Passive Seismic Control Using Shape Memory Alloy Springs

Abstract

In this paper, seismic response analysis is made both experimentally and numerically for a passive isolation device with pseudoelastic shape memory alloy (SMA) spring as a restoring force component. Thanks to the material nonliniarity and the geometrical nonliniarity, the SMA spring used in the device has well-defined softening, or “force limiting”, property that can suppress the acceleration response of the superstructure by limiting the seismic force transmitted from the ground. To illustrate how the presented device can suppress the acceleration response under the prescribed level, shaking table tests of a reduced-scale model of uniaxial isolator are carried out with seismic inputs appropriately scaled both in time and in amplitude. Then, a Preisach model of the SMA spring is constructed for the purpose of design study, and verified by comparing the simulated seismic responses with the experimental ones.