Time dependent reliability analysis of underground concrete pipes subjected to sulphide corrosion

Sulphide corrosion is known as the predominant form of deterioration which reduces the ser-vice life of sewer systems and increases the costs of maintenance and rehabilitation. Reliability analysis can help pipeline owners and sewer system managers to predict service life of the pipes and the time for repair or replacement. To include uncertainties in the reliability analysis, the corrosion process can be considered as a stochastic process. This paper presents a stochastic gamma process model to account for temporal variability and uncertainties associated with the corrosion process in concrete sewer pipes that typically increases the probability of failure with the aging of the pipe. The proposed methodology is then applied to numerical val-ues of a concrete sewer system in the UK. The Monte Carlo simulation method is also used to verify the ob-tained results. The results showed that a gamma process can properly model the monotonic behavior of aging and deterioration. The application of the gamma process presented in this paper would contribute to widening the use of stochastic processes for modeling of structural degradation processes such as wear, fatigue, corro-sion, crack, erosion, creep, and so on. The results can provide guidance for both the assessment of existing concrete sewers and the designing of new pipes with longer service life