Reliability-Based Assessment of Corroded Reinforced Concrete Bridge Girders Under Limit State Criteria

Resumo

The design and assessment of reinforced concrete structures rely on limit state principles, which define structural performance based on safety (ultimate limit state) and functionality (serviceability limit state). The ultimate limit state ensures that applied loads do not exceed the structural capacity, preventing collapse, while the serviceability limit state addresses the conditions required for proper usage over time. Although the ultimate limit state for flexure rarely governs the design of prestressed bridge girders - except in short spans - it must always be verified to confirm adequate capacity.This study introduces a reliability-based framework to evaluate the time-dependent performance of reinforced concrete bridge girders affected by pitting corrosion by taking into account both the ultimate limit state (ULS), which is connected to the beam's bending failure, and the serviceability limit state (SLS), which is related with the reinforced steel's onset of corrosion. Advanced numerical simulations, combined with the Monte Carlo method, are employed to analyze the probabilistic behavior of structural degradation. Both temporal and spatial variables are modelled as uniformly distributed random variables, allowing for a comprehensive understanding of corrosion effects. Additionally, the study investigates the influence of varying concentrations of the corrosive agent and examines the evolution of failure probability over time. The proposed approach is applied to a corroded reinforced concrete bridge girder, and the results are compared to a benchmark example from the literature. The methodology provides a robust decision-making tool for maintenance planning and resource allocation, ensuring long-term structural safety and durability.