Posted in Building Codes
Whole Lotta Shaking
After two weeks of brutal testing on top of the world’s largest earthquake shake table, the seven-story NEESWood Capstone Test Tower in Japan is sending shockwaves throughout the building industry on a global scale. These tests could influence building designs and codes for wood frame structures in seismic zones in many countries.
Colorado State University, in close technical collaboration with Simpson Strong-Tie, tested the 23-unit, one-million-pound condominium tower to help researchers find new construction methods for buildings in earthquake-prone, urban areas. The project was a part of the Network for Earthquake Engineering Simulation (NEES) and sponsored by the National Science Foundation.
Because the building satisfied NEES’s performance objectives, the state of California is expected to change its building code from a maximum of five stories in a wood frame building to six stories. This follows in the footsteps of both the UK and Canada, who have also recently increased the number of stories allowed for wood frame structures. Prior to the completion of these tests, the lack of earthquake research on wood frame structures has prevented the design of mid- and high-rise wood frame buildings in seismic zones. This, in turn, has limited builders’ ability to use wood materials in the construction of buildings in areas like California, Japan, China and Chile.
“This will be really important nationwide because wood-frame buildings are less expensive than steel and they are more friendly to the environment,” said David Clyne, president of Maui Homes, Inc., and general contractor for the project. “I hope to market and sell this type of building in Japan. Ninety percent of the homes I build are western-style homes for Japanese families.”
Clyne, along with 12 carpenters, began work on the building on March 9, 2009, and finished dry-walling on June 12. To construct the condominium tower, Clyne used products from Simpson Strong-Tie® Company, which makes structural connectors and anchor tie-down systems, along with LP Building Products, including LP® SolidStart® I-Joists and LP SolidStart Laminated Veneer Lumber.
Because Maui Homes built the tower adjacent to the test site, after it was finished two 400-ton cranes loaded it onto the E-Defense shake table, which is part of the Hyogo Earthquake Engineering Research Center in Miki City, Japan. Moving the massive building onto the platform also earned it a place in the Guinness World Book of Records as the largest structure ever to be relocated. The building then underwent 60 total shakes over the course of two weeks. The last shake, on July 14, measured 7.5 on the Richter scale.
The Northridge earthquake hit Northridge, Calif., in 1994, killing 72 people and causing an estimated $20 billion in damage. Because the design of the condominium was able to hold up to expectations with this final test, it is likely that wood materials will soon be utilized freely in the construction of buildings in seismic zones on both sides of the Pacific.
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