Nonlinear natural rubber bearings for seismic isolation

This paper summarizes the results of a ten-year joint research program on base isolation carried out by the Malaysian Rubber Producers' Research Association in England and the University of California at Berkeley. Special rubber bearings have been developed which protect buildings and their contents from earthquake damage without requiring additional mechanical devices to enhance damping or to avoid problems of wind movement. The lack of complexity in the system makes prediction of response more certain and reduces cost so that in many designs the additional protection will be achieved at a cost lower than that for conventional protection. The principles of design are explained and results given for the many experimental investigations of the system which have included measurements of the response of both the building and its internal equipment. Practical aspects of the use of the system are discussed with reference to a large structure at present being constructed on nonlinear natural rubber bearings in a highly seismic area.