Precast Solutions - July/August 2008 - (Page 18)

building as a whole. “Our intent was for it to be masonry-like without trying to replicate stone,” adds Debra Gerod, a partner with Gruen Associates of Los Angeles, the project’s executive architect. “We wanted a unique-to-Fresno, rustic and western attitude.” The federal building in Fresno is essentially a steel structure with a precast facade. “One of the simplest things we did was to come up with repetitive panel patterns that wouldn’t be perceived as repetitive once on the building,” explains Bob Dolbinski, senior associate at Moore Ruble Yudell. “We used the inherent properties of the precast to create shade and shadow,” adds Chen. The architects wanted to minimize the number of forms needed to create the precast facade while at the same time ensuring the building did not look like a panelized structure. According to Voss, there were 1,261 panels used in the creation of the building’s facade, and more than 1,000 of those panels were unique. “That’s unheard of in precast because of cost containment,” says Voss. “Our forms supplier had never seen anything like this.” But the designers got around the cost issue by having Clark Pacific develop about 100 steel forms that could be used over and over for different panels by shifting the starting point in the form to create differently sized and shaped panels. The patterning within each panel has a vertical symmetry that also allows them to be turned 180 degrees to create a different pattern. The longest precast panel was 35 feet. Dolbinski points out how precast allowed designers limitless possibilities in terms of panel shapes and sizes without the cost that would have been associated with conventional masonry. The panels have a variation in texture of 1 inch in or out, allowing for the intricacies of stone without the associated material expense. A stone facade would have meant another wall system for the stone to adhere to. With precast, the wall system and the facade are both the same. “It’s a one-skin system,” says Chen. Another big challenge apart from the extensive variation in panel shapes and sizes was the joint size. The architects didn’t want the federal building to look like a panelized structure, so they were opposed to the appearance of joints. As a result, there are no joints in the facade larger than 1 inch, allowing the joints to become a seamless part of the structure’s pattern. The panel joints mimic the 1-inch gaps between patterns. The panels also had to turn corners about 18 inches, according to Dolbinski, to avoid the look of thin panels and maintain the overall feel of monolithic masonry. It took nearly six months to fabricate the forms for the panels, and then Clark Pacific allowed for a sixmonth casting schedule. To save time, the company began erecting completed panels while others were still in casting stage. “One could have used natural stone, plaster or 18 PRECAST SOLUTIONS | JULY/AUGUST 2008

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Precast Solutions - July/August 2008 Contents What You Should Know About UHPC A Winning Hand Fresno Federal Expanding U.S. Wind Power Precast Concrete Pipe

Precast Solutions - July/August 2008

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