Seismic fragility analysis of reinforced concrete structures considering reinforcement corrosion

Reinforcement corrosion is an important factor that affects the durability of reinforced concrete (RC) structures. It can lead to elongation of structural natural period, change of structural demand, and deterioration of seismic capacity. This makes the seismic fragility analysis results for the corroded RC structures different from those for the uncorroded RC structures. An RC frame structure designed according to the existing code was taken as a study case. Nonlinear finite element models of uncorroded and corroded RC frame structures were developed and validated. Seismic fragility curves and the corresponding parameters of the case study building under the uncorroded and corroded conditions were obtained by both the cloud method and the stripe method. The special characteristics of the seismic fragility analysis method for the corroded RC structures were analyzed and their effects on the corresponding seismic fragility results were examined. The results show that the seismic fragility of the corroded RC structure cannot be estimated correctly without considering the elongation of structural period due to reinforcement corrosion. The seismic fragility analysis using the cloud method probably results in a lower failure probability exceeding a specific limit state for the corroded structure than that for the uncorroded counterpart. Therefore, the stripe method can better reflect the effect of reinforcement corrosion on the seismic fragility of RC structures than the cloud method. Ignoring the deterioration of structural seismic capacity will underestimate the results of seismic fragility of corroded RC structures. The Pushover-based limit state definition method is recommended to be used in the seismic fragility analysis of corroded RC structures. © 2022, Editorial Office of Journal of Building Structures. All right reserved.