Blast fragility analysis of RC columns considering chloride-induced corrosion of steel reinforcement

Abstract

Chloride-induced corrosion of steel reinforcement is one of the key factors that influences the life cycle performance and load-carrying capacities of concrete structures. For concrete structures that might be subjected to explosion hazards during the service life, the fragility analysis with the consideration of chloride-induced rebar corrosion provides quantitative information on lifecycle performance of structures against blast loading. This study performs the fragility analysis of reinforced concrete (RC) columns considering chloride-induced corrosion of steel reinforcement subjected to blast loading. General corrosion and pitting corrosion are considered in this study. Monte Carlo simulations are carried out in the study to calculate the failure probabilities. The mean and standard deviation of the degraded diameter and yield stress of the reinforcement up to 90 years after the corrosion initiation is established, which is incorporated in the existing empirical formulae for constructing the P-I curves of RC columns to predict its deteriorated blast loading-resistance capacity with time. In the analysis the blasting scaled distance is used as the demand intensity measure, random fluctuations of the peak reflected pressure, positive blast loading duration, concrete compressive strength, thickness of the concrete cover, diameter and yield stress of steel reinforcement are considered in the simulations. The blast fragility curves of typical RC columns are generated with respect to different damage levels corresponding to the number of years after corrosion initiation. It is found that the damage probability of RC columns increases significantly with steel reinforcement corrosion deterioration. Parametric analyses have shown that the column size is a more dominant factor, in comparison with the reinforcement ratio, of the RC columns on the blast resistance capacity corresponding to the minor damage levels. It is also found that the longitudinal reinforcement ratio is a less dominant factor than transverse reinforcement ratio on blast fragility curves of RC columns to resist blast loading. The blast resistance capacity of RC columns deteriorates significantly with corrosion damage.