Chris Gannon from Robinson Seismic explains how we know base isolators work – we can’t wait for the next big earthquake to test them.
The base isolation technology has been tested in test rigs like this one here all round the world. With lead rubber bearings there is two lots of tests, what is called prototype testing in which we test them through every possible scenario of an earthquake, which includes perhaps wind loading, a big wind blowing at the same time as an earthquake, lots of people being in the building in an earthquake etc, so we know that the bearings themselves will handle anything that an earthquake can throw at it. And then we do a series of productions tests and they’re sometimes just random bearings that are tested before it goes into the structure, and so from that we know that the whole structure will react as was predicted in the calculations. It’s also been tested in real earthquakes so earthquakes in Kobe and in North Ridge in America, where lead rubber bearings have been installed, the structures have survived very well indeed and other structures that were very similar were completely demolished by the earthquake or afterwards because they were so badly damaged.
National Information Service for Earthquake Engineering