Temporal-spatial reliability analysis of RC bridges with corroded steel reinforcement bars

Corrosion of steel bars is one of the most significant causes of deterioration of reinforced concrete (RC) structures. The performance of RC structures is affected by many factors such as materials, environments, and load conditions, which usually possess uncertain features. Some of uncertainties may be time- and space-dependent, and the corresponding reliability problems become more challenging. To address these issues, this paper studies the temporal-spatial reliability analysis of RC bridges with corroded steel reinforcement bars. At first, a compound corrosion model is developed in which the combined effects of carbonation (general corrosion) and chloride penetration (pitting corrosion) are considered. In the reliability analysis, both the temporal and spatial variability are accounted through a stochastic process and a random field, respectively. An extended instantaneous response surface (t-IRS) method is then proposed to evaluate the temporal-spatial reliability. Unlike the original t-IRS method, in addition to the original variables, the random variables transformed from the random fields and the space variable are also used as the input variables of the extended surrogate model. When generating sample points, both the time variable and the space variable are treated as uniformly distributed random variables within given intervals. Finally, the proposed method is applied to a RC bridge example with corroded steel reinforcement bars and the results are compared with that of Monte Carlo simulation (MCS) method, demonstrating the effectiveness of the extended t-IRS method.