Precast Solutions - May/June 2008 - (Page 28)

Concrete is married to lightgauge steel studs by means of shear transfer strips. Weldedwire mesh is sufficient to reinforce the thin-shell concrete, because the steel framing is designed to carry axial and transverse loads. Courtesy Metal Stud Crete is that the system can be used by any precaster, and it saves time. Because of the reduced weight, overnight curing typically achieves sufficient strength for the assembly to be lifted out of the forms the next day, speeding the casting beds’ cycle time as compared with conventional precast. Panels can then be moved to a storage position to continue curing before shipment. inches of conventional concrete. By using these panels, we reduced the weight about 65 percent.” He estimates this choice cut more than 1,000 tons of dead load from the 90,000-square-foot building. Precise interior climate control was one of the primary requirements of the building in order to protect the valuable collection. The light weight of the wall system made it practical to transport and erect very SMALLER LOADS, BIGGER PANELS large panels, minimizing the number of joints to be sealed against air and moisture infiltration. Panels as large as 16 feet tall by 40 feet long were produced by Coreslab Structures Inc., Los Angeles. Bob Konoske, vice president and general manager of Coreslab, comments, “It was very aggressive to make precast panels this large. Practically, we could not have made conventional panels this big.” The entire interior surface of the precast panels was sprayed with closed-cell foam to achieve a moisture barrier and thermal break. Temperature in the building can be maintained to within a tolerance of plus or minus 1 degree F. The large panels made it possible to locate joints where they could be concealed by architectural elements: vertical joints occur at changes in wall plane and horizontal joints are behind moldings. The broad, apparently unbroken concrete surface achieves a monolithic appearance not possible with individual quarried blocks. To harmonize with the neoclassical style of the Huntington’s original buildings, the concrete is finished to look like natural stone, and entrances and Although it is a proven technology, the ramifications of the lightweight design are still being explored. Architects and engineers who turn to lightweight wall panels to solve specific problems often discover additional benefits. This was the case with The Munger Research Center at the Huntington Library, San Marino, Calif. The Munger Research Center, located in one of the most seismically active areas of North America, was designed as an essential structure to protect one of the world’s premiere collections of rare books and manuscripts. Building to 150 percent of code, the deadload of conventional precast would have required huge expense in the support structure. Designer/builder Earl Corp., Irwindale, Calif., selected lightweight wall panels weighing 35 to 45 pounds per square foot rather than the 100 to 140 pounds per square foot for conventional precast. According to structural engineer Jackson Wu of Johnson & Nielsen Associates, Monrovia, Calif., “We would have needed an average 8 28 PRECAST SOLUTIONS | MAY/JUNE 2008

Table of Contents Feed for the Digital Edition of Precast Solutions - May/June 2008

Precast Solutions - May/June 2008 Contents Sustainability and Practicality Security Blanket A Frank Lloyd Wright Takes Shape Concrete Joins MENSA Precast Lightens Up

Precast Solutions - May/June 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.