Archive for October 2008
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Engineering Home Runs in Houston
Posted by MSC on October 13, 2008 at 3:58 PM.
The Structural Association of Texas (SEAoT) will hold its 2008 State Conference in Houston, November 6-8 at Houston’s Minute Maid Park, home of the Houston Astros. It’s a big event in a state known for doing things big; according to SEAoT, it’s the largest gathering of structural engineers in the state. The theme of this year’s conference is “Engineering Home Runs” and speakers will cover topics ranging from business management to structural engineering technical issues. Professional attendees can expect to attain up to eight PDHs by attending the conference sessions. For more information, visit www.seaot.org.
Diaster Site Safety Consideration
Posted by MSC on October 13, 2008 at 3:57 PM.
With hurricane season in full throttle, the National Association of Tower Erectors (NATE) has issued a safety bulletin outlining considerations when performing disaster relief work on broadcast and wireless communication towers. The bulletin includes bid considerations as well as advice on safe working conditions. “Do not be pushed to complete tasks faster than you can safely [do],” the bulletin advises. “Safety needs to remain the number one priority on all job sites, even more so regarding disaster relief work. Please ensure that, when pricing the work to be performed, you can do the job safely and for a reasonable price. And if you accept the bid, please work safely.” To view a copy of the bulletin, visit www.natehome.com.
AISC Certification Releases Draft Standard for Public Review
Posted by MSC on October 13, 2008 at 3:56 PM.
The AISC Certification Standard for Bridge and Highway Metal Component Manufacturers will be available for a second period of public review beginning October 7, 2008 and concluding after 21 days on October 28, 2008. This standard has completed balloting by the AISC Certification Committee. A copy of the approved draft standard dated August 19, 2008 will be available from the AISC web site www.aisc.org with instructions for submitting comments.
This second review period provides individuals and organizations that may be affected by implementation of the standard, an opportunity to share concerns and offer value-enhancing suggestions and recommendations on changes made since the first public review, which concluded on July 27, 2007. The draft available from the AISC web site will include indication of the substantial changes made since the first public review. Comments submitted during this second public review period will be given full consideration by the AISC Certification Committee.
The standard will support the new Component Manufacturer Certification, a new AISC Certification program. The Component Manufacturer Certification will confirm to owners, design professionals, and the construction industry that a firm has the personnel, organization, experience, procedures, knowledge, equipment, and commitment to produce components of the quality required for normal bridge and highway construction. It is anticipated that the Component Manufacturer Certification program will provide a valuable means for qualifying firms, and serve as an effective way for steel bridge fabricators and manufacturers participating in the program, to communicate their commitment and capability with respect to quality.
The Component Manufacturer Certification program is expected to become available to the industry by the beginning of 2009.
TAUC Leaders Tackle Tough Questions
Posted by MSC on October 13, 2008 at 3:55 PM.
Some of the country’s top union leaders recently took part in a town hall-style forum that is now available for viewing on The Association of Union Constructors’ (TAUC) web site, www.tauc.org.
Never before have such prominent labor leaders gathered for such a unique discussion that included an audience of several hundred contractors from around the nation. The five general presidents responded to hard-hitting questions at TAUC’s 2008 Leadership Conference, an annual event that attracts leading union contractors, labor representatives, employer associations, and construction users from around the country to discuss the future of the union construction industry. The forum was moderated by construction industry strategist and speaker, Mark Breslin.
“This was a critical step in the ongoing path to improving the dialogue between the building trades and contractors. Ensuring a viable working relationship between both groups means high-quality and affordable industrial construction,” said TAUC CEO, Stephen Lindauer.
Prequalified Moment Connection Standard Supplement Now Available for Public Review
Posted by MSC on October 13, 2008 at 3:54 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 a second 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 an appendix for cast steel material and quality.
The only item to be reviewed in this ballot is Section A.2.4(2)b. The proposed revision increases the sampling to 50% of the production castings from 25% in the previous ballot. This change was made as a result of negative comments received on the first ballot and the committee’s determination that this rate would be more consistent with that necessary to assure a quality product.
The complete supplement is available for your review by downloading the document at the links provided below. A hard copy of the supplement can also be requested for a fee of $15 by e-mail to email@example.com.
Please submit your comments electronically to firstname.lastname@example.org using the comment form available at the links below, or mail to:
One East Wacker Drive, Suite 700
Chicago, IL 60601
All comments are due by October 20, 2008.
To download the public review document, visit www.aisc.org/358s2.
To download the comment form, visit www.aisc.org/358s2PRcomments.
To download the existing 2005 ANSI/AISC 358 Standard visit www.aisc.org/AISC358.
Tracking the Progression of the AISC Spec
Posted by MSC on October 13, 2008 at 3:49 PM.
By James Fall and Jie Zuo
Every few years, AISC releases a new specification for steel buildings. New research often breeds significant improvements to the specification, and it is important to understand what changes were made and how they affect the design of future steel buildings.
Several major changes have been made between the 1989 Specification for Structural Steel Buildings—Allowable Stress Design and Plastic Design and the ASD side of the newer 2005 Specification for Structural Steel Buildings, which also contains LRFD. (An extensive look at the detailed changes between the two specifications can be viewed online at www.aisc.org/crossrefASD.)
First, it is important to understand what sparked the industry to switch from allowable stress design to allowable strength design, a change reflected in the 2005 Specification. Allowable strength provisions are based on forces and moments that are absolute capacities; units are usually in kips or kip-ft. On the other hand, allowable stress works with proportional stress capacities, which usually indicates units in kips per unit area. By eliminating allowable stresses and introducing the safety factor, Ω, the provisions in the 2005 Specification can be applied to both ASD and LRFD, unifying the two design philosophies with each producing similar results.
Another important update is the introduction of the term limit state to the 2005 Specification. Since previous LRFD specifications have always used the term limit state to define the boundaries of which a building is adequate for its intended use, it was only fitting that it should be incorporated into the 2005 Specification. Interestingly, traditional allowable stress design was also formulated based on limit state principals, but the term was never used.
One problem with the 1989 Specification was that it dealt exclusively with U.S. customary units. Since most countries use metric units, this hindered the use of the specification outside of the U.S. Now that many design firms are working on international projects, the inclusion of metric units into the 2005 Specification facilitates design outside the U.S. by avoiding pesky conversions. For example, in Table J2.4, Minimum Size of Fillet Welds, millimeters are provided in parentheses next to inches. This is typical throughout the 2005 Specification.
Taking it one step further, all ratios in the 2005 Specification were non-dimensionalized by factoring out the modulus of elasticity of steel, E. Once again, this change allows flexibility for designers to use either U.S. customary or metric units in their calculations. High-temperature design, which allows for a smaller E value, has also benefitted from this change.
On that Note
Although not considered part of the 2005 Specification, User Notes were inserted throughout, with useful information to assist users. The content of these User Notes consists of helpful design tips, general rules-of-thumb, approximations, recommendations, and references to relevant documents. To avoid confusion, they appear in shaded boxes to help segregate them from the actual specification.
In addition, several important topics were added to the 2005 Specification, most notably Chapter K, Design of HSS and Box Member Connections. Originally, the provisions that governed HSS design were included in a separate specification titled AISC Specification for the Design of Steel Hollow Structural Sections, which was last published in 2000. The provisions were abridged and combined with the 2005 Specification. The appendices were completely revamped, and the most obvious change is the addition of six entirely new appendices, some of which reflect new research and newly developed methods, such as the appendices on structural design for fire conditions and the direct analysis method.
While new content accounts for the majority of the differences between the 2005 and 1989 Specifications, some parts of the 1989 version were entirely removed, most notably Chapter N, Plastic Design and Appendix F, Beams and Other Flexural Members, which covered the design of web-tapered members.
Besides the removal and addition of content, the actual organization of the specification was overhauled. Some sections moved from one chapter to another, while others were combined into a single section. For example, former Sections B4 and C1 were combined into C1.1, General Requirements.
James Falls is an undergraduate student at the University of Florida in Gainesville, and Jie Zuo is an undergraduate student at the University of Illinois at Urbana-Champaign. Both were 2008 summer interns with AISC.
Brochure Touts Green Aspects of Galvanizing
Posted by MSC on October 13, 2008 at 3:46 PM.
The American Galvanizers Association has released Sustainable Solutions for Corrosion Protection, a free brochure detailing new research regarding the strength and sustainability of hot-dip galvanized steel in the alternative energy market.
Sustainable Solutions explores how using hot-dip galvanized steel in biofuel, wind, hydroelectric, and solar structures not only protects them from the effects of corrosion, but also is highly sustainable and earth-friendly. Highlighting the inevitability of corrosion, this brochure stresses the importance of making intelligent environmental and economic decisions, supported by real-life case studies from each sector of the alternative energy market. It also explains how the natural, recyclable zinc coating created in the galvanizing process will provide superior corrosion protection without requiring the costly carbon footprint of maintenance.
Learn how to further the earth-friendly efforts of alternative energy sources by incorporating hot-dip galvanizing. Request a free Sustainable Solutions brochure by visiting www.galvanizeit.org.
Facade Attachment Guide Now Available
Posted by MSC on October 13, 2008 at 3:44 PM.
Design Guide 22: Façade Attachments to Steel-Framed Buildings, by James C. Parker, P.E., is now available. This new AISC design guide addresses the design of façade attachments to steel-framed buildings.
“Structural engineers will find this to be a practical resource when designing the interface between the façade system and a steel structure,” says Cynthia Duncan, AISC’s director of engineering. The objective of the design guide, according to the Introduction, is to “assist the practicing engineer in achieving economical slab edge details for steel frames that are structurally sound, durable, and accommodating of the performance requirements of the particular façade system.”
Façade system fundamentals are discussed, along with building performance issues that influence attachment design. The details of various façade systems are exemplified, including masonry cavity wall systems with concrete-block or steel-stud back-up, precast concrete wall panels, aluminum curtain walls with glass and/or metal panels, glass-fiber-reinforced concrete panels and other lightweight panels, and exterior insulation-and-finish-system panels. Design examples for the various systems are also provided.
For more inforamtion or to order the guide, visit www.aisc.org/epubs or www.aisc.org/bookstore.
AISC Joins Scrap Coalition
Posted by MSC on October 13, 2008 at 3:43 PM.
AISC and the Concrete Reinforcing Steel Institute (CRSI) have joined the American Scrap Coalition (ASC), and both institutes urged strong, immediate government action to eliminate the taxes and other market barriers that numerous offshore governments maintain on their exports of steel scrap. The American Scrap Coalition (www.scrapcoalition.com) now includes industry associations representing more than 3,200 companies.
“Rising scrap costs are beginning to have a chilling effect on the construction industry and the U.S. economy in general,” stated Roger E. Ferch, president of AISC. “The growing use of steel scrap export taxes by foreign governments is artificially increasing the cost of steel scrap in the U.S. and driving up domestic costs unfairly and in an anti-competitive way.”
“Our fabricator members are being squeezed by scrap and other raw material costs,” said Bob Risser, president and CEO of CRSI. “They have long-term projects with established pricing, but their costs have increased tremendously. They are not only losing money, but in some cases their companies are threatened.”
The American Scrap Coalition is calling on Congress, the U.S. Trade Representative, and the Commerce Department to immediately address scrap trade barriers. The Coalition has identified several priority issues:
Identification and removal of barriers to trade in steel scrap, which hinder U.S. companies and global competition.
The U.S. carbon steel industry recycled approximately 75 million tons of ferrous scrap last year, with approximately 80% of that scrap consumed in Electric Arc Furnaces. Recycling scrap metal is the most efficient way to make steel, and therefore results in the lowest level of greenhouse gas emissions. The American Scrap Coalition will support and promote policies to encourage the recycling, recovery, and use of recycled scrap material in production of new steel products.
Consider actions by Congress, the Commerce Department, and the Office of the U.S. Trade Representative to remove trade barriers.
Companies and industries wishing to join the American Scrap Coalition can register at www.scrapcoalition.com. The web site contains additional information on scrap trade barriers, import and export levels, and prices.
In July, ASC released its newly compiled list of foreign trade barriers to steel scrap and called for the removal of these barriers. The Coalition identified more than 25 countries that have imposed barriers on the trade of steel scrap and other raw materials, harming U.S. companies and their workers.
According to Tom Danjczek, president of the Steel Manufacturers Association, the U.S. government has long rejected imposing export restrictions on U.S. scrap and has instead focused on removing foreign trade barriers. “If that is still the case, it is now time for the U.S. Government to get serious,” Danjczek stated in an ASC release.
In particular, the Coalition singled out Russia’s recent announcement that it plans to raise export tariffs on steel scrap from the current 15% level to 120-130 euros ($191-$207) per metric tonne.
Other countries imposing scrap export bans or particularly heavy export taxes include: Indonesia, Saudi Arabia, Vietnam, Pakistan, Argentina, India, and Ukraine. The Coalition’s complete list of barriers is available at www.scrapcoalition.com under “Latest News.”