Concave sliding isolator's performance under multi-directional excitation

Due to their large displacement capability and stable energy dissipation associated with a compact shape and new highly performing materials, the use of concave sliding isolators have been continuously increasing for application in buildings and bridges. In this paper the results of dynamic tests on full scale devices are presented. Their response was studied in a wide velocity range, for bi-directional patterns under different compressive loads. In this range of loading characteristics, which is typical of design for earthquake excitation, the behavior of these isolators appears significantly affected by the multi-directionality of the motion, and more specifically by the degradation of the coefficient of friction due to heating phenomena at the sliding surface. An analytical model, applicable to the prediction of bi-directional sliding behavior of friction-based isolators has been experimentally validated. Results of this study suggest that these phenomena should be considered in the design of structures equipped with these popular anti-seismic devices.