Coastal bridge piers suffer random performance deterioration owing to the presence of complex nonuniform corrosion characteristics and material uncertainties. Some of these piers will also be threatened by random earthquakes during a long-term service period, and therefore, structural safety needs to be probabilistically assessed by the seismic reliability method. To deal with this problem, we present a method to calculate the time-dependent reliability of the coastal bridge pier, comprehensively considering the randomness of a seismic event, nonuniform corrosion, and material uncertainty. First, the time-dependent M–N interaction diagrams are established by using the Monte Carlo simulation method. On the basis of the interaction diagrams, the moment resistance reduction function and time-dependent moment resistance distribution are determined. Subsequently, the moment demand under the seismic load is determined using the Poisson model and the response acceleration spectrum. Then, the formulas to calculate the time-dependent reliability of a nonuniform corroded pier are derived on the basis of the theorem of total probability. The proposed method is illustrated with a case study of a coastal bridge pier. It was found that the increase in corrosion damage would obviously increase time-dependent reliability. Furthermore, the increase in submerged zone height delayed the year when the failure section shifts from the pier bottom to the bottom of the splash and tidal zone, and it reduces the failure probability of the coastal pier. The research results presented herein show that the nonuniform corrosion manifestations influence the failure mode–related time-dependent seismic reliability of the coastal bridge pier.

In recent years, the deterioration of seismic behavior for reinforced concrete (RC) bridges due to reinforcement corrosion has received increasing attention. Many studies have been performed to explore the seismic capacity of corroded piers by applying uniaxial cyclic loading. However, the uniaxial seismic responses of corroded piers cannot accurately reflect the true structural response influenced by corrosion condition and real multidimensional earthquake action. Pointing at this problem, in this study, the seismic performance of corroded pier columns suffering biaxial lateral cyclic loadings is investigated by conducting comprehensive numerical analyses. First, a fiber-based numerical model is built and verified by the cyclic experiment results of two RC pier columns under different displacement loading patterns and corrosion levels. Then, three corrosion levels and five uniaxial and biaxial displacement protocols are used in the verified numerical models. The simulation results show that the ultimate force, deformation capacity, and dissipated energy of the piers are significantly influenced by corrosion degrees and biaxial loading patterns compared with the uniaxially loaded uncorroded piers. The phase lag between the biaxial displacement trajectory and biaxial force trajectory has three stages: a small-range fluctuation stage, a wide-range fluctuating and rise stage, and a wide-range fluctuating and decrease stage. The RE pattern is the most detrimental pattern, which leads to the fastest damage accumulation of the same-level corroded bridge piers.