Probabilistic models applied to safety assessment of reinforced concrete structures subjected to chloride ingress

摘要

This paper addresses the analysis of probabilistic corrosion time initiation in reinforced concrete structures exposed to chloride penetration. Structural durability is an important criterion that must be evaluated for every type of structure. Considering reinforced con crete members, chloride diffusion process is widely used to evaluate durability, especially when these structures are constructed in aggressive atmospheres. The chloride ingress triggers the corrosion of reinforcements; therefore, by modelling this phenomenon, the corrosion process can be better evaluated as well as the structural durability. The corrosion begins when a threshold level of chloride concentration is reached at the steel bars of rein forcements. Despite the robustness of several models proposed in the literature, determin istic approaches fail to predict accurately the corrosion time initiation due the inherent randomness observed in this process. In this regard, structural durability can be more real istically represented using probabilistic approaches. A probabilistic model capable to model chloride ingress is presented in this paper. The chloride ingress is modelled using the Fick's diffusion law. This law simulates the chloride diffusion process considering time-dependent effects. The probability of failure is calculated using Monte Carlo simula tion and the first order reliability method with a direct coupling approach. Some examples are considered in order to study these phenomena. Moreover, a simplified method is pro posed to determine optimal values for concrete cover.