Testing of a Natural-Rubber-Base Isolation System by an Explosively Simulated Earthquake. Final Report

摘要

This report describes the base isolation experiment of the SIMQUAKE II test. The experiment used a 1/24-scale model of a containment structure. The model was mounted on a base isolation system that incorporated multilayer natural rubber bearings and a fail-safe system of novel design. The base isolation system was designed to produce a very low natural frequency of vibration in horizontal motion and much higher natural frequencies for the vertical and rocking motions. During the SIMQUAKE II experiment, the isolation system was subjected to two distinct ground motions. The first had peak ground accelerations of +-0.75 g horizontally and +1.25 g, -0.94 g vertically, and the second had +-3.0 g horizontal and +4.4 g, -5.6 g vertical ground accelerations. The isolation system easily overrode the first earthquake, but the second, having an upward acceleration greatly in excess of any possible earthquake and much higher than anticipated in the design of the bearings, caused them to fail in tension. The fail-safe system then activated and prevented collapse of the structure. (ERA citation 08:035911)