IMPACT RESPONSE OF STRUCTURES ISOLATED BY ELASTOMERIC BEARINGS

摘要

The seismic response of structures isolated by elastomeric bearings impacting upon adjacent structures during real earthquake ground motion is investigated. A shear beam analytical model with multiple-degrees-of-freedom at different floor levels is considered in the present study. The adjacent structure is modelled as a spring-dashpot impact oscillator for two sided impacts. Differential equations of motion of the structure with elastomeric bearings are solved approximating linear variation of acceleration over a small time step. The elastomeric systems considered are laminated rubber bearings and lead-rubber bearings with linear and bi-linear force-deformation behaviour, respectively. From the trends of the results, it is observed that with increasing stiffness of adjacent structures and flexibility of superstructure the top floor acceleration of the base-isolated structure is increased and bearing displacement reduced. However, with increasing the gap distance the superstructure acceleration decreases. It is also concluded that the impact of base-isolated structure upon the adjacent structures during earthquake has severe effects on the performance of elastomeric bearing for seismic isolation.