Seismic Responses Analysis of a Base Isolation Device Using SMA Springs and Proposal for Design Criteria of the Device

In this paper, seismic response analysis is carried out both experimentally and numerically for a base isolation device with pseudoelastic shape memory alloy (SMA) springs as restoring force components. Owing 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. Numerical simulations are conducted using Preisach-based SMA spring model. Then, assuming the scalability of the restoring force v.s. displacement curve of the SMA spring, seismic responses of the devices with SMA springs which have various restoring force characteristics are investigated, numerically. From their results, brief design criteria are suggested.