Bearings key to buildings withstanding earthquakes? UCSD tests new technology
A new test began last week on an earthquake shake table on the campus of UC San Diego. Researchers were testing building bearings.
San Diego researchers are testing bearings that could help buildings withstand earthquake-generated forces that make a structure sway side to side.
Scientists say the building will sway a lot less if mounted on bearings that allow the building's base to move.
A new test began this week on an earthquake shake table on the campus of UC San Diego. Researchers were testing friction sliding bearings.
The test of a bearing developed by a Taiwanese company was run by Gilberto Mosqueda, professor of structural engineering at UCSD.
The swaying caused by an earthquake will deform and damage any part of a building that is weak or vulnerable.
“When the building is subjected to an earthquake, the deformation has got to go somewhere,” Mosqueda said. “And, when the deformation is concentrated in the bearings themselves, instead of the building, the building itself moves as a rigid block.”
In the case of friction sliding technology, the building rests on top of the bearing, which shifts with the movement of a temblor. The device returns to the center of its bowl-shaped base when the shaking stops.
There are also bearings made from rubber that flex and bend with the building’s sway in an earthquake.
Mosqueda said the devices have yet to be tested by a monster earthquake. But the story of one earthquake in Mexico City was revealing.
“People were in a building that had this technology,” he said. “The people came out of this building to chaos in the streets, and they didn’t even know there had been an earthquake because they were so isolated from the shaking.”
Bearing technology can be found in several places in San Diego, such as the Coronado bridge and the San Diego County Office of Emergency Services building.
Mosqueda said the technology dated to the 1970s. And some buildings have been retrofitted with bearings mounted on their foundations. But the use of the technology in the U.S. has so far been limited to critical structures such as hospitals, and high-tech facilities that can afford it.
"But it would be really good to have it more widespread,” Mosqueda said, “used in apartment buildings, residential buildings like it is in Japan and other countries.”