CSU, SST collaborate on earthquake test

FORT COLLINS -- A group of researchers led by Colorado State University in close technical collaboration with Simpson Strong-Tie will take part in an unprecedented research event near Kobe, Japan, this summer. Construction of the largest building ever tested on an earthquake shake table will begin next week.

The seven-story, 40-foot by 60-foot condominium tower with 23 one- and two-bedroom living units and space to accommodate two retail shops will be subjected to simulated earthquakes of varying intensity on Japan s E-Defense (earthquake-Defense) shake table. The shake table is the largest in the world with the platform measuring approximately 65 feet by 49 feet. The shake table reacts against the rock in a nearby mountain and can support building experiments weighing up to 2.5 million pounds.

The series of seismic tests, known as the NEESWood Capstone tests, are scheduled for this June and July, and are the culmination of a four-year $1.4 million grant from the National Science Foundation (NSF) to develop a new design approach for taller wood-frame buildings in earthquake-prone areas.

NSF estimates more than 75 million U.S. citizens in 39 states live in areas at risk for earthquake devastation.

The test in Miki City, Japan, ultimately could help the building industry safely increase the height of wood-frame construction to six - possibly even seven - stories in active seismic zones, said John van de Lindt, Colorado State civil engineering professor who serves as the principal investigator for the project.

CSU is collaborating with four other U.S. research institutions as well as industry partners led by Simpson Strong-Tie, Maui Homes USA and technical collaborators at the U.S. Forest Products Laboratory. Other university collaborators include Texas A&M University, SUNY-Buffalo, RPI, and University of Delaware on the NSF grant.

"In the engineering and scientific community, we don t have quantitative data on how buildings of this size actually perform in an earthquake, said Steve Pryor, building systems research and development manager for Simpson Strong-Tie, a leader in innovative product development for woodframe buildings. Just expanding on typical one- and two-story design practices isn t the answer. We need a more robust design methodology to help us determine just how much strength and flexibility is needed, and where to put it. This testing will help us do that. Right now, it s all on paper we don't have a baseline for buildings this size in a major quake.

Van de Lindt has conducted tests over the past three years involving smaller structures at shake tables at CSU and in collaboration with co-investigator A. Filiatrault at the State University of New York-Buffalo in preparation for the capstone test in Japan. The Japan test will enable researchers to confirm that the new design approach meets expectations.

"Previous testing has shown us that our modeling procedures are accurate for low-rise woodframe buildings, but the test in Japan will confirm new models for mid-rise wood-frame buildings developed at CSU and design approaches developed at Texas A&M University as part of the project," said van de Lindt.

In Japan, researchers will simulate earthquakes ranging from fairly frequent events expected every 70 years or so, to more powerful earthquakes that are only expected every 500 to 2500 years, with magnitudes ranging from 6.7 to 7.3. The strongest simulated quake will occur in a 40-second test on July 17.

"We re grateful to Japan s National Institute for Earth Science and Disaster Prevention in Miki City for their collaboration and assistance on this very important stage in our research," said van de Lindt. We re honored to be the first U.S. organization to conduct experiments on their shake table.

Other contributors on the Japan project include FPInnovations, the U.S. Forest Products Lab/Forest Service, the Provincial Government of British Columbia, the American Forest and Paper Association, Stanley Bostitch, and Strocal, Inc.

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