Wood-Frame Construction Passes World’s Largest Earthquake Test
APA and its members participate in NEESWood Capstone tests to evaluate mid-rise wood-frame construction on the world's largest shake table in Japan.
A series of tests designed to evaluate the performance of mid-rise wood-frame buildings in earthquake-prone areas recently concluded in Miki City, Japan, with positive results. The NEESWood Capstone tests, conducted by a consortium of research institutes in the U.S. under the funding of the National Science Foundation and Japan’s National Research Institute for Earth Science and Disaster Prevention, featured a seven-story, 14,000-square-foot, wood-frame condominium tower erected on a shake table at E-Defense, a 3-D full-scale earthquake testing facility.
Shake tables simulate the ground motions of an earthquake. The NEESWood Capstone tests included simulated earthquakes from 6.7 to 7.5 in magnitude (as shown in video below). The final shake table test on July 14 subjected the building to the seismic force of an earthquake that occurs, on average, once every 2,500 years. APA staff members Tom Williamson, Vice President of Quality Assurance and Technical Services, BJ Yeh, Director of Technical Services, and Charlie Barnes, Director of International Services, witnessed the final test. “It’s the largest shake table test ever performed on a wood-frame structure,” said Tom Williamson.
"It was exciting to witness the magnitude of responses of the 7-story building to the seismic forces simulated by the shake table,” added Yeh. “The visual impact of the building movement was very impressive to witness in person.”
The tests were the culmination of a four-year-long research effort that involved five universities, the governments of the U.S., Canada and Japan, and several manufacturers. APA served as an industry advisor to the project, providing insight on the design and use of APA-trademarked products. APA also helped to facilitate engineered wood material procurements from its members, including OSB sheathing from Ainsworth, Glulam from Calvert Company, and prefabricated wood I-joists, LVL and rim boards from LP Corporation.
“We can be proud that a substantial portion of the building tested was made of products trademarked by APA,” said Yeh. “The engineered wood system demonstrated its strength and ductility, which are essential to building safety in seismic events and beyond.”
Technical data is still being analyzed, but minimal damage to the building was uncovered following the tests. This outcome, Williamson says, will encourage the acceptance of multi-story wood buildings in earthquake-prone areas. ”These results will demonstrate to code official and design professionals that a mid-rise wood-frame structure can be effectively engineered to resist the most severe anticipated seismic event.”
The National Science Foundation, which provided a $1.4 million grant for the project, estimates that 75 million Americans live in areas at risk from earthquakes. In most cases, mid-rise wood-frame buildings are not permitted in earthquake-prone areas, but Williamson thinks that will change. “Code acceptance could take many years, but the NEESWood Capstone tests clearly demonstrate how engineered wood products can be used to meet future mid-rise building construction opportunities.”
Video of July 14, 2009 NEESWood Capstone test simulating a 7.5 magnitude earthquake - approximately 1.5 times the intensity of the 1994 Northridge earthquake in California.
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