ASSESSMENT OF PROBABILISTIC CORROSION PROPAGATION MODEL FOR EXISTING REINFORCED CONCRETE BRIDGE DECK AND ITS RESIDUAL FLEXURAL CAPACITY

Abstract

This research presents an assessment approach for a probabilistic corrosion propagation model for embedded steel rebar in concrete subjected to chloride. The approach is applied to predict the level of corrosion propagation in the exterior layer of steel rebars of a highway bridge deck that was exposed to chlorides from various severe chloride concentrations. The probability of the corrosion propagation stage at different chloride concentrations was investigated using the performance function defined in different intervals of time (the time between the corrosion initiation and when the corrosive cracks appear, and the time after corrosive cracks appear). The probability of corrosion propagation was calculated using the Monte Carlo simulation method. This method accounts for uncertainties in the parameters governing the physical models of corrosion during the propagation stage, including concrete cover depth, the diameter of the steel rebar, and the compressive strength of concrete.  The governing parameters are modeled as random variables with different levels of correlation. The proposed flexural capacity loss calculation was conducted due to corrosion in a reinforced concrete (RC) deck. A prediction equation model was developed to investigate the corrosion depth and the decrease in the corroded steel rebars as functions of time, from corrosion initiation to the appearance of the corrosive crack, and after its appearance, at different chloride concentrations. Finally, the percentage of reduction in the flexural capacity at various steel rebar diameter reductions compared to the intact rebar diameter utilized for the RC deck and T-Girder was assessed at various corrosion rates.