Effect of Reinforcement Corrosion on Reliability of Bridge Girders

Abstract

Aging reinforced concrete structures have been not only subjected to in-service loading but also exposed to an aggressive environment which will cause corrosion of reinforcing steels embedded in concrete. An approach that is akin to the nested reliability method is proposed for the time-dependent reliability analysis of bridge girders under corrosion attack. The approach can be used to investigate directly the effects of the uncertainty in surface chloride concentration and critical chloride concentration for corrosion initiation, and the possible nonlinear corrosion growth on the reliability. The consideration of the nonlinear corrosion growth is due to the fact that the corrosion current density may not be a constant. Analyses of the reliability of bridge girders to the parameters governing the corrosion are performed using the proposed approach and typical statistics of load effects and material strength parameters. Results suggest that consideration of the nonlinear corrosion growth is very important in determining the remaining service life of existing concrete structures, and that the uncertainty in the variables controlling the corrosion initiation has only small effect on the estimated time-dependent reliability.