Residual drift ratio evaluation of double-column RC bridges with additional self-centering energy dissipation dampers under near-fault ground motions

The post-earthquake residual drift ratio of double-column reinforced concrete (RC) bridges is a vital index parameter for evaluating the traffic function, and an excessive residual drift ratio may seriously reduce the post-earthquake traffic function of the bridge structure. The application of self-centering energy dissipation damper (SCED) is an effective measure to reduce the residual deformation of RC bridges, and the self-centering ability of SCED improves with the increase of self-centering ratio. This study established the relationship between the self-centering ratio of damper and the residual drift ratio of the RC bridges, to obtain satisfactory traffic function of a bridge structure. To this end, sensitivity analysis of the RC bridges with additional SCEDs was performed, and 10 key parameters that have a large influence on the engineering demand parameters (EDPs) were selected when the peak drift ratio and residual drift ratios were used as the EDPs. Then, 550 samples of double-column RC piers with additional dampers were generated by using the Latin Hypercube Sampling, and 82,500 nonlinear time-history analyses under near-fault ground motions were performed. Subsequently, the residual drift ratio boundaries of the double-column RC piers were established for SCEDs with different self-centering ratios using linear regression methods. Based on the above analysis, the relationship between the energy dissipation ratio of SCED, the structural residual drift ratio and the peak drift ratio was obtained using nonlinear surface regression. The distribution intervals of the residual drift ratio under different structural peak drift ratio were given considering the self-centering ratios of the SCED, and the boundary equations for the intervals were then established. Finally, a double-column RC bridge with additional SCEDs was selected as an example, and 12 cases were set up by considering different target peak drift ratios to verify the reasonableness of the residual drift ratio evaluation.