This report describes an experimental and theoretical study of the feasibility of using fiber reinforcement to produce lightweight, 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 mechanical characteristics of multi-layer elastomeric isolation bearings in which the reinforcing elements, normally steel plates, are replaced by a fiber reinforcement. The fiber in the fiber-reinforced isolator, in contrast to the steel in the conventional isolator (which is assumed to be rigid both in extension and flexure), is assumed to be flexible in extension, but completely without flexure rigidity. The theoretical analysis on which the design of steel-reinforced isolators is based is then extended to accommodate the stretching of the fiber-reinforcement. Several examples of isolators in the form of long strips were made by Dongil Rubber Belt Company Ltd., of Pusan, Korea, and tested in the Structural Research Laboratory of the Earthquake Engineering Research Center, University of California, Berkeley. The tested isolators had significantly large shape factors, which for conventional isolators require accounting for the effects of material compressibility. The theoretical analysis is then extended to include compressibility, and the competing in fluences of reinforcement flexibility and compressibility are studied.
The theoretical analysis suggests, and the test results confirm, that it is possible to produce a fiber-reinforced strip isolator that matches the behavior of a
steel-reinforced isolator. Furthermore, the fiber-reinforced isolator is significantly lighter and can be made by a much less labor-intensive manufacturing process. The advantage of the strip isolator is that it can easily be used in buildings with masonry walls. The intention of this research is to provide a low-cost lightweight isolation system for housing and public buildings in the developing countries.
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