Corrosion-induced cracking fragility of RC bridge with improved concrete carbonation and steel reinforcement corrosion models

摘要

Corrosion-induced cracking is one important limit state in the durability performance analysis of the reinforcement concrete (RC) structures. A comprehensive probabilistic approach is established for the corrosion-induced cracking fragility analysis of the RC bridge in the urban atmospheric condition with improved concrete carbonation and steel reinforcement corrosion models. The improved deterioration models have a probabilistic formation by adding correction and error terms to the existing deterministic models. The deterministic parts are selected from reviews and discussions on existing models. The correction terms are sets of explanatory functions representing the influencing factors related to the potential bias in the deterministic models. The statistical distributions of unknown model parameters are calibrated and the optimum collections of the explanatory functions are selected through the Bayesian rule based on long-term data from onsite tests or natural exposure experiments. The probabilistic analysis approach for the corrosion-induced cracking fragility are generated based on the improved deterioration models. Fragility curves, parameter sensitivities and random variable importance are achieved for the example RC bridge. The results show that increases on the concrete strength, cover depth and steel bar diameter, or decrease on the CO2 density, are efficient countermeasures to improve the durability performance of the RC bridge against corrosion-induced cover cracking and the uncertainty of the problem mainly comes from the concrete carbonation model.