Potential change of failure modes and time-dependent behavior of RC beams under a marine atmospheric environment

Abstract

Stirrups always corrode earlier than the longitudinal steel bars in RC beams, and the corrosion degree is higher. Stirrups will lose their bearing capacity due to corrosion, leading to a decrease in shear strength. Thus, the failure mode may change from bending to shear failure. Previous studies have proposed models to predict corroded RC beams' flexural and shear behavior, respectively. The missing link in these models was the absence of the change of failure modes on the structural behavior. This paper covers the authors' study of corroded RC beams, investigating the effects of reinforcement corrosion on the transformation of failure modes. A numerical simulation was performed to analyze RC beams' time-dependent behavior and failure modes. The effects of the concrete cover thickness, the corrosion initiation time, the concrete strength, and the reinforcement configuration were also investigated. The analysis showed that the stirrups corroded earlier than longitudinal steel bars, leading to potential shear failure rather than bending failure. The larger diameter of stirrups could be adopted in the design to delay the deterioration of structural behavior and the transformation of failure mode. Prolonging the corrosion initiation time using thicker concrete cover thickness and higher strength of concrete is also effective.