Damage prediction of RC columns with various levels of corrosion deteriorations subjected to blast loading

Abstract

Coastal structures are often exposed to harsh environmental conditions such as saltwater, high humidity, and coastal winds, leading to corrosion damage to the reinforcing steel and degradation of concrete. The blast risk is characterized by a relatively low likelihood but a significant consequence. The blast resistance of structural members with deteriorated properties due to corrosion and the corresponding post-blast performance is of significance to evaluate the lifecycle structural safety facing explosion threats. In this study, the damage of reinforced concrete (RC) columns of coastal structures with various corrosion degrees subjected to blast loading is investigated. The corrosion effect was modelled by considering the deterioration of rebar diameter and yield strength, bond strength between rebar and concrete, and rust expansion pressure effect. The numerical model was validated by simulating drop weight impact tests of RC beams with different corrosion degrees. Based on the validated model, the finite element (FE) models of corroded RC columns with the maximum corrosion degree of 15% were established and their responses and damage to blast loads of various blasting scenarios were calculated. It is found that the blast response of the column increases with the degree of corrosion. The blast damage mode may change from combined shear and flexural damage to concrete spalling damage with the increment of corrosion degree. Furthermore, the residual axial loading capacity and stiffness of post-blast columns were calculated and it is found that they degrade as the corrosion degree increases. A blast damage index is defined in terms of the residual axial loading capacity of the column, which is found to increase with the corrosion degree. The damage amplification factor due to corrosion deterioration (CAF) is then proposed as a function of corrosion degree, TNT equivalent mass, standoff distance, concrete strength, and reinforcement ratio to predict the blast damage of corroded columns.