Design of an isolation table in horizontal planeconsidering the long-period earthquake ground motion

Abstract

In our previous study, an isolation system was proposed for not only the short-period ground motion but also the long-period one. The basic concept is that the dynamic property, which is the natural frequency, is changed by adding a spring when the amplitude of isolation table exceeds a threshold value. In the experimental equipment, there are some problems, such as, the complicated setting of clearance and the large acceleration at contact between the isolation table and additional spring. In this study, we improve the contact mechanism using the permanent magnets and soft sponges, and an isolation table for two direction is constructed. The applicability of the new isolation table is checked by using the experimental setup. As a result, the system can suppress the resonance phenomenon for two direction without large acceleration at contact time.