Dynamic characteristics and response reduction of the metal-touched type of base-isolator

Abstract

In seismic isolation system for lightweight structures, sufficient effect is not acquired when laminated rubber bearings are used. It is because that the pressure on the surface is small. Since sliding base isolators expect the performance even when the pressure on the surface is small, sliding base isolators are used for lightweight structures. Generally, the frictional coefficients of sliding base isolators are assigned in the range 0.01-0.10. However, it is examined by three-dimensional finite element method that it is effective in the case of a big earthquake even if the frictional coefficients are 0.20. The purpose of this study is to examine the effect of base-isolated structures using sliding bearings by experimental and analytical methods. The experiment by horizontal earthquake excitation (modified JMA KOBE 1995) was conducted, and the frictional coefficient was identified. As a result, the values are identified around 0.20. By using the identified frictional coefficients, the response reduction effect of multi-degree-of-freedom system model is investigated by a simulation. The responses are reduced by in the range 50-80%.

A Comparative Study on Effectiveness of Using Horasan Mortar as a Pure Friction Sliding Interface Material

“…In the study of Nishimura et al [17,18], the experimental damping coefficient, static frictional coefficient, dynamic frictional coefficient and frictional coefficients were assigned as c = 0.03 -0.352, =0.17 -0.22, = 0.07 -0.09, = 0.05 -0.1 respectively. It was also shown that even if = 0.1 -0.2, it could be effective in the case of strong earthquakes.…”

“…Shake table tests were conducted on the same materials and the optimum friction coefficient were found to be 0.1 and 0.2, respectively. Furthermore, Nishimura et al [19] conducted another research on the results of two previous studies, where they investigated a metal-touched type base isolator, for which they assigned the experimental damping coefficient, static frictional coefficient and dynamic frictional coefficient as c = 0.096 -0.153, = 0.17 -0.21, and = 0.11 -0.16, respectively, and used a simulation to evaluate the response reduction effect of a multi-degree-freedom system model. The responses were in the range of 50-80% reduction.…”