A gamma distributed degradation rate model for reliability analysis of concrete pipes subject to sulphide corrosion

Ageing and deterioration of structures and infrastructure is one of the main concerns of structural engineers and asset managers for reliability analysis and service life prediction purposes. In order to model monotonic progression of the deterioration process in concrete sewers (i.e., concrete corrosion), the paper proposes a gamma distributed rate model to account for temporal variability associated with the corrosion process in buried concrete sewer pipes that typically increases the probability of failure with the ageing of the pipe. The proposed methodology is used for reliability analysis of concrete sewers in Harrogate in the UK. The results are then verified by a common reliability analysis method (i.e., Monte Carlo simulation). A good agreement between the results from the two methods was concluded. The effectiveness of different basic random variables on the level of reliability is also estimated by a focused sensitivity analysis.