Stochastically Modeling of Service Life of Concrete Structures in Chloride-Laden Environments

In traditional service life modeling, the durability concerns associated with chloride-induced corrosion of rebar in concrete are addressed with the deterministic technique, using the Nernst-Planck equations and the conservation law. As such, the effect of stochastic nature on the degradation process is not included in many of the existing numerical models. Such treatments fail to adequately describe concrete degradation, thereby underestimating or overestimating the risk of chloride-induced concrete deterioration. In this paper, a stochastic model is presented to simulate the service life of concrete structures subject to chloride ingress, the goal of which is to develop a reliable technique to predict structural deterioration and assess life performance of concrete infrastructures in typical aggressive environments with the Finite Element Method (FEM). The mathematical framework and the numerical implementation of the model are extensively described, where diffusion coefficients and surface concentrations follow gamma distribution, and chloride threshold value follows triangle shape distribution. Combined with the experimentally obtained chloride diffusion coefficients and chloride binding isotherms, a complete picture of service life assessment will be depicted for reinforced concrete structures, providing a reliability-based tool for structural engineers and asset managers with regard to concrete maintenance and rehabilitation.