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Why Steel?
Posted by Geoff Weisenberger on May 22, 2008 at 10:20 AM.

In a continuing effort to answer this seemingly simple question, AISC has recently launched a specialized web site as part of its industry mobilization program. Created exclusively for the structural steel industry, www.WhySteel.org is a controlled-access web site; visitors must join the site to access its content.

 

Users of the new site are not necessarily members of AISC; they just have to be part of the structural steel industry. The site provides access to educational articles, newsletters, discussion forums, and tools that the industry can use to learn about and promote structural steel.

 

Perhaps most importantly, it provides the steel industry with reasons why any project should be built with steel and includes hints, tips, and ideas for convincing those in the design and development community that “There’s always a solution in steel.”

 

Some of the sections of www.WhySteel.org include:

 

  • Industry Mobilization. Find out how you can help your industry—and why you should. You’ll also find hints and tips to get started and answers to frequently asked questions. Get started in helping your industry be even stronger than it is today.
  • Structural Steel Benefits. Learn about the advantages and benefits of building with steel. One area of this section is devoted to understanding the benefits of steel as it relates to different types of projects, enabling you to talk sensibly to the local design community about steel and provide them with handouts and case studies of specific project types.
  • Education/Learning. Access talking points about the industry and learn about the other players in the steel supply chain. Gain an understanding of terms and terminology, and increase your knowledge of steel’s competition.


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Call for EJ Papers
Posted by Geoff Weisenberger on May 22, 2008 at 10:18 AM.

AISC is always looking for Engineering Journal articles on interesting topics pertinent to steel design, research, steel fabrication methods, or new products of significance to the uses of steel in construction. We are especially seeking technical articles with practical applications in the steel industry.

 

If you have a new idea or an improvement on an old idea, please submit a paper to AISC for publication in the Engineering Journal. All published papers are eligible for the Best EJ Paper of the Year award. The winning author of this annual award is selected by our readership and receives a free trip to the North American Steel Construction Conference as well as acknowledgment at the conference.

 

Please send your paper in duplicate to:

 

Engineering Journal

Editor, Cynthia Duncan

AISC

1 E. Wacker Dr., Suite 700

Chicago, Illinois 60601

duncan@aisc.org

 

Detailed information on our review process and requirements for submittals can be found on the inside back cover of each Engineering Journal issue.


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Keeping Up with the AISC Spec
Posted by Geoff Weisenberger on May 22, 2008 at 10:17 AM.

Important changes to the AISC specification can be easy to lose track of, and often the challenge is to understand when the changes were made. Design Guide 15: AISC Rehabilitation and Retrofit Guide (DG 15), Appendix A1 provides a comprehensive source of historical information that references changes made to the specification.

 

Currently, DG 15, Appendix A1 provides a list of changes to the specification through the 1999 LRFD Specification for Structural Steel Buildings. An update to this list, including the changes from the 1999 LRFD specification to the 2005 specification, is now available at www.aisc.org/crossref99. An overview of some of the more prominent revisions is outlined below.

 

The 2005 specification contains numerous unifying changes, which can be seen in Chapter A, General Provisions. While this list of updates only pertains to the LRFD portion of the specification, the most noticeable change is the combination of the ASD and LRFD provisions. Additionally, the scope of the specification has been expanded to include “other structures”, which are defined as “those structures designed, fabricated, and erected in a manner similar to buildings, with building-like vertical and lateral load-resisting elements.” Less noticeable but equally useful to the 2005 specification is the inclusion of the specifications for single angles and HSS sections. Incorporating these specifications has mitigated the need for other provisions.

 

Revisions to Chapter C, Stability Analysis and Design, reveal major organizational and substantive changes; most notable is the requirement to address second-order effects in the analysis and design. A new procedure, the Direct Analysis Method, which is described in Appendix 7, will satisfy the requirements of Chapter C. Additionally, stability based on plastic design must follow Appendix 1, which also includes other provisions for inelastic analysis and design.

 

Chapter F, Design of Members for Flexure, has also been renamed and reorganized. The chapter is now divided into sections based on member type and the axis of bending. Table User Note F1.1, Selection Table for the Application of Chapter F Sections provides a summary of the chapter by illustrating each cross-section addressed and stating the applicable limit states for that member.

 

The updates to Chapter I, Design of Composite Members, reflect research results and allow the use of higher strength materials, as well as provide better consistency with ACI 318-05, Building Code Requirements for Structural Concrete. Shear stud strength is now dependent on the location of the stud in the flute of the metal deck, the number of studs welded within one flute, and the orientation of the metal deck with respect to the beam. Composite column design is based on new interaction formulas that better reflect behavior and strength.

 

Some changes have been made to Chapter J, Design of Connections, and one of the most notable organizational revisions is the inclusion of the effects of concentrated forces previously appearing in Chapter K of the 1999 LRFD specification. The 1999 LRFD specification combined concentrated forces, fatigue, and ponding into one chapter. The 2005 specification separates these sections where Design for Ponding is located in Appendix 2 and Design for Fatigue is located in Appendix 3.

 

The all-new Appendix 4, Structural Design for Fire Conditions, provides much-needed criteria for the design and evaluation of structural components for fire conditions. This appendix discusses the effects of elevated temperature on materials and accounts for these changes in the design.

 

A review of the complete list of changes will help engineers using LRFD to become more acquainted with the 2005 specification. To get up to speed with all the changes to the specification, be sure to visit www.aisc.org/crossref99.  

 

- By Matthew Fadden and Jill Rajek

 


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Proposed ASHRAE Standard Delves into Structural Issues
Posted by Geoff Weisenberger on May 22, 2008 at 10:15 AM.

The structural steel industry has a long track record of success in sustainable development, consistently leading the way in implementing energy, carbon, and resource utilization improvements for the past 25 years. Today, however, the structural steel industry is faced with a significant challenge, one that originates not from a lack of accomplishment with respect to sustainability, but rather from being too successful in this area.

 

AISC has significant concerns with some provisions in the recently published second draft of the proposed ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) Standard 189.1, Standard for the Design of High-Performance Green Buildings Except Low-Rise Residential Buildings. AISC’s concerns with this proposed standard are that:

 

  1. It is outside the scope and expertise for which ASHRAE is ANSI-accredited.
  2. It will result in adverse environmental impacts.
  3. It includes provisions that are unfair to steel, and inappropriately preferential to the interests of the concrete industry.
  4. It adversely restricts the freedom of design professionals in their selection of structural framing materials.

 

The proposed ASHRAE standard being developed jointly with the U.S. Green Building Council and the Illuminating Engineering Society of North America is intended to provide minimum requirements for high-performance green buildings.

 

While addressing HVAC and lighting issues, the standard also establishes prescriptive requirements for construction materials, an area that AISC believes to be outside the scope and expertise of ASHRAE, USGBC, and IESNA. In addition, the committee responsible for the proposed 189.1 standard was not constituted in a balanced manner under appropriate ANSI consensus protocol. AISC also believes that the committee lacks expertise in the area of construction materials, particularly as they relate to structural framing systems.

 

This apparent lack of balance and expertise has resulted in provisions that appear to be significantly slanted toward the interests of the cement/concrete industry under the guise of encouraging less sustainable industries to become more sustainable.

 

For example, today a typical structural steel frame provides an 11% credit towards the overall recycled content of a building. A concrete frame may provide one to two percent. At the same time, the reinforcing steel in the concrete structure will provide an additional 5% credit. The proposed standard will limit the contribution for any material at 5%. The result: structural steel gets capped at 5%, while concrete still gets its full credit AND the 5% credit for reinforcing steel.

 

Similarly, the definition of recycled content is that portion of a material by mass that originates in either pre- or post-consumer waste streams. But the ASHRAE committee has decided to allow the calculation of the recycled content of concrete to violate that definition. Instead of reflecting the actual recycled content of the concrete, ASHRAE 189.1 allows the recycled content of the cementitious portion of the concrete to be used as the recycled content of the entire concrete mix.

 

For example, at present, substituting 25% fly ash for Portland cement in concrete with no other recycled content, results in an actual recycled content of 3%. Under ASHRAE 189.1 the cement and concrete industries are allowed to claim a 25% recycled content.

 

The committee’s justification is that they wish to encourage the use of fly ash in concrete. In reality, they are discouraging the use of recycled aggregates, removing over 50% of the mass of a concrete building from green considerations and providing the cement/concrete industry with an unfair advantage in the marketplace.

 

It is not the role of a standard to provide incentives and to favor particular products. The selection of structural framing materials should be based on the merits of the materials as judged against a consistent metric.

 

The inclusion of this standard in building codes is being encouraged by ASHRAE as an appendix at the national level available for local adoption. Including these provisions in a local building code will significantly limit the opportunity of design professionals to select construction materials for high-performance green buildings that properly balance economic, environmental, and design issues.

 

The structural steel industry believes strongly in the need for high-performance green buildings. AISC also believes that standards for the selection and optimization of structural framing materials should be developed in a balanced, consensus-based ANSI process that engages design professionals, industry associations, and interested parties with the required level of expertise to develop a fair and environmentally sound standard. AISC would welcome the participation of the concrete, cement, masonry, wood, precast, light-gauge steel, per-engineered building, and any other affected industries in that process.

 

AISC’s objection to 189.1 is not a rejection of sustainable construction practices or the need for green buildings. Much to the contrary, AISC’s commitment is to continue to be the leader in sustainable construction materials and to actively pursue additional sustainable practices within our industry.

 

When the domestic structural steel industry experienced a rebirth 25 years ago, purposeful decisions were made to create a sustainable industry. A central decision was the transition from basic oxygen furnaces (using iron ore and coke) to electric arc furnaces (using scrap as the primary raw material and electricity and natural gas as energy sources).

 

The gains from this transition have positively impacted sustainable construction:

 

  • Wide-flange structural steel products average in excess of 90% recycled content.
  • A 96% recycling/reuse rate for structural steel members removed from existing structures.
  • An increase in mill productivity by a factor of 20 moving from 10 to 12 man-hours per ton to 0.6 man-hours per ton.
  • A reduction in energy consumption per ton of product by 30%.
  • A reduction in carbon emissions by 47% since 1990; by comparison, the Kyoto protocol would have mandated a 5.2% reduction by 2012.
  • A recycling rate for automobiles now exceeding 100%, emptying out salvage yards.
  • The elimination of all production water discharges and the minimization of water utilization.
  • An increase in the strength of structural steel by 38% over the past 10 years, reducing the quantity of structural steel required in a typical building.

 

For more information, contact Scott Melnick, AISC’s vice president of communications, at melnick@aisc.org.

 


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Going Up?
Posted by Keith Grubb on May 9, 2008 at 3:55 PM.

In the case of one 11-year-old Chicago office tower, “up” was the only way to go. Lohan Associates (now Goettsch Partners) designed the 33-story steel-framed Blue Cross-Blue Shield tower with vertical expansion in mind: columns had been stubbed through the roof, and a dramatic glass-enclosed atrium was designed to become high-rise elevator shafts. Now that Blue Cross has outgrown the tower, a 24-floor vertical expansion is underway.

 

Adding more floors to an existing structure is not without its challenges, especially when you’re starting from 500 feet in the air. For example, a 17-ton derrick was hauled up through the building in sections on a 6,000-lb-capacity freight elevator. The 17-ton derrick was used to bring up the pieces for a 35-ton derrick, which was then used to dismantle the 17-ton derrick and assemble the first of two tower cranes. The location of the building, just a few blocks from the lake Michigan shoreline, made winds an issue. City of Chicago rules prohibit crane assembly when winds are more than 30 mph, delaying tower crane erection by 30 days.

 

Read more about this carefully-planned steel project here.


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AISC Statement on Proposed ASHRAE Standard 189.1 for the Design of High-Performance Green Buildings
Posted by Geoff Weisenberger on May 2, 2008 at 12:52 PM.

The structural steel industry has a long track record of success in sustainable development, consistently leading the way in implementing energy, carbon and resource utilization improvements for the past 25 years. Those improvements have been driven by the three hallmarks of sustainability — environmental, social and economic stewardship.

 

Today, however, the structural steel industry is faced with a significant challenge, one that originates not from a lack of accomplishment with respect to sustainability, but rather from being too successful in this area.

 

AISC has significant concerns with some provisions in the recently published second draft of the proposed ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.) Standard 189.1 Standard for the Design of High-Performance Green Buildings Except Low-Rise Residential Buildings. AISC’s concerns with this proposed standard are that we believe it:

 

1.  is outside the scope and expertise for which ASHRAE is ANSI-accredited.
2.  will result in adverse environmental impacts.
3.  includes provisions that are unfair to steel, and inappropriately preferential to the interests of the concrete industry.
4.  adversely restricts the freedom of design professionals in their selection of structural framing materials.

 

The proposed ASHRAE standard, being developed jointly with the US Green Building Council and the Illuminating Engineering Society of North America, is intended to provide minimum requirements for high-performance green buildings. The apparent goal of ASHRAE is to include 189.1 in the International Building Code as an appendix available for local adoption.

 

While addressing HVAC and lighting issues, the standard also establishes prescriptive requirements for construction materials, an area that AISC believes to be outside the scope and expertise of ASHRAE, USGBC and IESNA. In addition, the committee responsible for the proposed 189.1 standard was not constituted in a balanced manner under appropriate ANSI consensus protocol. We also believe that the committee lacks expertise in the area of construction materials, particularly as they relate to structural framing systems.

 

This apparent lack of balance and expertise has resulted in provisions that AISC believes to be significantly slanted toward the interests of the cement and concrete industry under the guise of encouraging less sustainable industries to become more sustainable.

 

For example, today a typical structural steel frame provides an 11% credit towards the overall recycled content of a building. A concrete frame may provide one to two percent. At the same time, the reinforcing steel in the concrete structure will provide an additional 5% credit. The proposed standard will limit the contribution for any material at 5%. The result: structural steel gets capped at 5%, while concrete still gets its full credit AND the 5% credit for steel.

 

Similarly, the definition of recycled content is that portion of a material by mass that originates in either pre- or post-consumer waste streams. But the ASHRAE committee has decided to allow the calculation of the recycled content of concrete to violate that definition. Instead of reflecting the actual recycled content of the concrete, ASHRAE 189.1 allows the recycled content of the cementitious portion of the concrete to be used as the recycled content of the entire concrete mix.

 

For example, at present, substituting 25% fly ash for Portland cement in concrete with no other recycled content, results in an actual recycled content of 3%. Under ASHRAE 189.1 the cement and concrete industries are allowed to claim a 25% recycled content.

 

The committee’s justification is that they wish to encourage the use of fly ash in concrete. In reality, they are discouraging the use of recycled aggregates, removing over 50% of the mass of a concrete building from green considerations and providing the cement/concrete industry with an unfair advantage in the marketplace.

 

It is not the role of a standard to provide incentives and to favor particular products. The selection of structural framing materials should be based on the merits of the materials as judged against a consistent metric.

 

The inclusion of this standard in building codes is being encouraged by ASHRAE as an appendix at the national level available for local adoption. Including these provisions in a local building code in order to provide incentives to certain materials will significantly limit the opportunity of design professionals to select construction materials for high performance green buildings that properly balance economic, environmental and design issues.

 

The structural steel industry believes strongly in the need for high-performance green buildings. We also believe that standards for the selection and optimization of structural framing materials for those buildings should be developed in a balanced, consensus-based ANSI process that engages design professionals, industry associations and interested parties with the required level of expertise to develop a fair and environmentally sound standard. We would welcome the participation of the concrete, cement, masonry, wood, pre-cast, light gauge steel, per-engineered building and any other affected industries in that process.

 

AISC’s objection to 189.1 is not a rejection of sustainable construction practices or the need for green buildings. Much to the contrary, our commitment is to continue to be the leader in cradle-to-cradle sustainable construction materials and to actively pursue additional sustainable practices within our industry.

 

When the domestic structural steel industry experienced a rebirth 25 years ago, purposeful decisions were made to create a sustainable domestic structural steel industry. Central to that decision was the transition from Basic Oxygen Furnaces using iron ore and coke to Electric Arc Furnaces using scrap iron and steel as the primary raw material and electricity and natural gas as energy sources.

 

Resulting from this transition have been numerous gains positively impacting sustainable construction:

 

  • Wide flange structural steel products average in excess of a 90% recycled content.
  • A 96% recycling/reuse rate for structural steel members removed from existing structures.
  • An increase in mill productivity by a factor of 20 moving from 10 to 12 man-hours per ton to 0.6 man-hours per ton.
  • A reduction in energy consumption per ton of product by 30%.
  • A reduction in carbon emissions by 47% since 1990 — by comparison the Kyoto protocol would have mandated a 5.2% reduction by 2012.
  • A recycling rate for automobiles now exceeding 100% emptying out salvage yards.
  • The elimination of all production water discharges and the minimization of water utilization.
  • An increase in the strength of structural steel by 38% over the past 10 years reducing the quantity of structural steel required in a typical building.


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Supplement to ANSI/AISC 358-05 Prequalified Moment Connection Standard Now Available for Public Review
Posted by Geoff Weisenberger on May 2, 2008 at 12:50 PM.

Supplement No. 1 to the 2005 AISC Standard Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications (ANSI/AISC 358-05) is now available for public review. This supplement includes limited revisions to existing provisions for End-Plate and Reduced Beam Section (RBS) Connections, and provides design provisions for additional moment connection technologies, including the Bolted Flange Plate (BFP) Moment Connection, the Welded Unreinforced Flange – Welded Web (WUF-W) Moment Connection, and the Kaiser Bolted Bracket (KBB) Proprietary Cast Moment Connection. The Supplement also includes a draft appendix for cast steel material and quality.

 

The draft supplement is available for your review by downloading the document at the links provided below. Please vote and submit comments on the Supplement using the attached ballot form. A hard copy of the supplement can also be requested for a fee of $15 by calling 312-670-5411 or by e-mail to cummins@aisc.org.

Please submit your comments electronically to hewitt@aisc.org using the comment form available at the links below, or mail to:

 

Christopher Hewitt, S.E.
American Institute of Steel Construction
Suite 700
One East Wacker Drive
Chicago, IL 60601

 

All comments are due by May 12, 2008.

 

To download the public review document, visit www.aisc.org/358s1.

 

To download the comment form, visit www.aisc.org/358s1PRcomments.

 

To download the existing 2005 ANSI/AISC 358 Standard, visit www.aisc.org/AISC358.


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Best EJ Paper of 2007 Winner Honored at NASCC
Posted by Geoff Weisenberger on May 2, 2008 at 12:45 PM.

The winner of the Best EJ Paper of 2007 competition is James O. Malley for his paper “The 2005 AISC Seismic Provisions for Structural Steel Buildings,” which was published in the first quarter 2007 issue of AISC’s Engineering Journal.

 

The winning author was offered complimentary registration to the 2008 NASCC, held in Nashville last month, as well as travel expense reimbursement; the award was presented during the conference.

 

Be sure to participate in selecting the Best EJ Paper of 2008. Voters are eligible for a drawing to receive complimentary registration to NASCC, including travel reimbursement. Manuel Perez, employed by the City of Los Angeles, was the winner of this year’s drawing.


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OSHA Targets Crystalline Silica
Posted by Geoff Weisenberger on May 2, 2008 at 12:45 PM.

OSHA has launched a National Emphasis Program (NEP) targeting health hazards associated with occupational exposure to crystalline silica. The new program directs OSHA regional offices to inspect workplaces with elevated exposure levels and to provide “compliance assistance” to employers. Crystalline silica is a carcinogen and can lead to silicosis, a disabling and irreversible lung disease.

 

The directive lists streel fabrication as one of the industries at risk for exposure. The exposure potential comes from sand blasting steel with silica sand. While not prevalent in the fabrication industry, sand may still be used in some situations. Companies using sand for blast media are encouraged to use the NEP to establish and enforce rigorous procedures to prevent exposure to blast personnel and bystanders. The NEP includes inspection procedure information and an inspector checklist. You can view the diretive at www.osha.gov/OshDoc/Directive_pdf/CPL_03
-00-007.pdf
.


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AGC Adds BIM Addendum to ConsensusDOCS
Posted by Geoff Weisenberger on May 2, 2008 at 12:44 PM.

The Associated General Contractors of America (AGC) recently announced its approval of the addition of the Building Information Modeling (BIM) Addendum to the ConsensusDOCS catalog.

 

The ConsensusDOCS BIM Addendum is the first and only industry standard document to globally address the legal uncertainties associated with using BIM. The 21 leading associations representing owners, contractors, subcontractors, sureties, and designers that are actively supporting ConsensusDOCS have endorsed or are anticipated to endorse this consensus standard document.

 

The ConsensusDOCS BIM Addendum will be published in the first half of 2008 as part of the ConsensusDOCS comprehensive catalog of contracts and forms, which address all project delivery methods. The BIM Addendum provides a tool to utilize BIM from start to finish, thereby allowing contractors to more closely integrate project delivery with owners and design professionals. It is also flexible enough to be used as an addendum in more traditional contracting methods. The BIM Addendum has received extensive comment from the design professional community through the AGC BIMForum, a conglomeration of leaders throughout the AEC industry that have joined forces to facilitate and accelerate the adoption of BIM.

 

ConsensusDOCS is made up of more than 70 collaboratively drafted construction contracts. Its release last year represented the first time that broad industry representation has had an equal voice in collaboratively drafting construction contracts.


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