Archive for March 2008
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Engineering Conference Seeks Presenters
Posted by Geoff Weisenberger on March 31, 2008 at 3:27 PM.
Presentation proposals are now being accepted for the for the 2008 Structural Engineers’ Buildings Conference & Expo, to take place October 2–3 in Atlanta. One-page proposals should be submitted by May 15 to Amy Walsh at email@example.com or online at www.sebuildings.com. Please call 508.651.1559 with questions. Applicants will be notified of acceptance in June. Conference themes include:
Building Codes: Navigating Your Way through the Updates and Changes
Wind Design: Mitigating the Effects of Natural Hazards on the Built Environment
Industry Evolution: Market Changes Affecting Your Business
Business Management: Successful Strategies for Effective Leadership
Technical Innovation: Cutting Edge Building Design Techniques and Tools
The Life and Times of an Engineering Giant
Posted by Geoff Weisenberger on March 31, 2008 at 3:26 PM.
Professor Wai-Fah Chen is one of the major figures in the history of modern civil engineering. He is known to the steel construction community for his many contributions to structural analysis, stability theory and its applications, and behavior of connections. Many of the results of his research have found their way into several specifications of the AISC. He was a member of the AISC Committee of Specifications for many years, and he is presently an emeritus member of this group.
After his recent retirement as the dean of engineering at the University of Hawaii, he sat down and wrote a 450-page book, My Life’s Journey—Reflections of an Academic, that delightfully combines his personal life experiences and family history; a history of the intellectual and practical developments in structural engineering, engineering mechanics, plasticity theory, and geo-engineering in the past half-century; experiences in engineering education; reminiscences about teachers, colleagues, and friends; reviews of his research contributions; and general philosophical comments on the past, present, and future of the civil engineering profession in general and the academic teaching/research community in particular.
Wai-Fah Chen had a very adventurous youth during World War II and the following Chinese Civil War, eventually ending up in Taiwan where he obtained his BCCE degree. He describes these early years through a lively narrative, setting the tone for the rest of the book. Many of the readers of MSC will find their name, or the names of their teachers and colleagues, in the book. They will also be able to trace the origin of many of the criteria that are now a part of their daily design life. Engineering teachers will appreciate learning about the origins of steel design, concrete design, and soil mechanics concepts from the many books authored by Chen and his students.
Professor Chen is truly a giant in our professional field. Readers will not only be delighted and educated by this book, but will also feel proud to be part of a dynamic and creative profession.
—By Ted Galambos, University of Minnesota
Myths and Realities Report on Steel Bridges Now Available
Posted by Geoff Weisenberger on March 31, 2008 at 3:25 PM.
Did you know that modular prefabricated short-span steel bridges can be permanent structures? Or that bridge joints are not a prerequisite for steel bridges? Or that advanced, high-performance, EPA-approved steel bridge coatings can last more than 25 years? These topics and others are highlighted in a new free publication, Steel Bridge Construction: Myths and Realities, an updated, fact-based publication that addresses a wide range of topics about steel bridges.
Made available through a joint effort between AISC, the National Steel Bridge Alliance (NSBA), and the American Iron and Steel Institute (AISI), the 25-page document compiles and corrects top myths and misperceptions about the viability of steel in bridge design and construction for a wide range of bridge types.
The report references expert articles and studies from organizations such as the Federal Highway Administration (FHWA) and the American Association of State Highway Transportation Officials (AASHTO), as well as the Strategic Highway Research Program, professional associations, industry analysts, and academia.
One such reference refutes the perception that the life expectancy of a steel bridge is shorter than alternative materials. In fact, a 1992 study by Lehigh University analyzed the deterioration rates of the 577,000 bridges listed in the FHWA National Bridge Inventory and concluded that superstructure material type—steel, concrete, or other—was not an indicator of a bridge’s life expectancy. Instead, life expectancy is strongly dependent on a bridge’s age and average daily traffic.
The report also includes myth-busting analysis about topics such as the reality of maintenance-free bridges (regardless of material), cost competitiveness of simple-span bridges less than 140 ft in length, the viability of weathering steel, the value of jointless bridge decks, and the availability of simple, more economical bridge bearings.
To download a free PDF version of Steel Bridge Construction: Myths and Realities, visit AISI’s web site at www.steel.org/bridges/Myths_and_Realitie
s.pdf. To order printed copies of the report, visit www.steel.org and click “Shop AISI”—or call 202.752.7100 and ask for item #D432-07. Or, you can communicate your request via e-mail: firstname.lastname@example.org.
AISC and ASE Host Staggered Truss Presentation and Construction Tour
Posted by Geoff Weisenberger on March 31, 2008 at 3:24 PM.
Not surprisingly, Friday, February 8 was a cold, cloudy day in Chicago—not the best day to spend outdoors. But that didn’t stop nearly 200 engineers, contractors, and others in the steel industry from taking an open-air construction site tour in the city’s River North neighborhood. And that’s because it wasn’t just any site. The project, a 17-story Staybridge Suites hotel, will be the first staggered truss steel building ever constructed in Chicago.
The tour began with a breakfast presentation, sponsored by AISC and the Associated Steel Erectors. While filling up on a hearty breakfast to prepare them for the cold, participants were provided with an overview of the project by AISC’s midwestern regional engineer, Tabitha Stine, and members of the construction team: Duke Miglin of owner/developer Miglin Properties LLC; structural engineer Socrates Ioannides of Structural Affiliates International, Inc.; architect Matt Dumich of Valerio Dewalt Train; Scott Robbins of steel fabricator/erector K&K Iron Works; and Jeff Rodgers of the project’s general contractor, Walsh Construction Company.
While high-rise residential and hotel projects are often constructed with concrete, Stine noted that a staggered truss system—which works in tandem with precast concrete plank—can weigh 20% to 30% less, be erected quicker, and allow for more column-free space than when using a concrete framing system for the same project. AISC’s Steel Solutions Center provided the project team with a conceptual design study featuring the staggered truss concept in 2003.
According to Robbins, the project will use 815 tons of structural steel in the form of approximately 1,500 erectable pieces. There will be 115 steel trusses and 100 columns in the building.
After breakfast, participants were bused to the jobsite a few blocks away and were given the opportunity to walk through multiple levels of erected steel framing. Construction began in the summer of 2007, and the building is scheduled to open later this year. The finished structure will house more than 200 suites.
For more information on the Staybridge Suites staggered truss project, including photos, PowerPoint presentations from the breakfast, and a live webcam, visit www.aisc.org/staybridge. For more information on the staggered truss structural framing system, please go to www.aisc.org/residential or contact the AISC Steel Solutions Center at 866.ASK.AISC or email@example.com.
FMA and TPA China Tours
Posted by Geoff Weisenberger on March 14, 2008 at 3:12 PM.
The Fabricators & Manufacturers Association, International (FMA) and Tube & Pipe Association, International (TPA) have scheduled two tours to China in September that focus on sheet metal and tube and pipe, respectively. Each tour offers a unique opportunity to network with Chinese counterparts and witness China’s capabilities firsthand.
The tube and pipe itinerary also includes a special visit to the All China-International Tube & Pipe Industry Trade Fair in Shanghai. Each tour includes:
Visits to Chinese companies related to metal fabricating or tube and pipe, respectively, with current plans for plant tours in Guangzhou, Dongguan, and Shenzhen
Meetings with China industry trade associations and government officials
Transportation and accommodations in China (roundtrip airfare to China and an optional sightseeing tour are not included)
Dates for the sheet metal tour are September 13-20. Dates for the tube and pipe tour are September 20-27. For a complete itinerary, visit www.fmanet.org/china.
Deadline to reserve a place in either program is March 31. Space is limited.
AGA Announces Informational Packets
Posted by Geoff Weisenberger on March 14, 2008 at 3:03 PM.
The American Galvanizers Association recently released two new comprehensive informational packets intended to educate city/county and university officials on the benefits of using hot-dip galvanized steel in municipality and university projects.
The municipal packet, “Galvanize Your Community,” touches on municipality projects, while the educational packet, “Galvanize Your University,” focuses on educational institutions and university-based projects. Each packet contains a brochure that highlights many common considerations of any project, such as durability, sustainability, cost, and aesthetics, while explaining how the use of hot-dip galvanized steel meets these needs and more.
If you are interested in obtaining either of these free packets or have questions, please contact AGA Marketing Coordinator Robyn Burke at 720.554.0900, ext. 13 or firstname.lastname@example.org.
Bridge Welding Code Updated for 2008
Posted by Geoff Weisenberger on March 14, 2008 at 3:00 PM.
The American Association of State Highway and Transportation Officials (AASHTO) and the American Welding Society (AWS) jointly develop the AASHTO/AWS D1.5M-D1.5 Bridge Welding Code. The Code has been adopted by most states and transportation authorities (cities, tollways, etc.) to assure weld longevity in structures carrying millions of vehicles. The first edition was published in 1988, with revised editions in 1995, 1996, and 2002. AWS policy does not authorize interim changes, except for errata published in the Welding Journal, so there were no official changes between editions. The latest edition, 2008, is now available. Changes include:
Providing welding guidance for two grades of high-performance steel—ASTM A709 (AASHTO M270) HPS 50W/HPS 345W and HPS 70W/HPS 485W—and deleting Gr. 70W/485W, a quenched and tempered Gr. 50W/345W. The HPS steels have higher toughness and better weldability and weathering characteristics, but their chemistry requires different welding consumables than Gr. 50W/345W or Gr. 70W/485W.
Tables 4.1, 4.2 have been revised, including moving the increasingly popular metal-cored GMAW electrodes to Table 4.1, thereby reducing the need for procedure qualification testing under Section 5.13. In addition, minor changes have been made to Tables 4.3 (unpainted steel), 4.4 (preheat), and 4.5 (stress relief holding time).
The suggested Weld Procedure Specification (WPS) and Procedure Qualification Test Record (PQR) forms provided in Annex III have been amended, based on input from fabricators, owners, and consumable producers. The PQR form now provides areas to document test parameters, witnesses, and results, reducing the potential for later questions or disputes. The WPS form now provides an area for listing all significant variables, clarifying expectations for welders and inspectors. Shops working for multiple owners may improve common acceptance with these updated forms.
Illustrations for specifying and measuring intended camber have been included. These images better define the desired camber and how to assess post-welding acceptance tolerances.
Machining and testing tolerances for performance test specimens are now included. These do not entail significant changes to test equipment or specimens; rather, they better define the geometry and finishing needed to ensure consistent test conditions and accurate results.
Storage requirements for fracture-critical welding consumables have been amended. The absence of hydrogen is critical for weld soundness, and even small hydrogen-induced cracks can propagate under cyclic loading. Fracture-critical consumables must be certified “low-hydrogen” by the producer, and they must be handled and stored to remain that way. Requirements include GMAW and FCAW reels, and clarify drying SMAW electrodes.
RT film type and scanning patterns for UT are now addressed in Section 6, and NDT qualifications have been correlated between Sections 6.1 and 12.8. Also, additional welder qualification requirements have been clarified between 12.8 and Section 5, Part B.
A commentary was added for Section 4, and extensive changes were made for other sections, including moving notes and italicized items from the Code to commentary sections, and replacing mandatory language (”shall” and “must”) with permissive (”may”).
Other clarifications and modifications include: welder grinding deficiencies during a PQR that also proves qualification; correcting weld-induced distortion; dimensional tolerances; plasma cutting joint faces; undermatching weld strength; and clarifying fillet soundness tests.
Some future expected changes include the following:
AWS has adopted a policy permitting interim code changes before a subsequent edition. This will not be common practice, but may allow new technology or avoid problem details.
Narrow gap improved electro-slag welding (NGIESW) is expected to be included in the next edition.
Combining Tables 4.1 and 4.2, and merging the qualification test requirements of 5.12 (max or min-max heat input) and 5.13 (production) are also expected in the next edition.
The use of partial joint penetration (PJP) welds perpendicular to tensile stress.
Gr.50S/345S will be included to cover rolled beams.
The Bridge Welding Code has evolved over the past twenty years and will continue to change, reflecting owners’ needs for confidence, fabricators’ needs for consistency, and the ever-changing technology of welding.
—By Jon Edwards, former fabrication engineer with the Illinois Department of Transportation and advisor to the AWS D1.5M-D1.5 Subcommittee.
A Separate Standard
Bridge welding didn’t always have its own code. It was originally covered in Section 9 in the AWS D1.1 Structure Welding Code – Steel. However, as AASHTO and individual states added requirements, fabricators found that they had to undergo separate, expensive qualification tests for different owners. So, in the early 1980s, AASHTO and AWS formed a joint committee to establish a document for all owners to adopt, resulting in AWS D1.5M-D1.5.
After the initial publication, subsequent editions incorporated changes in technology, clarified areas of confusion or contention, improved efficiency for fabricators, and ensured that owners were satisfied with results. Significant changes included the addition of metric to the U.S. Customary units, Section 12 for Fracture Critical Welding (replacing the AASHTO Fracture Critical Guide Specification—which became the Fracture Control Plan for non-redundant structures)—and commentaries for Sections 1, 2, 3, 5, 6, 7, and 12.