Time-dependent ship hull reliability accounting for non-stationary stochastic degradation process

This study proposes a framework to estimate the time-dependent reliability of a ship hull girder accounting for the autocorrelation of deteriorated ship hull ultimate bending capacity and its dependency on the still water and wave-induced loadings. The ultimate strength is affected by ship hull structural corrosion degradation, modelled by a Gamma stochastic process. The reliability analysis employs the sequential importance sampling approach to address high-dimensional problems. The structural failure probability of a double-hull tanker is analysed to demonstrate the application of the proposed approach. The impact of considering the autocorrelation of the bending moment capacity and its dependency on the still water and wave-induced loadings on the time-dependent hull girder reliability is investigated. A sequential importance sampling method-based sensitivity analysis is also performed to quantify the influence of involved random variables in the limit state function. The results indicate that disregarding autocorrelation in bending moment capacity degradation may lead to an overestimation of ship hull failure probability, particularly under high degradation uncertainty. Additionally, the dependency between structural loads and degradation has a significant impact on the failure probability of the ship hull girder.