Seismic Assessment of Irregular Bridges Equipped with Shape Memory Alloy

Concentration of seismic damage on shorter piers is a common problem for irregular bridges subjected to strong ground motion. This study investigates the effectiveness of shape memory alloy (SMA) restrainer bars to reduce the seismic vulnerability of irregular bridges. SMAs are a unique class of materials that have the ability to undergo large deformations, while reverting back to their undeformed shape through the removal of stress (superelastic effect). To evaluate the effectiveness of the devices, nonlinear time history analyses are performed on a reinforced concrete single column bent viaduct using a suite of representative ground motions. The results showed that superelastic restrainers can significantly reduce the bridge damage index ratio (BDIR) mean response in controlled bridge compared to as-built bridge due to alleviating damage concentration on short pier. It is also found that SMA devices can effectively participate in dissipating hysteretic energy.