Just weeks after the University at Buffalo (UB) and Rensselaer Polytechnic Institute (RPI) successfully conducted the first tests of seismic dampers for residential applications, the firm that manufactures the dampers, Taylor Devices, made its first sale of the protective devices for a residence. Completed in early July, the damper tests were part of NEESWood, a four-year, $1.24 million National Science Foundation-funded consortium project. The goal of NEESWood is to develop a better understanding of how wooden structures react to earthquakes, so that larger and taller structures can be built safely in seismic regions worldwide.
The frame of the luxury home where the dampers will be installed is being built of steel, not wood. But, according to Douglas P. Taylor, CEO of Taylor Devices, the lessons learned during the tests are applicable. At an estimated cost of $50,000 including installation, the $35 million California project will use a dozen seismic dampers, which are designed to be installed within a home’s perimeter wall. Each silicon-fluid-filled damper, measuring approximately 20 inches long and 3.5 inches in diameter, can dissipate about 10,000 pounds of force. The dampers take the energy of the earthquake and convert it into heat, removing it from the structure.
In early July, under the supervision of Michael Symans, Ph.D., associate professor of civil and environmental engineering at RPI, a 73,000-pound, 1,800-square-foot townhouse equipped with four seismic dampers was subjected to a simulation of a magnitude 6.7 earthquake on UB’s twin shake tables. Those tests confirmed that the dampers were able to dissipate a portion of the energy from the simulated earthquake ground motions, thus reducing the energy that needed to be dissipated by the wood framing system.
"The reduced energy dissipation demand on the wood framing system indicates that the damage in wood buildings subjected to earthquakes could be reduced significantly by incorporating dampers," said Symans. The UB testing concludes in November, when the furnished, three-bedroom, two-bathroom townhouse will be subjected to the most violent shaking possible in a laboratory, mimicking what an earthquake that occurs only once every 2,500 years would generate. The tests are the first step in moving toward performance-based design for wood-frame structures. NEESWood will culminate with the validation of new design processes using a six-story, wood-frame structure that will be tested on the world’s largest shake table in Miki City, Japan, early in 2009.