# Seismic Performance Evaluation of Highway Bridges under Scour and Chloride Ion Corrosion
## 1 Introduction
It was concluded that scour action is beneficial to the seismic resistance of bridge column members, while increasing the seismic failure probability of pile foundation members. However, the relationship between scour depth and failure probability of the component has not been determined. [PERSON] et al. [17] proposed a model of failure probability under combined action of scour and earthquake. The values of reasonable scour depth and combination subfactors of scour action were discussed. However, the coefficients were not based on the target reliability index and could not strictly provide guidance on seismic design of bridges from the perspective of a full probability limit-state design. Extensive research has been carried out to address the issue of seismic performance degradation of reinforced concrete bridge columns due to Cl\({}^{-}\) corrosion. In a comparison of the contribution of concrete carbonation and reinforcement corrosion due to Cl\({}^{-}\) to the structural failure probability of bridges in a marine environment, [PERSON] [18] found that the failure probability due to Cl\({}^{-}\) corrosion is much greater than that due to concrete carbonation. [PERSON] [19] found that the corrosion of transverse hoop rebars is greater than that of longitudinal rebars in concrete structures under Cl\({}^{-}\) corrosive condition, especially at the junction of longitudinal and transverse rebars where the hoops were severely corroded or even fractured. It is inevitable to lead to the reduction or even loss of the restraint effect on core concrete which in turn results in a decrease in the ductile properties of structural elements. [PERSON] et al. [20] investigated the effect of hoop corrosion on axially compressed concrete members. The test results showed that the load-carrying capacity and deformation capacity of restrained concrete decreased significantly with the increase of hoop corrosion. [PERSON] et al. [21] conducted tensile tests on nearly 300 trusted rebars from different sources to obtain their mass rust rate and ultimate tensile rate. The variation law of reinforcement strength with increasing corrosion rate was obtained and the stress-strain relationship of rusted reinforcement was proposed. [PERSON] et al. [22; 23] investigated the tensile properties of naturally and artificially corroded rebars as well as the effect of different sites on seismic performance of reinforced concrete beams. The experimental results showed that corrosion of longitudinal tensile rebars has significant adverse effects on yield displacement, yield load, and peak load, the corrosion of longitudinal compressive rebars has adverse effects on yield displacement, and the corrosion of transverse rebars has negative effects on yield displacement and ultimate displacement when the damage mode is bending-sheardamage. [PERSON] et al. [24] investigated the effect of discounted cross-sectional area of rebars and cracking of concrete protective layer on the degradation of strength and stiffness of bridge columns. [PERSON] and [PERSON] [25] researched the corrosion of bridge columns and established a curve of time-varying vulnerability for bridge components. [PERSON] et al. [26] studied the variation law of seismic performance of reinforced concrete bridge columns in corrosive conditions throughout their service cycles from a probabilistic perspective. It was concluded that the decay of seismic performance of bridge columns in corrosive conditions has a significant effect on its seismic response. [PERSON] et al. [27] investigated the degradation of the performance of offshore columns under consideration of Cl\({}^{-}\) corrosion. The time-varying seismic demand and seismic fragility of columns based on time variation during their remaining service life were researched at the same time. [PERSON] et al. [28] found through experiments that the concrete damage thickness and the degree of matrix damage increased with the number of wet and dry cycles growing.