Time-Dependent Reliability of Coastal Bridges under Service Loads and Climate Change–Accelerated Corrosion

Bridges are critical infrastructure that enables connectivity and facilitates efficient transportation. However, because of continuous exposure to aggressive environmental conditions, these structures experience gradual deterioration, which ultimately compromises their structural integrity. This study highlights the importance of accounting for climate change impacts on the performance of reinforced concrete (RC) bridges, with a particular focus on the structural reliability of an RC T-beam girder bridge subjected to chloride-induced pitting corrosion of reinforcing steel. The analysis incorporates spatial variability in evaluating corrosion progression, recognizing that climate change accelerates chloride ingress and steel deterioration. This corrosion-driven degradation results in both flexural and shear capacity loss over time. Additionally, the study considers the influence of time-varying live loads in assessing the structural reliability index. A probabilistic framework is developed and applied to an aging, simply supported RC T-beam girder bridge located in Surat, India, providing a more realistic and localized assessment of long-term structural performance under changing environmental and loading conditions. The findings of this study demonstrate that climate change–induced corrosion substantially degrades the shear and flexural performance of the bridge superstructure in the case-study region, leading to a reduction of approximately 5 to 12 years in its reliability-based service life. This accelerated deterioration highlights the need for earlier repair and maintenance interventions to ensure structural safety and longevity. Furthermore, the results indicate that increasing the concrete cover depth and reducing the water–cement w/c ratio can substantially improve structural reliability, extending the bridge’s service life by 15 to 32 years.