The Effect of Uncertainties on Calculation of Initiation of Corrosion of Reinforcement for Assessment of Reliability of Concrete Structures

Abstract

An important problem with the analysis of corrosion of reinforcements used in concrete structures is the calculation of corrosion initiation time. The type of concrete, water to cement ratio, curing time, surface chlorides concentration, temperature and thickness of concrete cover over reinforcements are among the most important factors influencing the time required for initiation of corrosion of reinforcement. The multiplicity of parameters and errors in measuring these parameters leads to uncertainties in estimation of corrosion initiation time. Qualitative calculation of the effect of uncertainties associated with the aforementioned parameters is very important to the assessment of the precision of the calculated corrosion initiation time. Knowing the corrosion initiation time and uncertainties in the calculated time helps take preventive measures before the initiation of the corrosion of reinforcement in order to protect structural performance. In this paper, uncertainties were introduced into the model through statistical parameters. Moreover, dispersion and precision of the predicted corrosion initiation time are calculated considering that random factors contributing to initiation of corrosion of reinforcement. In this study, the random properties of factors contributing to the prediction of corrosion initiation were considered. Next, the Monte Carlo random sampling method was used to assess the effect of statistical properties of each parameter on corrosion initiation time. According to the results, even with an increase in the estimation of input parameters used to precisely calculate the corrosion initiation time, the resulting time will be associated with at least 40% of uncertainty.