Estimation of time-dependent reliability of aging structures under correlated load and autocorrelation in resistance deterioration

This paper proposes explicit approaches for time-dependent reliability assessment of aging structures, taking into account the correlation associated with the load process and that arising from the resistance deterioration process. For the load process, temporal correlation may arise due to the impacts of underlying common causes. With this regard, a closed-form solution is developed for structural reliability, which models the sequence of load effects as a Markov process. Furthermore, the resistance deterioration is by nature a non-increasing stochastic process with autocorrelation on the temporal scale. The Gamma process is used to describe the stochastic behaviour of resistance deterioration, based on which an explicit reliability method is derived. The proposed reliability methods are straightforward to implement and thus are promising to be adopted in practical engineering regarding the safety evaluation of aging structures. Illustrative examples are presented to demonstrate the accuracy and applicability of the proposed approaches.