Abstract

Base isolation is, in recent times, an accepted design philosophy as an earthquake resistant strategy for structural systems and sensitive instruments. Predicting the behavior of laminated rubber bearings, usually obtained from Haringx’s theory, has been developed by many researchers. They have proposed a nonlinear, mechanical model for multilayer elastomeric bearings. However, in past theoretical and experimental studies, the effects of rotation in the bottom and top ends of bearings have been neglected. In this study, an analytical method is presented and formulated by considering the rotation of the top and bottom ends of multilayer rubber bearings, as new boundary conditions. According to these rotations, the horizontal stiffness of laminated rubber bearings, which is the one of the most important characteristics of bearings, will change. Comparisons of theoretical and experimental results show that the present analysis model has a good accuracy for analyzing laminated rubber bearings. Examples are presented to demonstrate the validity of the development method in predicting the horizontal stiffness of laminated elastomeric bearings with specified geometric parameters. The results of this study have shown that the horizontal stiffness of laminated rubber bearings will increase or decrease according different boundary conditions.

Key words: Seismic isolation, earthquake engineering, base isolation, elastomeric bearing, laminated rubber bearing, horizontal stiffness.