Stationary proposal importance sampling for structural reliability of aging RC bridges

Safety assessment of aging bridges may require the modeling of complex deterioration processes, further exacerbating in time the uncertainties involved in the mechanical response of critical members. Simulation-based techniques applied to life-cycle reliability problems may rely on time-consuming structural analyses, leading to untenable computational efforts and impairing the accuracy of the numerical estimates. This paper discusses an efficient computational framework for time-variant failure probability based on Importance Sampling (IS) with Stationary Proposal (SP) distribution. This novel methodology exploits numerical approaches traditionally developed for time-invariant structural reliability problems and extends them into a life-cycle context. Specifically, the simulation density is adaptively selected by minimizing the Kullback-Leibler Cross-Entropy from a chosen family of parametric distributions. The numerical procedure is applied to lifetime structural reliability of a reinforced concrete bridge exposed to chloride-induced corrosion.