Feasibility investigation of superelastic effect devices for seismic isolation applications

In the last few decades earthquake engineering has an important, complex though relatively fast, development. Major efforts have traditionally followed major earthquakes, in which significant life losses and economic damages were recorded. The main goal of earthquake engineering has always been the mitigation of seismic effect on structures; this is to avoid catastrophic failures and guarantee life safety of the occupants during strong earthquakes, but also minimize the damage for minor events and therefore reduce the reparation costs in terms of money and time.

Seismic isolation is a possible way to achieve these objectives. It forms part of a passive protection system which modifies the structural global response and improve performance, in particular shifting the main period of vibration and increasing global energy dissipation.

Some of the most common isolation devices are composed by an elastic element (usually rubber) and a dissipating element (usually lead).

In this work the feasibility of application of shape memory alloy based device characterized by a superelastic effect in isolation bearing is investigated and compared to traditional seismic bearing response.

A superelastic effect hysteresis device is nominally characterized by a smaller hysteretic dissipation capability respect to lead device, but an important advantage is related to the recentering capability which is the ability to have zero residual displacement after the event.

Feasibility of the proposed device has been checked through numerical time history analyses comparing the response of SMA bearing systems and “traditional” bearing systems and their effectiveness on the global structural response.