Swinging protection
IMAGINE a building swaying like a pendulum so that it doesn't crumble during an earthquake. Engineer Victor Zayas of Earthquake Protection Systems in San Francisco has designed just such a system (Science, Vol 262, No 5139). The new Friction Pendulum System (FPS) is quite unlike others, which dissipate tremor energy as springs or shock absorbers would.
FPS is being tested in the US Court of Appeals building in San Francisco, which was damaged in the 1989 earthquake. Beneath each of the 256 steel columns that make up the framework of the building, two hydraulic jacks are being installed between the foundation and the basement floor. A ball-bearing atop a small platform will then be slipped between the jacks. In the event of a quake, each of the columns will act like a pendulum, swinging gently and safely.