Writers of standards—both for general structural design and, in particular, structural steel design—rolled out their 2010 versions this month, completed in time to be referenced in the upcoming 2012 edition of the model “International Building Code.” An overriding goal, say the engineers responsible for the revisions, is to make the standards simpler to understand and use. Illustration: AISC Weld-access-hole geometry is included in steel standard, despite a patent issue. The major editorial change to ASCE/SEI 7-10 “Minimum Design Loads for Buildings and Other Structures” from the 2005 standard is a “complete” reorganization into a multiple-chapter format—first introduced for seismic loads
With cracks as sharp as the frozen Arctic air, a 1,357-ft steel communications tower in Port Clarence, Alaska, tumbled to the ground on April 28, the first step in the U.S. Coast Guard�s decommissioning of its network of LORAN radio navigation facilities across the country. Photo: Controlled Demolition Inc. Tower demolition is start of Coast Guard decommissioning of aging navigation signal network. The 400-ton, 45-segment triangular steel tower is the largest man-made structure to be felled by explosives, according to Controlled Demolition Inc. (CDI), Phoenix, Md., which performed the operation as a subcontractor to Jacobs Field Services North America. For
On April 15, opposing sides in a debate over the fate of a deteriorating, nine-year-old Seattle apartment tower presented their positions regarding the building’s future safety to Seattle’s Dept. of Planning and Development (DPD). McCarthy Building Cos. maintains the 26-story McGuire Apartments, with its corroding post-tensioned slab system, can be economically fixed. The owner disagrees. Photo: Kennedy Associates Contractor and owner at odds about ‘sick’ tower’s cure. + Image Source: Post-Tensioning Institute Post-tensioned slab The steps to post-tensioning are as follows: Place the tendons and nail anchors to the formwork, cast the concrete slab, remove the formwork, stress and anchor
A recent successful load test on a steel-fiber-reinforced-concrete beam, free of congestion-causing diagonal reinforcing steel, promises to positively impact constructibility of tall, moment-resisting frames in seismic zones. Using SFRC, engineers can reinforce high-aspect-ratio link beams, which span openings in shear walls, as regular beams, say the test’s researchers. Photo: Gustavo J. Parra-Montesinos Steel-fiber-reinforced-concrete beam (above, rotated 90°) needs no diagonal reinforcement. “We have a design for which you do not need diagonal bars, and you can still achieve large drift capacity under very high shear forces,” says Gustavo J. Parra-Montesinos, the test’s lead researcher and a Dept. of Civil and
The contractor for an occupied, 26-story apartment building in Seattle that has corroding post-tensioning cables disagrees with the owner’s assertion that the nine-year-old high-rise will become unsafe. McCarthy Building Cos. also disputes the cause and scope of the damage to McGuire Apartments, built for $33 million, stated by the local owner, Carpenter’s Tower LLC. Photo: Ken Lambert, The Seattle Times Problems of Seattle high-rise are too costly to fix, says owner. The contractor disagrees. On April 10, the owner announced plans to vacate the building over several months “due to extensive construction defects, which are financially impractical” to repair. A
The University of Nevada, Las Vegas, claims that a three-year-old student recreation facility at its main campus fails to meet some seismic requirements under the 2002 Uniform Building Code. The structure remains open, but a warning notice is posted. Photo: Luetta Callaway Investigator alleges differences between flexible and rigid components cause problems. Related Links: Engineer�s Report on UNLV Building Designed by the Phoenix office of DMJM Design, a unit of AECOM, with St. Louis-based Hastings+Chivetta Architects Inc., the building is likely to end up in court. Bennett & Jimenez Inc., Las Vegas, which has since shut down, was the structural
Design and construction of Minneapolis’s Target Field, a $545-million ballpark for baseball’s Minnesota Twins, was like stuffing 12 lb of potatoes into an 8-lb bag. The eight-acre site not only was hemmed in on all sides by roads and rails, it really needed 12 acres to comfortably accommodate the program for a 40,000-seat ballpark. Because the neighbors were so close, there was no lay-down area or viable crane path outside the bowl’s footprint. Thus, the ballpark had to be constructed from the inside out, which builders consider far from ideal. Slide Show Photo: Mortenson Construction The many restrictions, including up
Poor quality, often homemade concrete led to widespread building damage in Port-au-Prince following last month’s earthquake in Haiti, says Ken Hover, an engineering professor at Cornell University who had recently returned from the devastated city. Slide Show Photo: Ken Hover Some buildings suffered cracks rather than total failure from Haiti's devastating 7.0 magnitude earthquake on Jan. 12. Hover made his remarks Feb. 3 at the World of Concrete tradeshow in Las Vegas. He had performed structural assessments for two university-backed Port-au-Prince health clinics from Jan. 20-25. The clinics consisted of 15 separate structures. Hover says he used California's post-earthquake investigation
In an unusual move in the highly commercialized sports market, the city council of Irving, Texas, voted on Dec. 31 to award naming rights to the demolition of Texas Stadium to Kraft Foods Global. The city council says the partnership, nicknamed “The Cheddar Explosion,” will yield $1 million in promotional value for the city. Kraft agreed to pay $75,000 for the naming rights and provide an additional $75,000 in products to local food banks. Weir Bros. Inc., a Dallas-based contractor, received a notice to proceed on the demolition project on Oct. 20, 2009. The implosion of the stadium is tentatively
The specific date in December for the implosion of the faulty, 376-ft-tall condominium tower on South Padre Island in Texas has not been set. But the demolition contractor says it has solved almost all the quandaries of one of its most challenging razings using explosives. If all goes according to plan, when the dust settles, Controlled Demolition Inc. (CDI) will have broken the height record, which it set in 1975, for imploding a reinforced-concrete tower. Slide Show Photo: Controlled Demolition Inc. Aluminum alloy shores around failed columns have to be factored into implosion plan. Photo: Controlled Demolition Inc. Walls were