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December 1, 2006 Vol. 77,
no. 15F
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| SHEER FORCE: CEE associate professor Bozidar Stojadinovic gets ready to test a new shear wall design.
PEG SKORPONSKI PHOTO
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CEE team tests new metal shear wall design
Panels promise to lower construction costs for quake-prone regions
Though they look nothing alike, Davis Hall on campus
and the Transamerica Pyramid in San Francisco have one thing in common:
They are both built with shear walls. Shear walls are walls that have
been strengthened to withstand shear stress, which results from forces
exerted on a building during an earthquake or in high winds. Recently,
Berkeley researchers conducted dramatic tests on a new kind of shear
wall that promises to perform better and cost less for builders and
owners.
The new wall is made of corrugated metal plates screwed to metal studs.
It was conceived by local structural engineering firm, Tipping, Mar & Associates,
which is working with CEE associate professor Bozidar Stojadinovic,
graduate students Nat Kinsky, Daniel Tran and Luke Ruggeri and senior
Letran Bui to test the design. The researchers have conducted 30 tests
already in the Berkeley Structures Laboratory in Davis Hall, with good
results.
“This system will lead to important safety improvements in the
construction of new homes, as well as provide economical retrofitting
solutions
for existing buildings,” says Stojadinovic. “Everyone involved
wants this technology accessible to anyone interested. That is why
we’re excited to make the final design tables freely available
to the public.”
On November 20, project leaders invited industry representatives and
reporters to view a test of the panel’s performance in simulated
earthquake conditions. The test used a hydraulic actuator to rack the
panel back and forth. At first, the test was gentle, mimicking small,
frequent quakes, and the panel had no apparent damage. At the end,
researchers applied roughly the same force as a rare, catastrophic
earthquake. The metal groaned, popped and rippled, eventually deforming
in places, and some of its screws popped out, plinking onto the concrete
floor. Yet the panel didn’t collapse.
“What this shows,” said Stojadinovic, “is that the
panel will have no damage in frequent quakes and will hold up to strong
motions
during rare earthquakes. Even during the most intense part of the test,
the panel survived without collapsing. In a real building, people would
be able to walk away.”
The metal panels are preferable to plywood reinforcements, Stojadinovic
said, because they’re up to three times as strong, aren’t
combustible, won’t mold, are recyclable, may be cheaper to manufacture
and are easier to prefabricate and deliver to the jobsite.
CEE master’s student Nat Kinsky has been involved with the project
since last semester. He processes the data from the test, coordinates
student researchers and helps assemble the panels and bolt them into
the test assembly. “It’s a mix of manual labor and data
analysis,” he says. “I’m learning a lot about how
lateral systems work. It’s been fun.”
The team says it must complete about 10 more tests before it can release
its conclusions. Project leaders expect the panels to be available
for public use next year. The entire project is funded by the Charles
Pankow Foundation, which supports collaboration between academia and
industry on building design and construction.
See a video of the test at www.berkeley.edu/news/media/releases/2006/11/22_shear.shtml.
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