Reliability analysis of chloride penetration in saturated concrete

Corrosion of reinforcement in concrete is a major durability problem of reinforced concrete structures. The corrosion is initiated by chloride penetration into the concrete, which is a diffusion-controlled process involving many complex physical and chemical mechanisms. Large random variation has shown in the corrosion damage of reinforced concrete structures, and there is a pressing need to develop a reliability analysis method for chloride penetration and for the onset of steel corrosion in concrete. In order to conduct a reliability analysis, a comprehensive material model for chloride concentration is developed and described, and some of the model parameters (water–cement ratio and curing time) are selected as random variables. By including uncertainties in the selected variables, the chloride penetration front at a point in time can be represented by a time-dependent probabilistic distribution. Similar to the concepts of supply and demand used in structural reliability analysis, the chloride penetration front at a target level (depth) with respect to time can be represented by the probability distribution of crossing the target level. A detailed description of the basic concepts and numerical examples are given. To include the effect of uncertainties of the material parameters, a recently developed Monte Carlo simulation program was used in numerical examples.