Smart restorable sliding base isolation system

A modern base isolation system is proposed for the aseismic control of structures. It is composed of steel-Teflon Flat Sliding Bearings, to support the gravity loads while allowing large horizontal displacements, and simply connected Shape Memory Alloy (SMA) truss elements, to provide the necessary horizontal stiffness as well as a proper restoring capability. The system is referred to as Smart Restorable Sliding Base Isolation System (SRSBIS). Depending on the arrangement of the auxiliary SMA elements, SRSBIS can exhibit a geometric nonlinearity in addition to the nonlinearity of materials. In this paper, the dynamic characteristics of SRSBIS are first examined in terms of the force-displacement behavior, effective period of vibration, and equivalent damping. After that, the earthquake response of buildings equipped with SRSBIS, designed in accordance with a direct displacement-based approach, is evaluated through extensive nonlinear time-history analyses. The effects of the design parameters on the system behavior are then investigated within a comprehensive parametric study and the seismic performances of SRSBIS are finally compared to those of similar practical isolation systems. Based on the results, it is shown that SRSBIS can be suitably used for the seismic protection of structures.