Precast Solutions - July/August 2008 - (Page 20)

to erect.” “In California, we’re very used to seismic regulations,” points out Voss, “but this job went well beyond the code.” In the case of the Robert E. Coyle U.S. Courthouse, the precast panels can literally be hanging off the building in a seismic or blast event. In a typical precast structure, panels would have been designed to move in such an instance, but the project architects required a maximum joint of 1 inch to maintain the monolithic look of the facade, which meant From plant to work site: At top, a large single precast panel is stripped from its form. At center, precast panels are loaded for transportation to the job site. At bottom, one of the many specialized panels is being erected onto the building. Photos courtesy Clark Pacific the contractor had to come up with an innovative solution for meeting the demands of blast resistance. Another challenge of the project was that spandrel panels had to wrap around corners and switch directions. In a seismic event, panels at corners can smack together, Togel explains, but not fall off the building because they are fastened to the structure via a slip-tilt connection. This makes for a tethered breakaway detail at the cornerstone. If the cornerstones fail, they’ll be caught on a cable. It took five months total to erect the panels on site. Not only do they exceed building code guidelines, they also offer extreme weatherability. “Architectural precast is generally 4 to 6 inches thick,” explains Voss. “It’s not perfectly impermeable, but it’s among the very best of materials with regard to weatherability.” He says Clark Pacific tested the panels extensively by trying to draw water through them. EARLY COLLABORATION MAKES THE DIFFERENCE Despite the complexity of the Robert E. Coyle U.S. Courthouse project, the design and construction process was on a very tight timeline. Builders broke ground in April 2002, and erection was completed by the end of October 2003. The building was ready for occupancy by summer 2005. Voss attributes the project’s success on a tight budget and timeline to the collaboration of all involved parties. “Really close communication was imperative,” he says. Given the intricacy of the building’s facade design, all parties in the planning and construction process had to be willing to work together and willing to confront unique challenges. “You need a precast fabricator who really wants to achieve something different to pull off a project like this,” notes Chen. She also admits that designers and contractors have 20 PRECAST SOLUTIONS | JULY/AUGUST 2008

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Precast Solutions - July/August 2008

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