The Effect of Stochastic Properties of Strength Reduction Function on The Time-Dependent Reliability of RC Structures

Quantitative calculation of structural safety using its specific limit-states is of great importance. Due to the stochastic properties of strength, loading, and environmental reduction functions, these parameters cannot be considered as deterministic variables. In this paper, a probabilistic model including the stochastic properties of the strength reduction factor was proposed to calculate the time-dependent reliability of concrete structures. In this model, the statistical properties of applied loads were also considered. The strength reduction model was calculated quantitatively using the statistical properties of the reducing agent. In this research, the major factor contributing to the strength reduction is the reduction in the cross‐section of the steel bars, reduction of bonding strength, and the spalling of the concrete cover due to reinforcement corrosion induced by chloride ingress. The results of this model were compared to the calculation of reliability using the direct implementation of strength values and another simplified method that only considers initial strength as a random variable. In the methods under investigation, the effect of the uncertainty of reducing factor on the mean and coefficient of variation of results was also studied. The results showed that the probability of failure increases between 25% to 50%  when the uncertainty of the reducing factor is taken into account. The proposed model has more realistic results than the simplified model, and these results could be improved for achieving more exact outcomes with lower uncertainty.