Precast Solutions - November/December 2008 - (Page 11) support the weight. This would have meant additional cost for Armada Hoffler. “Using heavy (materials) in a beach area would have added 45 pounds per square foot to the project,” Smith explains. “That means more than 3 million pounds of additional weight on the building.” It also would have meant driving more pilings into Virginia Beach’s poor, sandy soil to support the structure. As constructed, the building already rests on prestressed concrete piles driven 60 feet into the ground. More weight on the building would have meant more and deeper pilings. The lightweight panels also offered additional structure protection in the event of high winds associated with hurricanes. Because the panels are attached using anchors and are not welded to the building’s frame, the panels can move independently of the frame during times of severe wind loading and seismic shock. “This reduces wind load on the structure,” says Smith. “There is independent movement of precast from the frame and structure of the building.” Armada Hoffler and Smith-Midland tested the panels’ ability to bear the high winds Virginia Beach frequently experiences during hurricane events. The panels performed successfully in winds up to 169 miles per hour, the speed at which testing stopped. “Those panels passed with flying colors,” says Smith. FEWER PANELS MEANS FASTER CONSTRUCTION The lightweight panels also allowed for lower transportation costs to the building site. “The panels were shipped on flatbed trucks,” explains James McRoberts, Armada Hoffler’s senior project manager. “There was one panel per truck, and the largest panel was 400 square feet,” he says. Once on site, the panels went up pretty quickly. “We were on a fast-track schedule,” notes Smith. “The contractor wanted the panels to get installed about 10 to 12 floors behind the framing of the building.” This meant the builder was creating the frame for upper level floors while panels were being installed on lower floors. Because both processes required the use of a tower crane, builders worked on the frame during the day and Photo by Fred Figall The panels were installed vertically with each one covering three stories of the building. then used the crane to attach panels at night. With roundthe-clock construction, the 525 precast panels were NOVEMBER/DECEMBER 2008 | PRECAST SOLUTIONS 11
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