After spending seven weeks building a brand new two-story house, engineers tried to make it fall apart. The goal: To prove that the home is as close as possible to earthquake-proof.
Instead of a typical foundation, the house rests on sliding “isolators” that move along the ground. In an earthquake, the building slides back and forth. Because it doesn’t shake with the vibrations of the ground, walls and ceilings won’t crack.
Researchers from Stanford University and California State University tested the home on a giant “shake table”–a platform connected to a computer program that can duplicate the rolling and shaking ground in earthquakes from the past.
The engineers cranked up the table to four times the intensity of the earthquake that flattened parts of San Francisco in 1989. After sliding left and right, the house had basically no damage at all.
The design also uses extra-strength walls. “Houses used to have sturdier construction, so in a sense we’re trying to go back to some of the inherent strength and stiffness they used to have–but doing it in a much more engineered way,” explains Gregory Deierlein, an engineering professor at Stanford.
Sliding devices have been used in the past on buildings like San Francisco’s City Hall or parts of the San Francisco International Airport. But they were never affordable enough for average homeowners in the past. “Our goal was to bring down the cost and tailor it specifically to light-frame houses,” says Deierlein.
The new design works so well that homeowners could stop buying earthquake insurance, the researchers say. The design could also prevent the kind of damage that cost $25 billion in the 1994 Northridge earthquake and made thousands of people temporarily homeless.
The next step may be convincing committees to add the new technology to building codes, so that it becomes a standard part of building a house in earthquake-prone places like California. The researchers also hope that a large developer will want to test it out.
“We need an early adopter,” Deierlein says.