Seismic behavior of SMA retrofitted RC bridges subjected to strong main shock-aftershock sequences

Previous studies have shown that using active confinement as a retrofit measure for vulnerable reinforced concrete (RC) columns using Shape Memory Alloy (SMA) spirals can significantly improve the seismic performance of these columns. However, the global seismic behaviors of bridges with SMA retrofitted bridge piers are not understood yet. Hence, one of the main focuses of this numerical study is to investigate the sequence of plastic hinge formation at bridge piers retrofitted with SMA when the bridge is subjected to multiple strong seismic events (e.g. strong main shock followed by an aftershock). In addition, this study investigates the changes in the demands imposed on various bridge components such as expansion joints and abutments due to the retrofit of the piers with SMA spirals. The numerical results illustrate the level of confinement required for all bridge piers to achieve a target performance of the bridge, which is measured by the aftershock peak ground acceleration (PGA) that the bridge can resist. Accordingly, the optimal retrofitting design of the bridge is identified. It is also found that the displacement demands on expansion joints and abutments increased when the bridge was subjected to increasing intensity of aftershock.