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Reader Forum

Have a comment about an article? Post it here to share with others, or you can contact the MSC staff directly. Either way, we are always glad to hear from you.

If your question is of a more technical nature, please submit it to the AISC Steel Solutions Center by sending e-mail to solutions@aisc.org.

Temprature load in steel building
Posted by R A on January 14, 2012 at 11:58 AM. | No Comments »

If we provide expansion joint at roof purlins only (at 125 ft lehgth). Do we need to consider temprature load for building. Building is 350 ftx185 ft and 175 ft high industrial building. temprature variation is 80F. With expansion joint loads are very high at vertical braces location and seems unreasonable to design for these loads. Please advice. Thanks

Vertical load capacity?
Posted by Jim Westman on December 15, 2011 at 3:04 PM. | 1 Comment »

Hello all,

I am currently building a small steel structure using a 9-foot high 4×4-inch square tubing, mild steel, 1/4-inch thick, to vertically support another non-moving horizontal beam.

I am desperately trying to find a place/chart/website/anything that can give me a rough idea if I am relatively safe in terms of vertical load capacity of the 4×4 post (it’s plum).

The load will potentially be as much as 5,000 pounds.

Any help would be so much appreciated.

Thank you in advance.

Installation of sheet piles
Posted by on March 14, 2011 at 10:25 AM. | No Comments »

Sometime for short lenght sheetpiles of about 6 to 8 metters can be install sing a small hydraulic powered vibratory hammer attached to a heavy excavator. The bucket of the excavator had been removed and in it’s place a vibratory hammer is placed. It will be powered by the hydraulic system of the excavator.


This video below shows a vibratory hammer mounted to an excavator arm. It’s installing a sheet pile walls. Most likely the wall is to stabilize the ground behind the sheet wall. Infront of the wall is an open excavation.


Now as mentioned earlier in my earlier post it is not a good practice to install sheet piles by banging the steel sheet piles using the excavator bucket. Doing this may cause damage to the sheet piles and as well to the excavator bucket. If you see a dented excavator bucket, then you are sure that the excavator may had been subjected to abuse beyond what the excavator had been designed for.


However, if the sheet piles are not made of steel but of vinyl sheeting ( easily recognizable from it’s clean white color ) than the installation can make use of the excavator bucket. Like this video below shows. Sometime when difficult ground is encountered, the area where the vinyl sheet piles are to be installed may be loosen using water jet prior to installation. Vinyl sheet piles are popular near water areas like sea wall, river banks due to it’s non corrosive nature. Here is a video on how vinyl sheet piles are installed with an excavator bucket.


Ensuring proper and correct interlocking between sheet piles is one of the key and crucial requirement during the installation of sheet piles. Usually this is done manually and can be rather tricky if the the sheet piles need to be interlocked at a height.


Thus this required the hosting of both man and sheet pile high up from the ground to get the job done. And thsi can be dangerous due to the height involved and difficult too as the person esuring the proper interlocking of the sheet piles has to communicate with the crane operator from a height. Further more it will be virtually impossible to do thsi when there is stong cross winds.


Now a company had come out with an igenious solution. A gadget called the “Universal Sheet Pile Threader” solves all the invconvinience and problem as mentioned above. It is completely safe and require only two men ( one infront and the other behind the sheet pile) to install the gadget and done on ground level (thus very safe)


stair tread holes overlap on Stringer Mitre Cut
Posted by on December 22, 2010 at 11:18 AM. | 1 Comment »

When a stair was placed with the treads with respect to Run and Rise as specified in Design Drawing, there is a possibility that the tread hole may exactly come on the mitre cut of the Stair Stringer. What may the best possible solution in such cases?

ASTM A572 grade 50
Posted by on December 1, 2010 at 4:14 PM. | 1 Comment »

is it possible to use ASTM A 572 grade 50 in plates up to 5"?,if not, which is the recommended steel for substitute in a Bridge structre application

MSC June 2010 - Base Plates and Anchor Rods
Posted by on June 11, 2010 at 2:26 PM. | No Comments »

In the Erection section, the statement "It should be understood that anchor rods cannot be pretensioned ——" is not correct.  It is possible, and in some cases advantageous, to pretension anchor rods.  For pretensioning, it is necessary to use a washer, larger plate or other shape (i.e angle) at the embedded end nut or bolt head. Relying on bond to resist uplift of any kind is never acceptable.


Manuel Morden, S.E.   F SEAOC


seismic response modification coefficient
Posted by on March 10, 2010 at 12:56 AM. | 1 Comment »

dear sir/madam

I want to know if the "R" is different in ASD or LRFD method, is it depend on load combinations also?


thanks before


Design Load of Knee brace
Posted by on March 5, 2010 at 2:28 PM. | 1 Comment »

For portal frame rafters, what is magnitude of the force subjected to the knee brace resulting from preventing the rafter compression flange to deform?

a friend of mine told me that it’s about 5% of the compression force in the rafter

if it’s x%…then x is the force resulted from the laterlal torsional buckling at the particular point…?

Using Alignment Chart for Portal Frame Rafters and Columns
Posted by on March 5, 2010 at 2:16 PM. | 1 Comment »

I have a tapered Column and a Haunched rafter, how can I get "K" from the Chart while the Column’s moment of Ineria is not uniform along the column and rafter’s length…?

bolted column splice
Posted by on January 7, 2010 at 7:46 AM. | 1 Comment »

In Table 14-9 (continued), of the thirtenth edition of the AISC manual, at the center point of the splice the bolt c/c dimention goes to 3 1/2″ in stead of 3″. What is the reason for this?