(Photo by Douglas Levere, BA '89)
Build house. Shake vigorously. Repair damage. Repeat.
Thatís the recipe earthquake engineers at UB are following as they launch a series of unprecedented seismic tests on a full-scale, two-story, wood-frame townhouse over the next several months.
The 73,000-pound, 1,800-square-foot townhouse will be the largest wooden structure to undergo seismic testing on a shake table in the United States. The landmark testing at UB is part of a $1.24 million international project called NEESWood, funded by the National Science Foundationís George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES). In November, the full-scale, furnished, three-bedroom, two-bathroom townhouse will be subjected to the most violent shaking possible in a laboratoryómimicking what an earthquake that occurs only once every 2,500 years would generate.
In that final test, the townhouse is expected to suffer massive damage, according to computer simulations performed by the UB researchers and colleagues at other NEESWood institutions. To gather the data, the UB researchers are equipping the townhouse with 250 sensors that will provide detailed information about how each nook and cranny behaves during each simulated earthquake.
The experiments are being performed in UBís Structural Engineering and Earthquake Simulation Laboratory (SEESL), the only laboratory in the nation large and sophisticated enough to conduct the tests. (Details about SEESL are available at http://nees.buffalo.edu/.)
Between now and November, several dozen professors, students, contractors and local companies will be constructing, testing, repairing and retesting the two-story townhouse. It is being constructed on top of twin, movable shake tables in UBís SEESL that will be set to deliver the exact same earthquake payload with precise simultaneous synchronization. During each of the six testing phases being planned, the townhouse structure will be subjected to five increasing levels of shaking in three dimensions, the most authentic ground motions that can be produced in a U.S. laboratory. The ground motions will simulate increasing intensities that were recorded during the 1994 Northridge earthquake in the Los Angeles region.
The UB tests will be among the first to provide realistic data to engineers about how a typical, full-scale, two-story, wood-frame townhouse built to current standards in California will behave in an earthquake.
The ultimate goal of the four-year NEESWood project is to develop a design philosophy for wooden structures in seismic regions so that taller and larger wooden structures can be built, up to six stories in height. In some states, explains Andre Filiatrault, professor of civil, structural and environmental engineering, wood structures of up to four and five stories tall are being built, but no data are available on how such structures will perform in an earthquake.