Gamma process modelling for lifecycle performance assessment of corrosion affected concrete structures

Life cycle performance of corrosion affected RC structures is an important andchallenging issue for effective infrastructure management. The accurate conditionassessment of corroded RC structures mainlydepends on the effective evaluation ofdeterioration occurring in the structures. Structural performance deterioration caused byreinforcement corrosion is a complex phenomenon which is generally uncertain andnon-decreasing. Therefore, a stochastic modelling such as the gamma process can bean effective tool to consider the temporal uncertainty associated with performancedeterioration. This paper presents a time-dependent reliability analysis of corrosionaffected RC structures associated withthe bond strength degradation. Initially,analytical solutions are provided to evaluate the crack width at the cover surface andpredict the corresponding loss of bond strength between the corroded steel and thesurrounding cracked concrete. Then in orderto model the progression of bond strengthdeterioration during the life cycle of the RC structure, a gamma process model isadopted. The time-dependent reliability analysis is then applied to evaluate theprobability of failure of theRC structure. Finally, a numerical example is used todemonstrate the applicability of the proposed approach. The results from the illustrativeexample show that the proposed approach is capable of assessing performance of thebond strength of concrete structures affected by reinforcement corrosion during theirlifecycle.