The mechanics of fiber reinforced multi-layered elastomeric isolation bearings is studied in this paper. Such bearings offer the possibility of light-weight low-cost seismic isolators that can be mass-produced and used for public buildings and housing of highly seismic areas in developing countries.
The fiber reinforcement, in contrast to the steel reinforcement in conventional isolators, assumed to be rigid both in extension and flexure, is flexible in extension, but completely without flexural rigidity. In addition the rubber layers in these bearings tend to be very thin leading to large shape factors and the need to include bulk compressibility in the elastomer. These aspects of the bearings lead to interesting mechanics problems and in this paper the influence of the stretching of the reinforcement and the compressibility of the elastomer on the mechanical response is developed and confirmed by finite element analyses. A surprising result of the analysis of the combined response of the apparently unrelated effects of stretching of the reinforcement and compressibility in the elastomer is that the mathematical structure of the theory is the same for both effects and that they can be combined in the result- ing solution in a simple way. It is shown that it is possible to produce a fiber-reinforced isolator that matches the behavior of a steel-reinforced isolator. The fiber-reinforced isolator will be significantly lighter and could lead to a much less labor intensive manufacturing process.
