Quantification of multi-level residual drift ratios of RC bridge piers based on traffic flow capacity and its application in seismic failure assessment of RC bridge piers with EDBs

To enhance the post-earthquake traffic flow capacity of bridge structures, various energy dissipation braces (EDBs) have been developed and applied. However, the effect of various EDBs on the improvement of the post-earthquake functionality of the bridge is difficult to evaluate mainly due to the imperfections in the functional indexes of bridge structures. This study aims to quantify the multi-level residual drift ratios of RC bridge piers based on traffic flow capacity, and to assess the seismic failure of RC bridge piers with different EDBs based on traffic flow capacity. To this end, the traffic flow was categorized into five levels based on the relationship between the traffic flow capacity and the seismic performance of the bridge. The post-earthquake performance states were evaluated on the basis of the residual drift ratio as a performance indicator, and the corresponding residual drift ratio thresholds for bridge structures under different function levels were determined as 0.06%, 0.24%, 0.49%, and 0.85% based on the numerical analysis results. Using traffic flow capacity as the limit states, the failure probabilities of the RC bridge bents with buckling restrained braces (BRBs) and self-centering energy-dissipation braces (SCEBs) were further investigated. The results show that traditional BRBs show better performance with respect to the maximum drift ratio while the SCEBs show better performance with respect to the residual drift ratio. It is indicated that the SCEB is much more effective in improving the repairability and post-earthquake traffic flow capacity of the bridge.