maximum number of stories allowed for a steel parking garage structure with no fireproofing applied to the structural members? IBC 2006 is the referenced building code.
05-20-2010
Lateral Bracing for Cantilevers I have been told that bracing the tension flange of wide-flange cantilevers is more effective than bracing the compression flange in order to prevent lateral-torsional buckling. What is the rationale behind this statement?
05-20-2010
Minimum Composite Shear Connection When designing a composite beam, what is the significance of 25% composite action? I don’t find any requirement in the AISC Specification about 25% being a minimum, but some software design programs always assign this as a minimum requirement.
05-20-2010
One-Half of Uniform Load Capacity In the 9th edition AISC ASD Manual, it stated that if the design drawings did not indicate beam end reactions, the connections must be designed for one half the total uniform load capacity shown in the Allowable Uniform Load Tables. Does the AISC 13th edition Manual include this same statement?
05-20-2010
Historic Angle Shapes

I am analyzing steel roof trusses for a building constructed in 1928 with double angle webs and chords. I believe that the material was supplied from Bethlehem Steel. The top chord appears to be 2L5x3 with a thickness of either 9⁄16 or 5⁄8. Do you have any shape properties for this size angle? My manuals only go back as far as the 6th edition, and neither the AISC Iron and Steel Beams 1873 to 1952 nor AISC Design Guide 15 include properties of angle shapes.

 

I am also looking for information on structural steel and rivet properties for that timeframe.

05-20-2010
Bracing Connection Work Point I am studying the effect of moving the Work Point (WP) on a vertical brace connection. I have noticed that when moving the WP from column web to column flange, the gusset plate dimension is reduced. Is it a good practice to specify the WP at the column flange? This will cause an additional moment (force) in the column due to the eccentricity. Do we have to consider this additional moment for design? Which is the most economical solution? 04-20-2010
Minimum Fillet Weld Size Table J2.4 in the 2005 AISC Specification lists minimum sizes for fillet welds. Is this table limited to use with A992 steel only? 04-20-2010
Shape Surface Area Where can I find information to calculate the surface area of a 30-ft-long W24X68? 04-20-2010
Minimum Connection Depth Is there a minimum connection depth required for a beam framing to a supporting beam or column? 04-20-2010
Faying Surface Preparation The faying surfaces of a slip-critical connection have been prepared to meet the slip coefficient around the bolt locations only. Paint overspray has occurred on areas of the faying surface away from the bolt holes. Is this permitted? 04-20-2010
Beam Connection Location When using a double-angle shear connection for a beam-to-column (or beam-to-beam) connection is there anything wrong with installing the angles in the lower portion of the beam? Is there a limit to the location of the angle placement relative to the beam depth?
04-20-2010
Vibration Problem I am experiencing vibration problems in a steel-framed floor. I see in Design Guide 11 that the fundamental natural frequency is related to the deflection. If I camber the steel beam, the deflection would be less. In the calculations for frequency, what deflection should I use? Is camber going to help with vibration? 04-20-2010
Instanteneous Center of Rotation Is there a formula for determining coefficient C for eccentrically loaded bolt groups? Where can I find it? 04-20-2010
Prequalified Connection Is there a prequalified moment connection with a welded flange and bolted web available in ANSI/AISC 358-05? FEMA 350 includes a Welded Unreinforced Flange – Bolted Web (WUF-B) Connection. I do not see this connection included in ANSI/AISC 358-05 or Supplement No. 1.
04-20-2010
AISC Seismic Design Manual Table 4.2 Section 9.3a of the AISC Seismic Provisions references AISC Specification Section J10.6 for the panel-zone shear yielding strength, which has Ω = 1.5 for ASD. Table 4.2 in the AISC Seismic Design Manual provides a design aid for Special Moment Frames (SMF) that includes panel-zone shear parameters. However, the table only lists f = 1.0, which is for LRFD. Are these tables only good for LRFD or can they be used for both LRFD and ASD? 04-20-2010
HSS Dimensional Tolerances What is the tolerance for outside dimensions of an ASTM A500 HSS7½×3½×3⁄16? 04-20-2010
Specification Section J10 Limit States Section J10 of the 2005 AISC Specification specifies several parameters to resist local failures. However, after reading descriptions before each limit state, I still find it difficult to determine which limit states apply to a given load. For instance, it is hard to picture what “a pair of compressive single-concentrated forces or the compressive components in a pair of double-concentrated forces, applied at both flanges of a member at the same  location” looks like. I would be grateful if you could please provide clarification of the descriptions for the limit states in Section J10. 03-11-2010
Increasing Composite Beam Strength

Is it possible to add strength to an existing composite beam by adding mechanical anchors (expansion bolts) from below? The idea is to drill through the flange and install the anchor through the flange and into the concrete slab above.

03-11-2010
External Load on a Pretensioned Bolt What is the behavior of a pretensioned bolt subjected to an external tension load? Will the pretension force reduce the tension strength of bolt? 03-11-2010
Connection Filler Plates What criteria are used to design filler plates in connections?
03-11-2010
Shear on Box Shapes

I am working on the design of box sections in shear. According to Chapter G of the AISC Specification, the coefficient Kv should be taken equal to 5 for box sections. The commentary indicates that this is because the elements are restrained. Is Kv = 5 appropriate for each axis of a box shape?

03-11-2010
Maximum Fillet Weld Size

Section J2.2b of the AISC Specification states that the maximum size of a fillet weld permitted along edges for material 1/4 in. or more in thickness, shall not be greater than the thickness of the material minus 116 in., unless the weld is specifically designated on the drawings to be built out to obtain full throat thickness. Does this mean that the weld size can be larger than the thickness of the thicker part?

03-11-2010
Bolted Connections for High-Seismic Applications

Is it required to use slip-critical connections for high-seismic applications?

03-11-2010
Winter Construction What is the lowest air temperature in which we can weld? Can we avoid preheating? 03-11-2010
Torsional Constant of T-shape

I am trying to calculate the flexural-torsional buckling strength of a non-standard T-shape per Specification Section E4. How are the torsional constant and warping constant calculated?

03-11-2010
Preheat for Welding

Table 3.1 of AWS D1.1 lists the required preheat for welding based on the category of the base metal. When welding steels of different categories together, which category requirement do we follow?

03-11-2010
Member Stiffness Reductions The direct analysis method per the 2005 AISC Specification (Appendix 7 and its Commentary) requires the consideration of reduced axial/flexural stiffness and notional loads during analysis and design of any structure. How appropriate would it be to use this reduced stiffness and notional loads for serviceability conditions such as deflections/drift calculation? Is it necessary to run a separate analysis without any geometrical property reductions for applicable members to calculate the deflections? 02-01-2010
ASTM A490 Bolts Subject to Tension Section 4.2 of the RCSC Specification states that “pretensioned joints are required…for joints with ASTM A490 bolts that are subject to tension or combined shear and tension, with or without fatigue.” This is reiterated in footnote “c” of RCSC Specification Table 4.1. Can you please explain the reason for this provision in a connection without fatigue? Why are ASTM A325 bolts not required to be pretensioned under tension or shear and tension, unless subjected to fatigue loading? 02-01-2010
Delayed Construction We have a project that was shut down during construction due to the economy. It is ready to restart now. When the project was shut down, the structural steel was erected but no decking installed. Now the steel is rusted. Are there any industry standards related to dealing with rust on steel? 02-01-2010
Sx or Zx? I have recently been using the ASD option in the 2005 AISC Specification to calculate combined stress using square HS and am confused with the use of Zx for flexural design, versus the use of Sx in the older ASD specification. Is the use of Zx limited to LRFD load combinations? 02-01-2010
HSS Properties Why are the thicknesses of HSS different in the 9th edition AISC ASD Manual compared to the 13th edition AISC Manual? 02-01-2010
Bolt Entering Direction Using a single-plate shear connection with short-slotted holes, and with one washer; does it matter which direction the bolt passes through the hole, as long as the washer is on the slotted side?
02-01-2010
Stiffened Extended Single-Plate Shear Connection Based on my review of research papers (Muir and Hewitt 2009, Ghorbanpoor and Sherman 2003) and extended configuration design methodology provided in the 13th edition AISC Manual, it appears that test results indicate behavior is much different when an extended single pate is stiffened compared to a similar unstiffened connection. The Manual does not provide a stiffened extended single-plate connection design methodology. Is there such a design procedure? 02-01-2010
Column Tier Height Are there any specification requirements or OSHA regulations that limit the maximum length of columns that one can use as a single field section for steel erection? What is normal practice for location of column splices in multi-story construction? 02-01-2010
Tension Control Bolts What is the difference between an F1852 TC Bolt and an A325 TC Bolt? Which of these is superior in strength or more economical? 02-01-2010
Vertical Bracing Connection When using the general case of the uniform force method with a moment produced from Vb(α-α), where does this moment get resolved? Does the column take it or does the beam take it? 02-01-2010
Extended End-Plate Stiffener The stiffeners in the extended end-plate moment connection as shown in Design Guide 4 are detailed at a 30° angle. How is this angle selected? In many gusset connections the angles are set at 30°. What is the significance of the angle?
01-06-2010
Anchor Rod Tensile Strength When calculating the strength of a threaded anchor rod per Section J of the AISC Specification, is the strength based on failure in the threads or in the gross area?
01-06-2010
Tension Calibrator Is a torque wrench considered a tension calibrator?
01-06-2010
Flexure of an Unequal Leg Angle For bending of an unequal-leg angle about the major principal axis, Mn is found with Equation F10-2 or F10-3 using the Me value in Equation F10-6. What should be used to find the minor principal axis bending of an unequal-leg angle?
01-06-2010
Torsional and Flexural-Torsional Buckling Could you help me understand when torsional or flexural-torsional buckling needs to be checked for a column?  
01-06-2010
Minimum Lateral Load I'm working on the design of a large maintenance platform, and the construction is relatively light. The project is in one of the lowest seismic risk areas and the platform will be inside a building, so the lateral loads prescribed by ASCE 7-05 are quite low—no wind and the seismic loads are simply 1% of the seismic weight, W, of the platform. Isn’t there more that might need to be considered here?
01-06-2010
Field Cutting of Steel Is flame cutting or air-carbon arc cutting the preferred process for cutting steel in the field?
01-06-2010
C-Coefficients Why are the Coefficients C for Eccentrically Loaded Weld Groups listed in Table 8-4 of the 13th edition Manual for some weld groups different than those listed in the tables of the 9th edition Manual for the same weld groups?
01-06-2010
Temperature at Time of Erection Are the erection tolerances in the Code of Standard Practice, or COSP, to be considered based on a specific ambient temperature, say 70 °F? For example, if a column stack is within plumb tolerance at 70 °F and out of tolerance at 30 °F (due to contraction of the building), is this OK? 01-06-2010
Plug Welds for Doubler Plates Section 9.3b in the 2005 AISC Seismic Provisions indicates that a doubler plate can be restrained by plug welds to prevent buckling. Section J2.3b of the 2005 AISC Specification defines the diameter of the holes for plug welds. However, no requirement for the depth of the weld is stipulated. Since such plug welds are only there to prevent buckling of the doubler plate, what is the minimum depth of weld required to achieve this?
01-06-2010
Bearing Length - Nreq In Table 10-6 in the 13th edition AISC Steel Construction Manual, to what does the first column "Required Bearing Length Nreq" refer? What is this measured from? 01-06-2010
Reduction in Area for Bolt Holes Table 9-1 in the 13th edition AISC Steel Construction Manual lists Reduction in Area for Holes. For a standard hole, why is the reduced area calculated assuming that the hole diameter is equal to dbolt + 1∕8 in.? Shouldn't this be dbolt + 1∕16 in.? Table J3.3 shows that the standard holes are typically 1∕16 in. oversize compared to bolt diameter.
01-06-2010
Reuse of Bolts We are working on a bolted through plate girder bridge that is currently being dismantled and transported to be used at another location. The bridge was in service for roughly 5-7 years prior to dismantling. Can the bolts that have been removed for dismantling be reused? Would I need to look for certain types of damage before approving the reuse and/or any other items of concern that I should be aware of? 12-10-2009
Slip-Critical Connections When using slip-critical connections, is it common to exclude the threads from the shear plane, or does thread location matter since the design assumption is not based on load transfer by shear/bearing? 12-10-2009
UT of CJP Welds Can UT be done on a complete-joint-penetration groove weld if the thickness of the steel is less than 5∕16 in.? If not, can a visual inspection be performed, or can another type of NDT be done? 12-10-2009
K-Brace for OCBF System I am designing an ordinary concentrically braced frame using a K-brace. AISC 341 Section 14.3 states that the column for K-type bracing is to be designed for the unbalanced loading. Is that accurate? Designing the column for the forces specified in Section 14.3 seems very high. Is there any alternative, such as designing the column for the amplified seismic load? 12-10-2009
Beam Bracing I am designing a one-story open-framed (no decking) building and must provide lateral stability bracing of the beams. Working with the 2005 AISC Specification, Appendix 6.3 addresses the force required for both nodal and relative bracing in beams. I have a situation where nodal bracing is desired for architectural reasons. I am aware that this bracing force must be delivered to a rigid support at bracing ends. Does the bracing force act in an additive manner? For example, I have four parallel beams restrained from rotation via nodal bracing; does the bracing have to be proportioned to resist four times the force computed from Eq. A-6-7? 12-10-2009
Channel Columns What Section of the AISC Specification covers channel columns?    12-10-2009
Bolt Hole Alternatives for Fit-Up In many instances bolt holes are required to be enlarged at the site because the size of bolt holes does not accommodate allowable deviations in the erection of the structure. Which of the following alternatives do you recommend to address this issue?
     1. Provide oversized holes during fabrication.
     2. Limit the allowable dimensional deviations
         during erection.
     3. Enlarge holes in the field for only joints where
         the misfit occurs.

12-10-2009
Use of Overstregnth Factor The AISC Seismic Design Manual (Page 3-43) does not use the overstrength factor in the design of the column in that example. However, other references design both columns and beams considering the overstrength factor. Which is correct?
12-10-2009
Number of Washers What is the maximum number of washers allowed on a bolt under the nut? What if it is for an anchor rod embedded in concrete for a column base?
12-10-2009
Calculation of Weights

If I purchase steel plate as a raw material for a project and the customer is quoted a price per pound for the product, is he required to pay for the remaining skeleton of the steel plate if it is not useable in the project? Example: I purchase sheets that are 4 ft by 10 ft and burn two pieces that are 44 in. by 58 in. from each piece. I have a skeleton left over that is not useable. Does the customer pay for 40 sq. ft of material or only the weight of the two pieces?

11-02-2009
Document Discrepancies

In case of a discrepancy between plans and specifications for

buildings, which one governs?

11-02-2009
Pipe Design Section F8 of the 2005 AISC Specification addresses flexural

design of round HSS. Can Section F8 be used for the flexural

design of steel pipe?

11-02-2009
Allowable Stresses in 1967

What was the allowable stress for A36 steel, fabricated in 1967?

11-02-2009
Large Bolted Connections

We currently have a job with 1¼-in. diameter bolts

(approximately 50 per connection) with 2 plies of 3-in.-thick

steel. The hole size specified is 15
16 in. Needless to say all

of the holes do not exactly line up perfect. What are the

dimensional tolerances for the locations of holes in large

bolted connections?

11-02-2009
High-Seismic Column Splice

Section 8.4a(2) of AISC 341 requires the available strength

for each flange (LRFD) is noted as 0.5RyFyAf . Is the term Af

the area of one flange or the total area of the two flanges?

11-02-2009
Steel Properties at Elevated Temperatures

What is the reasoning between the different material ratios

vs. temperature (i.e. Modulus of Elasticity vs. Temperature

& Yield Strength vs. Temperature) given in the AISC 13th

ed. Table A-4.2.1 versus the graphs (Figures 3.2 and 3.3)

published in ASCE, The Structural Design of Air and Gas Ductsfor Power Stations and Industrial Boiler Applications? When

comparing the ratios for yield strength, AISC gives a reduction

beginning at 800 °F (i.e. 0.94), and the ASCE publication

shows almost a linear reduction in yield strength beginning at

100 °F. Conversely, when comparing the ratios for Modulus of

Elasticity, the AISC ratios drop much faster than what is given

by ASCE. I would appreciate your help in understanding the

discrepancies between these reported values.

11-02-2009
U-Factor in 1989 Column Tables How was the factor U that was tabulated in the 9th edition

ASD Manual column tables calculated? This factor is used to

determine an equivalent axial load for beam-columns.

11-02-2009
High-Seismic Column Splice Location

AISC 341 requires column splices to be no closer than

4 ft, 0 in. from beam to column connection. What is the basis

of this requirement? Can the splices be closer than 4 ft, 0 in.

if complete-joint-penetration groove welds are used?

11-02-2009
Fillers

In Section J5 of the AISC Specification, one of the alternatives is that "The fillers shall be secured with enough bolts to uniformly distribute the total force in the connected element over the combined cross section of the connected element and the fillers." What does this mean? What are the design criteria to compute the number of bearing bolts in the filler plate outside of the primary connection?

10-05-2009
SCBF X-Brace

Is a one-story X-braced frame permitted for a Special Concentrically Braced Frame?

10-02-2009
Evaluation of Existing Structures

Is it permissible to use the ASD provisions of the 2005 AISC Specification to analyze an existing structure designed using the Specification of the 8th edition era? We’re currently involved in the renovation of a structure designed and built in 1987/1988, and will need to slightly increase the load on several floor beams. Using the 8th edition steel manual several beams will be overstressed, from 8% to 13%. If the ASD provisions of the 13th edition are used, then these same beams are not overstressed.

10-02-2009
Bolt Hole Sizes

If a fabricator has detailed 7⁄8-in. diameter holes for 3/4-in. diameter bolts can this still be considered a bearing-type connection? The loads are small—less than 10 kips per connection. It is for a pipe rack. Also, can you use slip-critical connections with galvanized steel?

10-02-2009
Class A and Class B Coatings

How are Class A and B coatings qualified for slip-critical connections?

10-02-2009
Second-Order Analysis

I attended a seminar on second-order analysis, where I heard that the loads must be multiplied by the alpha value of 1.6 when using ASD for the member design. Do the analysis results get divided by the same value of 1.6 for member design, or are they calculated? I have been using the analysis results as calculated, and not dividing by 1.6.

10-02-2009
Panel Zone Shear Strength 1. Based on AISC 341-05 Section 9.3a, panel zone shear strength is calculated per Specification Section J10.6. In J10.6, there are two sets of equations; one assumes panel zone is elastic, the other considers the inelastic overstrength. My question is when to use the inelastic equation.

2. After comparing panel zone shear demand with the column web shear capacity, we may need to provide a doubler plate. To calculate the required thickness of the doubler plate based on the additional strength required, what is the length of doubler plate that can be used? Do you suggest counting the full column depth or using the actual length of the doubler plate, which is (Column depth – 2 ´ column flange thickness)?

10-02-2009
Conventional Configuration Single-Plate Shear Connections

Design limitations for conventional configuration single-plate shear connections imply that long-slotted holes are not permitted. Why are these not permitted? Also, for the extended configuration, are long-slotted holes permitted? The limitations for the extended configuration refer to AISC Specification Section J3.2 requirements, which imply that long-slotted holes may be used. If these are permitted, would they need to be slip critical?

10-02-2009
Nut Type for Anchor Rods

We have a project with anchor rods specified as ASTM F1554 Grade 105. ASTM A194 Grade 2H nuts were substituted for ASTM A563 Grade DH nuts. Are the A194 nuts considered equivalent in this application.

10-02-2009
HSS Steel Availability

What yield strengths are typically available for HSS2x2x1/4 and HSS3x3x1/4?

09-01-2009
Installation Torque

What is the normal torque for ASTM A325 and A490 bolts used in non-slip-critical connections?

09-01-2009
Axial Strength of Channels The AISC Manual tables for columns do not include channels. How does one determine the axial strength of such shapes? 09-01-2009
Thermal Cutting

If an oxy-acetylene torch is used to flame cut the edge of a new steel beam or plate, what impact does that have on the steel? Is the strength of the steel affected? Is the edge distance or bolt hole spacing affected by this process?

09-01-2009
Mill Cut or Square Cut? What is the difference between mill cut and square cut? 09-01-2009
Puddle Welds We have a project where we have asked the structural engineer of record to change a 5/8-in. puddle welded connection to a connection using powder-driven fasteners. He has indicated it is acceptable to use powder-driven fasteners as long as they meet or exceed the uplift resistance of the assembly when using welds. Can such fasteners provide the uplift resistance of a 5/8-in. puddle weld? 09-01-2009
Anchor Rods

For base plate anchor rod design, why is ASTM F1554 the preferred specification? Is ASTM A449 suitable? What is the reference for torque values of base plate anchor rods?

09-01-2009
Increase Fillet Weld Size for Gap? On braced-frame connections we specify a weld size from a slotted HSS to a gusset plate. The HSS are generally slotted about 1/8-in. larger than the thickness of the gusset plate, so theoretically 1/16-in. of weld is lost on each side. Do I need to show the increased weld size on the design drawings? 09-01-2009
Delayed Steel Erection A delivery on a job has been delayed by eight months. Because the steel is to be fireproofed, it is not painted and has rusted. The owner has expressed concerns about the steel and the effects of the rust. Would this affect the steel as far as strength? 09-01-2009
Prequalified Weld Details In Table 8-2, the prequalified weld for a single-bevel corner joint groove weld(4), on pages 8-43 and 8-44 of the 13th edition AISC Steel Construction Manual, one diagram shows the bevel in the horizontal plate and no bevel in the vertical plate. Wouldn’t this be a problem of lamellar tearing? If not, why isn’t it? Are there some load conditions in which this geometry would be acceptable? 09-01-2009
Bolt Spacing for Prying Action

All of the equations for prying action include the symbol p (the spacing between bolt rows). However, if we have only one bolt row in a connection, there is no spacing between rows. If p = 0, it seems to invalidate equations related to calculation of prying action. Are there alternative equations when p = 0?

08-01-2009
Shear Center

How do I calculate the shear center of a rolled shape?

08-01-2009
Section Modulus Relative to Angle Leg Toe in Compression How does one calculate Sc for Section F.3 in AISC 360-05? What does “elastic section modulus to the toe in compression relative to the axis of bending” mean? What if the entire  angle leg is in compression? When one has an equal-leg angle with no lateral-torsional restraint bent about a geometric axis, Sc = 0.8S, what if the angle does not have equal legs? 08-01-2009
Edge Distances for Single-Plate Shear Connections

In the October 2006 issue of Modern Steel Construction, a range for the support line to bolt line (a-distance) is given as 2½ in. to 3½ in. for single-plate shear connections. Does this necessarily mean a = 2 would not work properly? If the connection were a through plate passing through a 6-in. column could a = 2 in. be used?

08-01-2009
Use of the Overstrength Factor Ω0 How do I use the system overstrength factor Ω0. Is it used as a multiplier on the load side or the strength side of the equation? 08-01-2009
Evaluating Existing Bracing Connections

We are modifying an existing structure that has wide-flange vertical bracing members that were designed using the 7th edition AISC Manual. The connections used friction-type bolted joints with oversize holes in web plate connections to the gusset on both edges. The AISC Specification requirements applicable to the 7th Edition did not require friction bolts to be checked for bearing, as is required today.

In general, the connections work for the slip-critical portion of the calculation, but many fail the bearing strength check. In order to prevent the connections from slipping into bearing, I’ve considered adding welds to the joint. Do you have any suggestions as to how to evaluate these connections?

08-01-2009
Beam Bracing

What constitutes a lateral brace for a beam? Does properly attached roof deck act as a continuous brace for the compression flange?

08-01-2009
Width-Thickness Limits for S-Shape with Cap-Channel

I am designing a monorail beam, which is an S-shape with a cap channel. I’m having trouble determining the limiting width-thickness ratios for strong-axis bending per Table B4.1 of the AISC 13th Edition Manual. For strong-axis bending I am checking three components:

  • channel web between two fillet welds per Table B4.1 Case 12
  • channel web between channel top flange and fillet weld as stiffened elements per Table B4.1 Case 12
  • S-shape beam flange as unstiffened element per Table B4.1 Case 2

Am I doing this correctly?

07-01-2009
Column Buckling

I am reviewing an existing built-up column. The section is singly symmetric (symmetrical about the weak axis). The column is subject to combined axial force and flexure about the strong axis. Does the web element for uniform loading fall under Table B4.1, Case 14 of the 2005 AISC Specification? While checking the limit states of flexural-torsional and torsional buckling, I am using Equation E4-5 for singly symmetric members. Is this the correct equation when the axis of symmetry is the weak axis?

07-01-2009
Countersunk Bolts I am trying to find the preferred material specification for countersunk high-strength bolts. Building codes are virtually silent on the subject of countersunk bolts for structural applications, yet there are occasions where, because of interference, a regular hex-head A325 or A490 bolt will not work and a countersunk bolt is needed. Is this addressed anywhere in the AISC Steel Construction Manual? 07-01-2009
Prequalified and Qualified High-Seismic Moment Connections

Table 2-2 of FEMA 350 allows bolted flange plate (BFP) moment connections as prequalified moment connections for OMF and SMF in high-seismic applications. ANSI/AISC 358 makes no mention of this type of connection. Is the use of BFP moment connections still permissible in high-seismic applications?

07-01-2009
HSS Seismic Connections Prequalified seismic moment connections only include W-shape beams. Can HSS beams be used for IMF? How can the seismic requirements for this type of connection be met? 07-01-2009
Design Using the 2005 Specification

I have been using the ASD 9th Edition Manual. I am trying to learn how to use the 13th Edition. I am having a hard time finding the allowable stresses for different members, such as tension members, compression members, and members in flexure just to name a few. Is the bending stress for flexural members still 0.66Fy and 0.6Fy, depending on my unbraced length? Where are these located?

07-01-2009
Rivet Head/Shaft Diameter Relationship

We are doing a project involving inspections of truss bridges, most of which were built in the early 1900s and are connected together with gusset plates attached with rivets. We have not been able to locate any literature relating the diameter of the head of the rivets to the shaft diameter. Is there any reference material that denotes the relationship of the diameter of the head to the actual shaft diameter?

07-01-2009
Single-Plate Shear Connections to HSS

Is there, or will there be, an update of the 1997 Hollow Structural Sections Connections Manual? I am particularly interested in finding information pertaining to single-plate shear connections to HSS.

07-01-2009
Shear Lag Could you please explain the term “shear lag?” 07-01-2009
Galvanized Slip-Critical Connections

Section 7.2 of the AISC Seismic Provisions indicates that bolted joints must have Class A faying surfaces. Section 3.2.2(c) of the RCSC Specification for Structural Joints using ASTM A325 or A490 Bolts indicates that galvanized faying surfaces are designated as Class C. Does this mean that we are unable to use steel members that are galvanized in the vicinity of the connections, for high-seismic applications?

06-01-2009
Floor Plate

A note at the bottom of the Floor Plate Bending Capacity table on p. 2-145 in the 9th edition ASD Manual indicates that the loads are based on an extreme fiber stress of 16 ksi and simple-span bending. The 16 ksi allowable stress seems to be very conservative, assuming that the plates would likely have a yield strength of not less than that for A36 steel. What is the 16 ksi allowable based on?

06-01-2009
Rotational Restraint at Support

AISC Specification Section J10.7 requires full-depth stiffeners at the “unframed ends of beams and girders.” What does this mean? Would an example be a girder bearing on a column with no beam framing into it at the column?

06-01-2009
Bolting for High-Seismic Applications Are slip-critical connections required for seismic connections? And if so, for what seismic design category are they necessary? 06-01-2009
Nut Engagement We have a situation where bolts have been installed too short (the bolt tip is below the top of nut) in a steel-to-steel joint. Is there a way to assess the reduced capacity based on the percentage of thread engaged? 06-01-2009
Hole Sizes for Galvanized Bolts An engineer designed the structural steel connections using standard holes in all plys for ASTM A325-N bolts such that the connections need not consider slip-critical limit states. The steel is to be hot-dip galvanized. The galvanizer is requesting that the standard holes be increased by an additional tolerance of 116 in. to account for the coating thickness. I’m hesitant to grant approval for a hole size that would require slip-critical limit states to dictate connection design. If the hole size is increased, would the connection design need to be reevaluated for slip-critical conditions? 06-01-2009
Stiffeners for an EBF Link Commentary Section C15.3 in the AISC Seismic Provisions indicates that for EBF links that are less than 25 in. deep, the stiffener need be on one side only. What is the interpretation of “need be?” Does it mean “must be” or “may be?” Many practicing engineers are interpreting this as “may be.” When EBFs were tested, what was the protocol? Have they tested intermediate stiffeners on one side only? Is there any detrimental effect on the inenelastic rotation of link beam due to increased rigidity of link beam when stiffeners are used on both sides? 06-01-2009
Tensile Strength of Anchor Rods Where does one find values for futa (specified tensile strength of anchor steel) as used in Appendix D of ACI 318? Also, is the fya (specified yield strength of anchor steel) equal to Fnt given in Table J3.2 of the 2005 AISC Specification? 06-01-2009
Punching Shear

Why is there a requirement to check punching shear on the wall of an HSS column with a single-plate shear connection, but no similar check when connecting to the web of a W-Shape?

06-01-2009
Shear Lag Factor Table D3.1 of the 2005 AISC Specification gives shear lag factors (U) for various cases of tension connections. I have a situation like Case 4, where two plates are transmitting tension through longitudinal welds only. The U-factors are based upon the length of the weld (l) and the width of the plate (w).  No U-factors are tabulated for the condition where l < w.  The plate I have is 4 in. wide and the weld can only be 2 in. long. What U-factor is appropriate for this situation? 06-01-2009
Direction of Bend Where can I find information on bending of plates with respect to the direction of the rolling? 05-01-2009
Moment Connections In AISC Design Guide No. 13, the author chose to neglect story shear in all 13 design examples. Is it always conservative to neglect story shear? The author does not address this in the Guide, yet the effects are not included in the examples. 05-01-2009
ASTM A449 Threaded Rods The project specifications call out ASTM A449 threaded rods with nuts on each end for connecting two members. The plans specify to pretension these rods as opposed to just snug-tight. The RCSC Specification defines specific tensioning and inspection requirements for ASTM A325 and A490 bolts. Are there any codes or written recommendations on what is considered pretensioned on ASTM A449 rods (i.e., pretension load) and also for inspection requirements? 05-01-2009
CJP Weld for HSS Is it possible to get a prequalified CJP groove weld on an HSS without a backing bar? 05-01-2009
W/D Ratios Where are W/D values for W-shape beams published? I don’t know where to look for these, but was told that AISC could provide them. 05-01-2009
Elevated Temperature Service Where can I find properties of steel at high temperature? 05-01-2009
Lifting Plate Can Part 15 of the 13th Edition Manual, covering bracket plates, be used as a procedure for the design of lifting plates? Instead of the load applied downward, the load is applied upward.  05-01-2009
Weak-Axis Flexure of Plates Section F6 of the 2005 AISC Specification does not mention plates bending about the weak axis. Can we use the same F6 equations for weak-axis bending of plates, or do we revert back to the 0.75Fy? Also, on the Basic Design Values card, the weak axis bending says to use 0.9FySy for ASD applications. Where does the 0.9 come from, and do we apply the 1.67 ASD omega factor to that? 05-01-2009
Camber Measurement We have a project with cambered beams. The contractor is requiring a survey of the camber after erection as a measure of compliance with the specified camber. The AISC Code of Standard Practice indicates that this is not a correct procedure. What is the proper procedure for measuring camber? 05-01-2009
Non-Destructive Testing of CJP Welds Is there an industry standard defining the amount of NDT that should be done on full-penetration welds of moment connections? 05-01-2009
Eccentrically Loaded Weld Groups The table values for the eccentrically loaded weld groups published in the 13th Edition AISC Steel Construction Manual result in much greater strength than the comparable table published in the 9th edition ASD Manual. What is the reason for this increase? 05-01-2009
Thickness Limitation for Single-Plate Shear Connection Why is there a thickness limitation of tdb/2 + 1/16” for single-plate shear connections? 05-01-2009
Cb for HSS Beams?

Are Cb values permitted in the design of HSS beams? Are Cb values greater than 2.3 permitted, in any case, in ASD? Is there an instance where Cb = 4.7 for an unbraced square HSS cantilever with a concentrated load at the end is justifiable?

04-01-2009
ASTM F1554 vs. ASTM A449 Anchor Rods

I am trying to better understand when to specify F1554 vs. A449 for anchor rods. Table 2-5 in the Manual does not indicate a preferred material specification for high-strength anchor rod.  Is there a reason for this?  Is there a preferred material for anchor rods?

04-01-2009
Reuse of ASTM A325 Bolts ASTM A325 bolts have been specified to connect lifting lugs to column cap plates. After the columns are loaded onto trucks, the lifting lugs need to be removed due to shipping height restrictions. Can these bolts be reused at the job site to lift the columns again, if the bolts are just snug-tight previously? 04-01-2009
Brace Stiffness I have been questioned about calculations for a stability bracing member per AISC 360-05 Appendix 6, Equations A-6-7 and A-6-8. I can calculate the required brace stiffness, but how do I calculate the actual brace stiffness provided? 04-01-2009
Fire Rating of Concrete-Filled HSS Where can I locate fire rating information for concrete-filled HSS? 04-01-2009
Welding or Bolting? Does welding steel decrease the strength as opposed to bolting? What are the benefits/pros to bolting versus welding? 04-01-2009
Design Guide 11—Walking Speeds I could not find information in AISC Design Guide 11 whether to assume "fast," "moderate," or "slow" walking speed criterion when designing for sensitive equipment.  The remainder of the criteria for sensitive equipment vibration calculations seems rather straightforward. My problem is that I can easily achieve good results for walking speeds of 75 steps per minute (moderate) or less, but it’s nearly impossible to achieve this for fast walking speeds of 100 steps per minute. The examples indicate that fast walking speeds are generally conservative, but I could use additional direction. The moderate criterion for 75 steps per minute seems reasonable to me, but I have no reference. Do you know of any additional sources of information that provide guidance as to where fast, moderate, and slow walking speeds should be used? 04-01-2009
Column Leveling Plate For column bases, what is the relationship between the base plate size and leveling plate size? 04-01-2009
Round HSS or Pipe? What is the difference between round HSS and pipe shapes? 04-01-2009
Extended Single-Plate Shear Connection I have a question pertaining to Example IIA-19 (Extended Single-Plate Connection­—Beam-to-Column Web) from the Design Examples CD that is issued with the 13th edition AISC Steel Construction Manual. Why is e = 10.5 in. used for calculating shear strength of the bolt group, while a = 9 in. is used to calculate the required strength of the plate? Should we use a = 10.5 in. in this case? 04-01-2009
Single-Angle Connection Tables I do not understand the reason behind one of the notes for Table 10-11 in the 13th edition Manual. I’m unclear why a “smaller half web will result in these values being conservative.” 03-01-2009
Referenced Design Standards

I have several design spreadsheets that are written around the ASD 9th edition Manual, and I was wondering if any of the new IBC or ASCE codes reference a certain manual, like the new 13th edition, or if the older edition is still acceptable to use for design purposes.

03-01-2009
Brace Stiffness

I have been questioned about calculations for a stability bracing member per AISC 360-05 Appendix 6, Equations A-6-7 and A-6-8. I can calculate the required brace stiffness, but how do I calculate the actual brace stiffness provided?

03-01-2009
ASTM F1554 versus ASTM A449 Anchor Rods

I am trying to better understand when to specify F1554 vs. A449 for anchor rods. Table 2-5 in the Manual does not indicate a preferred material specification for high-strength anchor rods. Is there a reason for this? Is there a preferred material for anchor rods?

03-01-2009
Calculating Cb

I’m wondering how to analyze a W-shape beam at an inflection point in terms of the Cb value. I understand that the inflection point cannot be considered a braced point, so when you calculate the Cb value some moment values will be negative and some moment values will be positive.  The Specification says that Cb is permitted to conservatively be taken as 1.0. Is this a requirement? If not, then which one is true in order to get a Cb value?

Case A:

Use the absolute values for Ma, Mb, Mc and Mmax across the entire unbraced section. (This would include positive and negative moments.)

 

Case B:

Use the absolute values for Ma, Mb, Mc and Mmax from one brace point to the inflection point. (This includes only negative or positive moments.)

03-01-2009
The Richards Factor

Design examples 3.10 and 3.11 in the Seismic Design Manual, take the stress for the welds as the greater of fpeak or 1.25favg. Is this design practice specified somewhere in the Manual or some other publication?

03-01-2009
Cb for HSS Beams?

Are Cb values permitted in the design of HSS beams? Are Cb values greater than 2.3 permitted, in any case, in ASD? Is there an instance where Cb = 4.7 for an unbraced square HSS cantilever with a concentrated load at the end is justifiable?

03-01-2009
Shear Connectors Used in Multi-Story Construction

I have heard that rigid-frame beams in multi-story construction should not have welded studs applied to make them composite beams. Can you please give me a reference where this is stated?

03-01-2009
Double-Angle Connection Capacity

Table 10-1 Page 10-23 of the Steel Construction Manual for All-Bolted Double-Angle Connections lists the available ASD capacity at 32.6 kips for 1/4-in.-thick A325N bolts. However, my calculation for angle shear rupture shows a value of 33.7 kips. If the hole diameter is changed from 13/16-in. to 7/8-in., the value is 32.6 kips, per your table. Is a 7/8-in. hole size assumed for a 3/4-in.-diameter bolt, and if so, where is this stated? Otherwise, how is the 32.6 kip value obtained?

03-01-2009
Basic Design Value Cards

AISC “Basic Design Values 1” (laminate card, copyright 2005) shows bending about weak axis = 0.9FySy (ASD). Please verify the coefficient is 0.9 and not 0.75.

03-01-2009
Extended Single-Plate Shear Connections

The last paragraph on 10-103 of the 13th edition AISC Manual states that this design procedure permits the column to be designed for an axial force without eccentricity. Does this also apply to girders used as the supporting member? In other words, if this design procedure is followed for a beam-to-girder connection, does the girder need to be designed for an eccentric load from the extended single-plate beam connection?

02-01-2009
Compactness Criteria for Angles

Could you help me understand the connotation of the "Compactness Criteria for Angles Table" shown on page 1-47 of the 13th edition Manual?

02-01-2009
IMF and OMF Connections

Is an IMF connection required to be stronger than an OMF connection?

02-01-2009
kc Factor?

Table B5.1 in the 9th edition Manual incorporates a kc factor for defining the Compact/Non-Compact behavior of flanges for I-shape welded beams in flexure. Why is this factor used and is there any update to this provision?

02-01-2009
Bending Bolts?

Is it okay to heat and bend a structural bolt that was placed in concrete in the wrong place? The contractor placed the bolts anywhere from 1.5” to 3.5” out of alignment, then heated the bolts and bent them like a snake and told me that they would be okay. I do not feel comfortable with this assurance. I did find one article that says to look in the 9th edition of the AISC Manual on page 4-4, but I do not understand what this means. Could you explain this in more detail?

02-01-2009
Restrained or Unrestrained Rating?

My understanding is that we are able to consider all beams in a building as restrained for fire protection requirements, regardless of whether they are part of an interior bay or an end bay. Can you provide me with insight into the accuracy of this statement?

02-01-2009
Camber Measurement

Section 6.4.4 of the AISC Code of Standard Practice includes the following sentence:

“For the purpose of inspection, camber shall be measured in the Fabricator’s shop in the unstressed condition.”

What does the term “unstressed” imply? Does the “unstressed condition” include or exclude the dead weight of the beam?

02-01-2009
Iyc of Compression Flange

Section H1.1 of the AISC Specification states, “...Iyc is the moment of inertia about the y-axis referred to the compression flange.” Could you please expand on the definition of Iyc?

02-01-2009
What is rts ?

What does the rts listed in Table 1-1 of the AISC Steel Construction Manual represent? How is this function calculated?

02-01-2009
ASD Flexural Capacity in the 2005 Specification

When designing a channel for flexure, I am somewhat confused regarding the allowable/available moments that are published in the 13th edition Manual. 

I came to the conclusion that all of the channels now have an allowable bending stress of 0.75Fy as opposed to the older 0.66Fy.  Am I correct in assuming that this is what the new allowable stress is for channel beams?  Can I also get an explanation as to why the sudden increase in allowable stress has been made to be 0.75Fy?

01-01-2009
Steel Types

When were A36 and A6 steels in general use for building construction?

01-01-2009
Knee-Braced Frame

Is a frame with a kick brace considered a special braced frame?

01-01-2009
Dynamic Analysis

What type of structure requires a dynamic analysis?

01-01-2009
Skewed Single-Plate Connection

Per the discussion on page 10-151 of the 13th edition AISC Steel Construction Manual, the maximum beam-web thickness is a function of the maximum root opening and the angle of skew in a skewed single-plate connection. Why?

01-01-2009
Prequalified 4ES Connection Table 6.1 of AISC 358-05, Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications, lists 10¾ in. as the only width allowed for the end plate of a 4ES connection. Is this correct that the identical max. and min. values are the same? 01-01-2009
Prequalified Connection Standards I am attempting to design my first SMF using a prequalified connection from AISC 358-05. The only prequalified connections listed are the RBS and the unstiffened and stiffened end plates. Does this document supersede FEMA 350, which lists such connections as the WUF-W as valid for SMF framing systems? Do the FEMA 350 connections not listed in AISC 358-05 lack the proper testing for the AISC 358-05 prequalification?

I have also heard that some proprietary connections have been submitted for prequalification. Is there a location where I can find a list of the connections that have been approved since the publication of AISC 358-05?

01-01-2009
Doubler or Stiffener Plate?

My question pertains to the design of column web reinforcement for directly welded flange moment connections.

When local yielding of the column web occurs, is it acceptable to use web doubler plates in lieu of a pair of transverse stiffeners to provide for the additional material necessary to exceed the design strength requirements? The reason I ask is because all of the AISC design examples, and also the software that we use for connection design, always provide for transverse stiffeners instead of doubler plates when local yielding of the column web is an issue. 

01-01-2009
Thermally Cut Holes

On one of my projects, the fabricator is asking to use thermally cut bolt holes. He is citing Section M2.5 of AISC 13th edition Steel Construction Manual. That section states that thermally cut holes shall be permitted with a surface roughness not exceeding 1,000 min.  

What are the advantages and disadvantages of thermally cut holes?

How does roughness of surface come into the picture for cutting the holes?

01-01-2009
ASTM A500 Rounds

A steel subcontractor on our project says he has a U.S.-made A500 Grade B round HSS. I believe that this material only comes in square and rectangular shapes. Can you confirm the availability of these shapes?

12-01-2008
A325SC Bolts?

How are ASTM A325SC bolts designed and installed? In past projects we typically used A325N and we are now using A325SC. Do both of these types of bolts need to be checked for bearing?

12-01-2008
Connecting a Cambered Truss

We have a 120-ft-long, 12-ft-high truss made up of wide-flange beams for the upper and lower chords. The truss will be fabricated with a 5-in. camber. At the worse loading condition, the truss will still be 1 in. above flat. How is the connection made from the member end to the column? Will the fabricator detail the member so the bolt holes in the cambered member are vertical and in line to the connection plate or angles holes, or do they offset the bolt holes? If the truss is to rotate downward 4 in., should oversized holes be used in both the plate and member to allow for rotation?

12-01-2008
Welding Anchor Rods to Rebar

Can anchor rods be welded to the reinforcing bars to be embedded in the slab to be cast? I cannot find anything in the codes in reference to this subject. Can you help?

12-01-2008
Base Metal/Fastener Compatibility

Where can I find information pertaining to compatibility when using different types of base metal and fasteners in a connection?

12-01-2008
Beam "Sweep"

Where can I find information for the allowable amount of beam sweep in an erected building?

12-01-2008
Double-Concentrated Forces

Section J10 of the AISC Specification addresses double-concentrated forces. Could you please explain the meaning, or give an example of a double-concentrated force as it applies to this section? 

12-01-2008
Effective Length of Vertical Braces We are having a discussion in our office about the design of a compression diagonal angle in an "X" braced frame. Some engineers believe the unbraced length for compression design is reduced based on the fact the other member in the brace is in tension and will prevent the compression angle from buckling. Is this a valid assumption? Is there any information that would support this design assumption? 11-01-2008
Specifying End Reactions Non-composite beam end shear connections for wide-flange beams to columns are typically specified based on 50% of the total uniform load table capacity of the beam. These requirements are given to the steel detailer to develop/detail the connections. Is there a similar table for HSS beam end connection design; or a way to specify end connections for the steel detailer to detail, etc.? The AISC 13th edition Steel Construction Manual has Table 3-12 “available flexural strength, kip-ft” for rectangular HSS. Can end beam reactions be tabulated from this table? 11-01-2008
Beam/Column Connection with Axial Compression I have a beam connected to a column flange using clip angles. The beam has quite a big compression load. Do I need to check column flange bending or anything else? The AISC Manual states that a flange local bending check is required for tensile forces only, but one of my coworkers told me I’d need to check column flange bending for the connection. Could you give me some advice? 11-01-2008
Single Angle in Flexure The 2005 AISC Specification has new single-angle bending equations. I have also looked at the design example provided by AISC on CD.  When do you use geometric bending without lateral support as opposed to principal-axis bending? It seems to me that if there is no lateral support, you should use principal-axis bending, but that is not how AISC arranges the section. In the example, the single angle supporting a uniform load is only supported at the ends. This would allow the angle to deflect laterally and vertically, which would indicate bending about the principal axis. Should I use the geometric axis for design or should I use the principal axis for design? 11-01-2008
Extended Single-Plate Shear Connections In the procedure for the extended configuration of the single-plate shear connection, the bolts are designed for the eccentricity of the connection, and it says that the column does not need to be designed for a bending moment for the eccentricity. The first question I have is, according to these assumptions, the weld to the column will be only in shear. Why then is it taken as 58*tp, instead of designing it for the shear at the support? This produces some huge welds for the plates that are necessary for bending in some cases. The second question is, how is the rotation of a simple shear connection achieved when the eccentricity is in the bolts and the weld is only in shear? I am thinking of a 7- or 8-row connection where it is obvious that no rotation will be allowed at the weld. 11-01-2008
Bracing for Cantilever Beams Must braces be added to the bottom flange (compression) of cantilevered steel beams? After reading the 1999 LRFD Specification, Section C4a, it seems like I should brace the tension flange of the cantilevered portion instead. Is this correct? 11-01-2008
Slip-Critical Bolts? TC bolts were used in a bolted splice for W8s.  The beams have corrugated deck on top of them that will receive 6 to 12 in. of concrete, and the assembly forms a ramp for foot traffic. The engineer wants us to remove the TC bolts and replace them with slip-critical bolts. I am under the impression that slip-critical is a connection and not a type of bolt.  Is this a valid point from the inspector? Do we have to replace the bolts, or is the use of TC bolts acceptable for this condition? 10-01-2008
Charpy V-Notch Requirements AISC 341-05 Section 6.3 specifies a minimum Charpy V-notch value for structural steel in the SLRS with flanges 1½ in. and thicker. Commentary Section C6.3, however, states that steel with flanges exceeding 2 in. is subject to the same requirement. I assume the Standard is correct and the Commentary is incorrect? Please verify. 10-01-2008
Flare-Bevel Groove Welds I am detailing an HSS-to-HSS weld and have a flare-bevel groove weld, which is shown in the latest edition of the AISC Manual (page 8-61). The effective weld size (E) is shown as 5/8T1. In Table J2.2 of the Specification, the effective weld size of a flare-bevel groove weld is given as 5/8R for the GMAW process. Which one is correct? 10-01-2008
Lessons Learned from the AISC Seminar

In discussions with several engineers, I am hearing it said that the 13th edition is forcing engineers to abandon the ASD method, and to conform to the LRFD method.

Two things that I remember from this year’s AISC seminar on the 13th edition are:

  • The LRFD strength is equal to 1.5 times the ASD strength, and
  • either approach can be used, and the designer just has to remain consistent with the chosen method during the calculation.
Unfortunately, I am not knowledgeable enough with the 13th edition to convince them that ASD is still permitted. Can you explain this a little more convincingly?
10-01-2008
Welding in the K-Area? Section 3.9.6 of Design Guide 21 discusses the potential effect of welding in the k-area for column doubler and stiffener (continuity) plates. Does this same concern apply to welding of beam stiffener plates in the k-area? 10-01-2008
Turning the Bolt Head A contractor told us that applying the pretensioning by turning the head of an ASTM A325 bolt does not produce as good a result as turning the nut.  I never heard of that. Is there any merit in his contention? 10-01-2008
Block Shear Strength

I need some help understanding the Block Shear Equation (J4-5) in the 2005 Specification. For block shear strength:

 

Rn = 0.6Fu Anv + Ubs Fu Ant ≤ 0.6Fy Agv + Ubs Fu Ant

 

The left side of the equation must be less than or equal to the right side. For ASTM A36 steel, Fu = 58 ksi and Fy = 36 ksi, which means that 0.6Fu will always be greater than 0.6Fy. The net area in shear, Anv, is smaller than the gross area in shear, Agv, but not enough to overcome the difference between 0.6Fu and 0.6Fy.

 

As an example, consider a 3/8-in. plate with 1.5-in. edge distance and 6 rows of 3/4-in. bolts in STD holes at 3-in. spacing.

 

Agv   = ( 3/8-in.)(5 x 3-in. + 1.5-in.)

= 6.19 in.2

 

Anv   = Agv – hole area deduction

= 6.19 in.2 – ( 3/8-in.)[5.5 holes x (13/16-in. + 1/16-in.)]

= 4.39 in.2

 

From this, 0.6Fu Anv = 153 kips, and 0.6Fy Agv = 134. That is, this shows 0.6Fu Anv > 0.6Fy Agv.

 

So where did I go wrong? When will 0.6Fu Anv ever be less than 0.6Fy Agv?

10-01-2008
KL/r Modified for Single-Angle A question and answer on this subject appeared in the January 2008 Steel Interchange (reprinted below). LeRoy Lutz, a member of the AISC Specification Task Committee covering the design of members, was kind enough to provide the following supplementary discussion pertaining to the design of single-angles: Single-Leg Angles per E5. 09-01-2008
Flexural Capacity of Channels Why are the maximum strong and weak axis bending stress values for channels limited to 0.6Fy and 0.66Fy respectively? The weak axis limit seems particularly conservative given that compact, doubly symmetric sections and plate have a 0.75Fy limit. 09-01-2008
Fillet Weld Strength I am familiar with the method of determining the fillet weld strength using the ASD load approach, but I am having difficulty determining this strength when using the LRFD load approach.For a simple ASD fillet weld (load at 90° to the fillet) the magic number is 0.9 kips/in. of weld, which is based upon 0.3*70 ksi electrode per 16th of weld.I noticed in the 13th Edition Manual that the weld strength is increased when the load is at 90° to the fillet. I always thought a weld had the same strength whether a load was in the same direction, along the weld or perpendicular to the weld. The 13th Edition Manual seems to indicate that it is 50% stronger when loaded at 90°. 09-01-2008
Anchor Rod Push-Out

Section 2.9.1 of Design Guide 1 contains the following statement:“When designing anchor rods using setting nuts and washers, it is important to remember these rods are also loaded in compression and their strength should be checked for push-out at the bottom of the footing.”

How does one go about calculating the push-out of the anchor through the bottom of the footing?

09-01-2008
Fillet Weld for Single-Plate Shear Connection My question has to do with single-plate connections to supports. Chapter 10 of the 13th Edition (page 10-101) states “the weld between the single plate and the support should be sized as 5⁄8 tp, which will develop the strength of the plate.” Is this a minimum or maximum limit? Should we design the required weld size needed, and then compare to this value? This question stems from the 9th Edition Commentary on single-plate connections (page 4-53) where it stated the weld size need not exceed 0.75t. Are these (2) requirements discussing the same subject? It seems that the 9th Edition is trying to make sure we have more web thickness than weld, but the 13th Edition Commentary is stating to use an exact amount of weld. Can you shed light on this? 09-01-2008
Lp for Non-Compact Shapes I have a question regarding a value in Table 3-2 of the 13th Edition Manual pertaining to the W21x48 (page 3-17). The listed value for Lp is 6.09 ft, whereas when I calculate the value myself (for a 50 ksi beam) I get 5.86 ft. Can you please review this value and let me know if this is an error? 09-01-2008
ASD or LRFD?

What is the AISC position on use of LRFD or ASD design? It appears that the equations in the 2005 AISC Specification can be utilized in the LRFD or ASD method by multiplying by the Ω factor or dividing by the φ factor. Is this correct, because people are telling me one cannot use the ASD method anymore? What about the IBC—do you know if they specifically require the use of LRFD?

09-01-2008
Matching Filler Metals to Base Metals When combining materials from AWS D1.1 Groups I and II, where can I find information on prequalified welding details? 08-01-2008
Edge Distance Requirements Does AISC require the minimum edge distance to be maintained on unloaded edges of bolt holes? For 30-plus years I’ve understood the minimum edge distance to be needed to prevent tear-out of edges that are loaded.  08-01-2008
Joint Type in Seismic Applications

In the Specification for Structural Joints Using ASTM A325 or A490 Bolts, in the last paragraph of the Commentary to Section 4.1, it states that “snug-tightened installation is not permitted for these fasteners in applications involving non-static loading” for bolt assemblies in direct tension.

We have drag struts with relatively small seismic loads, compared to the gravity loads. In such cases, there will be no “net” non-static loading whatsoever. As such, is a snug-tightened joint acceptable?

08-01-2008
Effect of Flange Slenderness on Beam Capacity My question concerns weak-axis bending of I-shaped members, Section F6. For the limit state of flange local buckling, Equation F6-2 is for sections with noncompact flanges and Equation F6-3 is for sections with slender flanges. Would it be conservative to just check Equation F6-3 for both? You list the shapes that do not have compact flanges in the manual. Do you have a list of shapes that have slender flanges? 08-01-2008
Seismic Shear Loads on Components With regard to SCBF in AISC 341, does Section 8.5b(1) mean that the horizontal component of the required tensile strength of the bracing connections, as determined by Sections 13.3a and 13.3b, must be used to size the shear key at column base plates that attach to foundations? 08-01-2008
Fit-Up Problems For a bolted double-angle connection between a beam and column within the seismic frame, when there is a 3/16-in. gap present between the outstanding legs of the angle and the column face, can we go ahead and bolt them together, hopefully closing the gap in the process—or should shims be placed before bolting? The connection angles are 3/4 in. thick and the bolts are 1-in.-diameter A490 bolts, pretensioned. 08-01-2008
Beam-Column Design When designing roof beams to function as drag struts that support axial loads from wind and seismic loads, how does one determine their design unbraced length? 08-01-2008
W8 Columns I would like to know if there is a restriction on the use of W8 columns in two-story commercial buildings per today’s building codes. The area is highly seismic. Each story height is 11 ft. 08-01-2008
Support Condition for Torsion What is defined as a “simple beam” for torsion? For example, are the equations in Example 1A of the companion CD to the 13th Edition Steel Construction Manual applicable to a beam with shear tab connections only, or do the flanges have to be restrained laterally at the end connections for these equations to be applicable? 08-01-2008
Selecting Seismic LFRS What determines the design choice between special concentrically braced frames and ordinary concentrically braced frames for the seismic force resisting system? ASCE 7-02 Table 9.5.2.2 states that the building height limitation for a special concentrically braced frame is 160 ft and the height limitation for an ordinary concentrically braced frame is 35 ft. What other factors determine the type of system? 08-01-2008
Effects of High Temperature Where can I find mechanical properties of structural steel at elevated temperatures? 08-01-2008
Stiffeners Required? When a moment connection is required on either side of a W-shape column, typically stiffeners are welded to the column web and flanges to transmit the beam flange forces through the column web. What is required when the column is a tube section and the beams are typical W-sections? Is any stiffening of the tube required? 07-01-2008
Standard Bolt Hole Size The AISC standard hole is 1∕16 in. larger than the bolt. I am designing bearing-type connections, but the steel fabricator is asking to provide holes larger than the standard holes for constructability. He is proposing to use holes that are 1∕8 in. larger than the bolt diameter, rather than 1∕16 in. Since this is a bearing-type connection rather than a slip-critical connection, I am not quite sure if this will affect the shear strength of the bolt for the connections. I know that the oversized holes should not be used for a bearing-type connection. However, the holes that the fabricator is proposing are between the standard and oversized. Could you give your opinion on this issue? 07-01-2008
Fillet Weld/Base Metal Thickness Correlation On page 13-27 of the 3rd edition LRFD manual, the minimum gusset plate thickness is calculated as tmin = 6.19D/Fu. The explanation is that gusset plate thickness is checked against weld size required for strength. In the 2nd edition LRFD manual, this equation is 5.16D/Fy (page 11-37 of Volume II, Connections). Can you please explain where the 6.19 is coming from? 07-01-2008
Slip-Critical Faying Surfaces I have noticed a discrepancy between the 2005 AISC specification and the RCSC Specification for Structural Joints Using A325 or A490 Bolts. The Class A coefficient is 0.35 in the AISC specification and 0.33 in the RCSC specification. Which coefficient is correct? 07-01-2008
V and Inverted-V Lateral Systems For chevron braced frames, the AISC Seismic Provisions state that we must design the beam for the resultant force caused by one of the braces buckling in compression and the other yielding in tension. The beam design is generally an uncoupled design problem. However, it becomes coupled if using two-story X-braces or zipper columns (see Fig C-1-13.3 in 2005 Seismic Provisions).    It would seem to me that the design should proceed on a story-by-story basis. That is, you would assume that the brace buckling/yielding occurs in one story and then design the zipper/opposing V for the resultant. Is that true? Or do you assume that the buckling/yielding occurs in multiple stories simultaneously? 07-01-2008
Column Splice Locations We are designing a nine-story building, which makes it logical to have two column splices, with three segments of three-story columns. However, in some AISC articles on economy in steel design, it is noted that “three-floor columns are to be avoided due to erection difficulties.” I found one article that suggests that erection typically occurs in two-story increments, and mentions the resulting problem of another long column dangling in the air if you use three-story columns. Is that the reason for the recommendation for either two- or four-story columns? With nine stories, we would end up with either 4-4-1 or 2-2-2-3. What are your thoughts? 07-01-2008
Direct Analysis Method Section 7.3 of Appendix 7 of the 2005 AISC specification states, “For ASD, the second-order analysis shall be carried out under 1.6 times the ASD load combinations and the results shall be divided by 1.6 to obtain the required strength.” Can you explain what this means? How do you incorporate this when using a computer program? 07-01-2008
Singly Symmetric Shapes

I have questions pertaining to Equations (C-F4-3) and (C-F4-4) shown in the Commentary to the 2005 AISC specification. What is the significance of αβx? What is the Fyr being used in the calculation of Lr? It is not defined.

07-01-2008
Turn-of-Nut Method

One of the recommended methods for installing bolts is the turn-of-nut method. The RCSC specification indicates that turn-of-bolt can be used if it is impractical to use the turn-of-nut method. How is the turn-of-bolt method different than the turn-of-nut method?

06-01-2008
Web Slenderness Ratio

Please confirm that h/tw ratio in footnote [a] of Table B4.1 (page 16.1-18 in the 13th edition manual) is the height of the web (i.e., clear distance between flanges) over the web thickness (see Case 2). We just want to verify that this ratio should be used, and not the b/t ratio of the flange.

06-01-2008
Comparison of Historic Shapes to Current Shapes

Does AISC provide any written material that compares the properties of old designated beams sizes, such as 16B26, to the current properties of a standard wide-flange (W shape)?

06-01-2008
Two-Story X-Bracing

I have a question on AISC 341 Section 14.3 regarding the unbalanced earthquake load acting on beam due to a buckled brace. We have a two-story OCBF where the V and inverted V braces meet at the second floor beams, forming a two-story X. The braces above and below the beam tend to balance each other (opposing forces). We are not clear if this requirement applies to this configuration. Does it apply only for Chevron-type configurations where the braces are located only below (inverted V configuration) or only above (V configuration)?

06-01-2008
Restrained or Unrestrained?

I am looking into the difference between “restrained” and “unrestrained” ratings for a steel-framed building. I have read the AISC engineering FAQs at www.aisc.org/faq, as well as the ASTM E119 and other literature, and all seem to point me in the direction that a standard steel building is classified as restrained.

    That said, we have had some discussion in our office that the restrained classification depends on the continuity of the structure. While I understand that continuous beams spanning over more than two supports will offer more rotational restraint that a simple shear connection, are the simple shear connections enough? Could a single-bay structure (with simple shear connections) be considered restrained? Are there any special restraint requirements for perimeter beams? If one part of the structure becomes unrestrained, does that mean that the entire structure must be classified as unrestrained?

06-01-2008
Shape Group Numbers

In preparation for an ICC bolting examination, one of our technicians found a question asking what structural group number a W14×426 member was. We found the answer in the AISC 9th edition ASC manual, but not in the 13th edition Steel Construction Manual. The ICC test now references the newer manual, and I was wondering if this table is included in it, or if it was left out intentionally?

06-01-2008
Delamination

We have encountered a situation where it appears that the carbon steel framing is delaminating, for lack of a better word. I have searched the Internet, but have not found many articles or data concerning this specific issue. Do you know of the correct terminology to use when the steel is separating in layers?

06-01-2008
Seismic Design for Horizontal Bracing Members

Do horizontal bracing members need to meet the requirements of Sections 13.2a and 13.2d of the 2005 AISC seismic provisions? It is not clear whether “bracing” applies to horizontal and vertical, or just vertical bracing.

06-01-2008
Specifying Reactions

What is the best way to specify simple shear connection reactions on the design drawings? On a non-composite steel framing system, we typically specify that “All beam connections shall develop the full uniform load capacity the member can carry...” The connection designer can then easily obtain a design load using the AISC allowable load tables. This method also ensures that the connection will not be the limiting design element. We have found this procedure to be an efficient method to specify design loads for typical framing.

    We would like to specify composite beam connection design loads in a similar manner. Is there a design aid available that would allow a connection designer to easily obtain the maximum uniform load for a composite beam?

    Do you have any other recommendations to efficiently provide simple shear connection design loads for composite framing?

06-01-2008
CB Series Beams Can you tell me the Fy and allowable stress that the CB series beams were designed for? 05-01-2008
Drilled-in Anchors When drilling for post-installed anchors in a concrete support for a steel beam, we encountered embedded reinforcing bars at the intended anchor locations. Is it advisable to cut through the rebar to accomplish anchor installation? 05-01-2008
Historic Section Properties I need to know the section properties of several shapes. I seem to be having difficulty because these seem to be old shapes. The sections are W14×311, W14×287, W14×246, and  W14×167. Can you help? 05-01-2008
Use of Grade 65 Steel Do you have a safety factor on the material, particularly on grade 65 steel, when you design according to ASD or LRFD? 05-01-2008
Pretension for TC Bolts When installing a tension controlled bolt (TC bolt), what pretension force should be induced in the bolt? 05-01-2008
Remediation for Deflection Problems I have seen many articles on how to reinforce an existing beam for strength, but none appear to go over deflection issues. Do you know of a resource that discusses how to analyze and determine appropriate reinforcing for an existing steel beam that has adequate strength but fails deflection criteria? 05-01-2008
One-third Stress Increase I have reviewed the AISC specification (AISC 360-05) and the AISC seismic provisions (AISC 341-05) for allowable stress increases with wind or seismic loads. I cannot find any references in these documents. Is there something I am missing, or are no stress increases allowed for wind or seismic loads?  05-01-2008
Stiffness Reduction Factors Why are the stiffness reduction factors in Table 4-21 of the 13th edition manual different than those in Table 4-1 of the LRFD 3rd edition manual? 05-01-2008
Single-Angle with Single-Bolt End Connection I am trying to use the AISC 13th edition manual to design a single-angle member for a compression brace with one bolt through a leg at each end.  This is a commonly used brace in the automotive industry for bracing conveyors and falling parts guards.  There is usually very little load that must be resisted, and historically angles such as L2½×2½×¼ have been used. These braces often have a Klrz that is greater than 200. I have looked at Section E5, but this requires two bolts at each end and limits Kl/r to 200. 05-01-2008
R = 3.0 in SDC D? In the AISC seismic provisions (AISC 341-05) there is a discussion for R = 3. As I read the discussion, I understand that if I have a structure in seismic design category D and R = 3, I still have to follow the provisions of AISC 341-05. What I would like to do is reduce the R factor, which increases the base shear, and then not follow the stringent requirements of AISC 341-05. 05-01-2008
David T. Ricker

It is with great sadness we report that David T. Ricker died on February 22, 2008 in Payson, Ariz. Dave was a longtime member of the AISC Committee on Manuals and Textbooks and a frequent contributor of articles, papers, and answers to questions about steel design and construction, including in this feature, Steel Interchange. He authored several professional articles that are still provided with great frequency in response to questions received by AISC. To honor the memory of this friend of the steel industry, Dave is the focus of this month’s Steel Interchange.

04-01-2008
Welding to Existing Members

It is a general rule that welding on an existing structural member is not permitted unless provisions are made to unload the member first (for example, if the member is being reinforced) and that the weld must not degrade the properties of the material. Is there a written reference that discusses this from both a code perspective and a practical approach?

04-01-2008
Lifting Beams

A typical lifting beam or strongback in the materials handling, crane, and rigging industry takes the form of either a horizontal or wide-flange beam, with padeyes top and bottom at both ends. The lifting wire rope bridle with two legs at about a 45° angle attaches to the top padeyes, and the supported weight attaches to the bottom padeyes.

    The wire rope bridle induces both compression and bending moment in the lifting beam. Again, there is no lateral support. What analysis would be used to solve for the safe lifting capacity of this form of lifting beam?

04-01-2008
Double-Angle Connections

How is a welded double-angle connection designed when the [wider] double angles are connected to the [narrower] flange of the column and welded on the back side of the double angles? This may be necessary when the column flange is short.

04-01-2008
Crane Rail Tolerances

How does the AISC Code of Standard Practice address the possible tolerance for vertical and horizontal alignment of a crane rail in a mill-type building?

04-01-2008
Rivet Removal

During bridge repair, rivets are often removed and replaced with ASTM A325 or A490 bolts. Is there a standard procedure written for the removal of rivets and resizing of the fastener hole? If the base metal is going to be reused, I would think that it would be very important not to damage or overheat the base metal around the fastener hole. This base metal could be a multiple build-up of two-, three- or four-plys. Should these rivets be removed with a machine or cutting torch? Rivets are pressed in when newly installed; should they be pressed out? What preparation should be taken to remove and rework a riveted connection?

04-01-2008
Historic Lattice Columns In the December 2007 Steel Interchange, there was a question pertaining to lattice columns. Ted Galambos, Ph.D., was kind enough to add his expertise on the subject: 03-01-2008
Flexural Strength Comparisons

The elastic moment strength of a beam listed in Table 3-6 of the 13th edition AISC manual seems low as compared to the 9th edition ASD manual and the 3rd edition LRFD manual. As an example, for a W16×77 with Fy = 50 ksi:

    13th edition,Table 3-6, pp. 3-60

       ASD: Mr/Ω = 234 kip-ft

       LRFD: ΦMr = 352 kip-ft

    9th edition ASD, pp. 2-11

       ASD: MR = 369 kip-ft

    3rd edition LRFD, Table 5-4, pp. 5-62

       LRFD: ΦMr = 405 kip-ft

Could you tell me why there are such differences?

03-01-2008
Multiple Cranes in Runway I am designing a building with three top-running bridge cranes. The cranes all run in the one aisle and are separated from each other by 20 in. The runway beams will be a simple span. Would I need to design the runway beam and building frame for vertical and horizontal loads from all three cranes being adjacent to each other and being fully loaded at the same time? The MBMA design manual says to design for the single crane producing the most unfavorable effect and for the loads of two adjacent cranes producing the most severe effect. Is this due to a low probability of the cranes all being fully loaded at the same time? 03-01-2008
Evaluation of an Existing Structure If a building was built in the early 1900s, can we utilize LRFD design to check the existing steel beams? 03-01-2008
RBS Moment Connections
  1. When the cuts for an RBS are determined by a, b, and c (identified in AISC 358-05, Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications), does this cut section need to develop the maximum moment as required for that member?
  2. Bracing as per AISC 358-05, Section 5.3.1 ,(7) is required for RBS beams. If there is a steel decking floor system with shear studs on top of the RBS beam, can this flooring system be considered an adequate form of bracing for this beam?
03-01-2008
Backing Bar Thickness Is there an industry standard for the size (thickness) of backing bars used in moment connections? 03-01-2008
Flexure of Single Angles Is there an accepted procedure for the design of a steel angle in bending supporting a uniform load? The compression leg is upward and unrestrained, while the load is seated on the other (horizontal) leg. 03-01-2008
Edge Distance for Anchor-Rod Holes in Base Plates I am trying to find a table or equation that gives the minimum/maximum bolt spacing required for the base plate, as well as the minimum edge distances. Any suggestions of where to look in the AISC manual or elsewhere would be much appreciated. 03-01-2008
Nut Tightening on Anchor Rods

When considering nut installation on a threaded anchor rod, how is the pretension specified on the drawings? The desire is to prohibit loosening of the nut under load reversal. I see the recommendations for anchor-rod nut installation on pages 14-10 and 14-11 of the 13th edition AISC manual; however, the minimum bolt pretension force shown in Table J3.1 does not seem to apply. Is the required tensile force still 0.7Fu of the anchor rod?

02-01-2008
Combined Forces

The title of Section H1.3 of the 2005 AISC specification is “Doubly Symmetric Members in Single Axis Flexure and Compression.” This title indicates that this section can be used for doubly symmetric I-sections and rectangular (or round) HSS as well. Bending can be either in the major axis or the minor axis. After reading the Commentary, my understanding is that this section is intended for doubly symmetric I-sections subjected to major axis bending only. Is section H1.3 applicable to HSS?

02-01-2008
Determining rt

I am searching for information pertaining to rt. I am looking to see if there are any equations that can be used to calculate this value. I have looked through a couple of text books but have not found an equation for this. Can you point me in the right direction?

02-01-2008
LRFD or ASD

What is the difference between LRFD and ASD design?

02-01-2008
Steel for High-temperature Applications

The Brockenbrough and Merritt text referenced in Part 2 of the 13th edition AISC manual indicates that “For special elevated-temperature applications in which structural steels do not provide adequate properties, special alloy and stainless steels with excellent high-temperature properties are available.” Can you direct me to publications on the properties of these special alloy and stainless steels?

02-01-2008
Diagonal Brace Connection

In considering a brace-to-gusset connection for a SCBF, it is my understanding that the Uniform Force Method is generally the most economical method for determining gusset size and welds (13th edition page 13-3). However, I noticed that most of the examples in the new Seismic Design Manual use the Whitmore section (pages 3-58, 3-66, etc.). Are there any advantages and/or restrictions in using the Whitmore section versus the Uniform Force Method? Is there any reason the Whitmore section was used in the Seismic Design Manual versus the Uniform Force Method?

02-01-2008
Section Properties of Historic Shape

I recently attended the AISC seminar Design Steel Your Way (www.aisc.org/seminars) and received the AISC manual and companion CD. In a project I am working on we have a shape that we cannot locate in the historical shapes database that was included on the CD, nor in any texts that we currently have. I was wondering if you might be able to shed some light on some of its dimensions and properties.

     The building was built by the government in 1951. On the drawings the shape is called out as a 12WF19. We are looking to do some analysis on this structure and wondering if you could direct us to where we can find the properties?

02-01-2008
Strain Hardening

AISC 341-05 requires 1.1Ry for the design of some connections and Ry in other places. Why is this so? Should it not be only 1.1Ry, since I understand the 1.1 is to account for the increase in strength due to strain hardening under cyclic load? If this is the case, all elements would be subject to cyclic loading in a seismic event, and hence 1.1Ry should be applicable everywhere.

02-01-2008
Connection Strengths in the 13th Edition Manual I have questions about the evolution of the connection strengths shown in the 9th edition manual compared to the values in the 13th edition. Why are they different? 01-01-2008
PJP Weld Throat How is the throat calculated for a partial-joint-penetration groove weld with fillet weld reinforcement? Is it the addition of the two weld throats? 01-01-2008
Washers for Anchor Rod Installations I have a project where base plate anchors were set too short to install both a washer and nut. The holes in the base plate are only one-sixteenth inch oversized for 1-in.-diameter anchors, so the contractor is requesting to eliminate the washers. How can I assess the uplift capacity of such an installation? 01-01-2008
KL/r Modified for Single-Angle For a single-angle compression member, I followed AISC specification section E5 to calculate the modified KL/r. I also calculated KL/rz, and it turns out to be greater than KL/r modified. Should I use the larger of the two (KL/r modified, or KL/rz) in section E3? 01-01-2008
Shoring Removal In composite beam design and construction, if the design basis is shored construction, how long do the shores need to remain in place? 01-01-2008
Double Angle Connection - Table 10-1 The beam web strength portion of Table 10-1 in the 13th edition manual checks block shear rupture, shear yielding and shear rupture depending on the coping condition of the beam in question. When determining the connection capacity for a bolted-welded beam-to-girder connection, both Table 10-2 and the bolt and angle portion of Table 10-1 must be checked to find the limiting value. If the beam is coped at one or both flanges, there are no additional checks against block shear rupture, shear yielding, and shear rupture. Does AISC recommend checking these limit-states, or is it unnecessary for a connection with a welded beam web? If they must be checked, is there another table to expedite this check?  01-01-2008
Recycled Content We are working on a project that is pursuing LEED certification. We are pursuing material resource credits 4.1 and 4.2 and are using structural steel as a major part of achieving this credit. We would like to bump them up as much as possible without creating a non-competitive bid environment. Where can I find information to determine the appropriate credits? 01-01-2008
Butt Splicing W-shape Beams I have a contractor who would like to butt splice two W14x22 beams together. He is proposing to use a complete joint penetration groove weld that will be done in the shop. The splice will occur 4 ft from the end on a 20-ft span. Will this weld develop the full strength of the section? 01-01-2008
Fully Restrained or Partially Restrained What is the ratio of end moment to beam rotation that must be achieved to consider a connection fully restrained rather than partially restrained (slope of FR line in Figure 12-1 of the 13th edition Steel Construction Manual)? 01-01-2008
Suspended Sprinkler Loads The fire marshall is objecting to hanging fire sprinkler pipe from the bottom chords of steel bar joists. I can find no reference to disallow this in our building code. Numerous contractors are contacting our building department, wanting to know the basis of this objection. I would assume that the design professional of record has reviewed what is being hung from the joists and has performed a structural calculation of the imposed loads.   01-01-2008
Historic Lattice Columns

We are examining an existing building constructed roughly in 1919. The columns in the building consist of double-angle flanges with lattice steel webs. We are trying to determine allowable loading for the column but have been unable to find any documented information. Any help would be appreciated.

12-01-2007
Evaluation of an Existing Structure

I am working on an addition to a 1922 steel-framed building. When I check the columns using ASD (unreinforced concrete encased, Fa = 18000 – 70L/R), many are overstressed. However, the results appear to be better using LRFD.

Is there anything in the AISC specification that would require that we use ASD and not LRFD to check the existing structure? Is it reasonable to apply today’s load and resistance factors to historic steel?

12-01-2007
Shear Stud Requirements

Is there a minimum height requirement for studs used in the design of composite beams?

12-01-2007
Crane Runway Forces

Where are “crane runway horizontal forces” addressed in the current AISC specification? This was formerly covered in Section A4.3 of the 1989 ASD specification. If it is not addressed in the new specification, where do I need to go to find these requirements?

12-01-2007
Expansion Joint Location

What is the maximum length permitted between expansion joints in a steel building?

12-01-2007
Reduction for Splice Length

In the 3rd Edition AISC LRFD manual, footnote "e" in Table J3.2 requires that a 20% reduction is taken on bolt patterns in tension splices where the bolt pattern length measured parallel to the line of force is greater than 50 in.

Is any tension connection considered a splice? I am evaluating diagonal tension members in a truss that connect to the top and bottom chords as well as vertical members. Does this reduction apply?

12-01-2007
Seismic Retrofit of 1931 Building

I am doing a seismic retrofit for a structure designed and built in 1931. I guess it must be A7 steel. Could you let me know what values Fy, Fu, and Ry should be used?

12-01-2007
Single Angle Design

Can you help me clarify the design of a single unequal leg angle in bending utilizing the new AISC specification? A very common situation for longer span masonry brick openings is to use an L6x31/2x5∕16 LLV. Do you have an example or some clarification on the design?

12-01-2007
Bolt Torque/Tension Equation?

I understand that the torque required for bolt installation in a slip-critical joint depends on the bolt class, the bolt diameter, and the faying surfaces properties. Can you tell me what equation to use to determine the torque required developing the required tension in the bolt?

12-01-2007
Required Bolt Length

I am relocating a structure where there is not proper documentation of existing conditions, and I am unable to determine the required length of the structural bolts.

We have the connection drawings of the columns and beams, and the thickness of the splice plate. I want to know what should be the length of the bolt and length of the threaded portion, taking into consideration the height of the nut and the thickness of the washer.

12-01-2007
Weak Axis Bending

I have an H-shape in bending about the weak axis. Chapter F, Section F2 of the AISC manual notes, "Lateral bracing is not required for members loaded through the shear center about their weak axis, or for members of equal strength about both axes." Do we still need to consider the lateral torsional buckling effect if the beam is bent about the weaker axis? Based on my understanding, lateral bracing prevents torsion and lateral deflection only. What is the exact relation between "lateral bracing to prevent torsion" and "lateral bracing to prevent lateral torsional buckling"?

11-01-2007
Design Forces

A fabricator has recommended providing member end forces (for beams) and axial member forces (for braces) for economical connection design. What are "transfer forces" with regard to connection design, and how does one calculate these? What is the rationalization as to why member end forces acting transverse to the longitudinal axis (in the weak axis direction) are ignored in connection design?

11-01-2007
R=3

I understand that there is a provision that will allow me to not design steel connections per the AISC Seismic Provisions if I use an R value of 3. Can you tell me where I can find this information?

11-01-2007
Steel Availability & Fabricator Listings

Could you suggest a resource where I can obtain mill pricing on structural shapes and information on availability? Could you also suggest a resource where I can obtain list of domestic steel distributors and major fabricators?

11-01-2007
Bending Radius

What is the minimum allowable bend radius for 1.5-in.-  and 1.75-in.-diameter bars in ASTM A572 Grade 50?  When hot bending is required, are there code provisions for the temperature required?

11-01-2007
Shape Availability

I was informed by my engineering team that a W24x160 beam is commercially available. Can you tell me by whom such a beam is being produced?

11-01-2007
Historic Steel Specifications

I remember seeing a download that shows the historical steel specifications used in industry—for example, what years ASTM A7 steel was used. Can you help?

11-01-2007
BF in Table 3-2

Table 3-2 in the 13th edition manual has a column showing value of BF; however, the symbol list does not include the term BF. General Nomenclature (Index) indicates that BF is factor that can be used to calculate the flexural strength for unbraced length Lb between Lp and Lr. How is that done? Table 3-2 also lists Mrx. How was this calculated?

11-01-2007
Unbraced Tee in Flexure

Does the limit state of yielding apply to an unbraced tee flexural member with stem in tension? The compression flange is non-compact.

11-01-2007
Penetration into the Base Metal

I am concerned with a fabrication shop that is using E70C-6M. When inspecting heavy columns, I noticed the welds at the gusset plate have little or no penetration into the base metal. My wire book is saying the wire is good on carbon steel up to 70 ksi. Is the gas-shielded metal-cored wire, which I see as having little penetration, acceptable on structural steel because the drawing calls for the use of E70XX filler metal?

10-01-2007
Section Properties

I am trying to calculate the Ix values found in Section 1 of the 13th edition AISC manual. The numbers that I get are close, but don’t quite match what is printed. Are you including the fillets in the calculation? What shape do you assume they are? Where is the thickness of the flange equal to tf when shapes have an inner flange surface slope? Is it at the location half way between the face of the web and the end of the flange?

10-01-2007
PJP Weld Capacity

When AISC gave a seminar on the new code, they gave out laminated “short-cut” cards that identify the ASD tension capacity of a PJP groove weld as 0.32FEXXAw. I am having trouble coming up with the origin of the 0.32 factor. For ASD I have always used an allowable shear stress of 0.3 times the nominal tensile strength of the weld metal. Can you explain the difference?

10-01-2007
Single-Angle Bending

Upon reviewing a condition I have encountered of an unequal-leg single angle bent about a geometric axis (X-X in this case) with no restraint against lateral-torsional buckling along its length, I do not see in AISC specification Section F10-2 any subsection that encompasses this condition. Is it advisable to assume that since this condition is not explicitly covered with a definition for Me, that there is no case in which LTB will cause the failure of an unequal-leg single angle bent about a geometric axis? If not, which equation would be applicable to determine the LTB criteria for this condition? 

10-01-2007
Slip-Critical Surface Classes

AISC 341 lists only Class A surface preparation for bolted connections that are part of the SLRS. This would appear to eliminate galvanizing as a corrosion control method, since, when roughened, it is considered a Class C surface. Is this correct?

10-01-2007
Edge Distance for Anchor Rod Holes

What and where are the requirements for edge distance for the recommended maximum-size holes for anchor rods listed in table 14-2?

10-01-2007
Historic Steel Beam Designation

We are renovating a job dated 1914. Beams are called out as 9x21. Is this an "I-shape," 9 in. deep at 21 lb. per ft?  Is there a source for the old beam properties?

10-01-2007
Single-Plate Connections with Axial Loads

Is it acceptable to design single-plate connections for shear and axial loads? If so, what are the design criteria for the axial load?

10-01-2007
Repairs at Protected Zones

When installing the light gauge framing on a special moment frame with RBS connections, four shot pins were inadvertently installed into a beam flange in a protected zone. What criteria can we apply to determine if this exceeds an acceptable level? And if it does, what repairs are available to us? 

09-01-2007
Design Wall Thickness

What is the reason for the smaller gross areas of standard pipes in the new (13th edition) steel manual?

09-01-2007
65ksi Steel & LEED Certification

We are considering the use of 65 ksi steel for building columns. Can you tell me what the availability would be for 65 ksi W-shapes? We are currently looking at sizes ranging from W14x61 to W14x605—the whole range!
    Additionally, the project (located in Chicago) is to be LEED certified, so we would be looking for steel manufacturers within a 500-mile radius. Do you have any recommendations for steel suppliers that would be able to fulfill this requirement and supply 65 ksi W-shapes?

09-01-2007
Slip-Critical Connection What is a slip-critical connection and when must they be used? 09-01-2007
Plate Girder Design

Where can I find the current design criteria for plate girders? What used to be Chapter G in the 1989 ASD specification doesn’t appear to be in the new 2005 AISC specification.

09-01-2007
Traceability

Is it required to have evidence of traceability of heat numbers for clip angles, bar sections, or plate from inventory?

09-01-2007
Maximum Size of Fillet Weld

Why is the maximum size of a fillet weld limited by the thickness of the thinner plate?

09-01-2007
Specification Conformance for Existing Buildings

I have a multi-story building constructed circa 1970 that is being considered for re-use as a senior center. Should the structural engineer be required to check the bolts for conformance with modern criteria?

09-01-2007
Extended Single-Plate Shear Connections

Does one use the 1.25 multiplier over the bolt shear values for the extended configuration single-shear plates? Per p. 10-103 in the 13th edition AISC manual, the 1.25 multiplier is used to determine the moment strength of the bolt group. But when you are calculating the bolt shear strength, is it correct to use the bolt shear values directly from the tables and multiply these by the "C" factor for the eccentricity?

09-01-2007
Thread Engagement

Is there a minimum number of threads that a nut needs to be engaged on a bolt?

09-01-2007
Elevated Slab Tolerances

For a steel-framed project with concrete slabs on metal deck, I know that the AISC Code of Standard Practice sets the tolerances for the steel, but what typically defines the tolerances for the top of concrete slab on metal deck? Normally, the concrete subcontractor uses the ACI "F" number criteria from the cast-in-place section of the project specifications, but is this correct if one just references the basic ACI and AISC standards without additional project specifications?

08-01-2007
OCBF and Tension-Only Bracing

Section 14.2c of the 1997 version of Seismic Provisions for Structural Steel Buildings does not allow tension-only bracing. The 2005 version states that tension-only bracing can be used, but not in K, V, or inverted V configurations.

     Am I reading this correctly? When did it change that tension-only could be used? I do see that there are many restrictions to this.

08-01-2007
Pretensioned Bearing-Type Joints

Please let me know whether a bearing-type connection can be pretensioned.

     If yes, should the pretension (70% of the proof load of the bolt) be taken into account and checked for combined shear and tension when using N- or X-type bolts?
     What is the purpose behind pretensioning bearing type joints?  Is the pretension to be in accordance with RCSC 2004?  Will prying occur in a pretensioned joint?

08-01-2007
Historic Shape Data

I am interested in purchasing a copy of the book Dimensions and Properties, Rolled Shapes—Steel Wrought Iron Beams and Columns, as rolled in the USA, Period 1873 to 1952. It was compiled and edited by Herbert W. Ferris, and it looks like the 9th printing was in 1983.

08-01-2007
Stiffeners and Concentrated Forces

We need more information on Section J10.8 in the 2005 AISC specification. The basic question is: Where do the 25tw and 12tw parameters come from? What about when you have two stiffeners within 25tw/2 of each other? Are the strengths additive? Is there any provision by which the 25tw limit can be increased?

08-01-2007
Girt Bracing

I am designing a building with vertical siding, channel girts, and sag rods. I was told that the industry standard is to consider the channel braced at the sag rods. How is this possible, since the sag rods are neither at the compression flange nor able to act in compression? Is this the appropriate way to look at bracing the channel, or is there a more appropriate method?

08-01-2007
Required Edition of a Standard

Do you have a good response to engineers who forbid the use of the AISC 13th edition for connection design on their projects? I am running across a few engineers who take the position that since the IBC predates the 13th edition, the 13th edition cannot be used.

08-01-2007
Certification Exemption

How does AISC Certification for fabrication of steel building structures relate to the IBC 2003 Paragraph 1704.2.2, Fabricator approval?  If a fabricator is AISC Certified, can I assume they qualify for the special inspections exemption under IBC?

08-01-2007
Base Anchorage in Seismic Zone

Should anchor rods be designed for base shear forces only, not amplified loads, using the Ω factor and not the vertical or horizontal component of the RyFyAg force of the brace?

We do a lot of one-story commercial buildings where the base shear forces are quite small, and we are being questioned by fabricators, contractors, architects, etc. over huge gusset plate connections that result from the RyFyAg of the tube braces. The footing, anchor rods, and even column sizes seem disproportionate to the brace connection. Where does the force go if you ignore it in the design of these members?

We are under the 1999 Standard Building Code, which does not differentiate between special and ordinary concentric braced frames (except through referring to ASCE 7). This code refers to the 1997 AISC Seismic Provisions, which would technically allow us to ignore the seismic provisions for one- and two-story structures. However, we have been trying to use the 2002 provisions to be more up-to-date. The 1997 provisions allowed for the brace connection for OCBF to be designed for load combinations 4-1 and 4-2, but we see that this was taken out in the 2002 provisions for OCBF, along with the one- and two-story exception. The SCBF still allows the connection to be designed for the maximum force that can be transferred by the system. If you design the foundations for the base shear and let that limit the system, then aren’t you basically cancelling out the requirement for the connection to be designed for the RyFyAg force, which effectively puts you back at square one?

07-01-2007
Backing Bar Removal

We have a steel building frame where we are using ordinary moment frames (OMF) with a seismic force resisting system defined as "Structural steel systems not specifically detailed for seismic resistance," R = 3. Since this category does not require compliance with the AISC Seismic Provisions for Structural Steel Buildings, which requires removal of backing bars for OMFs, I would surmise that we do not need to remove the backing bars. Is this correct?

07-01-2007
Moment Strength of Bolt Group

On p. 7-19 of the 13th edition Steel Construction Manual, an equation is given for the pure moment capacity of a bolt group when the instantaneous center is at the center of the bolt group. Where does the 1.25 in the equation come from? What is the design capacity using LRFD?

07-01-2007
Shear Stud Placement

For design of composite steel beams, is there a good reason to consider the use of a non-uniform spacing over the span? I have heard of placing more at the ends where the shear is higher. Would that be reasonable?

07-01-2007
Additional Capacity Needed

I am designing a new stair that will be supported on an existing structural steel composite floor system. The beams are designed very close to their limits, so I must reinforce them. When I attempt to add steel (WT, C, L) to the bottom flange of the beam, the percentage composite drops below 25%, and I lose the ability to consider the beam composite, which means I would have to add a lot more steel. Has AISC done any research on adding studs to a composite beam to increase its composite action capability in order to accommodate additional loads?

07-01-2007
Bearing Length

I am trying to design an unstiffened seated connection using Table 10-6 in the 13th edition manual. What is the definition of the required bearing length Nreq (in.) shown in the table? Is this referring to the actual beam bearing length on the angle, and if so, why do the allowable load values decrease as the bearing length increases?

07-01-2007
Column Table Using Rx/Ry

I recently attended a seminar on the new manual, which included a study book outlining the seminar and including examples. I have been trying to familiarize myself with the axial compression section of this book (Chapter 2). An example uses a W14x120 column checking Pa using equation E3-2. This result is then checked against the capacity listed in Table 4-1. The results come out the same. I did a second problem using a W12x72 following the same approach and am coming up with significantly different values. I am not sure that I am using rx/ry correctly. Can you explain the use of the rx/ry  factor in assessing the column capacity?

07-01-2007
Bolt Torque

What is the required installation torque for each diameter of bolt?

06-01-2007
External Load Applied to Pre-Tensioned Bolt

If addtional external load is applied on a pretensioned bolt, is the load additive?

06-01-2007
f Factor for Shear

In Chapter G of the 2005 AISC specification, the h/tw limit is 2.24√(E/Fy) for webs of rolled I-shaped members. This is a slight change from the 2.45√(E/Fy) from the 1999 LRFD specification. Why?

06-01-2007
Low-Temperature Service

Ambient air temperatures in the northern regions can reach below zero routinely--say -20 °F. Is the AISC specification still valid?

06-01-2007
LRFD Design

Recently, I have seen many references to the "LRFD method" in connection with structural engineering. Can you please advise me on how I might become familiar with this procedure?

06-01-2007
Non-Sesimic Braced Frame

I am designing a 12-story concentrically braced steel frame building. The Seismic Design Category is C. I'm taking R = 3, so the AISC Seismic Provisions are not applicable. What's more economical: HSS field-welded braces or W-shape field-bolted braces?

06-01-2007
Recycled Steel

Does the AISC specification distinguish between the uses of recycled steel versus that produced from raw ore?

06-01-2007
Seismic Braced Frame Seminar

I remember that AISC presented a series of seismic braced frame seminars last year. Are there any scheduled in the future?

06-01-2007
Serviceability & Strength Considerations for SC Bolted Joints

When designing for wind moments with oversized holes in a flange plated moment connection, can the slip-critical bolts be designed for serviceability or must they be designed for strength based on the 2005 AISC specification?

06-01-2007
Tension-Only Bracing

We are designing a material handling system in a high seismic and high wind region, Seismic Design Category D. The system classification is Special Concentrically Braced Frames due to the height of the structures. Referring to the 2005 Seismic Provisions, is it acceptable to design the bent bracing as tension-only X-bracing?

06-01-2007
Undefined Yield Strength in Manual Listing

There is no listing for yield strength of ASTM A307 bolts in Table 1-C of the 9th edition ASD manual. Why is this not listed, and what is the value for it? Also, what is the definition of proof load listed in the table?

06-01-2007
Backstepping

I just saw the word "backstep" in reference to a welding note on a structural drawing. What exactly does this mean?

05-01-2007
Filler Metal for High-Seismic Applications

Where can I find the filler metal requirements for high-seismic design?

05-01-2007
Heat-Straightening Columns

A two-story column on our project was erected approximately 1&7/8 in. out-of-plumb. The erector would like to heat one face of the HSS column and then cool it quickly in order to bend the column back to plumb. All other issues aside, what will this heating and cooling process do to the material properties of the column? It seems as though there will be some residual stresses in the column as well that may present a problem.

05-01-2007
Holes in Base Plates

On one of my projects, it was reported by the inspector that holes in some of the column base plates were enlarged in the field to accommodate anchor rods that were misplaced. Some of the holes were enlarged significantly, and some of the plate edges were notched out around bolts. The columns are part of a moment frame, so the bases were designed for the lateral forces. Is it possible to repair the plates by welding an angle or plate on top with drilled holes to receive the anchor rods? If a new plate is added on the top, the anchor rods may not have adequate projection. The rods are A307 material. Is this weldable, or would a coupler be required?

05-01-2007
Iy and J for Double-Angles

In attempting to calculate the lateral-torsion buckling of double-angles per the AISC manual, I cannot find properties such as Iy and J. Are these tabulated in the 13th edition manual?

05-01-2007
Knifed Connection

What is the definition of knifed connection? I have looked in several textbooks without any success.

05-01-2007
SCBF Brace Reinforcement

The 2005 AISC Seismic Provisions for SCBF states:

Where the effective net area of bracing members is less than the gross area, the required tensile strength of the brace based upon the limit state of fracture in the net section shall be greater than.... RyFyAg (LRFD).

For an HSS brace, Fy = 46 ksi; Fu = 58 ksi; Ry = 1.4; Rt = 1.3

The required tensile strength of the brace based upon the limit state of fracture is 0.75RtFuAe = 56.55Ae and the required tensile strength is RyFyAg = 64.4Ag. Setting the required tensile strength of the brace greater than RyFyAg results in Ae = 1.14Ag, which is not possible. It seems that you cannot stiffen the member to increase Ae without also increasing Ag. How can the requirement of 13.2b(a) can be met?

05-01-2007
Slip-Critical Bolt Values

Has Table 3, "Allowable Load for Slip-critical Connections," which appeared in the 9th edition AISC manual, not been included in the 13th edition?

05-01-2007
Slip-Critical Bolts Used in Shear Tabs

I had the impression that we could not use slip-critical bolts with extended shear plates because the flexibility of shear plate connection is achieved by the plowing of the bolts against the main material. Based on the 13th edition AISC manual, it seems we can use slip-critical bolts with the extended configuration. What makes the connection flexible in this case?

05-01-2007
Base Plate Bending

I cannot find the requirements for how to determine the thickness of a base plate subjected to a weak-axis column moment in AISC's Design Guide 1: Base Plate and Anchor Rod Design. Could you provide some references?

Question sent to AISC's Steel Solutions Center

04-01-2007
Bolt Values

I noticed that the bolt values have changed for A325 N bearing bolts from the 9th edition manual (7/8" A325 N bolt = 12.6 kips) to the 13th edition (Table 7.1 gives 14.4 kips). Is that true?

Question sent to AISC's Steel Solutions Center

04-01-2007
Column Splice Design

On the contract drawings, the engineer calls for us to develop the column splice for 100% of the gross moment capacity of the upper column. Usually we use Table 14-3 from the 13th edition manual, and in this situation, Case VI, because the engineer requests bolted/welded. I am assuming this table does not incorporate the 100% requirements. If this is the case, can you lead us in the right direction to design for such requirements?

Question sent to AISC's Steel Solutions Center

04-01-2007
Composite Steel Beam

What are the key advantages of choosing composite steel beam and steel deck with concrete slab instead of a non-composite system? Is it possible to specify that the shear studs be shop-welded to the beams prior to arrival on-site? How can overall quality of shear stud installation be ensured?

Question sent to AISC's Steel Solutions Center

04-01-2007
Single-Plate Shear Connections

What are AISC's recommendations regarding the use of single-plate beam-to-girder shear connections? Typically, we do not use this type of connection, but I was wondering if there is an article discussing the pros/cons of this connection type.

Question sent to AISC's Steel Solutions Center

04-01-2007
Torsional Unbraced Length

What is the torsional unbraced length? Isn't this equal to the lateral unbraced length? If a simply supported W-shape beam is laterally supported at the top flange every 5 ft and at the bottom flange every 10 ft, is the lateral unbraced length 5 ft for the top flange and 10 ft for the bottom flange? Isn't the torsional unbraced length the same?

Question sent to AISC's Steel Solutions Center

04-01-2007
Wind Connections in Seismic Areas

I am designing a large retail store with moment frames. In one direction the wind governs and in the other direction seismic governs. For the flexible moment connection (Type 2 with wind), page 4-100 of the 9th edition manual mentions that the moment connection is to be designed for wind moment only, and it is assumed to rotate enough to be considered simply supported for gravity loads. Does this assumption also apply to moment connections for seismic load?

Question sent to AISC's Steel Solutions Center

04-01-2007
ASD and LRFD

What are the major differences between the ASD and the LRFD design methods in the current AISC specification?

03-01-2007
ASTM F1554 Grade 36 vs. ASTM A36

What is the difference between ASTM A36 anchor rods and ASTM F1554 Grade 36 anchor rods? They both have the same tensile and yield properties.

03-01-2007
End Panel

My questions relate to panel zone shear and tension field action. The 2005 AISC Specification, Section G3 states that tension field action cannot be used in the "end panel." There is no definition given for end panel.

Is the end panel not intended to be a support zone from the bearing stiffener, if run up from the center of the support to a cantilevered or fixed end, where the deformations are constrained? Who originally contrived the end panel notion, and what reference could we use to determine the intent?

03-01-2007
Flare Bevel Groove Welds in Tension and Compression

I'm designing a flare bevel groove weld between a rectangular HSS16x8x1/2 and an A36 plate. The load is parallel to the weld axis (tension and/or compression). Table J2.5 states "Tension or compression in parts joined parallel to a weld need not be considered in design of welds joining the parts." So, how do I design the weld?

03-01-2007
Historic Bolt & Rivet Strengths

I am working on design modifications to an existing power plant built between 1967 and 1970. I can reference back the steel member designations to the AISC Steel Construction Manual, fifth edition. Based on field observations, the building was constructed using standard beam connections. The general connection notes required the fabricator to design the bearing or friction connections (appears to be fabricators choice) for the forces indicated on the drawings or for the full member strength if no forces were given. The fabricator was to use rivets or high-strength bolts.

I have an old copy of the 5th edition AISC manual. I noticed connection strength tables for standard beam connections, but they are for rivets. Based on my field observations, the connections use 3/4-in.-diameter bolts. What were the shear and tension properties of high-strength bolts at that time?

03-01-2007
Technical Bulletin No.3

In a recent project, a reference to "Technical Bulletin No. 3" was made when specifying steel material. Can you please advise where this bulletin can be found?

03-01-2007
What is the Difference Between Rt and Rts?

In the 9th edition AISC ASD manual, the value of rt was tabulated, and one can refine it by using the St. Venant equation as given in Commentary. The 13th edition AISC manual tabulates values of rts. Are both values same? If not does one need to calculate the rt?

03-01-2007
WT in Flexure

Section F9 of the AISC Specification covers tees loaded in the plane of symmetry. Equations F9-4 and F9-5 cover the stem being in tension or compression. I'm designing a member that is loaded in its axis of symmetry (the y-axis for a tee or double angle), which produces tension or compression in the stem. However, the formulas use Iy, the moment of inertia of the weak axis. Using the weak-axis moment of inertia for bending about the strong axis is counterintuitive to me. Why is the weak-axis moment of inertia used in these equations?

03-01-2007
1964 Drawings

I am examining a set of documents from 1964. Which manual of steel construction might have been used for steel design in 1964? I see shapes listed as 14B22, 14B17.2, etc. Furthermore, the drawings simply state that "fs = 22 ksi." Was steel of this vintage ASTM A36 with Fy = 36 ksi or something else?

02-01-2007
AISC Specification Seminar

I have a question on an example in the 2005 AISC specification seminar. You apply Eq. E7-17 to obtain the equivalent width of the web. AISC specification Section E7.2(a) indicates that this equation is valid only for b/t ≥ 1.49(E/f)0.5. The value of this expression is 1.49(29,000/28.2)0.5 = 47.8. The value of b/t = 39.6, which is less than 47.8 and it would seem that Eq. E7-17 is, therefore, not applicable. No alternative to Eq. E7-17 is provided in the specification. What is the intention of the AISC specification in this situation?

02-01-2007
Backing Bar Requirements

Is a backing bar required when welding the beam bottom flange to the column flange on a SMF if the beam flange is tight to the column?

02-01-2007
Block Shear

I noticed that the tension yield component of the block shear check is no longer included in the 2005 specification, Eq. J4-5. The new procedure is obviously simpler without the need for dealing with the tension yield component. Could you explain the change?

02-01-2007
Braced Frame Seismic Connections

I am trying to understand the requirements for bracing connections in AISC 341-02 (the 2002 AISC seismic provisions). In Sections 13.3a and 14.2, the required strength of the connection is the expected tensile strength of the brace, RyFyAg. How can I meet that strength requirement for tension in the connected elements? According to Sec. 13.3b:

The design tensile strength of the bracing members and their connections, based upon the limit states of tension rupture on the effective net section and block shear rupture strength, as specified in LRFD Specification Section J4, shall be at least equal to the Required Strength of the brace as determined in Section 13.3a.

The tensile rupture limit state is given in Sect. J4 as φFuAe with φ = 0.75 (LRFD) and 0.5FuAe (ASD). For all standard steel grades, RyFyAg is greater than the tension rupture strength. Does that mean that all bracing members need to be reinforced at the connection? If so, how far from the connection should the reinforcing extend?

02-01-2007
Cantilever Framing

I am analyzing and retrofitting a building from 1965. It is a one-story roof structure. Column bays are typically 30 ft by 60 ft. Steel bar joists are spaced at 3 ft o.c. and span the 30 ft dimension. Beams are cantilevered 9 ft over the columns with 42 ft infill beams spliced between the major girders. There is no bottom flange bracing or full-depth stiffeners at any point along the major girders. Are there any references from this era that describe this system and the design philosophy at the time?

02-01-2007
Lally Columns?

We are reviewing the roof of a steel-framed building built in 1951, but we only have a few sheets of the original contract documents. The columns are referred to as 5-in. "Lally Columns." The column-beam connection is a single 1/4-in. steel knife plate through the column with six 3/4-in. bolts.

Was "Lally" used as a generic term for pipe columns? The connection described wouldn't work with today's Lally columns. It would seem to me that we are closer to a standard pipe column.

02-01-2007
Slotted-Hole Dimensions

Table J3.3 in the 2005 Specification for Structural Steel Buildings gives dimensions for slotted holes. What is the definition for the slotted hole length? Is it the total length of the hole (i.e., from the outermost radius points on the circular portion) or the length of the straight portion of the hole?

02-01-2007
Tee Stem in Flexural Compression

Does the 2005 AISC specification cover the case of a WT member loaded in the plane of symmetry with the stem in flexural compression? Section F9 does not distinguish whether or not the stem is in compression or tension, but it does not seem to check the buckling of the web, which I would suspect is necessary for this case.

02-01-2007
Galvanizing High-Strength Steel

Is there a problem with hot-dip galvanizing high-strength structural steels?

Question sent to AISC's Steel Solutions Center

01-01-2007
High-Strength Bolts in 1956

I am analyzing a building constructed in 1956. The plans specify high-strength bolts for the lift-slab columns, but don't give an ASTM designation. Do the A325 and A490 designations go back to 1956? Do you have any other suggestions for approximating design strength of these bolts without testing?

Question sent to AISC's Steel Solutions Center

01-01-2007
Historic Non-ASTM Shapes

I am currently working on modifications to an existing ship unloader at a terminal in the U.S., built around 1980. The design was done by a German company that has since gone out of business. The task at hand is to determine a demolition plan for part of the structure so that modifications can be made. The existing mechanical and structural drawings are all in German, but conversion of dimensions and loads are easy. However, many of the structural shapes are designated in a form that is not recognizable to us. We are accustomed to using metric equivalents used in modern construction; however, these members are designated in a non-standardized metric system notation.

For example, some wide-flange sections are noted as HEA 200; it seems obvious that this represents a 200-mm (about 8-in.) beam. Scaling the drawings confirms the depth, assuming they are properly to scale. Scaling flange width and flange thickness, it appears that this shape is nearly equivalent to a W8x35. I'm a bit nervous relying on scaling to confirm member sizes for strength and weight. There are other members designated HEB 200, HEA 500, etc. Is AISC aware of a steel reference that indicates these member sizes and section properties?

Question sent to AISC's Steel Solutions Center

01-01-2007
HSS Slot Tolerance (updated from October 2006)

This question originally appeared in the October 2006 Steel Interchange. AISC received follow-up correspondence from a fabricator to supplement the original response.

What is the recommended width tolerance of a slot in a tube shape that is to receive a plate? 1/8 in. larger? 1/16 in. larger?

Question sent to AISC's Steel Solutions Center.

01-01-2007
Pile Shape?

We specified HP12x53 for a pile foundation system. However, the contractor wishes to use W12x53 instead of HP12x53 due to the limited availability of HP12 shapes. Is there any technical reason not to permit the W12 substitution?

Question sent to AISC's Steel Solutions Center

01-01-2007
Slip-Critical Bolts?

I was recently performing fabrication inspection on a project, and the fabricator informed me that Type X bolts are slip-critical and Type N bolts are not. Is this true in general?

Question sent to AISC's Steel Solutions Center

01-01-2007
Steel Availability

What is a steel service center? Where can I find the names and phone numbers to some of the closest steel service centers to a particular location?

Question sent to AISC's Steel Solutions Center

01-01-2007
Welding Carbon Steel to Stainless Steel

Could you please advise on any special requirements for welding carbon steel to stainless steel? I have a condition where I have stainless steel plates that are to be welded to the end of HSS carbon steel sections, and want to make sure this is possible. Are there any references available that you could recommend on this topic?

Question sent to AISC's Steel Solutions Center

01-01-2007
Deep Column Section for SMF

I am designing a Special Moment Frame (SMF) in accordance with FEMA 350 and using a reduced beam section. In the past, and in the FEMA 350 document, the columns for SMF have been limited to W14s. However in a recent AISC seminar, the speaker indicated that it is acceptable to use deeper column sections (W24s, W27s, etc.) for SMF using the reduced beam flange connection (dog-bone). I could not find any documentation supporting this unless specific testing is required. Can you point me in the correct direction?

Question sent to AISC's Steel Solutions Center

12-01-2006
Design Stress for Compression Members

In the third edition of the LRFD Manual of Steel Construction, on page 16.1-143, there is a table for design stress for compression members in relation to Kl/r. Where is this table in the Steel Construction Manual, 13th edition?

Question sent to AISC's Steel Solutions Center

12-01-2006
Minimum Connections

Section J1.7 in the AISC specification covers "minimum strength of connections" and requires a factored load not less than 10 kips for connection design. Where does the "10 kips" come from? Is that empirical? Can I use this load for the connections of precast concrete structures?

Question sent to AISC's Steel Solutions Center

12-01-2006
Section Properties of Back-to-Back Channels

Does AISC provide a spreadsheet that calculates the section modulus of two channels welded back to back?

Question sent to AISC's Steel Solutions Center

12-01-2006
Thermal Cutting

I received an RFI requesting a modification that includes thermal cutting (torching) of the deck closure angles (diaphragm chords). The special inspections agency is requesting that we verify this modification. I am trying to research the effects of thermal cutting. Do you have any recommendations on where to look for information as far as codes or technical references?

Question sent to AISC's Steel Solutions Center

12-01-2006
Weld All Around?

Current details show an all-around fillet weld symbol at wide-flange column to base plate connections. I thought that this wasn't a good practice. Could you please comment?

Question sent to AISC's Steel Solutions Center

12-01-2006
Welding to 65ksi Steel

Full penetration welded column splices of columns with 65 ksi yield strength were completed using 70 ksi weld metal, when 80 ksi weld metal was required. We realize something needs to be done as the weld no longer develops the strength of the base material. Can the columns simply be reinforced at the connection, i.e. reinforcing flange and web plates to resist for the excess not developed by the weld; or does the 70 ksi weld no longer have any analytical capacity because it used with 65 ksi material?

Question sent to AISC's Steel Solutions Center

12-01-2006
Workable Gage

I noticed that the workable gage for W8x24 and W8x28 in the 13th edition Manual changed from previous editions of the steel manual. The 13th edition shows the workable gage as 4". for those members; previous editions list them as 3 1/2". Is this intended or was it a typo? Also, I was wondering if you can explain the difference between workable gage and useable gage as was listed in older U.S. Steel or ASD manuals.

Question sent to AISC's Steel Solutions Center

12-01-2006
Floor Plate Design

Do you know of any resources or design aids for the design of solid plate floor decking such as "diamond plate"? We tend to do quick designs using ASD and 0.75Fy for bending; then check deflections - but this seems too conservative.

Question sent to AISC's Steel Solutions Center

11-01-2006
Hooked or Headed Anchor Rod Embedment?

I understand that changes have been made in AISC's Steel Construction Manual, whereby hooked anchor rods are to be replaced by headed anchor rods in tension applications. When does this become effective in the various building codes? What are the dimensional specifications for the head configuration? Has AISC published guidelines for material specifications, etc.?

Question sent to AISC's Steel Solutions Center

11-01-2006
Limit States for HSS Flexural Members

The table User Note F1.1 lists yielding, flange local buckling, and web local buckling as the limit states for rectangular HSS in bending. Are rectangular HSS in flexure not affected by unbraced length? Is there no lateral-torsional buckling mode? I know that HSS are good for torsion, but as you get to some oblong sections (say an HSS 16x4), I would think that lateral-torsional buckling should begin to affect the strength.

Question sent to AISC's Steel Solutions Center

11-01-2006
Nominal or Tensile Stress Bolt Area?

Why does Table 7-2 in the 13th Edition Manual use the nominal bolt area and not the net tensile area in determining the available tensile strength of the bolts? If I were to use a 1" diameter ASTM A490 bolt, Table 7-2 indicates a nominal area of 0.785 sq.inch and a tensile strength of 66.6 kips. But, if calculated based on the net tensile area of 0.606 sq.inch given in Table 7-18, the strength would be 51.4 kips. What am I not seeing?

Question sent to AISC's Steel Solutions Center

11-01-2006
Shop Camber - Field Measurement Conflict?

We seem to have a recurring issue with camber in composite floor systems. We mechanically camber the member in the shop, and our QC staff visually verify with a string line and tape that we have induced the specified camber per the shop/contract drawings. However in a number of cases, during surveys of the in-place members, as much as half of the camber we originally induced has relaxed out of the member.

We are familiar with Section 6.4.4 and the Commentary in the AISC Code of Standard Practice, and frequently provide our clients with a copy of it. We frequently ask the client to survey the floor prior to placing that concrete to address any related issues so that we can shore beams, if necessary. As indicated above, that's when we find that the camber is no longer the same as it was when it left the shop.

We're looking for any type of information that would help support the commentary in section 6.4.4 that it can only be measured in the shop and how to overcome the end user's perception of expected floor performance.

Question sent to AISC's Steel Solutions Center

11-01-2006
Use of "Actual" Tested Yield Strength for Design

Is it correct and permissible to use the "actual" tested yield strength of a square HSS (e.g., Fy = 49.3 ksi) in lieu of the "design" yield strength of ASTM A500 grade B (46 ksi) for the calculation of the flexural strength?

Question sent to AISC's Steel Solutions Center

11-01-2006
Edge Distance for Base Plate Hole

Is the minimum bolt edge distance on a steel base plate 2d (where d is the bolt diameter)? Is this typical? What about the relationship with the base plate thickness?

Question sent to AISC's Steel Solutions Center
10-01-2006
AISC Series B-3 Connection

I am reviewing a set of existing drawings dated 1953 to investigate proposed structural framing modifications. The drawings reference a B-3 connection. Is there a detail available of this connection?

Question sent to AISC's Steel Solutions Center
10-01-2006
Bolt Installation Method

When you are using snug-tightened bolts, is the proper installation method the "turn-of-the-nut" method?

Question sent to AISC's Steel Solutions Center
10-01-2006
No W8 Columns?

I was just looking up some preliminary column sizes in the 13th Edition of the AISC Manual and the W tables have been truncated at W8x31. I could have sworn there were smaller sizes, so I looked at the 2nd Edition LRFD Manual; it includes W8x24 and also lists W6s, W5s, and W4s. Have these shapes largely been supplanted by HSS sections and therefore deemed not worthy of book space? Why the change?

Question sent to AISC's Steel Solutions Center
10-01-2006
Non-Building Structure

I have an elevated walkway (20 ft high) that is foundation-supported. I understand the building code considers this a non-building structure. IBC 2003 refers you to ASCE 7 section 9.14.7, which gives you a different Table (9.14.5.1.1) for R values. I am using braced frames as the lateral system. For concentric braced frames ASCE refers you back to the typical Table 9.5.2.2. Do I now select special/ordinary/etc. braced frames and comply with all respective detailing, thus treating the walkway just like a building?

Question sent to AISC's Steel Solutions Center
10-01-2006
Shear Tabs on HSS

Equation K1-10 (2005 Spec) appears to be the only check required on the HSS wall for shear tabs on rectangular HSS shapes. Can you confirm that bending of the HSS wall does not need to be considered?

Also, for pipes or round HSS, what are the limit states for checking the HSS for a shear tab connection? For smaller pipes, it seems that arching will help, but as the diameter increases, and the surface becomes flatter, the shape more closely resembles a flat surface, like a rectangular HSS.

Question sent to AISC's Steel Solutions Center
10-01-2006
Tube Slot Tolerance

What is the recommended width tolerance of a slot in a tube structure that is to receive a plate? 1/8 in. larger? 1/16 in. larger?

Question sent to AISC's Steel Solutions Center
10-01-2006
Wireless Interference

During the design phase of a project our office is doing, we were asked by the client representative if choosing steel as the construction material (in lieu of concrete) will cause any potential wireless interference (the project is a hospital). The other concern was possible audible vibration (due to human activities and mechanical systems).

Question sent to AISC's Steel Solutions Center
10-01-2006
Beam Splice in Protected Zone

Are there any criteria in AISC 341-02, Seismic Provisions for Structural Steel Buildings, that would prohibit a beam splice outside the protected zone for an IMF in SDC D?

Question sent to AISC's Steel Solutions Center

09-01-2006
Bolt Hole Sizes
  1. Is there any difference in hole diameter for an expansion bolt vs. a normal bolt?
  2. Is there any difference in hole diameter for a tension control bolt (TC), vs. a normal bolt, vs. a slip critical bolt (SC)?

Question sent to AISC's Steel Solutions Center

09-01-2006
Column Base Anchorage

Is there a minimum strength in tension required between a column and a footing even though the column will never see any tension?

Question sent to AISC's Steel Solutions Center

09-01-2006
Historic Shape Information

I am working on modifications to an existing hotel in Manhattan that was built about 1928. I have access to some of the erection plans which indicate beam sizes for which I have no reference data, including a "CB" designation. Where can I find information on old rolled shapes?

Question sent to AISC's Steel Solutions Center

09-01-2006
Pipe or Tube?

What ASTM specification should I use for steel pipe? Should I use A53 or A500? I previously used A53, but I read in an article in MSC that we should no longer designate pipe as, say, 4 in. diameter schedule 40, but rather as HSS 4.5×0.237, and that I should specify A500 instead of A53. Which is correct?

Question sent to AISC's Steel Solutions Center

09-01-2006
Preheat Requirements

What are the preheat requirements for fillet welding a 3.5"-thick base plate to a W14x283 column?

Question sent to AISC's Steel Solutions Center

09-01-2006
WUF-W Connections for Special Moment Frames (A discussion of the subject by three seismic experts) 09-01-2006
100-Year-Old Steel

I am trying to determine the load-bearing capacity of a roof on a building that is about 100 years old. The steel has been identified as S9x19.75 (purlins) and S15x33 (girders). Is there any way, for purposes of calculations, to determine the yield strength of the members? I'm guessing it's unlikely that the members are ASTM A36 steel. What was standard for the time?

Question sent to AISC's Steel Solutions Center

08-01-2006
Bent Anchor Rods

I recently received an RFI stating that one of the four 11/4 in. diameter ASTM A307 anchor rods at one braced column was bent out-of-plumb by 22° and asking for a fix solution.

In the past I have seen steel workers swinging big sledgehammers to straighten crooked anchor rods. However, I am hesitant to recommend this practice. I would like to recommend that they heat the offending rod and bend it gently back into place using a large piece of pipe as a lever. Is this an acceptable way to straighten slightly bent anchor rods or is there a preferred or published methodology? Some related questions are "If heat is used, how much should they heat the rod?" and "Could this procedure be utilized for various grades of anchor rods?"

Question sent to AISC's Steel Solutions Center

08-01-2006
Grade 50 Angle Availability

Are angle shapes produced in Grade 50 material?

Question sent to AISC's Steel Solutions Center

08-01-2006
Metric Bolts

I would like to know the industry standard conversion for 1" ASTM A325 Imperial bolt to a Metric bolt. Please indicate the standard metric size bolt.

Question sent to AISC's Steel Solutions Center

08-01-2006
Seismic Requirements for Composite SLRS

I would like some clarification on the seismic design provisions of AISC 341-02, AISC LRFD-99 and the provisions of IBC 2003. Table 1617.6.2 of IBC permits designing steel structures as "Structural Steel Systems not Specifically Designed for Seismic Resistance." IBC 2205.3, "Seismic requirements for composite construction," states that in Seismic Design Category B or above, the design of composite systems shall conform to AISC 341, Part II. If I'm in a SDC C, and want to avoid "detailing for seismic", if I use R = 3, Ω0 = 3 and Cd = 3, can I design a composite system per AISC LRFD-99, without following AISC 341 Part II?

Question sent to AISC's Steel Solutions Center

08-01-2006
Seismically Braced Frame

I have a building in which I used X-braces to transfer the lateral loads to the foundations. In a few bays, I have to move the bottom of the braces up three feet from the finish floor elevation to allow access for doors. This building is in a high seismic area (Seismic Design Category E), and is a one-story building (approx. 18 ft to bottom of steel). Can this still be considered an Ordinary Concentrically Braced Frame?

Question sent to AISC's Steel Solutions Center

08-01-2006
Shear Tab Edge Distance

Table 10-9a of the 13th edition Manual appears to incorporate a vertical edge distance of 1 1/4 in. instead of 1 1/2 in.

I had read that the hole in shear tabs can get rounded up to 1/4 in. when the bolt goes into bearing. Also, when the plate is sheared, there is 1/4 in. of material that may be "mushed," and not counted as part of the material, which is the reason why you are permitted an edge distance of 1 in. for flame or saw cut edges, as compared to 1 1/4 in. for sheared edges. If this is true, then the final calculable vertical edge distance for the bottom bolt on these plates will be 3/4 in., after removing 1/4 in. for the "mush" from the shear, and then 1/4 in. for the vertical elongation from the bolt in bearing.

Question sent to AISC's Steel Solutions Center

08-01-2006
1945 Steel

We have a large manufacturing building that was designed in 1945 and built in 1946. Is it true that A7 steel with a yield stress of 33 ksi was used at this time and until 1964? Is it acceptable to use current design methods for allowable bending, tension, and compression using 33 ksi for the steel yield strength? The "Historical Record, Dimensions and Properties-Rolled Shapes" published by AISC and edited by Herbert Ferris references the 1936 AISC specification and states the allowable basic working stress to be 20 ksi. This appears to come from 0.6 Fy (assuming 33 ksi steel). Does this mean Fb = 0.66 Fy could not be used if applicable? We have a copy of the AISC fifth edition specification published in 1947. Were the unit stresses shown in Part III of the specification the same in the fourth edition, which we are assuming was used until 1947?

Question sent to AISC's Steel Solution Center

07-01-2006
Fireproofing HSS Beams

While there may be some structural advantages with HSS, there seems to be growing concern in the industry with fireproofing HSS when they are used as structural beams. Is spray-applied fireproofing a suitable method for protecting HSS beams? There do not appear to be any UL designs for fire protecting HSS beams. Can you address this common issue?

Question sent to AISC's Steel Solution Center

07-01-2006
Minimum Fillet Weld Size

Table J2.4 in the ninth edition ASD manual and the third edition LRFD manual shows the minimum sizes of fillet welds based on "thicker part joined." The new 13th edition manual is now based on "thinner part joined." Why has this changed?

Question sent to AISC's Steel Solution Center

07-01-2006
No More Group Numbers?

In the ninth edition ASD manual there is a table on page 1-8, Table 2. In the LRFD third edition, the table is found on page 2-27, Table 2-4. Can you please tell me where this table is found in the new 13th edition AISC manual?

Question sent to AISC's Steel Solution Center

07-01-2006
Thermal Cutting

Is it now permissible to use plasma or flame cutting methods to make bolt holes?

Question sent to AISC's Steel Solution Center

07-01-2006
Using OCBF in SDC D

We are designing a structure in accordance with IBC 2003, which references the AISC 341-02 Seismic Provisions for Structural Steel Buildings. We have an ordinary steel concentrically braced frame and are in Seismic Design Category C. Per IBC 2003 Table 1617.6.2, for an ordinary steel concentrically braced frame, special detailing should be provided per Chapter 14 of AISC 341-02. This chapter requires connections of bracing members to be connected for an expected tensile strength of RyFyAg. However, in Chapter 1 of AISC 341-02 under "Scope," it states that "These provisions shall apply to buildings that are classified in the applicable building code as Seismic Design Category D (or equivalent) and higher or when required by the engineer of record." Do we need to detail according to the Seismic Provisions requirements in Chapter 14 per IBC, or does the statement in Chapter 1 of AISC 341-02 allow us to not follow these provisions because we are in Seismic Design Category C?

Question sent to AISC's Steel Solution Center

07-01-2006
Weight of Paper

The AISC manual lists paper as weighing 58 lb/ft3. I have spoken with people in the file storage industry (condensed filing) and they use 40 to 43 lb/ft3. Do you know where AISC got the value they use and what it represents?

Question sent to AISC's Steel Solution Center

07-01-2006
Combined Loads on Anchor Rods

How do you design anchor rods for combined loads of tension, shear, and bending? What equation do you use to combine the forces?

Question sent to AISC's Steel Solutions Center

06-01-2006
Cruciform Columns and RBS

Is there any concern relative to using a cruciform column (symmetric column in both directions with one column web cut and welded to the other column web) in an SMF? If so, are there any design criteria or is there research regarding the use of this type of column? The column and beam combination in either direction are pre-qualified per FEMA 350.

Question sent to AISC's Steel Solutions Center

06-01-2006
Reduced Coefficient of Slip Resistance

I have a building that was designed as a special concentrically braced frame (R = 6). It is a one-story building, and most of the vertical braces were detailed to be shop or field welded. However, there are some horizontal connections that are to be field bolted. The AISC Seismic Provisions for Structural Steel Buildings require that the surfaces be prepared for slip resistance (Section 7.2), which we did. However, the contractor has accidentally painted over these holes, and the building is now erected. Would it be possible to use primer paint in place of a reduced coefficient of friction (lower than 0.33) to justify that the bolts have a lower than class A coating, but still satisfy the need to be slip-critical for the building?

Question sent to AISC's Steel Solutions Center

06-01-2006
Rod vs. Nut Strength

I understand the capacity of a threaded rod in tension is equal to the gross (nominal) area times 0.33Fu. Does the 0.33 factor include the effects of the potential for stripping of the threads of the rod through the nut placed at the rod end?

Question sent to AISC's Steel Solutions Center

06-01-2006
Shear Connection Capacities

I just received my copy of the 13th Edition Steel Construction Manual. Am I misreading these tables or have all of the connection capacities for ASD connections really been beefed up this much? For example, a shear tab connections with a 3⁄8 plate with two 3/4 bolts now can carry 21.2 kips.

Question sent to AISC's Steel Solutions Center

06-01-2006
Strength of Truss Connections

Section J1.5 of the 9th edition ASD Manual of Steel Construction states: "The connections at ends of . . . members in trusses shall develop the force . . . not less than 50% of the effective strength of the member . . ." Chapter 13 of the 13th edition Steel Construction Manual seems to indicate this is no longer required (see the paragraph titled "Minimum Connection Strength"). Is this correct?

Question sent to AISC's Steel Solutions Center

06-01-2006
Anchor Rod Embedment Detail

A contractor on one of my projects has substituted ASTM F1554 threaded rod with loose nuts in lieu of the specified headed anchor rods. Some of the rods are resisting tensile loads. It is my understanding that the nuts were not welded to the threaded rod as recommended by AISC Design Guide 1: Column Base Plates. Are there any additional recommendations for corrective action for anchor rods with loose nuts embedded in concrete that will be used to support tensile loads?

Question sent to AISC's Steel Solutions Center

05-01-2006
Axial Compression Capacity in March 2006 Steel Interchange

A response given for the question "Axial Compression Capacity" in the March 2006 edition of Steel Interchange (available at www.aisc.org/steelinterchange) was, in part, as follows: "For the 2005 AISC specification, we recognized that UM plates are no longer available and eliminated them from the determination of the resistance factor and factor of safety. As a result, phi is 0.9 and omega is 1.67 in the 2005 AISC specification; hence, the difference in strength you noted." I have checked both LRFD and ASD versions of the steel manuals cited below and here are the results:

  • LRFD 13th edition = 892 kips
  • LRFD 3rd edition = 844 kips
  • ASD 13th edition = 594 kips
  • ASD 9th edition = 608 kips
  • The explanation of the increased phi value for the LRFD version seems okay, as the new 13th edition manual states a higher load capacity compared to the previous LRFD manual. However, as you can see, the new ASD table in the 13th edition appears to have a lower capacity value compared to the previous ASD manual, which is the 9th edition. A decrease in omega, as explained in the article, should have resulted in a higher capacity in the new ASD table.

    What explains the decrease in load capacity, comparing the new 13th edition ASD table with the old 9th edition for the member size W14×132 and effective length of 30'?

    Question sent to AISC's Steel Solutions Center

    05-01-2006
    Bolt Bearing Resistance

    On page 10-124 of the 13th edition manual, rn = the nominal strength of one bolt in shear or bearing, kips. Please define "or bearing." Which bolt edge distance governs: the bolt closest to the edge of the connection material or the bolt in the interior of the connection? Furthermore, the specification on page 16.1-111 specifies, "For connections, the bearing resistance shall be taken as the sum of the bearing resistances of the individual bolts." Which is it?

    Question sent to AISC's Steel Solutions Center

    05-01-2006
    Determining Iz for Single Angles

    I am searching for a method to calculate the Iz of an L6×4×3⁄8. The rz is listed in the LRFD manual; but not the Iz.

    Question sent to AISC's Steel Solutions Center
    05-01-2006
    Historic Specification Issue Dates

    Where can I find historic information on old AISC manuals and standards like the AISC specification, Code of Standard Practice, RCSC specification, and common ASTM standards? Is there a separate list of the dates of publication of these standards?

    Question sent to AISC's Steel Solutions Center

    05-01-2006
    Overstrength Requirement for Seismic Design of Diaphragms

    When applying the amplified seismic load with a system overstrength factor of 2 as required by Table I-4-1 of the 2002 Seismic Provisions, what overstrength factor should be used for the roof diaphragm? Do I need to apply the same factor?

    Question sent to AISC's Steel Solutions Center

    05-01-2006
    Allowable Stress for Anchor Rods

    Where can I find the allowable shear stress values for ASTM F1554 grade 105 anchor rods?

    Question sent to AISC's Steel Solutions Center

    04-01-2006
    Bracing of Double Angle Diagonal

    What effective length should be used for diagonal double angle cross bracing? At the intersection, one set of double angles is continuous and the other is bolted or welded to a gusset plate. I reviewed literature that indicated the tension diagonal can be used to brace the compression diagonal. However, this was for single-angle cross bracing where each member is continuous at the intersection. It would be conservative to just use the diagonal length for out of plane buckling, but that may be more conservative than necessary.

    Question sent to AISC's Steel Solutions Center

    04-01-2006
    Column-Beam Moment Ratio

    What are the requirements for column-beam moment ratio for ordinary moment frames, if any, for Seismic Design Category A, B, or C? Do the strong column/weak beam requirements for special moment frames apply to OMF as well? Also, if there are requirements, do they change whether one is using the Seismic Provisions or the Specification for Structural Steel Buildings?

    Question sent to AISC's Steel Solutions Center

    04-01-2006
    Cruciform Column in SMRF Design

    Is there any concern relative to using a cruciform column (symmetric column in both directions with one column web cut and welded to other column web) in an SMRF? If so, are there any design criteria or is there any research regarding the use of this type of column? The column and beam combination in either direction are pre-qualified per FEMA 350.

    Question sent to AISC's Steel Solutions Center

    04-01-2006
    Principal Axes Properties

    I am looking for design section properties for steel angles with respect to the principal major and minor axes (as opposed to the x and y axis listed in the Manual). Is there a reference for this?

    Question sent to AISC's Steel Solutions Center

    04-01-2006
    Seismic Response Modification Coefficient (R-factor)

    The AISC Seismic Provisions state that these provisions are applicable for structures in Seismic Design Category (SDC) D or higher. Does this mean that even if one uses R > 3 in SDC A, B, or C he or she does not need to apply these provisions? At the same time, the same paragraph ("Scope") says that the provisions are intended for structures for which the seismic design forces have been determined in assumption of inelastic response. This tells me that if one uses R = 5, thus relying on inelastic response, he or she should use the provisions regardless of the SDC.

    Question sent to the AISC Steel Solutions Center

    04-01-2006
    Strong Axis Bending of a Flat Plate

    What is the formula for allowable stress for strong axis bending of a flat plate? I can find the weak axis of 0.75Fy, but no strong axis.

    Question sent to AISC's Steel Solutions Center

    04-01-2006
    1925 Steel Rivets

    What grade of steel rivets was used in 1925 steel construction? I am presently checking an existing steel girder's riveted connection capacity. I would like to confirm the allowable tensions (Ft) and allowable shear (Fv) of the 1925 rivets.

    Question sent to AISC's Steel Solutions Center

    03-01-2006
    Axial Compression Capacity

    The example column design problem from Charles Page's article in the November 2005 issue ("SpecWise: Design Examples," available at www.modernsteel.com) indicated that the 13th Edition Manual of Steel Construction lists an LRFD axial compression capacity of 892 kips for the W-shape. Looking up the same column shape and effective length in the LRFD third edition manual, I found that the compression capacity is 844 kips. This is a +6% of capacity. I did not know that increased capacity was incident to this specification change. Is that the case?

    Question sent to AISC's Steel Solutions Center

    03-01-2006
    Bolt Length

    What is the rule of thumb for how far bolts should extend above the nut--two threads, 1/2" to 1"? I saw in an old structural steel detailing book from the 1970s that this should be around 1/2" to 1". In looking at newer publications, I have not found any recommendation on how far these should protrude.

    Question sent to AISC's Steel Solutions Center

    03-01-2006
    Cb Factor for Frames Braced Against Joint Translation

    Why does the ASD ninth edition manual require the use of Cb = 1 when computing Fbx to be used in equation (H1-1) for frames braced against joint translation? Generally, the columns in frames braced against joint translation will have bending moments in-span smaller than bending moments at the ends. On the surface it would seem to be an appropriate application of the Cb term as a reflection of moment gradient.

    Question sent to AISC's Steel Solutions Center

    03-01-2006
    Cambered Beam Connection

    Is it preferable to provide short-slotted holes on at least one end of cambered floor beams? I have been told that this practice allows subtle beam end rotation to take place as the concrete is placed and the camber is relieved.

    Question sent to AISC's Steel Solutions Center

    03-01-2006
    Demand Critical Welds OMF

    We use OMFs with bolted end-plate moment connections (neither the flanges nor the web of the beam are directly welded to the column). Section 11.2c of the 2005 Seismic Provisions lists three specific cases when the CJP groove weld is demand critical. However, none refers to end-plate connections. This is also consistent with the user note in 7.3b. I would appreciate further explanation, as it appears that the 2005 Seismic Provisions impose no additional welding requirement for the type of end-plate moment connections we use in OMFs.

    Question sent to AISC's Steel Solutions Center

    03-01-2006
    HSS in 50 ksi Material

    Are hollow structural sections available in Fy = 50 ksi steel strength? If yes, how do you specify the HSS?

    Question sent to AISC's Steel Solutions Center

    03-01-2006
    Load Tests

    Does AISC have a test procedure for performing a load test on in-place steel? If yes, what publication is it in?

    Question sent to AISC's Steel Solutions Center

    03-01-2006
    Seismic Prequalified Connections

    I am designing a rigid-frame structure in California. I have heard that AISC has published the 2005 version of the Seismic Provisions and a new Seismic Design Manual with a list of prequalified connections. Is it true that these new connections will allow columns to a greater depth than the 14" limited by FEMA 350?

    Question sent to AISC's Steel Solutions Center

    03-01-2006
    Calibrated Wrench Pretensioning AISC's Steel Solutions Center recently received several questions related to calibrated wrench pretensioning: 02-01-2006
    Cantilevered Beam Stability Bracing

    Why does Appendix 6.3.1 of the 2005 AISC specification mandate that bracing be attached near the top (tension) flange of cantilevered members?

    Question sent to AISC's Steel Solutions Center

    02-01-2006
    Cleaning Steel for Fireproofing

    I have structural steel that will receive spray-applied fireproofing. To what specification should the steel be cleaned, if at all?

    Question sent to AISC's Steel Solutions Center

    02-01-2006
    Contract Addenda

    We are working on a waste water treatment plant. The structural drawings show pipe supports that are fabricated from structural shapes. They also show a detail referencing the mechanical drawings. The original bid set of drawings called for this material to be mild steel, but there was an addendum issued during the bid process. I reviewed the addendum for architectural and structural references, drawing numbers, or specification sections and found nothing referencing the pipe supports. This information was sent to our detailers and they also reviewed the addendum for architectural and structural references and found nothing. An addendum to the mechanical drawings referenced changes to this material. The material was revised from mild steel to stainless steel. Is it common practice for the fabricator to check all drawings and spec sections of the addendum for work related to architectural and structural steel?

    Question sent to AISC's Steel Solutions Center

    02-01-2006
    Seismic Brace-to-Gusset Plate Offset

    Figure C-I-13.2 of the 2005 AISC Seismic Provisions shows the brace end offset from the gusset bend line. This is recommended for SCBF. Would the same apply to OCBF or is there a different detail?

    Question sent to AISC's Steel Solutions Center

    02-01-2006
    Weld Interactions

    When using LRFD, is there a specific interaction relationship between loads applied to a weld both parallel and perpendicular to the weld at the same time? Can the full calculated capacity be taken in each direction, or must the loads be combined?

    Question sent to AISC's Steel Solutions Center

    02-01-2006
    Bent Anchor Rods

    What is the correct method for repairing a bent 1" diameter A36 anchor rod? The anchor rod is one of a set of four for a W10 column in the final structure. The bend is approximately 60 degrees and is located in the threaded region of the bolt, with no apparent cracking or kinks at the bend. Heating and bending has been brought up, but not decided on. Is this an adequate solution? If so, what codes or guidelines are available that discuss temperature, bending procedure, etc.

    Question sent to AISC's Steel Solutions Center

    01-01-2006
    Charpy V-notch Test Results

    My customer requires me to supply Charpy test results on raw material steel. Where can I get this information? The information is not available on the mill tests.

    Question sent to AISC's Steel Solutions Center

    01-01-2006
    Flame-Cut Bolt Holes/Residual Stress

    Are there any provisions for flame-cutting holes into steel members regarding residual stresses?

    Question sent to AISC's Steel Solutions Center

    01-01-2006
    Modulus of Rigidity for HSS

    I am trying to find the torsion in an HSS 12×12. I am having difficulty finding a value for the modulus of ridgity. I checked your manual and I couldn't find a value. Is this information available? The steel is governed under ASTM A500 grade B.

    Question sent to AISC's Steel Solutions Center

    01-01-2006
    Short Anchor Rods

    I have a column (gravity loads only) where the projected length of the anchor rod is too short. At best, the top of the nut is level with the top of the bolt. However, on some, the nut is 1/8"; above the top of the rod. Is there a way to determine the capacity with a partially threaded nut?

    Question sent to AISC's Steel Solutions Center

    01-01-2006
    Slot Dimensions

    How are slotted holes applied -- to the centers of the round portions of the holes (the dimensions given in the AISC Specification) or to the edges of the slot (out to out)?

    Question sent to AISC's Steel Solutions Center

    01-01-2006
    Slotted Hole Length

    All steel books I have read list lengths of slotted holes as either short or long. How about the lengths in between? The shop where I previously worked used 13/16" × 1 1/16" slot punches. Would this still be considered a short-slotted hole? I have always asked, "When does the length change from short to long?" No engineer whom I have asked has been able to provide an answer. How about slots longer than 13/16" × 1 7/8"? I would assume that it would be treated as a long slot. Is that right?

    Question sent to AISC's Steel Solutions Center

    01-01-2006
    Welding HSS

    When welding flat surfaces to rectangular HSS, a flare-bevel situation is created. The effective throat size is defined by Table J2.2 as 5/16 of the radius. I found a little information on this radius in the appendix of the HSS specification, but is there a comprehensive table somewhere? It seems like the inner and outer radii should be included in Table 1-11 with the rest of the dimensions.

    Question sent to AISC's Steel Solutions Center

    01-01-2006
    Composite Filled HSS

    I am interested in using concrete filled HSS, but I am concerned about load transfer between the steel and concrete. Specification I2.4 addresses concrete encased columns but is silent on concrete filled HSS. Commentary I2.4 states that bond is commonly used on fixed offshore platforms, but no guidelines are available for other structures.

    My application is "other structures," and in my application the load is applied to the HSS. Would shear connectors be required to ensure composite action, or can bond be used on other structures? What would be used for shear connectors on HSS, and what are the design criteria? How is bond stress evaluated?

    Question sent to AISC's Steel Solutions Center

    12-01-2005
    Seismic Category

    I attended an AISC staggered truss seminar, and I have questions regarding some braced frame requirements: We are doing an industrial structure in California, Zone 3. We cannot find anywhere in the 1997 UBC, 2001 CBC, or AISC seismic provisions whether we can use an OCBF in a Zone 3, or if the lateral system must be a SCBF. There is not a lot of difference between the two, but we have approximately six braced bays on six different levels. To be able to use our OCBF spreadsheet would be helpful.

    Question sent to AISC's Steel Solutions Center

    12-01-2005
    Shear on Anchor Rods

    Is there any new thinking or literature regarding anchor rods loaded primarily in shear? This is especially important in metal buildings where a shear key welded to the base plate normally does not exist. How do you handle the effect of oversized holes in base plates? I normally ignore this (unless the loads are high) and assume the shear forces are essentially resisted by the anchor rods.

    I can come up with mechanical or welded connectors of some type, but it seems to be a needless expense, given that failure of anchor rods in shear does not seem to be a recurring problem. I was told that there are some new guidelines from AISC, but I haven't found them on the web site.

    Question sent to AISC's Steel Solutions Center

    12-01-2005
    Steel Plate Shear Walls

    The Canadian Institute of Steel Construction recently presented a seminar on steel plate shear walls at our office. They mentioned that there is an AISC committee studying this subject. Is there any information on design procedures and R values for seismic load determination in accordance with IBC 2000 or IBC 2003?

    Question sent to AISC's Steel Solutions Center

    12-01-2005
    Trial Size for Composite Beam

    I am curious about the origin/calculation behind the equation for a trial beam size shown on page 5-26 of the AISC LRFD manual.

    Question sent to AISC's Steel Solutions Center

    12-01-2005
    Welding to Old Steel

    We are designing the rehab of several old buildings. In at least two of them, we have structural steel framing that we want to weld to. One was built in about 1901, the other in 1912.

    We are in the agonizingly slow process of getting the CM to contract with a testing firm to test the steel for weldability. The CM is not overly concerned because he says that almost any steel is weldable -- it's just a matter of picking the right electrode. Sounds too good to be true. Any comments?

    Question sent to AISC's Steel Solutions Center

    12-01-2005
    Backing Bar Removal

    When using a field bolted/field welded moment connection, is it AISC standard practice to leave the backing bar in place after the weld is complete?

    Question sent to AISC's Steel Solutions Center

    11-01-2005
    Base Plate Minimum Edge Distance

    Are there any standards for the minimum edge distance required for column base plate holes?

    Question sent to AISC's Steel Solutions Center

    11-01-2005
    Fatigue Based on Stress Calculation

    I have a column with a hot-rolled crane bracket fillet welded to the inside column flange. Table A-K4.2, Case 21, in the 1989 ASD specification seems to apply. I used the elastic (vector) approach to design the web-to-column flange weld. Should I just take the applied kips/in. that I used for the welds and divide that by the web thickness to get a stress in ksi? That seems like a slightly simplified and conservative method.

    Question sent to AISC's Steel Solutions Center

    11-01-2005
    Mill and Fabrication Tolerances

    I am being asked to help resolve a dispute between a steel erector and another subcontractor who is installing handrail to the side of a vertical C channel. I believe that the top of this channel got pulled in during erection so the web is no longer exactly vertical. I can't find anything specifically addressing this case in the Code of Standard Practice for Steel Buildings and Bridges (COSP), but I am probably just missing something.

    Question sent to AISC's Steel Solutions Center

    11-01-2005
    Seismic Provisions and Collector Design

    The definition of the seismic load resisting system (SLRS) in the 2002 seismic provisions glossary includes collectors. Does it follow that Section 7.2 (seismic bolting requirements) applies to collector design? If yes, then how can one design an axial bolted connection for a ductile limit state?

    Question sent to AISC's Steel Solutions Center

    11-01-2005
    Weld Access Hole Requirements

    I understand the detailing and fabrication requirements for weld access holes in moment connected beams have changed in the last few years. Could you give me information on what the new requirements are?

    Question sent to AISC's Steel Solutions Center

    11-01-2005
    Welding to Sheared Edges

    Is there data providing support to the theory that welding to a sheared edge of a connection angle is acceptable? Angle thickness will vary from 5/16" to 3/4".

    Question sent to AISC's Steel Solutions Center

    11-01-2005
    Beam Size

    I am working on a remodeling project in an existing building that was built in the 1905 to 1915 time range. I field measured an I-shaped beam as follows: d = 15", bf = 5.5" and tf = 0.5". Do you know its properties and designation? Its Fy?

    Question sent to AISC's Steel Solutions Center

    10-01-2005
    Drawings Conflict

    I'm looking for some documentation that states whether the contract drawings or the project manual (or specification) dictates when there's a conflict. The architectural drawings call for painted lintels, but the spec calls for galvanized lintels. Which one takes precedence?

    Question sent to AISC's Steel Solutions Center

    10-01-2005
    Gusset Plate Yield Line (from July 2005)

    We are currently detailing our first Special Concentric Braced Frame (SCBF) in Seismic Design Category D and have a question. We understand the concept of creating a yield line through the gusset plate. Our issue concerns the column base at the floor slab. The gusset plate will need to be huge to establish the yield line above the concrete slab because the slab would confine the brace and gusset, preventing the yield zone from forming. The best idea we can come up with is to wrap the gusset and brace end with a layer of compressible material, such as rigid insulation, prior to pouring concrete. Is this something that has been discussed or written about already? Does our idea seem reasonable? We are assuming that slab confinement is an issue here and would like to know if it is typically dealt with or simply ignored.

    Question sent to AISC's Steel Solutions Center

    10-01-2005
    Repairing Bent Anchor Rods

    I am currently working on a project where an installed anchor rod was bent during backfilling against a concrete wall. The anchor rod projection from the concrete was bent to a 45 degree angle and the contractor would like to "slowly heat the rod and straighten it." Is this an acceptable repair? It seems that this may weaken the rod. Is it better to remove the anchor rod in its entirety from the concrete? What is the typical repair for this type of damage?

    Question sent to AISC's Steel Solutions Center

    10-01-2005
    Shop and Erection Drawings

    Is there an AISC requirement that structural steel shop and erection drawings be prepared under the supervision of and stamped by a licensed professional engineer in the applicable jurisdiction, or that the drawings are to be reviewed and stamped by a P.E.? Is either of these criteria a requirement of AISC?

    Question sent to AISC's Steel Solutions Center

    10-01-2005
    Translating Between ASD and LRFD

    I thought the LRFD values for bending should be FyZx rather than FySx as shown in the web site document "Basic Design Value" (available at

    Question sent to AISC's Steel Solutions Center

    09-01-2005
    Hot-Dip Galvanizing and Vent Holes

    I have a situation with an HSS 10x6x3/8 fitted with WT connections that enclose both ends. It is exposed to the weather so it has been specified as hot-dip galvanized. The question has been asked if the HSS will need vent holes, and, if so, how many and on which side for dipping? I am of the opinion that we will not need holes. Am I correct in this assumption?

    Question sent to AISC's Steel Solutions Center

    09-01-2005
    Conduit and Composite Slabs

    Is it permitted to run electrical conduit in the concrete floor slabs of composite steel beams? If so, how does one determine or specify an amount or size of conduit permitted? What if a large amount of conduit crosses perpendicular to a beam at either the center span, where compression is a concern, or the near the support, where shear transfer isa concern?

    Question sent to AISC's Steel Solutions Center

    09-01-2005
    Seismic End-Plate Moment Connection

    There was a Steel Quiz answer (July 2005, question nine) that stated seismic moment end-plate connections are to be prepared as slip-critical bolted joints, but designed as bearing joints. The answer refers to Section 7.2 of the 2002 AISC Seismic Provisions for Structural Steel Buildings, but not the corresponding Commentary, which better explains the provision and specifically relaxes the requirement of faying surface preparation for moment end-plate connections.

    Question sent to AISC's Steel Solutions Center

    09-01-2005
    Shear on Anchor Rods

    I am working on a project that was built in 1957-1958 and I am trying to check the existing column anchor bolts for shear. I have the 6th Edition Manual of Steel Construction (1967) which gives shear values for ASTM A307, A7, and A373 steel (Fv = 10 ksi). Do you know what type of steel (Fv) was predominately used in the late 1950s for anchor bolts?

    Question sent to AISC's Steel Solutions Center

    09-01-2005
    Structural Steel Inspection

    My firm specializes in inspection and materials testing. I am looking for a publication that covers the basics of structural steel inspection. Do you have any recommendations from AISC's publications or other sources?

    Question sent to AISC's Steel Solutions Center

    09-01-2005
    Continuous vs. Intermittent Welds

    I am analyzing an existing steel truss constructed of various sizes of W14 beams. A few of the top chord members are over-stressed. Could plates be added between the flanges of the existing section to increase the effective ry? This would lower the kl/r value in the weak-axis and increase the capacity of the member. In a recent Modern Steel Construction, the issue of continuous welding vs. intermittent welding was addressed. Could intermittent welding be used in this case, or would a continuous weld be required?

    Question sent to AISC's Steel Solutions Center

    08-01-2005
    Maximum Spacing

    In Section J3.5 of the AISC 2005 Specification (www.aisc.org/2005spec), the maximum distance from the center of any bolt to the nearest edge of parts in contact shall be 12 times the thickness of the connected part under consideration, but shall not exceed 6". What is the basis of this requirement?

    Question sent to AISC's Steel Solutions Center

    08-01-2005
    Seismic Provisions: Application of Ry

    Can you please expand on what is meant by the statement found in AISC Seismic Provisions for Structural Steel Buildings dated May 21, 2002 in Section 6.2 regarding when Ry can be applied to Fy in the determination of the design strength. The statement reads as follows: When both the Required Strength and the Design Strength calculations are made for the same member or connecting elements, it is permitted to apply Ry to Fy in the determination of the Design Strength?

    Question sent to AISC's Steel Solutions Center

    08-01-2005
    Splices and CVN Toughness

    If we weld a heavy cross-section beam to column using a partial-joint-penetration (PJP) groove weld, does the member still need to have the required CVN values in the "k" area or is the CVN testing from the flange specimen good enough?

    Question sent to AISC's Steel Solutions Center

    08-01-2005
    Weak-Axis Moment Connection Plates

    We have a situation where connection plates are required at beam to column web moment connections. The beam flanges are attached to the connection plates with complete-joint-penetration groove welds. The connection plates are the same thickness and are the same grade of steel as the beam flanges. The bottom of the lower connection plates were detailed to be flush with the bottom of the bottom flange of the beam. The beams were overrun at the mill. The as-built condition is that the bottom of the bottom flange is lower than the bottom of the lower connection plate by 1/4 to 3/8 inch. Is there a tolerance allowance for a condition such as this? Can a small eccentricity between the center of the flange and the center of the connection plate be allowed?

    Question sent to AISC's Steel Solutions Center

    08-01-2005
    What are kdetailing and kdesign Values?

    In the 3rd edition LRFD Manual, there are two different k values listed for a given wide-flange shape. One is kdetailing and the other kdesign. Why is this and which one should I use?

    Question sent to AISC's Steel Solutions Center

    08-01-2005
    Anchor Embedment Length

    Is there a standard chart to indicate the average embedded length for bent rod anchor rods?

    Question sent to AISC's Steel Solutions Center

    07-01-2005
    Anchor Rod Grades

    An engineer has specified ASTM A325 hooked anchor rods for a project. Would it be acceptable to use ASTM F1554, Gr. 105 hooked anchor rods as a substitute?

    Question sent to the AISC's Steel Solutions Center:

    07-01-2005
    Bending of Tee Sections

    Please provide guidance on how to calculate the allowable bending strength for tee sections. We are assuming that when the flange is in compression, the member can be treated as an I-shaped beam. What about when the stem is in compression or when the beam is subjected to weak axis bending?

    Question sent to AISC's Steel Solutions Center

    07-01-2005
    Factors for Base Plates

    The ACI -factor for LRFD bearing is 0.65 while AISC allows 0.60. Which factor is an engineer supposed to use?

    Question sent to the AISC's Steel Solutions Center

    07-01-2005
    Gusset Plate Yield Line

    We are currently detailing our first Special Concentric Braced Frame (SCBF) in Seismic Design Category D and have a question. We understand the concept of creating a yield line through the gusset plate. Our issue concerns the column base at the floor slab. The gusset plate will need to be huge to establish the yield line above the concrete slab because the slab would confine the brace and gusset, preventing the yield zone from forming. The best idea we can come up with is to wrap the gusset and brace end with a layer of compressible material such as rigid insulation prior to pouring concrete. Is this something that has been discussed or written about already? Does our idea seem reasonable? We are assuming that slab confinement is an issue here and would like to know if it is typically dealt with or simply ignored.

    Question sent to AISC's Steel Solutions Center

    07-01-2005
    Use of Shims

    I am going to use oversized holes in flange-plated moment connections to a column utilizing slip-critical bolts. I would like to allow the erectors some leeway by letting them use shim plates between the flange plates and beam flanges. My questions are:

    1. Should shims be utilized at both the top flange and the bottom flange simultaneously, or just at either the top or bottom?
    2. What is the suggested maximum shim thickness? Can I just use that shown in Figure 3-4c on page 3-8 of the ASD 9th Edition Connections Manual?
    3. Is there a minimum shim thickness?
    4. Based on that shown on page 3-12 of the Connections Manual, is it correct to assume that either conventional or finger shims are permitted, even if the bolts are slip-critical in oversized flange plate holes?

    Question sent to AISC's Steel Solutions Center

    07-01-2005
    Constructability

    We are designing a one-story strong beam/weak column moment frame. The small columns we specified are W6x25s. They work fine in terms of structural capacity, but the fabricator is having trouble making the connections. They requested that the design be changed to a strong column/weak beam moment frame. Any thoughts?

    Question sent to AISC's Steel Solutions Center

    06-01-2005
    Continuity Plates for IMF

    For the case of steel intermediate moment frames in dual systems, are continuity plates required if the requirements of FEMA 350 equations are met,

    or are continuity plates always required? When are stiffener plates not required in steel intermediate moment frames?

    Question sent to AISC's Steel Solutions Center

    06-01-2005
    Design of HSS Base Plates

    I know that there is a different method to use in designing the base plates of an HSS column as opposed to that for a W-shape. What equation is used for HSS bases, and how does one determine the area of the plate needed?

    Question sent to AISC's Steel Solutions Center

    06-01-2005
    Fire Resistance of Concrete-Filled HSS Columns

    I have HSS16x16 concrete-filled tubes. In AISC's Design Guide 19, it appears that because the section is larger than 12", fire protection is required. Is there any additional research that includes larger sizes of HSS filled with concrete that will meet fire code criteria?

    Question sent to AISC's Steel Solutions Center

    06-01-2005
    Minimum Percentage of Composite

    According to Section I4 of the 1989 ASD Specification, the value of V'h for shear connectors used in composite construction is not permitted to be less than 1/4 the minimum of Equation (I 4-1) or (I 4-2). If the number of connectors provided is less than required to induce a horizontal shear capacity equal to 1/4 the shear capacity of the section, can V'h still be calculated and a composite section assumed or should the assumption be zero composite action with the steel beam resisting the total load?

    Question sent to AISC's Steel Solutions Center

    06-01-2005
    Punching Shear

    When designing a single-plate shear connection for a beam-to-HSS column (Figure 4-4 in the HSS Connections Manual), the limit state of punching shear in the HSS wall is checked. In the procedure for a single-plate connection to a girder web (Example 10.12 in the 3rd Ed. LRFD Manual), there is no punching shear check on the web. Are the restraints sufficiently different so it is not a likely failure mode? Has there been any research on the shear-plate connection to a web?

    Question sent to AISC's Steel Solutions Center

    06-01-2005
    Bolted End Plate Moment Connections

    Page 4-116 of the 9th edition ASD Manual indicates that an end plate moment connection can only be used for static loading. However, I have just purchased Design Guide 16, and I cannot find anything that would indicate that this connection must only be used for a static loading condition. Can this connection be utilized for seismic and wind moments?

    Question sent to AISC's Steel Solutions Center

    05-01-2005
    Continuous Versus Intermittent Weld

    Can you guide me as to how to decide or choose between using continuous or intermittent fillet welds?

    1. For a crane girder beam (I beam with channel on top) whether intermittent welding can be permitted.
    2. For built up columns and beams whether intermittent welding can be considered and if so under what situations.

    Question sent to AISC's Steel Solutions Center

    05-01-2005
    Erection Plan

    We have been asked to supply an AISC erection plan on a U.S. Army Corps of Engineers project that requires a Certified Fabricator, but not a Certified Erector. Is there such a thing as an AISC Erection Plan?

    Question sent to AISC's Steel Solutions Center

    05-01-2005
    IMF/Pre-qualified Moment Connections

    Pre-qualified moment connections in FEMA are for special and ordinary moment frames, not for intermediate moment frames. Must we use the pre-qualified FEMA special moment frame connection for an intermediate moment frame defined in AISC? Or can we use the FEMA pre-qualified moment connection of ordinary moment frame for intermediate moment frame defined in AISC?

    Question sent to AISC's Steel Solutions Center

    05-01-2005
    New ASD/LRFD Combined AISC Code

    How will the new combined code handle the different loadings requirements for the two design methods? Surely the loading requirements for the LRFD method will not change.

    Question sent to AISC's Steel Solutions Center

    05-01-2005
    Welded Moment Connections

    I am looking for the bevel angle, size, and length of weld, etc. for a moment connection.

    Question sent to AISC's Steel Solutions Center

    05-01-2005
    Welder Qualifications

    We are involved in the design of a roof framing system comprised of a two-way grid of trusses. The trusses have round HSS web members and round HSS bottom chords. There are other portions of the project that involve standard wide flange framing. In our specifications, is it sufficient to require that welders be certified per AWS D1.1? Is there any additional certification required for tubular members? We have a lot of critical welds connecting round HSS to other round HSS as a part of the roof truss framing, but I do not know if that alone requires additional certification.

    Question sent to AISC's Steel Solutions Center

    05-01-2005
    Architecturally Exposed Structural Steel

    I am working on a project where the architect wants to specify Architecturally Exposed Structural Steel (AESS) for the braced frame. I am hoping there are some standardized requirements so that the architect, engineer, fabricator, and erector are on the same page. Does AISC have a specification for AESS? The best information that I have located (so far) is the May 2003 supplement to Modern Steel Construction.

    Question sent to AISC's Steel Solutions Center

    04-01-2005
    Balanced Welds

    I seem to remember when an angle is welded to a gusset plate that the weld should be "balanced" about the angle's neutral axis. Can you direct me to a code reference or design guide that confirms my recollection?

    Question sent to AISC's Steel Solutions Center

    04-01-2005
    HP Shapes

    HP Shapes

    What does a steel shape that is called HP 10x57 look like? We have never run across this before nor has our steel supplier.

    Question sent to AISC's Steel Solutions Center

    04-01-2005
    Moment Connections to HSS Columns

    We have designed a moment-resisting frame consisting of wide flange beams and HSS columns. The applicable building code is IBC 2003. We have used an ordinary steel moment frame (OMF) with R = 3.5. We have detailed the connection to consist of column through-plates (horizontal) at the beam flange elevations, and complete penetration groove welds of the beam flanges to these thru-plates. The welds specified conform to AISC's Seismic Provisions for FR moment connections (including backing bar detailing, removal, and reinforcing welds). We received a phone call from a fabricator who told us he thought AISC does not permit using an R factor greater than 3 for moment frames with HSS columns. Is this true?

    Question sent to AISC's Steel Solutions Center

    04-01-2005
    One-Third Stress Increase

    This regards designing for block shear per page 4-8 of the 9th edition ASD Manual. Is it permissible to increase allowable loads resulting from these calculations by 1/3 for seismic loads per UBC 1612.3.2? Can these results be increased by 1.7 per UBC section 1633.2.6 for collector elements?

    Question sent to AISC's Steel Solutions Center

    04-01-2005
    Shop Inspection

    Do all components require inspection prior to leaving the fabricator for erection, even if it has been verified that the fabricator meets all the requirements for certification?

    Question sent to AISC's Steel Solutions Center

    04-01-2005
    Stud Weld Substitution for Deck Weld

    Does a welded stud take the place of a puddle weld on decking installation?

    Question sent to AISC's Steel Solutions Center

    04-01-2005
    Welding ASTM A992 Steel

    ASTM A992 is noted in the AISC LRFD Manual as the preferred structural steel for W-shapes. Does A992 have the same welding properties as the old A36?

    Question sent to AISC's Steel Solutions Center

    04-01-2005
    Design of Cantilever Beams

    The following is a brief paper presenting one engineer's opinion on design parameters for use with cantilever beams. The author has included a list of pertinent reference sources on the subject.

    Cantilever Flexural Member Design
    By Sam Eskildsen, P.E., Structural Design Group, Birmingham, AL

    03-01-2005
    Expansion Joints Required for Temperature

    I am designing a steel structure with 960' x 450' plan dimensions. Where can I find the design guideline for setting and designing expansion joints? Is it possible to design the structure without expansion joints if the architect does not want the joints?

    Question sent to AISC's Steel Solutions Center

    03-01-2005
    Minimum Flange Thickness for Welding Studs

    I am looking for information on what the minimum flange thickness requirements are for welding shear studs for composite action. Because I do not know what the actual weld size is, I cannot determine what the minimum flange thickness should be. We do specify 1/4" minimum.

    Question sent to AISC's Steel Solutions Center

    03-01-2005
    Tightening Tension Control Bolts

    On one of our projects, the EOR specified snug-tightened bolts for the majority of the connections. The erector chose to use twist-off bolts for the entire job. He snapped off all the splines without telling the EOR. As the inspector, should I approve them?

    Question sent to AISC's Steel Solutions Center

    03-01-2005
    Bottom Flange Bending Capacity (reprinted from December 1999)

    How do you calculate the lower flange loading capacity of a steel beam to be used to support an underhung crane? Are there any published ASD or LRFD design procedures?

    Question sent to AISC's Steel Solutions Center

    02-01-2005
    Edge Distance and Load Direction

    When shear is considered in a direction perpendicular to a bolt holes edge distance can the edge distances of table J3.4 of Specification Chapter J be reduced? If so by how much can it be reduced and is there a reduction in load capacity.

    Question sent to AISC's Steel Solutions Center

    02-01-2005
    Preheat & Stud Welding

    Preheat and Stud Welding (from November 2004)

    I have two questions:

    1. When welding headed stud to beams or plates using the standard welding gun, are there any requirements to preheat the base material in cases where the base material is, say, 2" to 3" thick or more? I know that when the stud is fillet welded, AWS specifies the base material to be preheated but there is no mention of preheat when the stud gun is used.
    2. Lastly, what problems can be expected if proper preheat is not provided and conventional fillet welds are used? Cracks in base metal? Cracks in weld? Other?

    Question sent to AISC's Steel Solutions Center

    02-01-2005
    Rehabilitation of ASTM

    Rehabilitation of ASTM A9 Steel and Rivets (from September 2004) We are reinforcing connections of an existing building from 1925 and have a few questions regarding the design approach that should be taken:

    1. We have done coupon tests for a beam and a column and the lab qualified the structural steel as ASTM A36 with Fy = 36 ksi. Can we assume that the angles and plates forming the different connections are made of the same material?
    2. The majority of the connections are riveted. Others are bolted. Can we assume that the riveted connections are slip-critical and therefore can be combined with new weld to enhance the connection capacity? In this respect we assume that the bolts are in bearing and their capacity should be ignored when reinforcing the existing connection with weld. Please advise.
    3. Based on an old AISC manual we have found that the maximum 3/4" diameter hand driven rivet capacity in shear is 4.42 kips. We assume this is a slip-critical value. Is there any corresponding bearing capacity or does it not exist in rivets.
    4. The rivet capacity in shear based on the old AISC manual is controlled by bearing (subject to the supporting member thickness) indicating different values for single and double shear. Are those values governed by the bearing on the rivet hole or bearing on the rivet itself. We are uncertain since the rivet material is weaker than the structural steel.
    5. We are considering reinforcing the riveted shear connections in two ways: a.Replace old rivets with new high strength bolts. b.Add weld around the connecting angles. If both ways are acceptable to the contractor, which solution is more cost effective?

    Question sent to AISC's Steel Solutions Center

    02-01-2005
    Single-Angle Shear Connection Eccentricity

    Regarding single-angle connections with the "girder" leg welded and the "beam" leg bolted, the strength is apparently based on eccentric shear in the plane of the weld. Why is the eccentricity normal to the plane of the weld (distance to the bolt line) not also considered?

    Question sent to AISC's Steel Solutions Center

    02-01-2005
    Base Plate Edge Distances

    Anchor traditionally have holes in base plates and in the anchor chairs/seats larger than is customarily provided for steel-to-steel connection bolts. What are the guidelines for edge distances for these holes? I have some field-enlarged holes for 1 3/4" dia. bolts in an anchor seat/chair that are 3 1/2" in dia. What edge distance criteria should I use? We plan to use 1"x5"x5" plate washers under the nuts for these bolts.

    Question sent to AISC's Steel Solutions Center

    01-01-2005
    Field Cutting of Openings

    What is the correct method for field cutting new openings in the web of a steel beam? The beam is already erected and the opening locations are acceptable.

    Question sent to AISC's Steel Solutions Center

    01-01-2005
    Older Steel Grades

    For a building constructed in 1961, what would have most likely been the specified yield stress for the steel? Would steel meeting ASTM A7 have been the typical steel used? Would the yield for A7 have been 33,000 psi?

    Question sent to AISC's Steel Solutions Center

    01-01-2005
    Rotational Ductility of Shear Connections

    I received a response from the AISC Steel Solution Center concerning the rotational ductility of an all-welded shear tab connection. The response stated that they did not recommend this detail due to its inability to provide adequate rotational ductility -- i.e. the lack of bolts eliminates plowing action against the tab holes as a means for accommodating beam end rotation. Another question has arisen, where the fabricator has detailed double angle connections that are welded to the beam web and then bolted (or welded) to columns or girder beams. The ninth edition ASD Manual, Chapter 4, clearly denotes the use of these two types of connections. Could you please explain why these two types of connections seem to be permissible when it appears as though the same situation as the "all welded shear tab connection" applies? Do these configurations assume the bolts in these connections can elongate to allow free rotation?

    Question sent to AISC's Steel Solutions Center

    01-01-2005
    Wind Connections

    I am reviewing a steel building constructed in 1950 (no existing drawings). I don't see any braced frames in the structure, but find that the beam-to-column detail is built as a standard double-angle three-bolt shear connection, also with a top and bottom angle with bolts to the column flange and the other leg welded to the beam flange. This appears to be a semi-rigid connection for a moment frame. Was this approach widely practiced back in the 1950s?

    Question sent to AISC's Steel Solutions Center

    01-01-2005
    All-Welded Single-Plate Shear Connection

    I believe there is an inherent difference between the "classic" shear tab with one end welded and one end bolted, and an "all-welded" single plate connection, correct? Does a bolted/welded shear tab allow rotation via bolt hole deformation and/or bolt oversize? I haven't found any information on single plate connections with both plate ends welded. My concern is that these all-welded connections allow end rotation of the supported beam. I have a construction project where the detailer specifies single plate, all-welded, simple shear connections. I spoke with him and he told me he details this type of connection all the time. He insists this isn't a problem because the beam web (in this case 0.20" thick), will experience a small amount of local yielding before the welds or shear tab yield (plate is 5/8" thick), which will allow for a small end rotation and hence provide a "simple shear" connection. Is this argument valid? I'm concerned the web could rupture or yield excessively.

    Question sent to AISC's Steel Solutions Center

    12-01-2004
    Anchor Rods Under Combined Tension & Shear

    I am looking for some insight into the tension shear interaction for ASTM F155-Grade 55 anchor rods. Using ASD, Table J3.2 indicates the allowable stress on fasteners and Table J3.3 indicates the allowable tension based on the shear, however these tables are specific to A307, A325, A490, and A449 bolts. Since the transition to the ASTM F1554 for anchor rods, is there an updated recommendation for this interaction? If there is not an updated recommendation, is the use of the interaction based on a corresponding material with a similar Fu, the most appropriate solution?

    Question sent to AISC's Steel Solutions Center

    12-01-2004
    Narrow Columns with Continuity Plates

    I am designing a moment connection between a W24x117 beam and a W18x46 column. The W18x46 column was sized to fit in a 6" wall. The beam is in a duct area, so width was not an issue. The column requires web stiffeners and LRFD Specification Section K1.9 (1) requires that the stiffener width be equal to one third of the beam flange width plus one half of the column web thickness. This equates to 12.8/3 + 0.36/2 = 4.1", which is problem due to the fact that my column width is only 6" and the stiffener would be past the column flange. Is it permissible to put in the required width of column web stiffeners, say 4 1/4" wide, and then notch the web stiffener the thickness of the column flange so that it meets back up with the abutting flange of the connecting beam? I don't know if it is allowed to have the web stiffener stick out past the column flanges to meet the requirement of LRFD Specification Section K1.9 (1).

    Question sent to AISC's Steel Solutions Center

    12-01-2004
    Slender WT Stem in Flexural Compression

    I am trying to design a WT with its stem in flexural compression per the 1999 LRFD Specification. The member has a slender stem and I have calculated Qs in accordance with Appendix B5.3a. I have checked the flexural limit states of yielding and lateral-torsional buckling strength per Section F1.2c. Does the reduction factor Qs apply to the lateral-torsional buckling strength and the yield strength? Or does it apply only to the yield strength?

    Question sent to AISC's Steel Solutions Center

    12-01-2004
    Welding to Galvanized Steel

    Where can I find reference material (with paragraph number) to prove to the contractor that the galvanization layer from galvanized steel members must be removed before welding these members together? In other words, the presence of zinc in the weld may weaken the weld capacity and be a source of health concerns for the qualified welders.

    Question sent to AISC's Steel Solutions Center

    12-01-2004
    Composite HSS Column-Minimum Wall Thickness

    Table 4-13 (Composite HSS Compression Members) in the 3rd edition LRFD Manual seems to include HSS that will not satisfy the minimum thickness requirement found in Section I2.1 of the 1999 LRFD Specification. For example, for an HSS 16x16x3/8, the minimum t would be 0.368". This is greater than the listed tdesign = 0.349", but is less than the nominal t of 0.375". Should we be using the nominal thickness rather than the tdesign for the minimum t criteria (which would contradict what is currently used for W-shapes, for example) or should this HSS be "disqualified"?

    Question sent to AISC's Steel Solutions Center

    11-01-2004
    Grout Packs & Base Plates

    Is there a maximum thickness recommended for a grout pack (assume a non-shrink grout) under a column base plate? Assume there are leveling nuts under the plate. Assume a multi-story structure. Would the grout thickness be predicated on the thickness of the base plate and the open space beneath it? Assume the method or placement (packed, poured, injected) will adequately fill the space between the concrete pier, footer, etc. and the underside of the base plate.

    Question sent to AISC's Steel Solutions Center

    11-01-2004
    Notches in Wide-Flange Beams

    If you take away most of one side of a top flange of a steel beam, say an 8" flange and on one side you notch out 3", what are some acceptable methods of reinforcement? There will be a pipe going through the notch, and I cannot do anything from the top. Is welding a plate of sufficient area to the underneath of the opposite flange ok? I see how this will replace the section modulus and compressive block that I am losing, but I am concerned with how the internal stresses of the beam "jump" from one side to the other.

    Question posted on SEAINT (www.seaint.org)

    11-01-2004
    OHSA & Double Connections

    We are reviewing our detailing standards and, the question of what "exactly" is required by OSHA concerning double connections was asked. I am sure you have addressed this question many times and hopefully have an (end all) answer. Could you please help us to clear up the confusion we have concerning this issue?

    Question sent to AISC's Steel Solutions Center

    11-01-2004
    Preheat & Stud Welding

    I have two questions:

    1. When welding headed studs to beams or plates using the standard welding gun, are there any requirements to preheat the base material in cases where the base material is say 2- or 3-inches thick or more? I know that when the stud is fillet welded, AWS specifies that the base material must be preheated but there is no mention of preheat when the stud gun is used.
    2. What problems can be expected if proper preheat is not provided and conventional fillet welds are used? Cracks in base metal? Cracks in weld? Other?

    Question sent to AISC's Steel Solutions Center

    11-01-2004
    Seismic Provisions & Bolted Joints

    I am required to use the 1997 AISC Seismic Provisions for a braced frame detail with typical loads and configuration, except that it has a significant axial transfer force from the beam to the column. The only way to get this transfer force from the beam into the column (sometimes to the flange and sometimes to stiffeners in the column web) is to weld the flange directly to the column. The weld is a CJP groove weld.

    Is it still allowable to use pretensioned bearing bolts in the gusset to column connection (again, it might be to flange or web)? The gusset to column connection is either two angles or an end plate with shear plates along the column web.

    My opinion is that pretensioned X-bolts are acceptable in this situation, since the weld is not sharing load in the same axis with the bolts and since the CJP groove weld in the beam flange to column, if properly detailed with proper weld access holes, will have sufficient ductility/flexibility to accommodate the small potential slip under full load. What about low-seismic situations?

    Question sent to AISC's Steel Solutions Center

    11-01-2004
    Beam Stability under Reverse Loading

    A composite steel beam (W12x19) with concrete on metal deck diaphragm 4" total thickness is loaded with uplift. Can we assume that although the slab is at the tension flange it still restrains the beam against lateral-torsional buckling, so that only local buckling of flange/web has to be checked?

    Question sent to AISC's Steel Solutions Center

    10-01-2004
    Fillet Weld Design Strength Increase

    I have a project for which I am using flange-welded moment connections. The fabricator has asked us to look into the possibility of replacing the full-penetration weld from the plates to the column flanges with two-sided fillet welds, sized to achieve the same capacity as the full-penetration welds. However, my supervisor believes there is some issue with fillet welds in direct tension, and that he is not comfortable with this connection as proposed by the fabricator. Can you refer me to any publication that shows the fillet welds are not the preferred way of making the connection?

    Question sent to AISC's Steel Solutions Center

    10-01-2004
    HSS Connection Economy

    Which is more economical to specify-shear tabs or through-plates when connecting a wide-flange beam to a HSS column?

    Question sent to AISC's Steel Solutions Center

    10-01-2004
    Knee Braces on Crane Support Columns

    It is my understanding that the practice of placing knee braces from crane support columns to the underside of crane support rails is not acceptable (in the past this was done to reduce the unsupported length of the crane rail). Just what is the reason for elimination of the knee braces?

    Question sent to AISC's Steel Solutions Center

    10-01-2004
    Prequalified Shop Welding

    I have a number of "cripple" beams where the engineer of record calls for the web and flanges to be complete penetration welded at the miter. Since the beam size is such that the flange and web are less than 5/16" thick, I would like to detail the piece with out prepping the flanges or web and use the designation B-L1b-GF. Is it reasonable to believe that most shops and the field can use this welding process?

    Question sent to AISC's Steel Solutions Center

    10-01-2004
    Pretensioning Low-Strength Anchor Rods

    We have a project that is all braced frame construction. The anchor rods specified were ASTM A36 from 1 3/4 to 2 1/2 diameters. The design specifications are requiring us to pretensioned A36 anchor rods to the minimum yield point specified for A36 steel. They request that this be done by the turn of nut method as indicated by the RCSC Specification for Structural Joints using ASTM A325 or A490 Bolts. This does not appear correct to our people. We see no correlation between RCSC and A36 anchor rods. Please give us your thoughts.

    Question sent to AISC's Steel Solutions Center

    10-01-2004
    Reduction in Stud Shear Connection Design Strength

    Section I3.5b in the 1999 LRFD Specification limits Nr to the "number of stud connectors in one rib at a beam intersection, not to exceed three in computations, although more than three studs may be installed." My question is does the above definition mean that more than three studs can be installed and counted on for strength but that only in equation I3-1 need the value for the parameter Nr be limited to a maximum value of three? Or does it mean that never more than three studs per rib at a beam intersection can be counted for any part of composite design?

    Question sent to AISC's Steel Solutions Center

    10-01-2004
    Anchor Rods Under Cyclic Loads

    I am looking for the tensile capacity of an ASTM F1554 anchor rod grade 36. In LRFD, its nominal strength is listed in Table J3.2 as 0.75(0.75F)A. However it is noted at the bottom of the page that this is only for static loads. What value should be used if anchor rods are exposed to fatigue loads?

    Question sent to AISC's Steel Solutions Center

    09-01-2004
    ASTM A490 Bolts and Fatigue Loads

    Can I use A490 bolts in structures subjected to fatigue loads, such as bridges? I thought I remembered the answer was no.

    Question sent to AISC's Steel Solutions Center

    09-01-2004
    Fillet Weld Terminations

    I am trying to clear up some confusion about fillet weld termination. We are fabricating beams for a 20-story building which have 1" gusset plates welded to top flanges of various large W shapes. The shop we are subletting some of the work to is terminating the fillet welds anywhere from 1/4" to 3/4" from the ends of the beams (welds vary from 5/16" in size to 5/8"). I say when a designer says to put fillet welds on both sides he means the total length of welds sides with no end termination. Could you please show me specifically where this issue is addressed and what exactly is acceptable?

    Question sent to AISC's Steel Solutions Center

    09-01-2004
    Rehabilitation of ASTM A9 Steel and Rivets

    We are reinforcing connections of existing building from 1925 and have a few questions regarding the design approach that should be taken:

    1. We have done coupon tests for a beam and a column and the lab qualified the structural steel as ASTM A36 with Fy = 36 ksi. Can we assume that the angles and plates forming the different connections are made of the same material?
    2. The majority of the connections are riveted. Others are bolted. Can we assume that the riveted connections are slip-critical and therefore can be combined with new weld to enhance the connection capacity? In this respect we assume that the bolts are in bearing and their capacity should be ignored when reinforcing the existing connection with weld. Please advise.
    3. Based on an old AISC manual we have found that the maximum 3/4" diameter hand driven rivet capacity in shear is 4.42 kips. We assume this is a slip-critical value. Is there any corresponding bearing capacity or does it not exist in rivets.
    4. The rivet capacity in shear based on the old AISC manual is controlled by bearing (subject to the supporting member thickness) indicating different values for single and double shear. Are those values governed by the bearing on the rivet hole or bearing on the rivet itself. We are uncertain since the rivet material is weaker than the structural steel.
    5. We are considering reinforcing the riveted shear connections in two ways:
      1. Replace old rivets with new high strength bolts.
      2. Add weld around the connecting angles.

    If both ways are acceptable to the contractor, which solution is more cost effective?

    Question sent to AISC's Steel Solutions Center

    09-01-2004
    Column Splice Gaps

    We have gaps at our column splices and are aware that a gap of 1/16" or less can be ignored. Is there something in writing that discusses the philosophy behind this statement?

    Question sent to AISC's Steel Solutions Center

    08-01-2004
    Cracks Over Composite Beams

    Do concrete cracks over composite beams affect the composite action of the beam? How can such cracking be prevented?

    Question sent to AISC's Steel Solutions Center

    08-01-2004
    Panel-Zone Web Sheer

    For the 1997 AISC Seismic Provisions, can an OMF connection be designed with panel-zone web shear as the primary source of inelastic deformation or as a way to utilize the exemption for the maximum force that can be transferred by the system?

    Question on SEAINT list server

    08-01-2004
    Sloped Column Continuity Plates

    If two moment girders frame into a column joint at offset elevations (3" or so), should skewed continuity plates in the column web adjoin the adjacent girder flanges, top and bottom and each side of the web (4 total), or is it better to add flat/level continuity plates at each girder flange, (8 total)?

    Question sent to AISC's Steel Solutions Center

    08-01-2004
    Specifying Connection Design Forces

    In preparing specifications for structural steel, is it common practice to have connections designed for 50% of member capacity? If so, is this a service load or factored load? What are your recommendations on how to properly specify connection design forces?

    Question sent to AISC's Steel Solutions Center

    08-01-2004
    Weak-Axis Lateral-Torsional Buckling

    In the April 2004 issue of Modern Steel Construction, the following Q/A was published:

    True or False: A shape bent about its weak axis must be checked for lateral-torsional buckling.

    The answer given was:

    False: Lateral-torsional buckling is a phenomenon that occurs only when rotation would produce a lower energy position for that shape. A shape bent about its weak axis is already in its lowest energy position.

    Question sent to AISC's Steel Solutions Center

    08-01-2004
    Backing Bar Removal

    We're designing an OMF using the IBC 2000 in Seismic Design Category "A". FEMA 350 states that lower flange backing bars should be removed to allow identification and correction of weld root flaws. On this project, the welding of the OMF joints is being observed full-time by inspectors. The question is now being asked, why are the backing bars specified to be removed? If the root pass is being observed by inspectors as it is installed, and is certified by those inspectors as being a good weld, why do we need to remove the backing bars to look at the weld again?

    As the Engineer of Record, I find these arguments for leaving the backing bars in place to be compelling, but I'm not a weld expert. Can you offer me any guidance on this issue? Could the backing bars be left in place without causing problems?

    Question sent to AISC's Steel Solutions Center

    07-01-2004
    Filling Weld Access Holes

    Please provide some opinions and guidance as to filling weld access holes in beam and column splices with weld metal for appearance sake. The AWS D1.1 welding code does not appear to address the issue. In your experience, do you usually leave them open or fill them?

    Question sent to AISC's Steel Solutions Center

    07-01-2004
    Grouting Base Plates

    We were told by a steel erector that they typically do not remove shims from column base plates after grouting. They also informed us that they do not back off leveling nuts below the base plates during the grouting process. Are these practices acceptable?

    Question sent to AISC's Steel Solutions Center

    07-01-2004
    Seperators in Double Angle Struts

    In the 3rd edition LRFD Manual, page 16.1-205 (or Commentary Section E4 in the 1999 LRFD Specification) states that for built-up compression members "the connectors must be designed to resist the shear forces which develop in the buckled shape." Can you provide some guidance on how to compute that required shear force?

    Question sent to AISC's Steel Solutions Center

    07-01-2004
    Sinlge Angle Under Axial Load and Bending

    We have developed a program to check single-angle members subjected to combined axial load and bi-axial bending per the LRFD 3rd Edition spec for Single-Angle Members. We would like to check the program against some example hand calculations.

    Does AISC have any example calculations that we could use, or could you direct us to another source that may have such calculations?

    Question sent to AISC's Steel Solutions Center

    07-01-2004
    Unbraced Length of Cantilever

    I was wondering what the laterally unbraced length value Lb is for a cantilever? My intuition tells me that I should use twice the actual length of the cantilever for Lb, but I don't see any provisions for it in Chapter F or Appendix F of the Specification. Does limiting the Cb value to 1.0 for cantilevers provide all that is needed, and then I would just use the actual length of the cantilever for Lb?

    Question sent to AISC's Steel Solutions Center

    07-01-2004
    Fillet Weld Size Limitations

    8.3.6. Why is a fillet-weld size generally limited to 1/16" less than the material thickness when placed along the edge of a connected part?

    This month's Steel Interchange is compiled from a few of the many frequently asked questions (FAQs) posted at www.aisc.org/faq. Numerical references such as "2.2.6" are references to FAQs in this feature of the AISC web site.

    06-01-2004
    Odd-Sized Holes

    5.1.1. Maximum hole sizes for bolts are specified in the 1999 LRFD Specification Table J3.3. What if an actual hole dimension is between two of the values?

    This month's Steel Interchange is compiled from a few of the many frequently asked questions (FAQs) posted at www.aisc.org/faq. Numerical references such as "2.2.6" are references to FAQs in this feature of the AISC web site.

    06-01-2004
    Paint on Faying Surfaces

    6.7.1. When is paint permitted on the faying surfaces of bolted connections?

    This month's Steel Interchange is compiled from a few of the many frequently asked questions (FAQs) posted at www.aisc.org/faq. Numerical references such as "2.2.6" are references to FAQs in this feature of the AISC web site.

    06-01-2004
    Paint Under Nuts and Bolt Heads

    6.7.2. Both the AISC and RCSC specifications require that paint on the faying surfaces of slip-critical connections be qualified (providing a minimum slip coefficient) or that such surfaces remain unpainted. Does this requirement apply to the surfaces under the bolt head and nut?

    This month's Steel Interchange is compiled from a few of the many frequently asked questions (FAQs) posted at www.aisc.org/faq. Numerical references such as "2.2.6" are references to FAQs in this feature of the AISC web site.

    06-01-2004
    Repairing Rough Edges

    2.2.7. When surface roughness for thermally cut edges does not meet the limitations in 2.2.6, how is the surface repaired?

    This month's Steel Interchange is compiled from a few of the many frequently asked questions (FAQs) posted at www.aisc.org/faq. Numerical references such as "2.2.6" are references to FAQs in this feature of the AISC web site.

    06-01-2004
    Roughness Limitations

    2.2.6. What are the appropriate roughness limitations for thermally cut edges?

    This month's Steel Interchange is compiled from a few of the many frequently asked questions (FAQs) posted at www.aisc.org/faq. Numerical references such as "2.2.6" are references to FAQs in this feature of the AISC web site.

    06-01-2004
    Selecting Paint Systems

    10.1.2. When a paint system is required, how should it be selected?

    This month's Steel Interchange is compiled from a few of the many frequently asked questions (FAQs) posted at www.aisc.org/faq. Numerical references such as "2.2.6" are references to FAQs in this feature of the AISC web site.

    06-01-2004
    Tolerances

    3.5.1. How are tolerances determined if they are not addressed in the applicable standards?

    This month's Steel Interchange is compiled from a few of the many frequently asked questions (FAQs) posted at www.aisc.org/faq. Numerical references such as "2.2.6" are references to FAQs in this feature of the AISC web site.

    06-01-2004
    Weld Symbols

    8.3.7. Is the weld-all-around symbol acceptable when a fillet weld must be continued out-of-plane?

    This month's Steel Interchange is compiled from a few of the many frequently asked questions (FAQs) posted at www.aisc.org/faq. Numerical references such as "2.2.6" are references to FAQs in this feature of the AISC web site.

    06-01-2004
    When To Paint

    10.1.1. When must structural steel be painted?

    This month's Steel Interchange is compiled from a few of the many frequently asked questions (FAQs) posted at www.aisc.org/faq. Numerical references such as "2.2.6" are references to FAQs in this feature of the AISC web site.

    06-01-2004
    Fatigue and Wind

    Is wind generally considered to be a fatigue loading?

    Submitted to AISC's Steel Solutions Center

    05-01-2004
    Hole Spacing

    The LRFD Manual of Steel Construction (3rd edition) assumes a 3" center-to-center hole spacing for most, if not all, of the examples utilizing bolted connections. Is this 3" spacing a code requirement?

    Submitted to AISC's Steel Solutions Center

    05-01-2004
    Stitching Requirements

    We have quite a few fairly short (~3") double angles to detail and are being questioned regarding using two intermediate connectors. The 3rd edition LRFD Manual appears to require a minimum of two intermediate connectors for all lengths (the tables go down to 2"). For such a short length, it seems excessive to have two intermediate connectors. Is there a way out?

    Submitted to AISC's Steel Solutions Center

    05-01-2004
    Stub Girder Construction

    How common is "stub-girder" construction?

    Submitted to AISC's Steel Solutions Center

    05-01-2004
    Threaded Coupler for Anchor Rods

    On a job where the anchor rods came up short, the contractor suggested using a threaded coupler to extend the rods. What detail can be used with a threaded coupler?

    Submitted to AISC's Steel Solutions Center

    05-01-2004
    Cambered Beam Connections

    On a cambered beam that has welded double angles on both ends, how should the angles be oriented in the fabrication shop? Should the angles be plumb to vertical or should they be perpendicular to the curve of camber? If they are plumb then what happens when the beam comes under load? If they are fit with the beam how do you bolt up in the field?

    Submitted to AISC's Steel Solutions Center.

    05-01-2004
    Anchor Rods and Load Path

    I am designing a six-story braced-frame building with an eccentric brace. I have very large loads. I am using 2"-diameter anchor rods of ASTM A449 material, but I have also used ASTM F1554 anchor rods on a previous project. What is the recommended material anchor-rod specification? What design criteria are recommended for designing the base for these forces?

    04-01-2004
    Bolt Tests

    What testing should be performed on high-strength bolts upon delivery from the manufacturer?

    04-01-2004
    HSS and Single-Plate Shear Connections

    The HSS Connections Manual indicates that a single-plate shear connection can be used if the following HSS wall slenderness ratios are satisfied:

    1. Rectangular tubes: b/t < 253/Fy0.5
    2. Round tubes: D/t < 3300/Fy

    Are these limitations alone enough to satisfy the requirements or must one also evaluate the wall for punching shear resistance? Do the HSS requirements also apply to ASTM A53 steel pipe? How about to large-diameter round and large-sized rectangular HSS?

    04-01-2004
    OCBF Lacking Diaphragm Action

    The question is concerning an OCBF system as specified in the AISC Seismic Provisions (May 2002). We are designing a building with horizontal braced frames (OCBF) as well as vertical braced frames, and there isn't a continuous diaphragm on which to rely for lateral shear transfer to the vertical elements. The diaphragm is made up of horizontal braced frames, and frequently there is just a single member making up the diagonal of the horizontal braced frame that serves as the load path.

    In designing a horizontal braced frame, is it a requirement to still design the connection of the brace for the full tensile capacity of the brace (RyFyAg) or is it possible to consider the member a collector and just design for Ω times the force in the brace?

    04-01-2004
    Re-Entrant Corners

    Is it required or recommended that the inside corners of blocked flanges (where beam flanges must be trimmed back to fit between column flanges) have radii similar to vertical web coping?

    04-01-2004
    Weak-Axis Moment Connections

    When designing a weak-axis moment connection (a beam connecting into the web of a column), where can I find information or an example calculation for this type of connection?

    04-01-2004
    Buckling Restraint

    What is the force required to restrain a compression member from buckling laterally?

    03-01-2004
    Developing Welded Elements

    Can a partial-joint-penetration groove weld be used when it is necessary to develop the strength of a welded element?

    03-01-2004
    Dimension Dilemma

    Section 3.3 of the 2002 AISC Code of Standard Practice reads, in part, "When discrepancies exist between scale dimensions in the Design Drawings and the figures written in them, the figures shall govern." This has been interpreted to mean that if no figures exist then it is proper to scale the drawing and use the resultant dimension to build. Is this, in fact, the intent of the code?

    03-01-2004
    Gages Gone

    Why did AISC stop publishing the usual gage dimension for W-shapes in the properties table? What was the basis for these values when they appeared in earlier editions (pre 9th edition ASD)?

    03-01-2004
    Non-Compact?

    I know there are a limited number of W-shapes considered non-compact (per ASD design). Do you have a listing of the non-compact sections for Fy = 36ksi and Fy = 50ksi?

    03-01-2004
    Seeing is Believing

    Why is visual inspection so important in welding?

    03-01-2004
    Sleeve Nuts

    Page 4-150 of the 9th Edition of AISC ASD Manual has a table of sleeve nuts and it states "Strengths are greater than the corresponding rod when same material is used." What is the ASTM designation of these sleeve nuts?

    Minoru "Ike" Ikeda, S.E.
    Martin & HBL

    03-01-2004
    Types of Bolts

    What is the primary difference between ASTM A325 and A490 bolts, other than the difference in strength?

    03-01-2004
    Weld Metal Myth

    Can weld cracking be prevented simply by specifying notch-tough weld metal?

    03-01-2004
    ASTM A325/A490 Bolts

    What constitutes "reuse" of ASTM A325 and A490 high-strength bolts? It has been my understanding that "reuse" would be a bolt that has been brought to specified pretension a second time for size and grade.

    Question sent to AISC's Steel Solutions Center

    02-01-2004
    Bearing Strength

    In Section J3.10 of the 1999 LRFD Specification, how does one determine if deformation is a design consideration? Does this "deformation" refer to slip, i.e., does equation J3-2a apply only to slip critical connections? We are evaluating an existing building and there are no notes or details to indicate that we are dealing with slip-critical connections. Can I assume the use of equation J3-2b (which gives a higher value)?

    Question sent to AISC's Steel Solutions Center

    02-01-2004
    HSS Seismic Braces

    One of our observations is that the criteria φFuAe > RyFyAg(Design Strength  > Required Strength) often cannot be satisfied with an ASTM A500 HSS anywhere along the whole length of the brace, even where there are no holes or slots. It seems to me the intent is to meet the criteria at the connection (not to build-up the section along its entire length.) Are HSS suitable for use as braces in concentrically braced frames?

    Question sent to AISC's Steel Solutions Center

    02-01-2004
    Seal Welds

    My question is relative to seal welding on a typical painted industrial project with the steel exposed to the environment. If there are no requirements for seal welding of all unwelded joints on a project in either the contract documents or the bid drawings, what should be the presumption made by the fabricator?

    Question sent to AISC's Steel Solutions Center

    02-01-2004
    Sufficient Thread Engagement

    The 2000 RCSC bolt specification in the 3rd Edition LRFD Manual defines sufficient thread engagement as having the end of the bolt extending beyond or at least flush with the outer face of the nut. That is easy to determine for ASTM A325 and A490 bolts. However, how would this apply to ASTM F1852 twist-off-type tension-control bolts?

    Question sent to AISC's Steel Solutions Center

    02-01-2004
    Welding Anchor Rods

    How can rod-type concrete anchors be welded to embedded plates?

    Question sent to AISC's Steel Solutions Center

    02-01-2004
    Blast Effects

    What are the damaging effects of explosions to structures?

    Reprint of FAQ 12.1.4 at www.aisc.org/faq

    01-01-2004
    Weathering Steel

    What are some design considerations for using ASTM A588 weathering steel? Should the steel be painted?

    Question sent to the AISC Steel Solutions Center

    01-01-2004
    Fatigue Stress Range

    With respect to Equation A-K3.1 in the 1999 AISC LRFD Specification, a question has come up as to why the design-stress range Fsr value has to equal or be greater than the life-stress range Fth? Would it seem that Fsr. should be less than or equal to Fth? Can you clarify?

    Question sent to AISC's Steel Solutions Center

    12-01-2003
    Making Fillet Welds

    How many passes does it take to make a 3/8" fillet weld? I want to tell the Engineers in our office to limit fillet-weld sizes to 5/16" (except where larger welds are absolutely needed) and I would like to show them that while a 3/8" fillet weld has 20% more strength than a 5/16" fillet weld, it takes ___% more time to install. I'm assuming that a two-pass weld takes twice as long as a one-pass weld, etc.

    Question sent to AISC's Steel Solutions Center

    12-01-2003
    Quality of Structural Drawings

    Where can I find published information regarding the requirements for completeness of structural design drawings?

    Question sent to AISC's Steel Solutions Center

    12-01-2003
    T-Stub Moment Connection

    During my review of the 3rd Edition LRFD Manual, I noticed that there is no mention of the T-stub moment connection as a fully restrained moment connection. Such a connection uses tee sections to connect the top and bottom flange of the beam to the column through bolting (single shear on the beam and tension with prying on the column flange). I also am aware that the extended end-plate appears to have taken the place of this bolted connection. Is AISC discouraging the use of the T-stub connection for FR moment connections?

    Question sent to AISC's Steel Solutions Center

    12-01-2003
    Changes in R Values

    11/03/2003

    There are several changes related to R (response modification coefficient) values, for example, the R value for Ordinary Steel Moment Frames changed from 4.0 (IBC 2000) to 3.5 (IBC 2003). What are the major reasons for these changes of R values?

    Uksun Kim, Ph.D.
    Georgia Institute of Technology

    11-01-2003
    Fire Temperatures

    Reprint of FAQ 11.3.3 at www.aisc.org/faq

    At what temperature does a typical fire burn?

    11-01-2003
    Industry Standards

    Please indicate industry standards for each of the following:

    1. Who is responsible for the design of the moment connections once the design criteria is provided on design drawings (reactions, moments, etc.)?
    2. Should we request in our Specifications that structural calculations be provided as part of the shop drawings from the fabricator?
    3. If the fabricator does not provide standard AISC details for moment connections, who is responsible for showing that they meet the design criteria?

    Question sent to Editor at Structural Engineer magazine

    11-01-2003
    Spray-Applied Fire Protection

    Reprint of FAQ 11.1.7 at www.aisc.org/faq

    Can spray-applied fire protection be applied to painted or galvanized steel?

    11-01-2003
    Steel After Fire

    Reprint of FAQ 11.2.4 at www.aisc.org/faq

    Can steel continue to be used in a building after it has been in a fire? How can you assess the capacity of steel that has been exposed to fire? Are there concerns about internal or residual stress effects that have to be considered?

    11-01-2003
    ASD and Seismic Provisions

    I am designing a steel-framed building per the 2000 IBC using ASD for steel design, so I am looking at Part III of the 1997 AISC Seismic Provisions. My question is specifically regarding the factor to apply to E in equations 4-a and 4-b.

    The AISC Seismic Provisions commentary discusses the factor and from that it seems to me that I should use E/1.4 but the commentary specifically references only equations 4-1 and 4-2 regarding the factor to apply to E. E is not directly in equations 4-1 and 4-2 and it seems that the logic of using E/1.4 would apply to all ASD equations.

    As I see it, the E/1.4 is simply because the IBC seismic forces are based on limit states and I am designing to ASD, so logically I should be reducing the "strength level" seismic forces to "service level" seismic forces by dividing by 1.4. Am I looking at this correctly?

    Question posted on the SEAINT.ORG list server

    10-01-2003
    Bearing Strength

    In the 3rd Edition LRFD Manual, Example 10.11 computes the required supported beam web thickness based on bearing strength without eccentricity. Since the current design criteria developed by Astaneh for single-plate shear connections assigns eccentricity to the bolts for shear, this seems somewhat unconservative. Why is eccentricity not considered for the bolts in the bearing check?

    Question sent to AISC's Steel Solutions Center

    10-01-2003
    Bolts in Extended-End Plate Connections

    In Example 12.4 of the 3rd Edition LRFD Manual pertaining to the design of a four-bolt unstiffened extended end-plate FR moment connection, ASTM A325 slip-critical bolts were specified. Shear is transferred through slip resistance offered by surfaces of end plate and column flange. Is this the reason why full tension capacity of the bolt is used per section J3.6, instead of capacity under combined shear and tension condition per J3.7?

    Is it mandatory to use slip-critical bolts instead of pretensioned bolts for this type of connection? What about a snug-tightened arrangement for this type of connection?

    Question sent to AISC's Steel Solutions Center

    10-01-2003
    Single-Angle Geometric Properties

    Please advise as to where you can find the value for Iw for single-angles for equal and unequal legs. Alternatively, if not directly given by AISC, how can one calculate this property? Is it a trigonometric function of Iz?

    Question sent to AISC's Steel Solutions Center

    10-01-2003
    Single-Plate Shear Connections

    Table 4-8 in the AISC HSS Connections Manualcontains support conditions characterized as rigid and flexible for single-plate shear connections. Please explain what flexible and rigid supports imply?

    Question sent to AISC's Steel Solutions Center

    10-01-2003
    Threads in Tension Rods

    In the August 2002 issue of Modern Steel Construction issue you describe in Steel Interchange how anchor rods are threaded. Would the same hold true for tension-rod bracing?

    Question sent to AISC's Steel Solutions Center

    10-01-2003
    Curved Shapes

    What are the maximum and minimum curved radii of HSS and W-shapes?

    Question Sent to AISC Steel Solutions Center

    09-01-2003
    Pretensioning Anchor Rods

    I have a project where there is a need to pretension the column anchor rods to 110 kips. I am using 1.75" diameter ASTM F 1554 Grade 105 rods. The contractor proposes using a hydraulic torque wrench in lieu of a hydraulic bolt-pretensioning device due to technical, safety, schedule and cost considerations. If we were to allow him to use the hydraulic torquing, what is the necessary torque (ft-lb) required to obtain the 110 kip pretension force? In your opinion at this 110 kip tension, how much of a risk is there for the anchor rod to fail as a result of the combined tension and torsion stresses? If this was a standard slip critical bolted connection and the bolt failed during tensioning it would not be a big deal, a new bolt could easily be inserted. However with a concrete-embedded anchor rod it would be an issue if the rod were to fail.

    Question sent to AISC's Steel Solutions Center

    09-01-2003
    Referencing Specifications

    I have a specification section that refers to AISC S335. Can any one tell me if this is a valid number? I have checked the AISC web site and it does not seem to be there.

    Question posted at steel-detail@yahoogroups.com

    09-01-2003
    Repairing Welds

    What procedures are available to repair a cracked weld between a diaphragm connection plate and the web of a box girder? The crack is more than 1" long and the web plate length is 60".

    Question Sent to AISC Steel Solutions Center

    09-01-2003
    Fillet Weld Strength

    Are fillet welds stronger when loaded transversely than when loaded longitudinally?

    08-01-2003
    Hot-Dipped Galvanized Bolts

    Are there any special requirements if we decide to use hot-dipped galvanized ASTM A325 Type 1 (medium carbon) bolts?

    Question sent to AISC's Steel Solutions Center

    08-01-2003
    Second-Order Effects

    When we performed the analysis of a frame, we found that our computed stresses were considerably higher than those computed by the design engineer. Upon further investigation, we found that these higher moments were due to second-order effects. The design engineer claims that he is not required to perform a second-order analysis under the ASD Specification. Is this correct?

    Question sent to AISC's Steel Solutions Center

    08-01-2003
    Shear Stud Reduction Factor

    The 1999 LRFD Specification, Section I3.5b states, "Where there is only a single stud placed in a rib oriented perpendicular to the steel beam, the reduction factor of equation I3-1 shall not exceed 0.75." Does this requirement apply to ASD design as well?

    Question sent to AISC's Steel Solutions Center

    08-01-2003
    Unauthorized Shop Splices

    Can fabricators shop splice scrap shapes to make them longer? Are these splices regarded as connections to be approved by the EOR on the shop drawings?

    Question sent to AISC's Steel Solutions Center

    08-01-2003
    Unpainted Steel

    What surface preparation should be specified for steel that is to remain unpainted?

    Question sent to AISC's Steel Solutions Center

    08-01-2003
    ASTM A572 Grade 50 and ASTM A992

    Are there any differences between steel grades ASTM A572 Gr. 50 and ASTM A992?

    Question sent to AISC Steel Solutions Center

    07-01-2003
    Bending Limits

    What are the maximum and minimum curved radii of HSS and W-shapes?

    Question sent to AISC Steel Solutions Center

    07-01-2003
    Critical Buckling Stress

    Please refer to 3rd Edition LRFD Manual, Example 9.1 on pages 9-17 thru 9-20. How can the critical buckling stress fFbc be greater than 0.9Fy? In the example (Fy = 50 ksi), fFbc = 77.3 ksi, which is much greater than 0.9 x 50 = 45 ksi. I am accustomed to using f for flexure of 0.9 (when in combination with Fy), so why is this different? On page 9-7, under "Local Buckling," the wording is: connection elements are thick enough that local buckling will not limit the design strength for flexure. Does this mean that a "cap" of 0.9Fy does not apply?

    Question sent to AISC Steel Solutions Center

    07-01-2003
    Designing For Large Cope Depths

    Beams coped at both flanges are constrained to c < 2,d and dc <0.2d in the 2nd Edition LRFD Manual, Vol. II, where c is the length of cope, d is the depth of the beam, and dc is the depth of cope. How can beams with deeper copes ( dc < 0.2d) be designed?

    Question sent to AISC Steel Solutions Center

    07-01-2003
    Expansion Anchors and Washers

    I often detail oversized (OVS) holes at expansion anchors as requested by the erector to facilitate field drilling. I also sometimes use OVS holes at lightly loaded connections that might be difficult to align in the field. The RCSC Specification for Structural Joints Using ASTM A325 or A490 Bolts calls for hardened washers at OVS holes, plus, the connection has to be designed as slip-critical (which requires no paint at the connection area).

    1. Should I specify hardened washers on the plan and detail sheets, or is this something that the erector knows to do?
    2. Do I need to detail no paint areas around the connection outer plies?

    Question from the steel-detail@yahoogroups.com list-server

    07-01-2003
    Height-Thickness Ratios

    Referring to LRFD Specification Sections F2.2, Appendix F2.2, and Appendix G.3:

    For all the standard rolled W- shapes, is the h/tw ratio always £ 260? In other words, if a standard rolled shaped is being considered, is it necessary to check for the limit states of web shear yielding or bucking? Also, for all the standard rolled W- shapes utilizing up to 50 ksi specified minimum yield strength, is it always true that:
    h/tw is less than or equal to 418/SQRT(Fy)?

    Stephen Crockett
    D. M. Berg Consultants, P.C.

    07-01-2003
    LEED Certification

    We have a customer that is interested in pursuing LEED certification on their building. They also like the idea of using recycled materials and would like to have some type of certification to the recycled content of steel. Do you have any information I can pass on to this customer?

    Question sent to AISC Steel Solutions Center

    07-01-2003
    Flame Cut Holes

    My question involves the method used to produce an anchor-rod hole. Our preferred method is to simply flame-cut the 2 5/8" hole. However, the engineer is requesting that we flame-cut an undersized hole and then ream to the final diameter. This takes additional time and effort. Can you provide any documentation that would help establish a case for flame-cutting without reaming?

    Question sent to AISC's Steel Solutions Center

    06-01-2003
    HSS Design Wall Thickness

    We are unsure if we need to use a design wall thickness of 0.93t for electric-resistance-welded HSS if we use the 1989 ASD Specification. We do know that it is a requirement in the 2000 LRFD HSS Specification, but is it required in ASD?

    Question sent to AISC's Steel Solutions Center

    06-01-2003
    Maximum Size of Fillet Welds

    Do the limitations on maximum size of fillet welds in Section J2.2b of the 1999 LRFD and 1989 ASD Specifications apply to details such as welds on column base plates, shear single-plate shear connections, etc.

    Question sent to AISC's Steel Solutions Center

    06-01-2003
    PR Connections

    09/01/2002

    Is it appropriate, as stated by Ackroyd in his 1990 Engineering Journal paper, to use a representative connection stiffness equal to 50% of the initial connection stiffness for distribution of the flexible end moments for design? Are there any recommendations for an appropriate percentage of initial connection stiffness to be used when performing drift calculations for PR frames?

    Question sent to AISC's Steel Solution Center

    06-01-2003
    Slip Factor of Galvanized Steel

    What is the slip factor between two hot-dip galvanized steel faying surfaces?

    Contributed by the American Galvanizers Association (www.galvanizeit.org)

    06-01-2003
    Tension-Field Action

    Does the AISC Specification actually allow the plate girder web to buckle (experience a slight lateral displacement) in order to develop true tension-field action?

    Question sent to AISC's Steel Solutions Center

    06-01-2003
    Torque and Bolt Pretension

    What torque do I need to achieve pretensioned ASTM A325 and A490 high-strength bolts?

    Question sent to AISC's Steel Solutions Center

    06-01-2003
    Torsion and ASD

    Is there an AISC Specification for torsion analysis per ASD?

    Question posted on the SEAINT.ORG list server

    06-01-2003
    "Cold Galvanizing"

    What is "cold" galvanizing?

    05-01-2003
    Abrasion Resistance of Galvanized Coating

    Does the galvanized steel coating of zinc resist abrasion?

    05-01-2003
    Differences in Galvanized Steel Appearances

    Why do galvanized steel appearances differ from project to project and galvanizer to galvanizer, and is there any difference in the corrosion protection offered by the different appearing coatings?

    05-01-2003
    Environmental Impact of Zinc Coatings

    Is there any environmental impact when the zinc coating sacrificially corrodes? Is zinc a safe metal?

    05-01-2003
    G90 and A60 Coatings

    What is a G90 or A60 coating?

    05-01-2003
    Galvanized Steel Exposure Temperatures

    Can galvanized steel in service withstand high temperatures for long periods of time?

    05-01-2003
    Galvanized Steel in Contact with Other Metals

    Should I be concerned when galvanized steel comes in contact with other metals?

    05-01-2003
    Galvanizing Large Articles

    What if the article to be galvanized is larger than the dimensions of the galvanizer's kettle? Can it still be galvanized?

    05-01-2003
    Hot-Dip Galvanized vs. Zinc-Plated Fasteners

    What is the difference between hot-dip galvanized fasteners and zinc-plated fasteners?

    05-01-2003
    Hot-Dip Galvanizing After Fabrication vs. Continuous Hot-Galvanized Sheet

    What is the difference between hot-dip galvanizing after fabrication and continuous hot-galvanized sheet?

    05-01-2003
    How Does Galvanizing Protect Steel?

    How does galvanizing protect steel from corrosion?

    05-01-2003
    Painting Galvanized Steel

    Why would you want to paint over galvanized steel?

    05-01-2003
    Performance of Galvanized Steel in Permanent Water Immersion

    How well does galvanized steel perform in permanent water immersion?

    05-01-2003
    Salt Spray Tests for Galvanized Steel

    Is a salt spray test in a laboratory appropriate to estimate the corrosion rate of zinc coated steel?

    05-01-2003
    Specifications For Hot-Dip Galvanized Steel

    What are the specifications governing hot-dip galvanized steel?

    05-01-2003
    Specifying Zinc Amounts on Steel

    Can I specify how much zinc to put on the steel?

    05-01-2003
    Steps of the Galvanizing Process

    What are the steps in the galvanizing process?

    05-01-2003
    Wet Storage Stains on Galvanized Steel

    What causes wet-storage stain and how can it be prevented?

    05-01-2003
    Bolt Hole Sizes

    Maximum hole sizes for bolts are specified in the 1999 LRFD Specification Table J3.3. What if an actual hole dimension is between two of the values?

    Question sent to AISC's Steel Solutions Center

    04-01-2003
    Effective Length Factor

    Is there any documentation regarding the assumption an effective length factor of K = 1.0 if a P-delta analysis is performed?

    Question sent to www.seaint.org

    04-01-2003
    HSS Slotted Gusset Plate

    On page 6-17 of the HSS Connections Manual, a "rule of thumb" for Lw is that it should be at least equal to the HSS depth. Is this a requirement? The 1999 LRFD Specification Section J2.2b (last paragraph on page 16.1-54 of the 3rd edition LRFD Manual) requires a similar minimum distance for longitudinal welds at the end of a flat bar member in tension. However, I don't consider a tube to be a flat bar, but obviously from the wording in the HSS Manual, it seems that I should be still adhering to this rule of thumb. Using the example I described above, is it allowed to use a length of weld less than the rule of thumb as long as the connection checks?

    Question sent to AISC's Steel Solutions Center

    04-01-2003
    Prying Action of Tees and Double-Angles

    The prying action models in the 3rd Edition LRFD Design Manual do not appear consistent with those found in the 9th Edition ASD Design Manual. In particular, the b dimension has traditionally been defined as the distance from the face of the tee stem, or face of the outstanding angle leg, to the centerline of the bolt hole. However, the latest Design Manual defines the b dimension as terminating at the centerline of the outstanding angle leg. Why the change for the prying action of double-angles?

    Question sent to AISC's Steel Solutions Center

    04-01-2003
    Seismic Force Reduction Factor

    Regarding the seismic force reduction factor R, there seems to be some discrepancies in values to use between the 1997 UBC and Supplement No. 2 of the AISC Seismic Provisions for Structural Steel Buildings. For example, for ordinary moment frames (OMF), the 1997 UBC requires R = 4.5 while Supplement No. 2 indicates R = 3.5. Which is correct?

    Question sent to list server at www.seaint.org

    04-01-2003
    Weld Access Holes

    FEMA 350 recommends a special weld access hole configuration for use with certain moment connections for ordinary and special moment frames. It is my understanding that this weld access hole configuration will also be included in the 2002 AISC Seismic Provisions. As you know, there has been an allegation that use of this weld access hole configuration constitutes an infringement of the patent for a proprietary slotted-web moment connection. What is AISC's position on this issue?

    C. Mark Saunders, S.E.
    Rutherford and Chekene Engineers
    San Francisco, CA

    04-01-2003
    ASTM A36, A572, and A992

    An inspector on our job insists that A36 is no longer manufactured. I have recently taken an advanced steel course and heard no mention of such a fact. I understand that the A572 Specification has been refined, but I find it difficult to believe that A36 is gone altogether. If you could direct me to a reference I would greatly appreciate it.

    Question sent to AISC Steel Solutions Center

    03-01-2003
    Height Limitations in OMFs

    Why has the height limitation of 160 ft for OMFs in UBC 97 been reduced to 35 feet in the IBC 2000, for structural steelwork buildings in Seismic Design Category (SDC) D? I can't point to an exact reason, but commentary from some of the steel seismic seminars leads me to believe that AISC wants people use special frames of all types for almost everything (except maybe SDC A and B). I would expect the penalties to keep going for using ordinary frames in zone with moderate seismicity as well.

    03-01-2003
    HSS Members in Seismic Design

    Are there any types of moment resistant HSS (beam) to HSS (column) connections that could satisfy the requirements for Special Moment Frames? Are there any types of HSS (beam) or HSS (column) to HSS (brace) connections that could satisfy the requirements of Concentrically Braced Frames?

    Joaquin Fidalgo
    Bogota, Colombia
    South America

    03-01-2003
    OCBFs in Low Buildings

    I have a low building in Seismic Design Category D and have run into a problem designing the bracing connection in an Ordinary Concentrically Braced Frame (OCBF). There used to be an exemption for low buildings (Section 14.5 of the 1997 Seismic Provisions) in OCBFs. It is unclear to me whether or not these exemptions still exist in AISC Seismic Provisions Supplement No. 2. The new provisions make it look as if the engineer has to design the brace connection in this low building to develop the full tensile capacity of the brace...for serviceability reasons, my brace is a 6'6 HSS (with a tensile capacity of about 300 kips). However, the greatest design load on the brace is only about 30 kips. Does the bracing connection have to be designed for the tensile capacity of the brace? Is there a good way out of this?

    Question sent to AISC Steel Solutions Center

    03-01-2003
    Ordinary and Intermediate Moment Frames

    The AISC Seismic Provisions Supplement No. 2 Commentary to Sections 10 and 11 regarding IMF and OMF, respectively, states "As a result of the SAC program (FEMA 2000a), the IMF as defined in the 1997 AISC Seismic Provisions for Structural Steel Buildings is no longer applicable. This system has been eliminated and the OMF as given in AISC (1997) has been split into two systems: the IMF based on a tested design procedure and the OMF based on a prescriptive design procedure." My question is that IBC 2000 currently prescribes an R value of 4 for an OMF and 6 for an IMF. This commentary seems to suggest that the level of ductility provided by an OMF and IMF are comparable and, therefore, the R values should be approximately the same. What are the thoughts of the AISC Seismic Provisions Committee? I have read the summary of the Lehigh test data for the prescriptive connection and, if I recall correctly, the level of ductility available within this connection if the current requirements are followed (weld metal meeting CVN toughness requirements, backer bar removal and welding requirements, welded beam web, good access hole geometry, and continuity stiffener requirements) is pretty high.

    Question sent to AISC Steel Solutions Center

    03-01-2003
    Sizing Washers

    Given the correct loading conditions, it is possible for nuts on anchor rods to pull through anchor rod holes or, when leveling nuts are used and the column is not grouted, for the base plate to push through the leveling nuts. Both failure modes may occur when a washer of insufficient size (diameter and thickness) is used. What procedures are available for properly sizing the washer to help prevent such failures?

    03-01-2003
    Avoiding Column Continuity Plates

    When designing moment frames, we will typically use continuity plates between the column flanges when a beam or girder frames into the column. Although this keeps the column size down, it also increases fabrication cost. Do you have any comments regarding the elimination of continuity plates by using a heavier column?

    Question sent to AISC's Steel Solutions Center

    02-01-2003
    Column Erection Tolerances

    In the 2000 AISC Code of Standard Practice, Section 7.13.1.1 states "the angular variation of the working line from a plumb line shall be equal to or less than 1/500 of the distance..." Is this the angle between the working line and plumb line, or is it the ratio of the displacement to the column length?

    Question sent to AISC's Steel Solutions Center

    02-01-2003
    Composite Floor Penetrations

    Where can I find literature or references regarding the design of composite floors with penetrations?

    02-01-2003
    Net Area Calculation

    According to Section B2 of the 1999 LRFD and 1989 ASD Specifications, the width of a bolt hole must be taken as 1/16" greater than the nominal dimension of the hole when calculating the net area. Please clarify whether this provision should read as 1/16" greater than the nominal bolt diameter, as the nominal hole dimension tables in the manuals are based on adding a 1/16" to the nominal diameter of the bolt.

    Question sent to AISC's Steel Solutions Center

    02-01-2003
    New ASTM Standards and Old AISC Specifications

    ASTM A992 wide-flange shapes and F1554 anchor rods are not listed in the 9th edition ASD Manual nor in the 1989 ASD Specification. Can I use these newer materials in designs involving the ASD, or does the design need to be based on the LRFD Specification?

    02-01-2003
    Order of Precedence

    Comment sent to AISC's Steel Solutions Center

    02-01-2003
    Seismic Column Splices

    Section 8.3a(2) of 1997 AISC Seismic Provisions [Section 8.4a(2) in the 2002 version] states that the minimum required strength for each flange shall be 0.5RyFyAf, where Af is the flange area of the smaller column connected. Does Af pertain to the area of just one flange or both flanges of the smaller column?

    Question sent to AISC's Steel Solutions Center

    02-01-2003
    Whitmore Section

    On page 7-114 of the AISC ASD/LRFD Connections Manual, a sketch of the Whitmore Section is shown for a particular example. Consider a connection with the brace connecting to a beam only (no column). I see the dimensions Lw, l1 and l2 remaining the same. The dimension l3 will increase in length from the corner of the section until a line parallel to the brace intersects the beam flange. Then per the last paragraph on the previous page, the column length would be the average of l3 and l1 (l2 is negative in this case). Would this be correct?

    Question sent to list server at www.seaint.org

    02-01-2003
    Bolted Hanger-Type Connections

    The AISC 9th Edition (ASD) illustrates procedures for bolted hanger-type connections with a single line of resistance to prying action on each side of the hanging member. If each line of resistance consists of a bolt group, what design and analysis methods should be used?

    Jay Shniderman, P.E.
    Van Nuys, CA

    01-01-2003
    Prying Action

    The 9th Edition ASD Manual illustrates procedures for bolted hanger-type connections with a single line of resistance to prying action on each side of the hanging member. If each line of resistance consists of a bolt group, what design and analysis methods should be used?

    Jay Shniderman, P.E.
    Van Nuys, CA

    01-01-2003
    Extended End-Plate Connections

    Symmetric tension bolt pitches are assumed in the published design procedures for this connection. However, due to ease of fabrication, we would like to use a different pitch above and below the top tension flange of the beam. Are there guidelines on this, or has this connection been prequalified for only symmetric pitches?

    11-01-2002
    Hollow Structural Sections and Pipes

    Is it true that I can take advantage of the 2000 LRFD HSS Specification for structural designs involving ASTM A53 Grade B pipe? What, then, are the differences between HSS and and pipe if both use the same specification?

    11-01-2002
    Consideration of Connection Eccentricity

    In exterior columns, should the eccentricities resulting from the beam connections be considered when the connections are not designed by the SER? For example, when a W-shape beam is framed into an exterior HSS column via a single-plate shear connection, the column could be designed for the eccentricity equal to the distance from its centerline to the bolt line. With that approach, it might make sense not to place the beams at the column lines and laterally brace the column by a light angle section.... Alternatively, the beams could be assumed to extend into the column centerlines and the specialty connection design engineer directed to design the connection for combined shear and moment. Can the AISC ASD Manual's tables for single-plate shear connections or eccentric bolted connections be used for that purpose?

    If the eccentricity is considered in column design, it should presumably be applied in two directions in corner columns and in columns where the exterior girders deliver vastly unequal reactions from the opposite sides. This might lead to the corner columns actually being heavier than the interior columns, which support four times the load.

    Alexander Newman, P.E.
    Maguire Group Inc.
    Foxborough, MA

    10-01-2002
    Shop and Erection Drawing Standard

    Does AISC or another organization publish specific standards or specifications for steel detailing and shop drawings? The drawings that I've seen coming from some of the new CAD software have not been consistent from one job to the next, nor have they matched the clarity that good steel detailers produce by hand. NISD publishes guidelines for information to be shown by the design engineer but nothing on standards for what the detailers will provide. I'm looking for some good balanced standards to reference as minimum requirements for steel shop drawings that are submitted to us. Some detailers have advised me that the information is there in the software. So, how can I communicate my requirements up front, so that the advantages of electronic data transfer are realized and properly balanced with the need for clear record documents?

    Richard A. Meloy, P.E.
    Butler Heavy Structures
    Kansas City, MO

    10-01-2002
    Single-Plate Shear Connection

    I have a question on designing single-plate shear connections. Should the weld between the plate and support be designed for shear only, or for both shear and bending moment?

    Question sent to AISC's Steel Solutions Center

    10-01-2002
    Tees Under Flexure

    How does one design a structural WT member under flexure when the stem is in compression? Chapter F of the 1989 ASD Specification does not appear to address this particular case?

    10-01-2002
    Thickness of Gusset Plate for Fillet Welds

    In order to check the minimum gusset plate thickness against the fillet weld size required for strength, the 3rd edition LRFD Manual contains the expression tmin = 6.19D/Fu. However, in the 2nd edition LRFD Manual, the expression is tmin = 5.16D/Fy. Is the new expression based on Fy = 0.833Fu and why use Fu instead of Fy?

    Question sent to AISC's Steel Solutions Center

    10-01-2002
    Thread Engagement

    The 1985 RCSC Bolt Specification found in the 9th edition ASD Manual uses the phrase "full thread engagement." However, the 2000 RCSC Bolt Specification appears to have dropped this nomenclature. Is the phrase "full thread engagement" still used by the RCSC Bolt Specification, and, if so, where can we locate this information?

    Question sent to AISC's Steel Solutions Center

    10-01-2002
    Circular Base Plate Design

    I would like to design circular column base plates. However, there appears to be little or no information on the subject. Does anyone know of papers, articles or design guidelines for the design of circular base plates?

    Question sent to AISC's Steel Solution Center

    09-01-2002
    Moment Frame/Seismic

    I am preparing to design a four-story moment frame office building on the east coast (seismic zone 0) and was wondering what other folks have been doing. What are some other engineers in this area requiring? What is standard practice?

    Question sent to www.seaint.org

    09-01-2002
    PR Connections

    Is it appropriate, as stated by Ackroyd in his 1990 Engineering Journal paper, to use a representative connection stiffness equal to 50% of the initial connection stiffness for distribution of the flexible end moments for design? Are there any recommendations for an appropriate percentage of initial connection stiffness to be used when performing drift calculations for PR frames?

    Question sent to AISC's Steel Solution Center

    09-01-2002
    Pretensioning Anchor Rods

    ASTM F1554 Grade 105 anchor rods will be used in a coastal area with wind gusts of 130 mph located in a very high seismic zone. We are planning to pretension the anchor rods to avoid the risk of inducing tensile fatigue from loading cycles resulting from wind loads. Do you agree with this as being a valid reason to pretension these rods?

    Question sent to AISC's Steel Solution Center

    09-01-2002
    Welding Through Paint

    Is there an AISC spec for painting at moment connections or is our erector just complaining about his welders having to burn through paint to make field welded moment connections?

    Question sent to the steel detailers list server at Yahoo Groups http://groups.yahoo.com/group/steel-detail/

    09-01-2002
    Anchor Rods

    A supplier on one of our projects is claiming that when we specify ASTM A307 anchor rods, he can supply anchor rods with rolled threads. The motivation is that these rods are slightly cheaper. His argument is based on the claim that ANSI B1.1, which is referenced by A307, reportedly lists rolled threads as an option. This causes problems since the bolt shank is slightly smaller which results in a weaker bolt and results in a larger space between rod and hole. I believe that the supplier is wrong since A307 specifies a minimum area and a tensile capacity that "trumps" B1.1. I may be wrong if the minimum area is measured at the threaded region. Is the supplier blowing smoke or do we need to modify our specifications to exclude rolled threads?

    Question posted at SEAINT list server www.seaint.org

    08-01-2002
    Built-Up Shapes

    With regards to built-up shapes, what are the minimum and maximum web thickness and flange thickness? Is there a minimum or maximum relationship between tf and tw?

    Question sent to AISC Steel Solutions Center

    08-01-2002
    Galvanizing

    Could anybody advise me on how to check the adequacy of galvanization of members of steel towers used for power transmission lines? What are the specifications that apply, and is the thickness of galvanization proportional to the thickness of the member?

    Question sent to AISC Steel Solutions Center

    08-01-2002
    Shear Capacity of Bolts

    A rigid support forces any beam-end rotation to take place within the connection. This leads to horizontal forces in the bolts, creating a couple. It seems to me that this imposed horizontal force in the bolts and plate will reduce the available capacity in a vertical direction when vectorially subtracted from the bolt's capacity (or plate's bolt-bearing strength, or weld capacity). Yet the HSS Connections Manual Table 4-8, and the LRFD Manual Table 9-10 (identical tables) show rigid connections having more shear capacity than flexible ones. Why is this?

    Question posted at SEAINT list server (www.seaint.org)

    08-01-2002
    Workable Gages

    Please explain how workable gages are calculated in the 3rd edition LRFD Manual. The dimension tables in the new manual sometimes use the same workable gage for flange widths that differ considerably for a given beam depth, such as W14. Why is this?

    Question sent to AISC Steel Solutions Center

    08-01-2002
    Material Specifications

    I am designing using the ASD Specification. Over the past few years, I have seen ASTM A992 specified for wide flange shapes and ASTM F1554 for anchor rods. These materials are not listed in the ninth edition ASD Manual. Can I design with these materials if I use ASD?

    Question sent to AISC's Steel Solutions Center

    07-01-2002
    Shape-Fillet Encroachment

    Can I use the fillet encroachment table in the AISC Manuals for encroachments to the web instead of those to the flange?

    Question sent to AISC's Steel Solutions Center

    07-01-2002
    Slip-Critical Joint Surface Preparation

    The Society for Protective Coatings (SSPC) specifies four different levels of blast cleaning: SP5, SP6, SP7, and SP10. Which form of blast cleaning must be used to obtain a Class B uncoated surface for a slip critical connection? Similarly, is there a minimum angular surface profile required for a Class B surface? Also, if blast cleaned steel develops surface rust while being stored on site, will it still meet the Class B requirement?

    Question sent to AISC's Steel Solutions Center

    07-01-2002
    Steel Deck Details

    Does anyone know what to do when you have a moment connection with a "thick" plate on top of the upper beam flange welded to it and to the column and you have to place the steel deck? Do I place the steel deck on top of it (it doesn't look good from the lower floor or level) or do I cut the steel deck around the perimeter of the plate so that the deck would rest on the upper flange level of the beam?

    Question sent to www.seaint.org

    07-01-2002
    X-Bracing Design

    When X-bracing is used in a situation where the two braces share the load, can the brace in tension be counted on to laterally brace the compression strut at midpoint against out-of-plane buckling (assuming the two braces are connected at midpoint)?

    Question sent to AISC's Steel Solutions Center

    07-01-2002
    Restrained Condition

    One of the issues in determining fire resistive properties per ASTM E 119 is whether the members are considered restrained. It is my understanding that the steel industry has decided that all moment connections result in a restrained condition. Does anyone know if there is any documentation on this?

    Question posted on SEAINT list server

    06-01-2002
    Shear Lag

    Question #6 in the March 2002 Steel Quiz stated that the reduction coefficient U for shear lag is applied to the net area of bolted tension members and to the gross area of welded tension members except for HSS members with slots for gusset plates. What is meant by this exception?

    Question submitted anonymously

    06-01-2002
    Square Tubular Section Arches

    What reference material is available for the design of square tubular section arches with respect to in-plane and out-of-plane buckling? Loading may be full uniform, partial uniform, or concentrated load at quarter or half point. Arches are braced laterally at third points for typical spans. Most technical papers that I have reviewed are concerned with I shape sections although some of the analysis is transferable.

    Susan Guravich, P. Eng.
    Skarborn Engineering Ltd.

    06-01-2002
    Bolt Orientation

    Often we hear that bolts should be installed pointing downward (with the heads on top) to prevent them from falling off if the nut got loose and slipped. Is there any code or steel installer manual or any written reference that supports, recommends or mandates this practice?

    Question sent to AISC's Steel Solutions Center

    05-01-2002
    Bolted Connection Design

    Is it accurate to state that specifying a connection as slip-critical will increase the strength of that connection?

    Karl Lankenau
    Dormitory Authority of the State of New York
    Albany, NY

    05-01-2002
    Bottom Flange Plate

    I heard that AISC has information for designing composite beams with a cover plate on the bottom flange. Please let me know how I could obtain this information.

    Question sent to AISC's Steel Solutions Center

    05-01-2002
    Gusset Plate Buckling

    My question is regarding compression buckling of gusset plate attached to a beam and column. For example, if my brace is in compression, how do I check the KL/r for the effective section of the gusset plate?

    Question sent to AISC's Steel Solutions Center

    05-01-2002
    Lacing Column Design

    Please provide any additional sources of information relative to AISC Specification section E4 (ASD Manual, 9th ed., pages 5-43 and 5-44) covering the proportioning of lacing members to resist a 2% shear stress.

    Additional references with discussions, the history of its origin, derivation and/or examples of the proper application of this specification would be greatly appreciated.

    W. H. Parker
    Derrick Engineering

    05-01-2002
    Masonry Shelf Angles

    How is a masonry shelf-angle designed?

    Question reprinted from www.aisc.org/faq.html

    05-01-2002
    Backing Bars

    When should backing bars and run-off tabs be removed after welding?

    Frequently asked question on AISC website, www.aisc.org/faq.html

    04-01-2002
    Seismic Design

    What is the difference in design philosophy between a building structure that has been designed to meet the AISC LRFD Specification for Structural Steel Buildings and a building that has been designed to meet the AISC Seismic Provisions for Structural Steel Buildings?

    Frequently asked question on AISC website, www.aisc.org/faq.html

    04-01-2002
    Seismic Design of Base Plates

    Shall I use the load combinations (shown below) with amplified earthquake load (Eqs. 4-1 and 4-2 of the 1997 AISC Seismic Provisions for Structural Steel Buildings) for the design of column base plate and anchor rods?

    1.2D + 0.5L + 0.2S + Omega0QE
    0.9D - Omega0QE

    Mike Ginsburg, P.E.
    Leo A. Daly
    Omaha, NE

    04-01-2002
    A325 and A490 Bolts

    I have a situation where I would like to use some relatively small diameter high strength (A325 or A490) bolts. What is the smallest diameter bolt that I can specify?

    Submitted anonymously

    03-01-2002
    Cambering Equipment

    Who manufactures equipment for cambering steel?

    Cheryl Vickroy
    Research Fellow
    Madison, WI

    03-01-2002
    Shear Tabs

    Are there any recommended procedures for designing single plate shear connections requiring multiple lines of bolts or a deep single line of bolts?

    Question sent to Steel Solutions Center

    03-01-2002
    Traceability and Identification

    What is the difference between traceability and identification of material?

    Reprinted from www.aisc.org/faq.html

    03-01-2002
    Web Panel-Zone Shear

    In the 1992 and 1997 Seismic Provisions, for SMF, the resistance factor for panel-zone web shear is 0.75. The Seismic Provisions are somewhat silent for panel-zone web shear in OMF. LRFD Specification Section K1.7 using a resistance factor for panel-zone web shear of 0.90. For OMF, do we default to Section K1.7 and use a resistance factor for panel-zone web shear of 0.90? Or is the resistance factor always 0.75 in OMF and SMF if the loading is non-static?

    Stephen Crockett
    D. M. Berg Consultants, P.C.

    03-01-2002
    Curved Members

    What are some good references for designing curved structural members?

    Question sent to AISC's Steel Solutions Center

    02-01-2002
    Bolt Projection Beyond Nut

    One rule of thumb that our office uses for the minimum projection of bolts beyond the nut is 4.5 threads. Is there any written information documenting a minimum allowable projection?

    Question sent to AISC's Steel Solutions Center

    12-01-2001
    Flexure in AISC ASD Specification

    In the 1989 ASD Specification, Section F1.3 provides calculations for allowable stresses in members with unbraced lengths greater thanLc. Equation F1-8 seems to provide a very low allowable stress for these members, yet it can be applied to members for any value of l/rt. Is there something that I am overlooking?

    Question sent to AISC's Steel Solutions Center

    12-01-2001
    Slip-Critical Connections

    Is there any situation where the design of a slip critical bolted connection would not be required to address bearing requirements? How about a connection using slotted holes?

    Question sent to AISC's Steel Solutions Center

    12-01-2001
    Biaxial Bending in Beams

    When calculating biaxial bending in beams, we generally use ASD equation H1-3:fa/Fa + fbx/Fbx + fby/Fby < = 1.0 which in many cases, allows us to use 0.66Fy as Fbx and 0.75Fy as Fby. However, we've recently reviewed calculations where Fbx and Fby are 0.60Fy, no matter what the compact length attributes of the beam are. Is the 0.6Fy for biaxial bending standard?

    Question from SEAINT list server www.seaint.org

    11-01-2001
    IBC 2000 and AISC Seismic Provisions

    In South Carolina we are using the provisions of IBC 2000 and most of the state's structures are now under seismic design category D. Section 2212.1.2 requires the use of AISC's Seismic Provisions for Structural Steel Buildings, dated April 15, 1997. If we design using Part III of this document (page 135, Part III Section C4.1), it encourages the use of the governing code or standard for the load factor on E. This governing code is now IBC 2000. If we use the alternate IBC 2000 load combinations of section 1605.3.2, is the intent that the combinations of formula 16-17 and 16-18 be used now instead of the equations 4-a and 4-b in AISC's Seismic Provisions? Please verify if the nominal strength per section 4.2a is to be used for equations 4-a and 4-b and 4-1 and 4-2 that it is ok to use this nominal strength with formulae 16-17 and 16-18 of the IBC 2000 (and not use any other increase factors). Paragraph 1605.3.2 of IBC 2000 states that stresses are permitted to "be increased where permitted by .... the referenced standard." What increases do the steel standards (seismic) allow for the formulae in section 1605.3.2? The IBC 2000 says in section 1617.1.2 to use an increase of 1.7 and Phi of 1.0 in ASD for Em in equations 16-30 and 16-31. Do these take the place of formulae 4-1 and 4-2 in AISC's Seismic Provisions, or should this be checked and also 4-1 and 4-2 with the actual resistance factors for steel as per section 4.3 on design?

    Question sent to AISC's Steel Solutions Center
    Greenville, SC

    11-01-2001
    Welding Through Metal Deck

    Can headed studs be welded thru 18 ga. metal deck without having the deck pre-punched?

    Question from SEAINT list server www.seaint.org

    11-01-2001
    Lateral Drift with Brick Veneer or Concrete Masonry

    There are numerous sources that provide recommendations and opinions regarding permissible lateral drift of steel buildings that are supporting exterior walls comprised of brick veneer or concrete masonry unit (CMU) block. These include AISC Design Guide No. 3 Serviceability Design Considerations for Low-Rise Buildings by J. M. Fisher and M. A. West. Does any other established entity comparable to AISC provide explicit specifications for this situation?

    Kevin B. Westervelt, S.E., P.E.
    Knoxville, TN

    10-01-2001
    Welding on Existing Members

    It is a general rule that welding on an existing structural member is not permitted unless provisions are made to unload the member first (for example, if the member is being reinforced) and that the weld must not degrade the properties of the material.

    Is there a written reference that discusses this, both from a code perspective, and a practical approach?

    Alan L. Blosser P.E.

    10-01-2001
    Anchor Rods too Short

    Are there any guidelines or recommendations concerning the repair of anchor rods without adequate projections? This question applies particularly to applications in rigid frames and braced frames where tension is a limiting design condition. Also these are applications where epoxy anchors are not applicable. We know of several methods of repair - couplers or cutting and welding bolt projections. Could you supply some information on the applicability of each repair-minimum/maximum size of anchor, minimum/maximum projection, minimum/maximum plate size?

    Kurt Swensson
    KSI Structural Engineers
    Atlanta, GA

    09-01-2001
    Building Lines

    While researching a column plumbness issue on a recent project, a dispute arose over the definition of the "building line" shown in Figure C-7.5 of the 2000 Code of Standard Practice for Steel Buildings and Bridges. We argued that the building line represented the exterior of the building, therefore at the 20th floor the column must not extend more than 1" towards the exterior or 2" towards the interior of the building. Where can we find AISC's definition of the term "building line" and are we correct in our interpretation?

    Greg Ruberto, P.E.
    Civilsmith Engineering, Inc.
    State College, PA

    09-01-2001
    Crane Design

    I would like to know if there's a reference similar to what could be called "Crane Rail Design for Dummies." I am looking for a handbook or manual on cranes for industrial buildings. Subjects mainly needed are bridge beams, runway beams, columns, bracings, brackets, load considerations, load combinations, etc. Crane information is not relevant because the supplier or manufacturer supplies it all. I would like a reference that focuses on the structure that supports them.

    Question from Structural Engineers Association International (SEAINT) email list-server

    09-01-2001
    Curved Structural Members

    Due to architectural characteristics, I am in the process of plan-checking a few moment frames using curved members (curved beams to column). I have questions regarding curved moment frames.

    1. Are they allowed in current codes?
    2. Has there been testing done on curved moment frames?
    3. In calculations, how do you design the beam-column connection? Will torsion be introduced in this connection and the frame members?
    4. If HSS beams and columns are used, please suggest a beam to column connection that will be acceptable.

    David Chung, P.E.

    09-01-2001
    Stiffener Requirements

    Regarding Chapter K of the ASD Manual, reference page 5-82 section K1-8 paragraph 3:

    If Sections K1.4 or K1.6 requires stiffeners, the stiffeners shall be designed as axially compressed members (columns) in accordance with requirements of Section E2.

    If Section K1.4 requires the stiffener, I would design the stiffener as compression member with an axial load of R from section K1.4. If Section K1.6 requires the stiffener, should the stiffener be designed for an axial load of Pbf from section K1.6 or from the computed force delivered by the flange? If Pbf is used, often the stiffener (assuming the same width as the flange) will be thicker than the flange and this appears odd to me.

    I would appreciate any information you could supply me concerning this information.

    Paul Howell

    09-01-2001
    1929 Properties

    I am performing a structural analysis on a spillway radial gate constructed in 1929. Do you know the strength values for steel used at that time? Also, if there is any difference in strength values for the following members: angles, channels, plates, rivets, bolts, could you report them to me.

    Any other information you might have on steel from this era would be appreciated, such as, unique failure modes, oddities, etc.

    Question submitted anonymously

    08-01-2001
    A36 Plate

    Does anyone have a "ready" number for the proportional limit for A36 plate, from 3/16" to 1/2" thick?

    Question from Structural Engineers Association International email list-server

    08-01-2001
    Braced Frames and 1997 UBC

    Can someone refer me to a design guide for the connection of steel braced frames to footings using the 1997 UBC? I am looking for some recommended connection configurations. I am particularly interested in what load factors I should be using and how to treat the grout space and oversized anchor rod holes.

    Chris A. Hasse, P.E.

    08-01-2001
    Cambering Galvanized Members

    Are there any special considerations that need to be made in specifying camber in a beam that is also to-be hot-dip galvanized?

    Question submitted anonymously

    08-01-2001
    Column Splices

    I am currently working on a job that has several column splices. The splices are made with outside flange plates only. The upper column is bearing directly on the lower, I am assuming, via a note that reads "finish columns to a column plane." The EOR has called out 1/2" flange splice plates, 7/8" SC bolts, and "fillers as required." What is the largest tolerable gap between splice plate, and upper column flanges? Is this documented somewhere?

    Question from Steel-Detail list-server

    08-01-2001
    Galvanizing Limits

    I am working on a project that will have 35' long pipe columns. Does anyone know what sort of lengths of steel can be hot-dip galvanized in the Seattle area? I can cut the pipe back to 29'-6" or so, if the limit is 30'.

    Question from Structural Engineers Association International email list-server

    08-01-2001
    Old Beam Sizes

    I am analyzing a structure to support a replacement chiller, and found on the original structural framing plans a beam designation of 18B35. The plans are dated 1970, and I am only familiar with W, C, M, and S shapes for steel beams. Can you help me identify what type/size beam this is?

    Question submitted to solutions@aiscmail.com

    08-01-2001
    Roof Deck Providing Bracing

    I am working with some 40 to 50 year old buildings (ASTM A7 steel). The roofs are metal deck about 1 to 1.5 inches deep. What parameters do I use to assume that the supporting purlins are laterally braced by the roof deck? Should I even consider this as the welding of deck is not verified, neither is the weld size or spacing.

    Question submitted anonymously

    08-01-2001
    Single Plate Connections

    Volume II of the LRFD Manual (Metric Conversion of the 2nd edition) states on p. 9-150 that the limit states for Bolted/Welded Single-Plate Connections are bolt shear, bolt bearing on (connection) plate, shear yielding of the (connection) plate, shear rupture of the (connection) plate, and block shear rupture of the (connection) plate. There is no mention of flexural yielding of the connection plate.

    My calculations verify that flexural yielding of the connection plate is not included in the Table 9-10 values. For instance the Table 9-10 value for two A325M(N), M22 bolts through a 6mm connection plate is 82.9kN. The limiting shear value for this plate based on flexural yielding is 72.1kN. On p. 8-226 of the same reference, flexural yielding is listed as an applicable limit state for the end of the supported member where the top and/or bottom flange has been coped.

    My question is why does the flexural yielding criteria apply to the coped beam end but not to the connection plate? They are seeing equal and opposite forces and have nearly equal geometry-assuming both top and bottom flanges are coped.

    Robert C. Tedrick

    08-01-2001
    Beam Camber

    Does AISC have any recommendations for sizes of beams which lend themselves well to cambering? Are there methods of cambering that are best used for light shapes such as W10x12's, W12x14's, etc.?

    Robert Naples
    William A. Kibbe and Associates
    Saginaw, MI

    07-01-2001
    Origin of K-factors for Columns

    I recently looked at the theoretical K factors and the recommended design value when ideal conditions are approximated on p. 2-18 of the 1993 edition of the LRFD specification. My question is how these numbers are related; I would have expected some system was used to decide on these values, as some of the cases (e.g. pinned-pinned) have a 0% change, while others have an increase in effective length of 30% (fixed-fixed). Considering that the effective length decreases strength of the column as a square, this is a 70% strength reduction for the fixed-fixed column that is not applied to the pinned-pinned column. How were these numbers produced?

    Brian Johnson
    URS Corporation

    07-01-2001
    Bolt Shear/Tension Interaction

    The equations for bolt shear and tension interaction in table J3.3 (ASD specification) for A325 and A490 bolts give an elliptical interaction curve. I am wondering if I can apply the same type of modification to these equations as was done in the LRFD specification, in which the elliptical interaction line is simplified into 3 straight lines giving "minor" deviations. I would like to do the same to the ASD equations to be able to graph them easier. What are the implications in making such a conversion?

    Zachary Goswick, EIT

    06-01-2001
    Semi-Rigid Connections

    In the design of semi-rigid connections in steel frame buildings I have typically used moment magnitudes generated by wind or seismic loading, based on chapter four of AISC's Engineering for Steel Construction.

    In the paper "Design Tables for Top- and Seat-Angle with Double Web-Angle Connections" (Kim and Chen, Engineering Journal, 2nd quarter 1998). they used 1/2 the plastic moment of the beam as the design moment for connection (six times my wind moments).

    Is this a limit state criteria? Should I redesign my connections based on this? Is this approach overkill for buildings less then 35' high and in low seismic regions?

    06-01-2001
    Steel Sheet Piling

    I would like to obtain a recent copy of the US Steel Sheet Piling Design Manual. I have an old copy (sixties vintage) but would like to obtain a more current edition Can you direct me to a source?

    Roger Hove, P.E.

    06-01-2001
    Tensile Area for Threaded Fasteners Why is the tensile stress area larger than the minimum root area for threaded fasteners? (See p. 4-147 of ASD 9th Edition) Shouldn't I be using the smallest cross section for my design?

    06-01-2001
    Welding Channels to Wide-Flange Beams Can you suggest some guidelines for welding channels to wide-flange beams to produce the combination sections shown in the tables in the Manual?

    Dipu Sengupta, S.E., P.E.
    Sato & Associates
    Honolulu, HI

    06-01-2001
    Lateral Support for Beams

    For a beam, fully braced along its top flange (such as a roof or floor beam supporting a deck), subjected to axial compression and bending along its major axis, what is the unbraced length of the beam along its weak axis? I know its somewhere between zero and the full length of the member, but is there a standard rule of practice for weak axis unbraced length for this situation?

    Robert Brodowski

    05-01-2001
    Notional Loads
    1. In order to take column buckling lengths equal to unity and use AISC-ASD design procedures, can we use P-Delta analysis taking notional forces into account arising from imperfections?
    2. Shall notional forces be included in the P-Delta combination in conjunction with dead and live loads?
    3. If buckling lengths are taken as unity with an appropriate analysis, AISC requires max KL/r as 200 for columns, how can this be checked as taking K = 1, or is this requirement no longer valid?
    05-01-2001
    Slip-Critical Galvanized Surface Preparation

    Slip-Critical Galvanized Surface Preparation

    As required in RCSC Specification Section 3(b)(5), galvanized surfaces in slip-critical connections must be roughened by means of hand wire brushing. I have heard one definition of the proper degree of wire brushing required as "an amount to visibly alter the surface without disrupting the continuity of the galvanizing".

    Can anyone provide a more quantitative description of the degree of wire brushing required to satisfy the RCSC specification for the use of slip-critical connections?

    05-01-2001
    Slotted HSS Connections

    For a slotted HSS/gusset plate connection...AISC recommends that the length of the weld shall be equal to or greater than the O.D. of the pipe. My interpretation is that this is a recommendation and not a definite requirement and that a shorter length may be used provided the numbers add up.

    Also, Cheng and Kulak (AISC Engineering Journal, Fourth Quarter 2000) suggest that "...the stiffening effect caused by the gusset plate precludes shear lag fracture as long as the weld length is 1.3 times the pipe diameter..." Any chance that AISC will reexamine this?&

    05-01-2001
    Welding Older Steel

    I have an existing steel frame building (1962) to be retrofitted with steel braces. Some of the existing columns are A440 steel. I believe this grade was discontinued in the 1970's. The AISC steel manual sixth edition simply states that the steel is not recommended for welding. Most of the existing connections to the columns are bolted. How do I specify welding criteria for this steel?

    05-01-2001
    OSHA Rules for Erection

    I was reading through the AISC advisory on the new OSHA rules for steel erection [available at www.aisc.org]. There has been talk of requiring safety-type double connections for beams. This advisory only talks about needing safety double connections only for columns or beams framing over columns. It doesn't say safety connections are needed for ALL double connections. How this will be interpreted?

    04-01-2001
    Shelf-Angle Design

    What information is available to provide guidance in the design of a shelf-angle and its connection to a wall in particular, with the bolt in tension and the lower edge of the vertical leg of the angle in compressive contact with the wall. What is the stress distribution in the angle? Is only part of the angle effective in resisting the applied loads based on the spacing of the bolts?

    Greg Michel, P.E.
    Mani Muthiah, P.E.

    04-01-2001
    Uniform Force Method

    This question concerns the design of horizontal brace connections using the Uniform Force Method (UFM), "bearing-type" bolts and single clip angles welded to the gusset plate.

    The UFM defines both shear and axial forces for the gusset plate connectors to the supporting surfaces. The single clip's outstanding leg (OSL) bolts will need to be designed for eccentricity. Thus these OSL bolts will need to be designed for the combination of tension and shear forces.

    When I use the tables in the 2nd ed. LRFD manual to calculate how many bolts I will need for the shear force eccentricity, I get an allowable "capacity" value which is based upon the instantaneous center of rotation method. How do I calculate the "actual" bolt shear stress for the reduction of the allowable tension stress per LRFD Table J3.3? My thought was to determine the number of bolts for the shear based upon the tables and then use the "elastic" method for determining the "actual" shear force/stress. Any thoughts?

    Dan Hakes, P.E.

    04-01-2001
    Second Order Analysis

    Consider a three dimensional four story building model with some unbraced frames in both directions (the rest are leaning columns) in which all the gravity load per floor is considered in calculating the second order (destabilizing) effects. Building codes require designers to include second order effects (structure instability and local instability) in the analysis of steel and concrete frames. ACI-318 accepts second order analysis for the structure instability (many software packages can do this) and provides a test for the designer when to test a member for local instability. AISC/ASD is silent on this topic. Researchers recommend to use K = 1 in the interaction equations when second order effects are included in the analysis. However, engineers use

    K = 1 or the value obtained from the nomographs. What are your thoughts on this subject?

    Nicholas Constantine
    Korda/Nemeth Engineering
    Columbus, OH

    03-01-2001
    Snug-tightened Bolts Make Sense

    From AISC 7th edition Manual, the preferred method of tightening structural bolts for bearing connections was the turn-of-nut method.

    Looking at current references, the method for bearing connections is called "snug tight." I prefer the turn-of-nut method and wonder if requiring it is an undue expense for the erector. What kind of cost difference is there between the two methods?

    03-01-2001
    Special Truss Moment Frames

    I am looking for design aids for special truss moment frames. Can you recommend any recent publications?

    Stephan Schambeck, P.E.
    PDC Consulting Engineers Inc.

    03-01-2001
    Surface Finishes

    What is the difference between calling out "tight fit", "grind to fit", and "grind to bear." They all sound the same to me, but I've seen details where more than one is called out.

    Michael LeComte
    Washington Group International
    Deerfield Beach, FL

    03-01-2001
    Technical Note: Specifying Anchor Bolts

    ASTM A325 and A490 are for steel-to-steel structural bolting only, not steel-to-concrete anchorage, because the y have special heading and threading requirements and are generally available in lengths up to 8 in. only. ASTM A354 is the strength level equivalent of ASTM A490 in a rod specification with more general heading, threading and other requirements.

    Take a look at ASTM F1554, which is a relatively new material specification that covers hooked, headed and threaded and nutted anchor rods in three strength grades: 36, 55 and 105.

    Grade 36 is most commonly specified, although grades 55 and 105 are normally available when higher strength is required. ASTM F1554 grade 36 or, if its availability can be confirmed prior to specification, ASTM F1554 grade 55 with weldability supplement S1 and the carbon equivalent formula in ASTM F1554 Section S1.5.2.1 can be specified to allow welded field correction should the anchor rods be placed incorrectly in the field. ASTM F1554 grades 36 and 105 are essentially the anchor-rod equivalents of the generic rod specifications ASTM A36 and A193 grade B7, respectively. ASTM F1554 grade 55, when specified with the weldability supplement, is similar to an ASTM A572 material that is intermediate between grades 50 and 60.

    Several other ASTM Specifications can also be used. For applications involving unheaded rods, ASTM A36, A193, A307, A354, A449, A572, A588 and A687 can be specified. For applications involving headed rods, ASTM A307, A354 and A449 can be specified.

    03-01-2001
    Bent Clip Plates for Connections

    A contractor has requested that I take a look at some bent clip plates (used to transmit beam gravity loads) due to the presence of cracks at the outside corner (they radiate from the neutral axis to the outside corner) of the bend. The cracks (two) also occur at the top and bottom edges of the bent corner of the plate. They are almost "surface" cracks in nature in that they are approximately 0.03" wide and 1/8" deep.

    The plate is 5/16" thick and 5 1/2" wide. The one outstanding leg is oriented approximately 120 degrees relative to the other. I've requested what bending radius was used and if the plate was bent parallel or perpendicular to its "roll."

    Are these type of cracks typical for bent plates?

    02-01-2001
    Heat Straightening vs. Mechanical Realignment

    Are there any guidelines as to when one might use heat straightening? I gather that there are relatively few people who are adequately experienced at heat straightening so I assume that this is a very expensive proposition and, therefore, not appropriate for the typical damaged column in an industrial structure. What degree of straightening might be achieved by each method? Would it be possible to reasonably determine in advance when additional reinforcing might be required?

    02-01-2001
    Load Transfer in Bolted Connections

    How do bearing connections and slip-critical joints differ in terms of load transfer mechanisms?

    02-01-2001
    Technical Note: ASTM A992 now costs less than A36 for W-shapes

    Nucor-Yamato Steel Company and TXI-Chaparral Steel, the two largest sources of W-shapes in the United States, have instituted a $10-per-ton surcharge on ASTM A36 W-shapes. But don't despair! The cost of ASTM A992 W-shapes has not increased.

    AISC recommends that ASTM A992 (Fy = 50 ksi, Fu = 65 ksi) be specified for W-shapes instead of either ASTM A572 Grade 50 or A36. In the past, this recommendation was based upon the rationale that ASTM A992 offers better material definition, including: an upper limit on yield strength of 65 ksi, a minimum tensile strength of 65 ksi, a specified maximum yield-to-tensile ratio of 0.85 and a specified maximum carbon equivalent of 0.47%. Now, Nucor-Yamato and TXI-Chaparral have added a financial incentive to specify ASTM A992 for W-shapes.

    You can find more information on ASTM A992 in the article "Are You Properly Specifying Materials" (Part 1) in the January 1999 issue of AISC's Modern Steel Construction magazine.

    02-01-2001
    Use of "Jam" Nuts

    I have not seen much technical information on the use and functionality of jam nuts on A307 grade A bolts. Jam nut applications do frequently appear, especially where there is vibration. I have noticed on many occasions seeing in detail drawings a jam nut specified on top of the normal hex nut. I take these to be in error. The jam nut should be tightened on the bolt first, followed by the normal hex nut. Can you clarify the proper use of jam nuts and their functionality?

    Cal. Graham
    JHI Engineering
    Portland, OR

    02-01-2001
    Checking Camber in the Field

    I have had problems with inspectors in the field checking camber after beams are in place. Some beams, even of the same size and weight, deflect varying amounts, with some even losing all of their camber. What is the proper way to inspect camber in field and what are the possible reasons for beams displaying differing amounts of camber loss -- even total loss of camber?

    01-01-2001
    Economical Composite Beam Design

    What are some general guidelines for making composite beam designs economical?

    01-01-2001
    Seismic Requirements for Simple Buildings

    I am designing a very simple building in a seismic application. Seismic loads even with R = 4 are quite within the frame capacity. Do I still have to meet the requirements of a special moment frame?

    01-01-2001
    When to Use ASTM A449 Bolts

    While researching an issue related to bolt specifications I encountered a confusing part of the AISC Specification.

    Section A3.4 states that A449 bolts are permitted only in connections requiring bolt diameters greater than 1.5". Table I-B in Part 4 of the Manual only provides tension loads for A449 bolts of 1.5" diameter or less, implying that this material is not available for diameters greater than 1.5". Am I misinterpreting something here?

    01-01-2001
    A992

    I understand the history of the creation of the ASTM A992 specification. Have the associated codes (for example, AWS D1.1) been updated to recognize A992 steel? As I understand it, AISC's "Technical Bulletin No. 3 dated March 1997" was written to cover the "gap" in industry codes until they had the opportunity to update. I've had quite a few jobs in the past few years that specified ASTM A992. Have the codes caught up?

    Rich Sellers
    Precision Detailing, Inc.
    Huntertown, IN

    12-01-2000
    Seismic Connections

    I did a preliminary design for a small ordinary moment resistant frame, several months ago, for a design-build project here in Fairbanks. It has six columns, four stories, and is 50' tall. I followed the 1997 UBC and the 1997 AISC Seismic Provisions (yellow book). Now it is time to do the final design and the client wants us to follow FEMA 302/IBC 2000.

    The height of my building is 50'. The permissible height in the 1997 UBC is 160' (seismic zone 3). In FEMA, it is 35' (seismic design category D). To move to an intermediate moment frame would require connection testing, something that is not in the budget or schedule.

    This is a small building with only a handful of moment connections. Appendix S in the Seismic Provisions states that it is not the intention of the Provisions that testing be required for all buildings if connections are based on established literature. I was planning on doing reduced beam section connections, using procedures from a 1999 AISC seminar. Is there literature out there that can "pre-qualify" my connections for an IMF? My columns were in the W12x65 range and my beams were in the W18x35 range. Any other suggestions or input would be greatly appreciated.

    Peter A. Jacobsen, P.E.
    Design Alaska, Inc.
    Fairbanks, AK

    12-01-2000
    Single Angles

    Could you recommend an ASD design aid for single angles in bending?

    12-01-2000
    Technical Note: Pipe vs. Round HSS

    Technical Note: Pipe vs. Round HSS

    12-01-2000
    Web Openings

    I have the Steel Design Guide No. 2, Steel and Composite Beams with Web Openings. I have some questions regarding constructing new web openings in existing beams. I am primarily concerned with stress crack propagation. Is there any practical construction method other than to flame cut the openings? Should the corner radii be drilled with a hole saw, or can they be ground smooth?

    Should any of the torch cut edges be ground smooth? Are there different design parameters for field-cut versus shop-cut beam web openings? I am looking for economical solutions for unreinforced and reinforced beam web openings.

    Matt Hykes, P.E.
    Buchart Horn, BASCO
    York, PA

    12-01-2000
    AASHTO Bearing Stiffeners

    A question has arisen in the interpretation of the ultimate capacity of bearing stiffeners under provisions of 1998 AASHTO.

    Under Part D "Strength Design Method," Bearing Stiffeners, Article 10.48.7 shall be designed for beams and girders as specified in Articles 10.33.2 and 10.34.6. These articles relate to allowable stress design. There are no apparent provisions for strength design provisions in reducing the factor of safety in the column formula (2.12 in allowable stress design) or increasing the bearing value (0.80 Fy).

    Is there some documented guidance as to what factor of safety, etc., should be used.

    Patty Schibuola
    Moffatt & Nichol Engineers

    11-01-2000
    Welding Studs Through Paint

    When studs are used in through-deck welding, it is recommended that the top flange be free of paint, scale, rust and debris within acceptable limits. However, we have been involved in projects where the EOR has waived the no paint requirement and has allowed complete top flange painting. What are the criterion the EOR might use in making this decision?

    If the paint is required as a rust inhibitor, how is the top flange touched up or painted after the deck and studs are installed if the top flange is unpainted to begin with?

    via email

    11-01-2000
    Bracket Plates

    The ASD method for determining the required section modulus for an eccentric connection plate differs in three separate examples in ASD Vol. II, Connections. In Example 7 (Page 3-62), the allowable bending stress (Fb) check uses 0.60Fy through the bolt holes, i.e., the critical section at net area, to determine the required connection plate thickness. In Example 4 (Page B-10), the Fb check uses 0.50Fu, also through the net area to determine the required plate thickness. Additionally, in Example 2 (Page 1-17), the Fb check includes both 0.60Fy on the gross area and 0.50Fu on the net area.

    The question is: shouldn't 0.60Fy be used at the gross section and 0.50Fu be used at the net section? That is, when designing the connection plate, shouldn't the plate thickness be based on the section modulus requirements utilizing the greater of M/0.60Fy based on the gross section and M/0.50Fu based on the net section? Is the upper limit for the allowable buckling stress (Fbc) 0.60Fy or 0.50Fu?

    If the value for Fbc,/i> is less than its limiting value, either 0.60Fy or 0.50Fu, should this value be used for checks at both the gross and net sections?

    Paul E. Crockett
    PEC Detailing Co., Inc.
    Walpole, MA

    10-01-2000
    Bridge Fillets and Haunches

    What is the minimum recommended fillet weld size on a bridge girder? Also, what is the typical haunch dimension (distance between the top of steel flange and bottom of the concrete slab)?

    (Not Specified)

    10-01-2000
    Minimum Connection Depth

    Is there an AISC Specification requirement that simple shear beam connections be a minimum depth? For example, what if a W21 has very little load and only two bolts are required by calculation? The AISC Manual shows a minimum of 4 bolts.

    Thomas Forsberg, P.E.
    L. Robert Kimball & Associates
    West Chester, PA

    10-01-2000
    Drafting Standards

    Are there any standards or guidelines for structural steel drafting, particularly for the presentation and content of design drawings? I am interested in finding "rules" about showing the weights of beams on plans and column weights on elevations, etc. Each company seems to have developed its own drafting convention, but I would like to know if there are industry-wide standards.

    Brian W. Bersch, P.E.

    09-01-2000
    Gas Metal Arc Welding (GMAW)

    I have a question regarding the Gas Metal Arc Welding (GMAW) process. For as long as I can remember, our steel specifications prohibit the use of GMAW. Despite this, we are finding fabricators using this method in their shop. It is my understanding that the prohibition of the GMAW process is due to the fact that the weld quality is dependent on maintaining controlled conditions, which cannot always be assured.

    Does AISC maintain a position on this welding process? Are there some types or locations of welds that should or should not use this process?

    James A. Boje, P.E.
    Structural Engineer

    09-01-2000
    Holes for Anchor Rods The LRFD Manual, Vol. II, part 11, includes a discussion on holes for anchor rods and grouting in column base plates. Table 11-3 recommends base plate hole sizes to accommodate anchor rods. The discussion indicates that "An adequate washer should be provided for each anchor rod." Why are the recommended holes sizes so much larger than those in the ASD Manual, Part 4? What washer materials and thicknesses would be considered adequate?

    Rick Drake, SE
    Fluor Daniel, Inc.
    Aliso Viejo, CA

    09-01-2000
    HSS Properties

    I have two questions. First, what is the physical meaning of the function shown on page 6-19 of the AISC Hollow Structural Sections Connection Manual?

    Second, it appears that the section properties for HSS indicated in the HSS Connections Manual are different than those shown in the ASD Manual of Steel Construction, 9th ed. and the LRFD Manual of Steel Construction, 2nd ed. Why is this?

    Jay Kleven
    EAPC Architects and Engineers
    Grand Forks, ND

    09-01-2000
    HSS Through-Plate Connections

    What is supposed to happen when you need through plates in each direction for a tube or pipe connection? It seems to me that you wouldn't get a lot of benefit out of just running the plate with the lesser load back into the other plate and butting against it.

    Not Specified

    09-01-2000
    Re-Use of Shop Drawings

    I recently detailed a job and used the engineer's drawings to place the shop marks for the structural steel, with my title block. I got a phone call from the engineer who chewed me out for using his drawings. In short, I had to apologize until I was blue in the face. Now I have to redraw the exact same thing, but with my handwriting on it.
    In all my years in the business, this was the first time I have had to apologize for something like this. I guess I have been lucky to work with people who didn't mind sharing their drawings. Is this client being overly picky, or am I doing something wrong?

    09-01-2000
    Twist-Off Bolts

    On one of my projects, the steel fabricator/ erector has chosen to use twist-off-type tension-control bolts. In a few locations at beam to column connections, they are requesting to remove the twist off extension and use the turn-of-the nut method or a tension-calibrated device because of clearances. The question becomes how to remove the extension. The erector wants to flame cut the extension. Is this detrimental to the chemical composition of the bolt? Should this be permitted?

    S. Craig Brown, P.E.
    Brown and Kubican, PSC
    Lexington, KY

    09-01-2000
    HSS Cap Plates & Drainage Holes

    What guidelines are available to determine the thickness and welding details for cap plates on HSS columns? Is the main purpose of the cap plate to keep water out, or to add structural integrity to the column? Or is there some other purpose? What is the current thinking regarding drain or weep holes for non-galvanized products? Years ago we used to provide drain holes in HSS columns.

    A-1 Detailing
    Millville, NB Canada

    08-01-2000
    Bolts with Cyclic Loads

    Can A490 bolts be used to resist shear loads in a cyclic application, such as for a tower crane? Can anyone direct me towards an appropriate reference?

    Laura Kannady, P.E.

    07-01-2000
    Exposed Steel

    I recently read the following note on an old drawing set:

    All structural and miscellaneous steel which shall remain exposed to view shall be fabricated and erected in accordance with the AISC "Specification for Architecturally Exposed Structural Steel" without gaps or open joints.

    Can anybody point me in a direction to find this or give me some insight on what the note refers to?

    Not given

    07-01-2000
    Floor Levelness

    Is it a correct assumption to say that a levelness criteria should not be specified for a composite slab on unshored structural steel? From everything I've read and in my dealings with numerous contractors, this appears correct. Basically, it seems you might get excessive ponding if you specified a levelness criteria which could be a problem in the pre-composite loading condition for the beams and the metal decking.

    Alan Holland

    07-01-2000
    Grade 50

    What are the design and application considerations when substituting ASTM A529 grade 50 for ASTM A572 grade 50 or ASTM A709 grade 50? What is the main difference in these grades of material as it relates to their application in construction?Keith Woods
    Pelham, AL

    07-01-2000
    Beam Gages

    What happened to the "standard beam gages"as listed in the Manual of Steel Construction, 7th edition? I can't seem to find gages for some of the newer shapes.

    06-01-2000
    Cold Galvanizing

    Does anyone have experience with Aerosol Zinc-Clad cold galvanizing compound? The fabricator wants to substitute this for hot-dip galvanizing on brick shelf angles. The Sherwin-Williams fact sheet says it is equal to or better than hot-dipped galvanizing.

    Mark Daskilewicz

    06-01-2000
    SCBFs

    I just picked up the May 2000 issue of Modern Steel Construction. The front has photos of chevron bracing. In the matching article, sketches show yield lines not square with the brace. As I understand it, the yield line, 2" from the end of the brace, must be parallel to the cut end of the brace and to the yield line at the opposite end. Testing has shown that other assumed yield lines may result in a curved yield line and then tear the gusset plate. It looks like the shown method may not meet either criteria. What is the practice by those who are designing SCBFs?

    David Merrick, S.E.

    06-01-2000
    Seismic Overstrength Factors

    If fixed base columns are used, should these seismic overstrength factors similarly be applied to the design of the column connection to the foundation? In other words, if fixed base steel columns were used, would the seismic overstrength factor need to be applied to the base plate and anchor bolt design? For columns at braced bays, should the seismic overstrength factor be used in the design of the anchor bolts?

    Paul H. Lind, P.E.
    Butler Construction
    Kansas City, MO

    06-01-2000
    Truss Analysis

    I am retrofitting some existing building trusses to handle additional loading. These trusses have continuous top and bottom chords and all welded connections. Even under existing loads, the only way that the truss members can be made to work is to assume that all members have pinned ends. Obviously, this eliminates all member bending moments from the analysis.

    Clearly this is what the original designer assumed. But, given the as-built conditions, I don't see how I can legitimately make the same assumption. Are there any references that discuss this?

    John Brock

    06-01-2000
    Composite Beam Deflections

    Does anyone know of any clearly documented, recommended guidelines for limiting the precomposite deflection of steel beams in composite floor systems? I've always tried to limit the total deflection to a reasonable number (1" or so, depending on the span) and the initial deflection was never a serious issue.

    Structural Engineers Association International email list-server

    05-01-2000
    Cope Radii

    Is there a minimum radius for a cope at the top of a beam? I can't find a specific radius in either volume of the AISC ASD Manual or my old copy of Detailing For Steel Construction. These references only indicate that a radius is required but do not specify a minimum radius. I'm working on a project that calls for a 1" radius and this seems large.

    Lowell McCormick

    05-01-2000
    Crane Rails

    I read the Steel Interchange article from December 1999 regarding the bending of steel crane rails (bottom flanges) due to the applied loads from underhung crane wheels. Are there any references for the capacity of the crane rail top flange when it is supported using a clamp system? In other words, the loads from the crane wheels are supported by clamping the top flange of the rail at the ends. This would impart a bending in the top flange as well as tension in the web.

    Stephen L. Nelson, P.E.

    05-01-2000
    Monorail Design

    Can you recommend a technical paper, book, or manual on the finer points of overhead monorail design, both straight and curved?

    Dick Neel
    Portland, OR

    05-01-2000
    SAE Bolts

    I have an long-time industrial client who recently replaced a bunch of "missing" structural bolts with "Grade 8" (I assume SAE, Grade 8) bolts. I can only guess what happened to the original bolts. I'm sure they weren't stolen, so that leaves the options of working loose or breaking under repetitive load cycles. This is a vertical bolt, attaching a crane girder to a column cap plate -- a fatigue condition. I'm not comfortable with this replacement. As far as I can tell, the grade 8 machine bolt is hard, tough, and brittle.

    I recommended replacing the new bolts with ASTM A325 bolts, but the client is reluctant to spend money twice for the same work. Thoughts?

    Not Specified

    05-01-2000
    WT Shapes

    What is the allowable bending stress for a WT member loaded in a direction parallel to the stem? I assume the allowable stress depends on whether the flange is in compression or tension. Does the AISC Specification for Allowable Stress Design of Single-Angle Members apply?

    William B. Kussro, P.E.
    Arcadis Giffels
    Southfield, MI

    05-01-2000
    Double Angle Connections

    Table 9-3 and its accompanying paragraph (page 9-16) in the LRFD Manual of Steel Construction, 2nd ed., Volume II, requires that for knife connections the leg of the clip angle welded to the supporting member be 4" (with reduction to 3 1/2" or 3" in some cases). If the connection is to be used on a column with a flange width of less than 8", can the clip be reduced to have a 2 1/2" leg welded to the supporting member without affecting its rated capacity in Table 9-3? The tables in the CISC Handbook are based on similar size angles.

    Lorne Hyatt
    Lambton Metal Works Ltd.
    Ontario, Canada

    04-01-2000
    "Safety" Connections

    I just received a fax from one of our fabricating customers that says that we must now provide what they call "safety holes" for beams framing into column webs. I'll try to see if I can adequately describe it.

    For example, the column web would have six rows of holes. The clip angle on one side of the column web would have five rows of holes and would bolt on the upper five holes of the column web. The clip angle on the other side of the column web would also have five rows of holes, but would bolt to the lower five holes in the column web. Four rows of bolts (middle four) would be in double shear and two rows (top and bottom) would be in single shear. I'm assuming this is for safety during the erection. Great idea! Is this now being required and specified by AISC? Will this affect the design and loading requirements?

    Randy Sedlacek

    03-01-2000
    Expansion Joints

    Is there a reference or any published guidelines that would assist the Engineer in deciding whether expansion joints are needed in a building structure and if so where they should be located?

    Joe Underwood
    Karl R. Rohrer Associates, Inc.

    03-01-2000
    "X"-Bolts

    Are we dangerously kidding ourselves when we specify "X" high-strength bolts? The allowable shear stresses are increased more than 40% for threads excluded from the shear plane. The installer of these bolts is an ironworker working many feet above the ground with a bolt bag filled with possibly many varieties of bolts. How does he know that the connection he is working with at the moment requires "X" bolts?

    There is also a very small tolerance for installing a bolt with the threads excluded from the shear plane. For example; a bolt with a 1/2" shank (unthreaded portion under the bolt head) that is installed from the clip-angle side (5/16" thickness) to the flange of a W8x40 column flange has the threads excluded. This same bolt installed form the column flange side (9/16" thickness) does not exclude the threads.

    Another aspect to consider is the ability of the structural steel inspector to verify that a bolted connection he observes after erection has in fact excluded the threads from the shear plane since the shank of the bolt is hidden from view.

    David E. Ayers, P.E.
    ESource Detailing
    Richmond, VA

    02-01-2000
    Butt Splices

    LRFD Manual of Steel Construction, 2nd edition, Volume II, page 11-69 gives typical butt plate thickness as 1 1/2" for W8 over a W10, and 2" for others. Is there any method to calculate the required thickness? What about same column splice (same cross sections above and below) where no bending is introduce in the butt plate?

    02-01-2000
    Girts

    Girts are typically designed to support the vertical tributary area weight of siding for each girt level as well as the horizontal (component and cladding) tributary area wind pressure for each girt member.

    Considering that siding is necessarily erected from the base upward and that the diaphragm arching effect of the siding would certainly bridge between columns and load them directly, why does it make any sense to consider channel girts to eccentrically support siding weight on one flange? Suppose no sag rods are used?

    James G. Brooks, P.E.
    OnBoard Engineering
    Newark, DE

    02-01-2000
    Single Plate Connections

    Part 9 of the AISC LRFD Manual of Steel Construction, 2nd edition, Volume II -- Connections, contains tables for single plate shear connections. These tables are dependent on the flexibility/rigidity of the supporting structural element. Part 9 defines a rigid support as a supporting member possessing relatively high rotational stiffness, such as a beam-to-column flange connection. A flexible support is defined as a member possessing relatively low rotational stiffness such as a one-sided beam-to-girder connection.

    These definitions are also discussed in the Hollow Structural Sections Connections Manual. Would the following single plate shear connections be defined as rigid or flexible?

    1. Beam-to-face of structural tube.
    2. Beam-to-web of wide flange shape.

    Is there any published information that provides guidelines for classifying supporting members as either rigid or flexible?

    John V. Novelli, P.E.
    Novelli Engineering
    Shaftsbury, VT

    02-01-2000
    Seismic Connections

    I am required to do lab testing of steel moment connections used in Special Moment Resisting Frames. Who does this type of testing, what does it cost, and what are the standards? I understand that it is possible to use previously tested joints, but this joint is a built-up retrofit of an existing structure. I am pretty sure it is not standard.

    01-01-2000
    Temperature Differentials During Erection

    What technical guidelines are available for consideration of temperature differentials during erection? We are designing a casino with several intermediate expansion joints (structural steel framing for casino level) spaced at approximately 500'.

    Jan Vacca

    01-01-2000
    Welding Through Paint

    We have a new inspector who claims that AISC does not allow paint where field welds are to be used. I have always been taught that you can weld directly over a paint system that is capable of being welded over. Can you point me to where AISC discusses this idea?

    01-01-2000
    Bottom Flange Bending Capacity

    How do you calculate the lower flange loading capacity of a steel beam to be used to support an underhung crane? Are there any published ASD or LRFD design procedures?

    James F. Jendusa, P.E.
    MSI General Corporation
    Oconomowoc, WI

    12-01-1999
    Flame-Cut Bolt Holes

    Are there any AISC guidelines for flame-cut holes used for bolted connections?

    12-01-1999
    Angles and Channels in 50 ksi Steel

    Does anyone have any information on the availability of angles, channels, and other rolled materials in 50 ksi material, rather than A36? Is the industry trending towards 50 ksi material in those shapes as well as wide flanges?

    11-01-1999
    Temporary Structures

    Is there an AISC (or equivalent) steel design code for temporary structures which is less conservative than ASD or LRFD?

    Mark A. Walters
    Westinghouse Electric Company
    Monroeville, PA

    11-01-1999
    Using A940 Bolts in Slotted or Oversized Holes

    The RCSC Specification for Structural Joints Using ASTM A325 or A490 Bolts (1994), tells us in section 7 (c) (7) that A490 bolts over 1" diameter, when used in slotted or oversized holes in the outer plies, must utilize a single 5/16" ASTM F436 hardened washer to cover said holes. Why can't one use two standard hardened washers (totalling 5/16" thick) to meet this requirement?

    David T. Ricker, P.E.
    Javelina Explorations
    Payson, AZ

    11-01-1999
    V-Braces

    Part I of the AISC Seismic Provisions for Structural Steel Buildings (1997), section 13.5, states:

    "A beam intersected by V braces shall be capable of supporting all tributary dead and live loads assuming the bracing is not present."

    Can anyone explain to me what exactly is the meaning of this?

    11-01-1999
    Cb Applied to Moment Frames With Pin Supports

    AISC's 1989 ASD Specification, Chapter F, states that Cb can (should) be taken as unity for cantilevers. Does this apply to columns of moment frames with pin supports? It appears as though the deformed shape, moment diagram, etc. are identical in the cantilever and the column (see figure). In one case the tip deflects, in the other case the support translates.

    Raoul Karp
    RAM International
    Carlsbad, CA

    10-01-1999
    Coatings on Connection Faying Surfaces

    Is there a limitation on the thickness and type of coating on the faying surfaces of a connection for developing the full strength of a bearing type connections with A325 bolts? The issue is particularly critical when shop applied fire protection coatings must be applied in two coats (for a thickness of 0.31 inches) to provide a two hour fire rating. The current practice appears to be to block out the connections from shop coating, and field coat them after the erection of the steel is completed.

    Ray Krishnan
    Bechtel Inc.
    Houston, TX

    10-01-1999
    Compression Element Restraint Coefficient

    In table B5.1 of the 9th ed. ASD Manual, footnote e defines a compression element restraint coefficient, kc. This expression includes the ratio h/t. What definitions of h and t are used in this equation? While I think that h is well defined, the value of t is open to interpretation as either tw or tf.

    I have been given different interpretations of both h and t by different people; however, I think that h is the clear distance between the flanges (height of the web) and t is the thickness of the web (t = tw). This interpretation appears to be backed up by the Example 12 on p. 2-220 of the 9th ed. However, it does seem unusual that the local buckling capacity of a flange is related to the stiffness of the web. Can someone please clarify this?

    Andrew Abbo
    Formation Design System
    Fremantle, Western Australia, Australia

    10-01-1999
    Plug Welding to Anchor Rods

    According to the August, 1999 Steel Quiz, plug welding a less-than-fully-threaded nut to an anchor rod is not an effective means of attachment. I would like to back up this recommendation with something more substantial than this reference from the Steel Quiz in Modern Steel Construction. Can anyone guide me to research, articles, codes, or books that deal with this topic in detail?

    Frank S. Griffin, Jr., EIT
    Fort Worth, TX

    10-01-1999
    Sidesway Behavior of Frame

    Is the Cm value for a beam in a moment frame based on the sidesway behavior of the frame? Specifically, should the beam be considered subject to sidesway, resulting in Cm=0.85 per the 9th ed. ASD Manual, or does the sidesway only apply to the columns whose ends can translate relative to each other?

    Raoul Karp
    RAM International
    Carlsbad, CA

    10-01-1999
    Simple Shear Tabs & Fillet Welds

    We have been wondering whether the "ends" of simple shear tabs need to be wrapped with a fillet weld when the weld symbol shows a typical fillet weld on both sides of the shear tab. A similar question has arisen with WF column stiffeners located at the top and bottom of a connection shear tab (not part of the lateral system), which are welded with fillet welds as opposed to full penetration groove welds. Does the weld need to continue across the end or edge of the stiffener where it is flush with the column flange?

    Ron J. Allen
    Western Steel Manufacturing Co.
    Boise, ID

    10-01-1999
    Erection Clearance & Slip Critical Connections

    Does the erection clearance required for "knifed" double angle connections affect the connection's ability to perform as slip critical?

    09-01-1999
    Short Slots in Double Angle Connections

    While reviewing shop drawings for a project, we noticed that the detailer provided slotted holes (short slots) in both of the outstanding legs of the double angle connections. The bolts are 3/4" ASTM A325. Is this ok?

    09-01-1999
    1/3 Stress Increase

    ASCE 7-95 section 2.4.3, part (b) states that the effect of two or more transient loads may be reduced provided that the allowable stress is not also increased. AISC's ASD Manual, 9th Ed., section A5.2 allows a 1/3 stress increase provided that the loads are not "calculated on the basis of reduction factors applied to design loads in combinations," and gives ANSI A58.1, which was updated as ASCE 7, as an example. My questions are:

    1. Is it acceptable to use the load combinations specified in ASCE 7, but not to reduce them and use a 1/3 stress increase when designing steel members?
    2. May the 1/3 stress increase be used when designing for a Dead + Wind combination?

    David MacGregor

    09-01-1999
    Short Shear Studs

    I note that the AISC specification for composite members requires composite floor shear studs to extend up to 1.5 in. above the top of the deck.

    How can a strength value be assigned to a stud that is short of this? While safe, it seems too conservative to say that the stud has no strength. LRFD Equation I3-1 considers stud length relative to deck height but is, as I understand it, designed to consider primarily the effects of narrow ribs. I will appreciate any discussion.

    Alfred Hendrickson, P.E.
    Whitten & Borges, PC
    Billings, MT

    08-01-1999
    Threaded Connectors in Tension

    Under what circumstances would one use a cross sectional area other than gross area, of a threaded connector in tension? Or, when would one use the "tensile stress area" or "minimum root area" provided in the tables for Screw Threads, as contained in the AISC Manuals? How are these issues related to material properties or specification? Consider, as an example, a threaded rod in a tension splice.

    Phil Pierce, P.E.
    Shumaker Consulting Engineering
    Vestal, NY

    08-01-1999
    "Banging Bolts"

    What are "banging bolts" and how do they affect structural steel framing?

    07-01-1999
    Properties for HSS Sections

    I've noticed that the properties for HSS sections are slightly different in the HSS Connections Manual (1997) than those in the LRFD Manual, 2nd edition (1994). Most properties have lower values in the newer manual. Why?

    07-01-1999
    Stair Stringers & Stiffener Plates

    Stair stringers are typically constructed from channels. Frequently, the stair stringers must be mitered to accommodate landings and connections to floor levels. The flange forces cause a prying action on the web of the channel in the mitered joint. Stiffener plates between the flanges are often required to resist these prying forces. Is there some point where the web of the channel can resist these prying forces thereby eliminating the need for a stiffener plate?

    Allan T. Goffe
    M. R. Richards Engineering
    Eugene, OR

    07-01-1999
    Welding Partially Restrained Connections

    In designing a partially restrained connection consisting of top and bottom angles and a simple shear connection, the point of inflection is between the beam flange bolt gage line and the face of the connection angle. In connections of this type the driving of bolts is difficult and it may be impossible to tighten the bolts even if the gage lines are staggered. For this reason, instead of using bolts in the top flange of the beam, can welds that meet the strength requirements be used if the weld does not encroach on the inflection area?

    Lawrence F. Kruth, P.E.
    Douglas Steel Fabricating Corporation
    Lansing, MI

    07-01-1999
    Column Base Plate Shear Lugs

    Is there a publication or research paper which discusses the design of column base plate shear lugs made out of the standard W sections? In particular, should such shear lugs be designed for overall section bending and shear only due to the bearing pressure exerted against the concrete face, or should the effect of local flange or web bending be considered? Shear lugs are assumed to be confined in shear pockets by a non-shrink grout.

    Mark Trojanowski, P.Eng.
    Hatch
    Mississauga, Ontario, Canada

    06-01-1999
    Crane Rails

    For crane rails, the AISC LRFD Manual, p. 1-139, recommends that "odd lengths, which must be included to complete a run or obtain the necessary stagger, should be not less than 10 feet long." What is the basis of this recommendation?

    Dennis Price
    Fair Hill Fabricators
    Lansdale, PA

    06-01-1999
    Drilled Holes for Anchor Bolts

    I need to get some clarification in regards to the permitted size of holes drilled in column base plates for anchor bolts. There appears to be two conditions. The standard db + 1/16" seems restrictive for a column with vertical loads and nominal lateral loads at the base. However, using larger holes in base plates for columns which are a part of a lateral load resisting system would allow slippage prior to the bolts engaging. Could you please shed some light?

    Dwight Drew (via email)

    06-01-1999
    Guidelines for Bent Anchor Rods

    Anchor rods (A307 or A36 material) occasionally get knocked and bent prior to the installation of the structural steel columns. Are there any guidelines or provisions for bending the anchor rods back into position? Are there limits to the degree of bending that can be straightened?

    Michael D. Gregory, P.E.
    Teton Structural Engineers
    Idaho Falls, ID

    06-01-1999
    Slenderness Ratio

    Are there any recommendations for a limiting slenderness ratio for drag collectors? Limiting Kl/r to 120 (the value for braces) seems overly conservative.

    Gary Harris
    Hunt and Joiner
    Dallas, TX

    06-01-1999
    Lateral Support for Beams

    For calculating the allowable bending stress on beams (ASD 9th edition, Chapter F) can I assume a pair of brackets welded from the top flange to bottom flange on both side of the beam serves as a lateral support to reduce the laterally unsupported length of the compression flange?

    Emha Antariksa

    04-01-1999
    Weathering Steel

    Are there any references on the maintenance of weathering steel wall panels or structural members? Can weathering steel be painted?

    04-01-1999
    Concrete Cover of Shear Stud

    What is the minimum concrete cover required above the head of a shear stud connector?

    03-01-1999
    Construction Joints

    In a large composite slab, construction joints may be required. Where should one put construction joints in composite floors?

    03-01-1999
    Design Strengths for Clevises

    The AISC Manual indicates that design strengths tabulated for clevises and turnbuckles are calculated using f = 0.3 in LRFD or a factor of safety of 5 in ASD. The Manual indicates that this conservative reduction is used because these devices are most often used for temporary rigging which may be subjected to dynamic and impact loading. When these devices are used in permanent applications and not subjected to these considerations, e.g. as part of the permanent bracing system, is it justified to use f = 0.5 in LRFD or a factor of safety of 3 in ASD?

    03-01-1999
    Bolt Hole Sizes

    I have received our client specifications and they indicate that they require all bolt holes that are in galvanized steel to be 3/32" over sized and not the standard 1/16". Our fabricator has indicated that this is a very costly request when the codes indicated that only 1/16" is required, and the 3/32" would require re-tooling the fabrication line which in turn delays the fabrication. Is there any economic justification on the constructor's side that the holes be oversized 3/32" for mechanically galvanized bolts? Hot dipped galvanized bolts? In addition to the higher cost of fabrication all engineering standard detail drawings would have to be updated to indicated this over sized hole.

    02-01-1999
    Definiton of "Mill to Bear"

    "Mill to bear" is a term often used in contract drawings and specifications. What precisely is the definition of "mill to bear", especially as it relates to AASHTO Standard Specification for Highway Bridges (16th Edition) and AWS D1.1 (1996)?

    While our drawings do not call the parts "stiffeners", the closest we can come to the above question is paragraph 5.23.10 in D1.1. Because our contract does not reference AISC, Section M4.4 of the LRFD Specification (2nd Edition) is not being recognized by our customer.

    Jim Tyvand, P.E.
    ADDISON Corp.
    Bend, OR

    02-01-1999
    Extended Shear Tabs

    LRFD Manual (Vol. II) on page 9-194 states that "If provision is made for ductility and stability, it follows from the lower bound theorem of limit states analysis that the distribution which yields the greatest strength is closest to the true strength." Can someone help to explain just how one "provides for ductility and stability" with an extended shear tab?

    02-01-1999
    Materials and Design Properties in Older Structures

    I am analyzing a structure which was fabricated in 1924. Am I correct in assuming that the material is ASTM A7? Where can I find the section properties for this material? In particular, I need the design properties for ship building channels, standard channels and angles from this era. Also, what is a good reference to use for determining the strength of riveted connections?

    02-01-1999
    NDE Inspection

    What NDE inspection beyond visual should be specified? What acceptance criteria should apply?

    02-01-1999
    Non-Destructive Examination

    What are the commonly used methods of non-destructive examination?

    02-01-1999
    OSHA Requirements for Column Base Plates

    What is the status/prognosis of the OSHA requirements for a minimum of four bolts in column base plates?

    Norman Golinkin

    02-01-1999
    Welding to A7 and/or A9 Steel

    What is the process and/or requirements for welding to A7 and/or A9 steel? Our office is working with a number of existing buildings of this era and would appreciate an answer, idea or reference.

    02-01-1999
    Friction Coefficients

    My question is regarding the shear friction design method used to transfer column shear forces to foundation systems. AISC Design Guide #1 (Column Base Plates) gives friction coefficients for use in determining frictional shear resistance. The friction coefficients are based on ACI 349-85. The design guide states that these friction coefficients are for limit state conditions and that a factor of safety of 2.0 should be used with these coefficients for ASD. In comparison, AISC Design Guide #7 (Industrial Buildings) also outlines the shear friction design method but makes no mention of the factor of safety nor is one used in the design example. Please clarify if a factor of safety on the friction coefficient for ASD is required or not.

    William B. Kussro, P.E.
    Giffels Associates, Inc.
    Southfield, MI

    12-01-1998
    Stiffening End-Plate Moment Connections

    When stiffening extended end-plate moment connections, if bolts are located on the usual gauge line of the column flange then stiffeners are often required due to column flange bending opposite the tension flange of the beam. Is it a legitimate practice to locate the bolts on a narrower gauge line to avoid needing stiffeners? If this is done, can the full effective width of the end-plate still be used for the end-plate thickness calculation?

    James M. Gleason, P.E.
    George Koch Sons, Inc.
    Evansville, IN

    12-01-1998
    Weak Axis Effective Length

    What is the weak axis effective unbraced length (KyLy) for a floor beam (W24x55 for example) subjected to axial load? The floor beam is loaded in compression along the neutral axis and is loaded in bending about the major axis via floor deck connected to the top flange. The beam has no perpendicular members framing into it.

    Karl Menches, P.E.
    Greenville, SC

    12-01-1998
    Base Plate Grouting

    When, during the erection process, do steel column base plates require grouting?

    11-01-1998
    Bolts in Extended End-Plate Moment Connections

    When designing extended end-plate moment connections, if bolts are located on the usual gauge line of the column flange then stiffeners are often required due to column flange bending opposite the tension flange of the beam. Is it a legitimate practice to locate the bolts on a narrower gauge line to avoid needing stiffeners? If this is done, can the full effective width of the end plate still be used for the end plate thickness calculation?

    James M. Gleason, PE
    George Koch Sons, Inc.
    Evansville, IN

    11-01-1998
    Machine Bolts

    Does the term "machine bolt" refer to the type of material (A307, A325) of the bolt or does it pertain to the thread geometry?

    Would it be accurate to call out a 3/4" diameter A325 bolt as a machine bolt on a structural drawing?

    11-01-1998
    Stiffener Member for Bending Moment

    In certain situations, the moment connections shown are used. How do you design the stiffener member for the bending moment(s) in the beam to be: (a) positive and (b) negative?

    Fran M. Lacsina
    Melrose Metal Products
    Fremont, CA

    11-01-1998
    Through Truss Pedestrian Walkway

    For a through truss pedestrian walkway constructed of HSS members, what guidelines do AISC recommend to ensure lateral stability of the top chord?

    C. Michael Holtz
    GSI International
    Assumption, IL

    10-01-1998
    Wind Load Applications: Enclosed vs. Partially Enclosed

    Can we design a steel or metal building as an "enclosed" for wind load applications when one sidewall is open for full size doors? When the doors are open, it will make the building "partially enclosed". However, when closed, will make it an "enclosed" structure. What should be the right approach?

    10-01-1998
    Oversized Bolt Holes

    Our company is in the underground support industry (mines, tunnels, shafts, etc.). It has been common practice for many years to make bolt holes 1/8" larger than the bolt to be used (A325). This is because the excavations are taking place under adverse conditions and the steel erectors have to place the supports as fast as possible. Does this mean the holes are oversized and require washers? The workers just do not have time to place the washers.

    rokkytop@aol.com
    via email

    09-01-1998
    Repair Code for Steel Beams

    Is there a repair code for steel beams?

    09-01-1998
    Bending Members

    In the Manual of Steel Construction, ASD, 9th Edition, Commentary, Chapter F, Section F3 "Allowable Stress: Bending of Box Members, Rectangular Tubes and Circular Members" page 5-147, Equation (C-F3-1) is given as:

    (l/r)equiv. = SqRt ((5.1lSx)/SqRt(JIy))

    The manual then states "It can be shown that, when d<10b andl/b>2500Fy, the allowable compression flange stress indicated by the above equation will approximate O.6OFy"

    How does one show when l/b>2500Fy that the compression flange stress will approximate 0.60Fy?

    Dale H. Curtis, PE
    Curtis Engineering Corporation
    San Diego, CA

    08-01-1998
    Specific Load Combination

    For a specific load combination, some bottom chord members of a continuous steel truss are in tension and others are in compression. Is it possible to consider that the node, located between a tension and compression member, can behave like a lateral support to evaluate the compression strength with respect to the weak-axis of this member (by analogy to the inflection point of a bending moment diagram acting as a lateral support from beam lateral-torsional buckling)?

    08-01-1998
    Rivet Removal

    During bridge repair, rivets are often removed and replaced with A325 or A490 bolts. Is there a standard procedure written for the removal of rivets and re-sizing of the fastener hole? If the base metal is going to be re-used, I would think that it would be very important not to damage or overheat the base metal around the fastener hole. This base metal could be a multiple build-up of two, three or four-plys. Should these rivets be removed with a machine or cutting torch? Rivets are pressed in when newly installed, should they be pressed out? What preparation should be taken to remove and rework a riveted connection?

    07-01-1998
    Steel Deck Diaphram on Gabled Roof

    What is the procedure for analysis of a steel deck diaphragm on a gabled roof? In particular:

    1. What are the chords? Are they developed at the ridge or along walls as with a flat horizontal diaphragm? This is particularly important for aspect ratio considerations.
    2. Should one view the gable roof more as a rigid box (i.e. the roof framing and deck acting together) and discount the gable geometry?

    Leonard Mule
    via email

    06-01-1998
    Composite Beam Design

    How is a composite beam designed when there is an opening in the concrete "flange" adjacent to the steel beam? Does the length of the opening affect the design, if the opening length is small relative to the beam length can it be neglected? Does the location of the opening, relative to the maximum moment, affect the design?

    For example: If designing beams "B2" and "B3" (see sketch) as composite beams, is it too conservative to treat the beams as edge beams for the total span (only accounting for the concrete "flange" on the opposite side of the opening the full length of the beam)?

    05-01-1998
    Reinforcement Design

    In my work, I often have to design reinforcing for existing steel beams that have cast in place concrete arches between the beam webs. The bottom flanges are usually exposed and if the concrete covers the top flange it is not enough to provide adequate cover for shear studs. Many times the top flange is below cinder fill and roofing which is not to be disturbed. The procedure that I use for design of the reinforcement for increasing the midspan moment capacity is as follows: First I calculate the existing stress in the beam top flange due to dead load only. I then size an inverted WT shape to be welded to the bottom flange of the existing beam. The WT is sized to limit the sum of the existing compressive stress in the unreinforced beam top flange and the additional top flange stress due to new dead and live loads on the composite section to less than the allowable compressive stress. The beam is also checked for the increased shear stress and the higher end reactions.

    Is this method overly conservative? Are there any references on reinforcement of non-composite beams? This method has its limitations when the existing dead load stress is close to the allowable.

    05-01-1998
    Composite Action in Encased Beams

    Section I1. of the 9th edition of the AISC ASD Manual of Steel Construction defines the requirements for the determination of composite members. The specification details two situations:

    1. When a beam is totally encased, relying on friction for composite action; and
    2. When a beam is not totally encased, utilizing shear connectors for composite action.

    What about other conditions? My situation is typical to many older industrial buildings. The beam is question is made up of a rolled steel section with concrete haunches and slab on one or both sides. This section does not meet code requirements for composite action because it does not have 2" of reinforced concrete soffit below the bottom flange, nor does it have shear connectors along the top flange. The beam does have reinforcing bars (#4 @ 12" EW) on both sides of the web that are welded to the flange and web.

    My questions are as follows:

    1. Is there any recorded research or publication available on the determination of composite action for members of this configuration?
    2. How is the stiffness of the section affected?
    3. Can the composite section be used in the determination of the natural frequency of floor framing?
    4. Is there anyone I can contact to discuss my situation?
    04-01-1998
    Full Contact Joints

    How much of a joint must be in contact to be considered to be in full contact?

    04-01-1998
    Long-Span Plate Girder

    In order to facilitate the fabrication and erection of a long-span plate girder or box beam bridge, would a constructor prefer to have the option of designating the location(s) of the field splice(s)? The constructor would design the splice(s) based upon design loads, moments, and shears shown in the contract documents.

    04-01-1998
    Seismic Provisions vs. LRFD Specification

    What is the difference in design philosophy between a building structure that has been designed to meet the AISC LRFD Specification for Structural Steel Buildings and a building that has been designed to meet the AISC Seismic Provisions for Structural Steel Buildings?

    04-01-1998
    Whitmore Section

    In many design examples in the 2nd Edition LRFD Manual of Steel Construction, yielding and buckling in a gusset plate or similar fitting are checked on a Whitmore section. What is a Whitmore section?

    04-01-1998
    OSHA Requirements for Tie Off Points

    OSHA safety requirements state that tie off points for fall protection be designed and evaluated for a 5000 lb. load. What is the correct load combination and associated steel member stress condition for acceptance for this required load?

    03-01-1998
    Pratt Truss

    Is there any need for a diagonal in the center panel of the sketch below (showing a Pratt truss with an odd number of panels)?

    03-01-1998
    Unbraced Length of Column

    The following figure shows the connection of a beam and a supporting column with a stiffener that is not full length. The beam is under uniform loading of w. There is nothing bracing the column along its length. What is the correct dimension for the unbraced length of the column?

    Kunming Gwo, P.E.
    HCI Steel Building Systems, Inc.
    Arlington, WA

    03-01-1998
    Checking Tube Wall for Failure

    What is the correct procedure for checking a structural steel tube wall for local failure due to a load applied by a clip angle?

    02-01-1998
    Designing Built-Up Section for Moving Concentrated Loads

    Clarification is sought when evaluating or designing a built-up section for moving concentrated loads like a crane transversing its girder for interpretation of the bf variable and resolution of the requirement if equation K1-7 is not met.

    First part, should one use the wider compression flange width of the top channel for bf in the computation of equation K1-7, or the narrower width of the bottom flange.

    Second part, if equation K1-7 results in requiring bearing stiffeners, where are they located (i.e. mid span?) since the concentrated load is transient? Also in the commentary section it states that, if the loaded flange is not restrained then the addition of bearing stiffeners alone will be ineffective. From this statement it would appear that both restraint and bearing stiffeners are required, whereas Section K5 states that bearing stiffeners shall be provided in the webs of members with flanges not restrained against relative movement by stiffeners or lateral bracing and subject to concentrated compressive loads when compressive forces exceed the limits established by Equation K1-7.

    J. Dollhopf III, P.E.
    Galletta Engineering Corp.
    Pittsburgh, PA

    02-01-1998
    Throat Thickness of Fillet Welds

    AWS 94 Code 2.3.2.4 states "The effective throat shall be the short distance from the joint root to the weld face of the diagrammatic weld." In the AISC Specification it states the same with the addition of "except that, for fillet welds made by the submerged arc process, the effective throat thickness shall be taken equal to the leg size for 3/8" and smaller fillet welds, and equal to the theoretical throat plus 0.11" for fillet welds larger than 3/8".

    Why is there an exception specified in AISC? Will SMA process for fillet weld get higher strength and will it cost more?

    Is SMA only used in shop conditions?

    Some drawings indicate: "SMA process will not be allowed". Why?

    02-01-1998
    End-Plate Connections

    I've come across the end-plate connections shown in the figure several times. Are they all rigid moment connections or are they semi-rigid connections?

    12-01-1997
    Minimum Length of Thread on Structural Bolts

    The structural steel design manuals establish a minimum length of thread on structural bolts, referencing ANSI B18.2.1. They also give a formula of 2D+1/4" for bolts less than 6" in length, and 2D+1/2" for bolts longer than 6" long. What are the consequences if the bolts are fabricated with thread lengths less than this amount, but still capable of making up a proper connection? Is this grounds for rejecting the bolts? Why is this length the same regardless of what type of bolted connection (N, X, SC) is used? It would seem that the thread length values should differ depending on the type. Finally, the Specification for Structural Joints Using ASTM A325 or A490 Bolts states "The length of the bolts shall be such that the ends of the bolt will be flush with or outside the face of the nut when properly installed." With this added criteria, it would seem that the thread lengths could be shorter than those specified in the Table, because a single nut and washer is never greater than 2D in length.

    12-01-1997
    Stiffener Welded to Flat Plate

    Consider a stiffener welded to a flat plate. The stiffener and some amount of participating plate are considered to be an effective section. If the calculated shear at the stiffener to plate connection can be carried by an intermittent weld, is there a practical limit on weld spacing beyond which the stiffener and plate no longer act as a single member?

    James M. Gleason, P.E.
    George Koch Sons
    Evansville, IN

    11-01-1997
    Allowable Stress for Steel Tank Wall

    Are there any references on allowable compressive stress (buckling stress) for large diameter (120 ft.) steel tank wall when it is empty and subjected to external soil pressure?

    10-01-1997
    Load Factors for Pre-Packaged Equipment

    AISC LRFD load factors and combinations address conditions encountered in buildings and bridges. What load factors and combinations should be used for steel structures supporting pre-packaged equipment (such as skid-mounted and modular units) and subject to temporary ground and sea transportation motion forces?

    John C. Clarkin
    UOP Equitec Services, Inc.

    10-01-1997
    St. Venant and Warping Torsion in Monorails

    Torsional stability in curved bridges is achieved through the interaction of girders and diaphragms. How do you design a single curved monorail beam to resist St. Venant and warping torsion? Also which standard governs the allowable stresses of monorails and lift beams, AISC or ANSI?

    10-01-1997
    Lifiting Beams

    A typical lifting beam or strongback in the materials handling, crane and rigging industry takes the form of either a horizontal or wide flange beam, with padeyes top and bottom at both ends. The lifting wire rope bridle with two legs at about 45 degree angle attaches to the top padeyes and the supported weight attaches to the bottom padeyes (see sketch).

    The wire rope bridle induces both compression and bending moment in the lifting beam. Again, there is no lateral support.

    What analysis would be used to solve for the safe lifting capacity of this form of lifting beam?

    09-01-1997
    Mig Wire Size for E70XX Specification

    What size mig wire is considered structurally acceptable or comparable to an E70XX specification? Is there a solid wire that is acceptable? With what gas? Can the penetration and weld properties be equivalent to arc welding with, say, an E7018 rod?

    09-01-1997
    Tolerance of Crane Rail

    How does the AISC Code of Standard Practice address the possible tolerance for vertical and horizontal alignment of crane rail in a mill type building?

    09-01-1997
    Weld or Bolt First?

    Should connections involving bolts and welds used in combination be welded first or bolted first?

    09-01-1997
    Welded Double Angle Connection Design

    How is a welded double angle connection designed when the double angles are connected to the flange of the column and welded on the back side of the double angles? See figure. (from March 1997 issue) This may be necessary when the column flange is short.

    09-01-1997
    A325 vs. A490 Bolts

    Our office design the structures for tall highway billboard signs. Recently another engineer reviewed our calculations and questioned the use of A490 bolts. He felt they were being used in a repetitive tension load. He wants A325 bolts to be used rather than A490 bolts.

    These signs are loaded principally by wind loads though dead loads do add a small tension stress to some of the connections.

    Please comment on the premise that wind constitutes a repetitive load. Fatigue was not mentioned.

    Please also comment on the use of A490 bolts in tension due to wind loads.

    Emil C. Hach
    Hach & Ebersole, Consulting Engineers
    Twinsburg, OH

    08-01-1997
    Allowable Stress in Lintels

    When rolled wide flange sections are used as lintels to support masonry wall openings, should the allowable stress be reduced in accordance with Formulae F1-6 and F1-7 from the AISC Specification for the following cases:

    1. Masonry is placed on the top flange. Sides are open. Masonry is unreinforced except for horizontal joint reinforcing.
    2. Same condition as above except masonry is placed on each side of the web between the flanges.

    Y Eugene Yamamoto
    Eugene Yamamoto & Associates
    Chicago, IL

    08-01-1997
    Design for Square Bins and Hoppers

    Are there any recommendations or reference materials on the design and or analysis of details (e.g. loads and connection designs) for square bins and hoppers, towable trailers, supports, and stands.

    R.C. Parsaghian
    Granite City, IL

    08-01-1997
    High-Strength Bolts and Welds If a connection combines high-strength bolts and welds, which is installed first? Are the bolts tightened before welding or is welding performed before the bolts are fully tightened? Will slipping of the bolts or cracking of the welds occur if it is not done in the proper manner?

    08-01-1997
    Minimum Length of Thread on Bolts

    The structural steel design manuals establish a minimum length of thread on structural bolts, referencing ANSI B18.2.1. They also give a formula of 2D+1/4" for bolts less than 6" in length, and 2D+1/2" for bolts longer than 6" long. What are the consequences if the bolts are fabricated with thread lengths less than this amount, but still capable of making up a proper connection? Is this grounds for rejecting the bolts? Why is this length the same regardless of what type of bolted connection (N, X, SC) is used? It would seem that the thread length values should differ depending on the type. Finally, the Specification for Structural Joints Using ASTM A325 or A490 Bolts states "The length of the bolts shall be such that the ends of the bolt will be flush with or outside the face of the nut when properly installed." With this added criteria, it would seem that the thread lengths could be shorter than those specified in the Table, because a single nut and washer is never greater than 2D in length.

    Richard Portier, P.E.
    Butler Heavy Structures
    Kansas City, MO

    08-01-1997
    Special Tolerances for Cladding

    Are special tolerances required to accommodate the cladding on structural steel frames?

    08-01-1997
    Weathering Steel High Strength Bolts

    Are there any advantages or disadvantages to using A325 or A490 Type 3 (weathering steel) high strength bolts on exposed exterior bolted structural steel members which are A36 steel? Is there any problem with corrosion between the two types of materials?

    S. Kalat
    Raytheon Engineers and Constructors, Inc.
    Seoul, Korea

    08-01-1997
    Cambered vs. Rolled Beams

    A structural design drawings roof plan specified "W10 x 17 (CAMBERED) ELEVATION. VARIES"

    The end result turned out to be a beam rolled the hard way on approximately a 10'-0" radius.

    Please define the difference between cambered and rolled beam.

    Jim Long

    07-01-1997
    Design Basis for Seat Angles

    What is the design basis for seat angles in seated beam connections in the AISC Manual of Steel Construction? What would the capacity be for an angle length other than 6" or 8"? Are shorter angle lengths permissible? Is it permissible to lacate the top angle in the optional location, shop-weld it to the beam, and field bolt it to the column with a single bolt?

    James M. Gleason, P.E.
    George Koch Sons, Inc.
    Evansville, IN

    06-01-1997
    Designing a Hole for Piping

    What is the procedure for designing a hole for piping in a simply supported steel beam? Are there special details?

    06-01-1997
    Equivalent Radius of Gyration

    AISC Commentary Chapter F of the Specification for Structural Steel Buildings, section F1.3, provides equation C-F1-1 for determining an equivalent radius of gyration, rT, for use in determining allowable strong axis bending stresses according to Eq. F1-6 and F1-7. Can this equation be used any time or are there restrictions?

    Warren S. Foy, P.E.
    Mason & Hanger Engineering, Inc.
    Lexington, KY

    06-01-1997
    In-Plane Effective Length Factor

    What is the in-plane effective length factor for each column of the frame assuming: a) the beam to be continuous but not rigidly connected to the center column? And b) the beam to be discontinuous at the center column with simple connections to it?

     

    06-01-1997
    Stepped Column Design

    How does one design a stepped column?

    06-01-1997
    Bearing vs. Slip-Critical Connections

    Should a bearing type connection be used in connection resisting seismic loads (reversible loading at low cycles) or should only slip-critical connections be designed?

    Rodney Hartunian
    Rinne & Peterson
    Palo Alto, CA

    05-01-1997
    Bolted Connections in Tension

    If I need a bolted connection that functions primarily in tension and I select A325 bolts, is it necessary to preload the bolt to minimum slip-critical values tabulated in the AISC Manual of Steel Construction?

    Ralph C. Dumack, P.E.
    Ralph C. Dumack, P.E. and Associates
    Levittown, PA

    05-01-1997
    Load Capacity for Lifting Beam With No Lateral Support

    What is acceptable practice for determining the load capacity for a lifting beam, similar to that shown in the accompanying sketch, for which there is no lateral support? Is it appropriate to use the full beam length to determine the bending strength of the member? Is doing so overly conservative? Are there design considerations other than strong axis bending capacity?

    05-01-1997
    Unbraced Trolley Beam

    Does an unbraced trolley beam that is loaded on the bottom flange have the same buckling characteristics as an unbraced beam loaded on the top flange?

    05-01-1997
    Warping Torsion Stresses

    When analyzing a steel beam for combined strong and weak axis bending, axial load and torsional load, to what allowable stress should warping torsion stresses in the flanges be compared in using AISC Eq. H1-1, H1-2 and H1-3?

    Warren S. Foy, P.E.
    Mason & Hanger Engineering, Inc.
    Lexington, KY

    05-01-1997
    I-beam Monorails

    How are stresses and strains calculated in curved I-beam monorails? Curved beam problems can be solved when the load is pointed to the center of the curve or away from the center. However, what is a practical solution for an I-beam with a curve for the trolley?

    11-01-1996
    Lateral Bracing

    One of the primary concerns in flexural design is the use of lateral bracing to control lateral-torsional buckling. What constitutes lateral bracing? Does the bracing member need to be a particular stiffness compared to the member being braced? Does it need to be a particular stiffness compared to the member being braced? Does it need to brace the compression flange, or will it serve its purpose if it braces the web? If the load is applied uniformly by a plate resting across the top flange of the beam, does the plate laterally brace the beam? What if the plate is welded to the beam?

    02-01-1996
    Structural Tee Beam

    Under the ASD design specification, how is the maximum unbraced length (Lc) of a structural tee beam to be determined if the tee stem is in compression? How is the allowable flexural stress to be calculated if the unbraced length exceeds this limit?

    03-01-1994