Life-cycle system performance of bridges: A robustness-based approach

Corrosion in reinforced concrete and steel structures is among the most damaging phenomena to structural safety and therefore one of the most demanding when facing the life-cycle analysis of such structures. However, the onset and progression of corrosion is highly uncertain. Because damage due to corrosion appears due to environmental aggressive agents which progress on time, it is of interest to develop suitable life-cycle measures of structural robustness with respect to a progressive deterioration of the structural system performance. In this paper, a robustness-based approach as presented in Cavaco et al. (2013) is used to quantify the effect of corrosion on safety and life-cycle maintenance. The level of corrosion is considered as an uncertain parameter. In this way, a probabilistic measure of the robustness, seen as the tolerance to damage, can provide a comprehensive description of the life-cycle system performance. Therefore, a robustness definition and the calculation of the corresponding robustness index are proposed in the paper and further applied to one reinforced concrete and one steel existing bridge to show the practical application and results when applied to real bridges. It is shown how the obtained robustness index for the bridges can be directly co-related to their life-cycle performance and also used to define the optimum intervention strategies.