Seismic performance of SMA retrofitted multiple-frame RC bridges subjected to strong main shock-aftershock sequences

Using Shape Memory Alloy (SMA) wires to retrofit vulnerable reinforced concrete (RC) bridge piers had shown promising results in recent analytical and experimental researches. However, most of previous researches had focused on performance of retrofitted RC piers on element level while the global response of SMA-retrofitted RC bridge has not yet been studied. Therefore, the main objective of this numerical study is to investigate the global seismic response of full-scaled SMA-retrofitted multiple-frame RC bridges, especially focusing on the sequence of formation of plastic hinges at bridge piers. Furthermore, the bridge is subjected to a sequence of strong main shock and aftershock ground motions to determine the effect of sequential seismic loadings on retrofitted bridge piers and on other bridge components such as expansion joints and abutments. The results demonstrate the level of retrofitting needed to improve the resilience of the bridge to a given target performance, which is measured by the aftershock PGA the bridge can resist. In addition, the optimal level of retrofit for the bridge is identified. It is also found that there is an increase in demands on intermediate hinges and abutments as retrofitted bridge is subjected to increasing intensity of aftershock.