Modeling deterioration in concrete pipes as a stochastic Gamma process for time dependent reliability analysis

Concrete sewer pipes encounter corrosion as a predominant form of deterioration that reduces the service life of the pipeline system and increases the costs of maintenance and rehabilitation. Reliability analysis can help pipeline owners and sewer-system managers to predict the 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 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 increase the probability of failure with the aging of the pipe. The proposed methodology is then applied to a specific concrete sewer system. The key element of the proposed method is the use of the gamma process concept. A gamma process can model the monotonic behavior of the ageing and deteriorating process. The application of the gamma process presented in this paper can potentially contribute to widening the use of stochastic processes for the modeling of structural degradation processes such as wear, fatigue, corrosion, crack, erosion, and creep.