Engineering Inc. - January/February 2009 - 21

MuLTI-PrOJeCT FeaTure deep and weighs 3,255 tons. The arches are more than twice the length of the Gateway Arch in St. Louis, according to officials at Walter P Moore, which designed and built the Cowboys Stadium roof. When the owners of the stadium began construction work in March 2006, their goal was to build a larger, amenityrich facility that would blend innovative design with the wellknown brands of Texas Stadium and the NFL’s Dallas Cowboys, says John Aniol, project manager at Walter P Moore. “In its quest to realize the owner’s vision, the design team found many opportunities for creativity,” Aniol says. “Inherent in the design of any covered stadium is the complexity of conquering the long span over the bowl and event area without obstructing views.” The owners wanted to make a bold design statement with this main roof span, which resulted in perhaps the cen- nment tral challenge of the project: the 1,225-foot twin arch box trusses that, upon completion, will support the world’s longest single-span roof structure. “It is difficult enough to command such a span to efficiently defy gravity, given its own weight and the weight of a ‘simple’ fixed roof,” Aniol says. “But add a moving roof to the equation, and the span begins to object. Add show rigging loads at the arches’ center, and the trusses’ protests gain intensity. Finally, demand that the twin arches permanently support the world’s largest centerhung video board—the equivalent of hanging a five-story building from the center of an almost quarter-mile span—and it seems too much to ask.” One of the unique features of the facility required a solution that pushed creative boundaries. The 70-foot-tall by 160-foot-long video board looms over the field in an enormous I-shaped plan that extends from 20-yard line to 20-yard line. “The structural design team created a 70-foottall steel structure that contains a 10-level network of catwalks and is clad on all sides with video displays,” Aniol says. The video board assembly weighs 1.2 million pounds, comparable to the weight of 350 mid-sized automobiles. The design team suspended the assembly using eight 3-inch diameter steel cables, plus eight sway steel cables. The cables are tethered to large steel box trusses that span the 256 feet between the twin arch trusses. “The inclusion of these video board box trusses reflects the traditional box trusses that sweep across the opening at the Cowboys’ original home, Texas Stadium, giving it a distinctive television signature,” Aniol says. Retaining the Texas Stadium’s hole in the roof—an icon that’s an integral component of the Cowboys brand—was important to the owners. But another January / February 2009 That’s By Bob Violino Member Firms bring imaginative expertise to the design of public entertainment facilities John Aniol, Walter P Moore goal was for the fully enclosed roof to protect spectators from inclement weather. The design team accommodated both desires with a sleek bi-parting retractable roof. Two panels meet above the 50-yard line when they are in the closed position. At the flip of a switch, a rack-and-pinion mechanization system springs to life. The system, designed by Uni-Systems of Minneapolis, in coordination with Walter P Moore, is the first application of this type of retractable roof in North America. enGIneerInG InC. 21

Engineering Inc. - January/February 2009

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