Reliability assessment of RC bridge piers under chloride-induced deterioration using nonlinear finite element analysis

The deterioration of reinforced concrete (RC) bridge piers in marine and coastal environments is a critical issue in Thailand due to chloride-induced corrosion. This study presents a reliability-based framework for assessing the long-term performance of RC bridge piers, demonstrated through a case study of the Chanthaburi River bridge. Three-dimensional geometric modeling was carried out using GID, and nonlinear finite element analysis (FEM) with chloride ingress effects was performed using ATENA Science. The results of the FEM simulations, including load–deflection behavior and reinforcement deterioration, were subsequently analyzed in SARA Science to evaluate the reliability index and probability of failure. The analysis considered service life intervals of 0–90 years, with chloride ingress modeled as a progressive degradation mechanism. Results showed a progressive reduction in ultimate load-carrying capacity over 90 years of chloride exposure, accompanied by significant reinforcement corrosion. Reliability assessment indicated a steady decline in the reliability index from 5.84 to 4.73 over the same period, with values falling below the Eurocode Class 3 threshold (β = 5.2) after approximately 60–70 years. These findings highlight the critical timeframe for maintenance or rehabilitation and demonstrate the effectiveness of integrating nonlinear FEM with probabilistic reliability analysis for durability-based design and management of RC bridges in chloride-contaminated environments.