Numerical study on the longitudinal seismic performance of novel prefabricated Concrete-Filled Steel Tubular (CFST) bridge piers

This study investigates the longitudinal (namely along the bridge length direction) seismic performance of a novel prefabricated concrete-filled steel tube (CFST) bridge pier. The novel CFST pier, constructed using prefabricated components and assembly joints, ensures a simple and efficient construction method along with significant cost benefits. Previous research indicates that CFST piers exhibit superior lateral seismic performance compared to conventional RC piers, with lower sensitivity to seismic fragility. However, the longitudinal seismic response of CFST piers under varying pier heights and connection types remains to be clarified. This study designs 14 continuous girder bridge cases, including six conventional RC pier cases and eight corresponding CFST pier cases. Through dynamic and seismic fragility analyses, the longitudinal seismic responses of the novel CFST piers are investigated. The results demonstrate that the longitudinal maximum displacement and curvature ratio of CFST piers are comparable to, or even lower than, those of conventional RC piers, especially when integrated with a rigid beam-pier connection system. Additionally, CFST piers demonstrate lower seismic fragility in the longitudinal direction. An assessment method integrating both curvature ratio and maximum drift is recommended for these CFST piers.