Test shakes house to its foundations

Prof. Carlos Ventura warns most B.C. houses are unlikely to fare well

There was a "whole lotta shakin' goin' on" recently as UBC earthquake experts subjected a full-scale, two-storey house to a 6.7-magnitude quake.

The engineered home sustained relatively little visible damage during the 80-second earthquake simulation, which took place on the largest shake table in North America, located in the Civil Engineering Dept.'s Structural Engineering Laboratory.

The test was modeled on the same shaking that was experienced at locations in the Los Angeles area during the 1994 Northridge quake. It marked the first time that anyone has conducted earthquake simulation studies on a full-scale house in Canada.

"The ability to use a full-scale house is important because it provides us with a better idea of how a residential home will behave under severe shaking. It takes us beyond what we can learn through a computer simulation," says Civil Engineering Prof. Carlos Ventura, principal researcher for the project. "The results will help us improve the design of wood construction homes," he says.

Ventura, who is also director of UBC's Earthquake Engineering Research Facility, is concerned that current building codes in Canada exempt small buildings from any seismic design requirements. He warns that a large number of homes in the Lower Mainland and the province would likely fare poorly in the event of a major quake.

Through the shake tests on full-scale houses, Ventura hopes to highlight how a typical B.C.-construction home would underperform an engineered home in an earthquake.

Unlike homes typically constructed in B.C., an engineered home is designed by a structural engineer or architect to ensure that all loads are properly and safely transferred to the foundation.

The test will be repeated on a house of typical B.C. construction later this fall. Ventura and his research team will compare the results to make recommendations to improve earthquake safety for engineered homes in B.C.

The shake tests are part of a larger research project involving TBG Seismic Consultants of Victoria, B.C., and Simpson Strong-Tie of California, as well as Forest Renewal B.C. and the Natural Sciences and Engineering Research Council of Canada.