Time-dependent finite element reliability assessment of cast-iron water pipes subjected to spatio-temporal correlated corrosion process

Reliable prediction of the service-life of water pipes is of great importance for asset managers and decision makers. This paper introduces a framework for evaluating the reliability of corroded pipelines. Incorporating the random field representation of corrosion into a finite-element analysis have always been a daunting task especially when the time-dependent reliability analysis is intended. This research addresses the issue by representing the cross-section reduction of a buried pipe due to corrosion through a combination of the Gamma process concept and copula. Moreover, spatial and temporal evolutions of the correlation structure that exists among the corrosion pits over the pipe surface are considered using a time-dependent correlation length model recently introduced by the authors. A three-dimensional non-linear finite element analysis is used to model the residual strength of pipes in terms of time. The method is applied to a case study for estimating the failure probability of a corrosion-affected cast iron water pipe. Furthermore, the impact of the correlation structure of the corrosion depths on the estimated probability of failure is investigated. The research concludes that the proposed method is able to predict the service life of corroding buried pipeline efficiently.