Seismic Testing Results Support Seven-Story Wood-Frame Construction

In NEESWood Capstone seismic testing—the culmination of a four-year, $1.4 million National Science Foundation grant to develop a new design approach for taller wood-frame buildings in earthquake-prone areas—Colorado State University in collaboration with Simpson Strong-Tie and other partners conducted a test on the world’s largest earthquake shake-table near Kobe, Japan, on July 14

Sources: Colorado State University, Fort Collins, Colo.; C.P. staff

In NEESWood Capstone seismic testing–the culmination of a four-year, $1.4 million National Science Foundation grant to develop a new design approach for taller wood-frame buildings in earthquake-prone areas–Colorado State University in collaboration with Simpson Strong-Tie and other partners conducted a test on the world’s largest earthquake shake-table near Kobe, Japan, on July 14. Though detailed data analysis is not yet available, initial results indicate that midrise wood-frame buildings can be built to withstand major earthquakes.

For 40-second intervals, researchers subjected a seven-story condominium tower, comprising 23 one- and two-bedroom units, to simulated earthquakes ranging in magnitude from 6.7 to 7.5 on the Richter scale. Early results of the testing 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, affirms Colorado State University Civil Engineering Professor John van de Lindt, principal investigator.

As the U.S. building industry rarely permits wood-frame buildings in excess of five stories in earthquake-prone areas, the researchers note, test results could increase the height of such buildings and influence the design of future wood-frame construction. The NEESWood Capstone tests have run parallel to Precast/Prestressed Concrete Institute research examining precast structural system response to major seismic activity. Last year saw shake-table testing of a half-scale, three-story parking structure at the NEES/Englekirk Structural Engineering Research Center in San Diego. The 28-ft.-tall precast structure featured one level each of three types of flooring components: pretopped double-tees, topped double-tees, and hollow-core slabs. That study followed a 10-year, 1990s initiative, Precast Seismic Structural Systems (PRESSS), which explored building connections for precast components. Using a large-scale, five-story precast building test to examine four frame alternatives and one shear-wall system, PRESSS demonstrated the superior performance of a hybrid structural frame system.