Spatial time-dependent reliability analysis of corrosion damage and the timing of first repair for RC structures

This paper presents a spatial time-dependent reliability analysis to predict the likelihood and extent of cracking for reinforced concrete structures exposed to chloride ion attack. A reinforced concrete surface is discretised into a large number of smaller elements and random field methods used to simulate the variability of the concrete damage over the entire area. Models predicting corrosion initiation and propagation, crack initiation and crack growth are used to track the evolution of the corrosion process for each element and thus allow the extent of damage as a function of time to be determined. A range of durability design specifications are investigated and maintenance thresholds are defined as being reached when a specified proportion of the bridge deck is damaged, say 1%. This will enable the minimum time to first repair to be estimated. The results provide a comparative tool to assist designers in selecting design specifications and possible maintenance regimes to achieve an optimal outcome in terms of service-life and life-cycle cost of the structure.