Probabilistic performance-based seismic assessment of corroded RC structures

The impact of corrosion on seismic behaviour of a prototype reinforced concrete (RC) frame is investigated through probabilistic Incremental Dynamic Analyses (IDA). To this end, Nonlinear Finite Element Model (NFEM) of a RC frame including the coupled effects of corrosion on inelastic buckling and low cycle fatigue degradation of longitudinal reinforcements is developed. The spatial variability of pitting corrosion along the full length of individual components is also included in the model. The model is capable to predict multiple failure modes of corroded RC frames owing to level of corrosion, reinforcement detail, geometry, and load history. A set of time-dependent damage limit states are developed for use in fragility analyses. This method will treat the damage limit states of ageing structures as time-variant parameters, which can realistically predict seismic performance of corroded frames. The analyses results show that the probability of exceeding from a specific damage limit state is higher in corroded frames in comparison with the uncorroded frames. The analyses results show that disregarding the time-variant damage limit states for corroded frames results in underestimating the failure probability of such structures. This paper reports a summary of the results of this study.