Stability and post-buckling behavior in nonbolted elastomeric isolators

Abstract

This paper is a theoretical and numerical study of the stability of light-weight low-cost elastomeric isolators for application to housing, schools and other public buildings in highly seismic areas of the developing world. The theoretical analysis covers the buckling of multilayer elastomeric isolation bearings where the reinforcing elements, normally thick and inflexible steel plates, are replaced by thin flexible reinforcement. The reinforcement in these bearings, in contrast to the steel in the conventional isolator (which is assumed to be rigid both in extension and flexure), is assumed to be completely without flexural rigidity. This is of course not completely accurate but allows the determination of a lower bound to the ultimate buckling load of the isolator. In addition, there are fewer reinforcing layers than in conventional isolators which makes them lighter but the most important aspect of these bearings is that they do not have end plates again reducing the weight but also they are not bonded to the upper and lower support surfaces. The intention of the research program of which this study is a part is to provide a low-cost light-weight isolation system for housing and public buildings in developing countries.