Better Metal Wall System Coming for Seismic Zones

11/27/2006 By ENR Staff

	Panel performed as expected, says Stojadinovic. Peg Skorpinski Photography

By April, structural engineers may be able to get building department approval, on a case-by-case basis, to use generic metal shear wall panels for low-rises in high seismic zones. The metal panels, currently undergoing load tests, offer three times the strength of plywood shear walls, twice the strength of any proprietary system and ultimately are more economical, say sources.

The goal of a two-year research effort is to come up with “a very simple way” to provide lateral bracing for a conventional metal-stud wall, says Steven Tipping, president of Tipping Mar + Associates, Berkeley, Calif. Tipping is the champion of the $172,000 effort, funded by the Pankow Foundation, to develop and load-test the approach.

The system, appropriate for buildings up to six stories, consists of metal studs with infill panels made from corrugated metal deck, oriented vertically with flutes running horizontally, and screws—much like a giant wash board. “We are dealing with familiar components,” says Tipping. They are “reliable and installed by laborers, not welders,” he adds. Proprietary metal systems use thin sheets, have tighter tolerances and are more difficult to install, he says.

The University of California, Berkeley, is testing 40 “deck” panels in a variety of configurations. Researchers are changing panel gauge from 22 to 20 to 18; stud gauge from 20 to 18 to 16 and using various screw sizes. “We will build a matrix and come up with a combination table for wall systems to achieve certain design values,” says Tipping. “Structural engineers will be able to pick combinations that work for their buildings.”

On Nov. 20, Berkeley tested a 4-ft-wide, 8-ft-tall panel with 18-gauge metal deck, 16-gauge studs and #14 screws spaced 3 in. on center. As predicted, the 10-minute test achieved a maximum force in the panel of about 25,000 lb before it started to break, says Bozidar Stojadinovic, the UC Berkeley associate professor of civil engineering conducting the tests, interpreting results and preparing building code language. Code approval could take three years, he says. Until then, engineers will be able to use the program’s report, due out in March, as a basis for getting a building permit, on a case-by-case basis.