Experimental Study of Friction‐Pendulum Isolation System

A shake‐table study of the friction‐pendulum isolation system, installed in a six‐story, quarter‐scale, 52‐kip model structure, is presented. Two bearing materials are studied, one with a peak friction coefficient of 0.075 and another of 0.095. In both cases, the isolation system has a rigid‐body mode period of 1 sec. The isolated structure is found to be capable of withstanding strong earthquake forces of different frequency content. In tests with the El Centra motion, the isolated structure sustains, without any damage, a peak ground acceleration six times greater than what it could under fixed‐based conditions. It is found that the bearing displacements are low and that the permanent bearing displacements at the end of free vibration are very small, in general, not exceeding 6% of the bearing design displacement. The system is shown to have quantifiable properties, and analytical techniques are presented that provide accurate prediction of the response.