World's Largest Earthquake Test Could Help U.S. Building Industry

[1] The test, which was conducted on a seven-story condominium tower with 23 one- and two-bedroom living units, approximated a 7.5 magnitude earthquake.

FORT COLLINS — Colorado State University [1] along with industry leader Simpson Strong-Tie [2] and other partners successfully led the world’s largest earthquake shake table test in Japan on July 14, showing that midrise wood-frame buildings can be built to withstand major earthquakes (view videos of the test [1]).

“Thorough detailed analysis of the data won’t be available for weeks, but scientists are pleased with the initial results,” said John van de Lindt, principal investigator on the test and civil engineering professor at Colorado State University.

Tuesday’s 40-second test, approximating a 7.5 magnitude earthquake, was the strongest test, occurring on a seven-story condominium tower with 23 one- and two-bedroom living units. The test was held in Miki City, near Kobe, Japan, on the world’s largest earthquake shake table owned by Japan’s E-Defense, a facility of Japan’s National Research Institute for Earth Science and Disaster Prevention. The tower is the largest wood-frame building ever built and tested.

“Early results of the testing this summer show that the building performed so well and had so little damage that it validated the design philosophy developed by Colorado State, other universities in the National Science Foundation’s Network for Earthquake Engineering Simulation and our industry collaborators,” said van de Lindt.

Steve Pryor, structural engineer for Simpson Strong-Tie and project collaborator added, "The testing thus far has shown that performance-based design for light-frame wood structures works. This will allow the engineering and building community to provide safer, better performing buildings in the most cost-effective manner."

The U.S. building industry rarely permits wood-frame buildings in excess of five stories in earthquake-prone areas. The data gathered from this test could increase the height of these buildings and influence the design of future wood-frame construction. The government of British Columbia is particularly interested in the results of the test after enacting a new law April 1 that increases the height of wood-frame structures from four to six stories.

Researchers spent the summer simulating earthquakes ranging from fairly frequent events expected every 70 years or so, to more powerful earthquakes that are only expected every 500 to 2,500 years, with magnitudes ranging from 6.7 to 7.5 on the Richter scale. The Northridge earthquake, for comparison, measured roughly 6.7.

The seismic testing, known as the NEESWood Capstone tests, is the culmination of a four-year $1.4 million grant from the National Science Foundation to develop a new design approach for taller wood-frame buildings in earthquake-prone areas. That grant is a collaboration between five universities, including Texas A&M University, Rensselaer Polytechnic Institute, University at Buffalo, and University of Delaware.

Other contributors on the Japan project include the U.S. Forest Products Lab/Forest Service, the Provincial Government of British Columbia, FPInnovations, Maui Homes and numerous material contributors.