Modelling guidelines for corrosion-fatigue life prediction of concrete bridges: Considering corrosion pit as a notch or crack

Corrosion accelerates the fatigue damage accumulation and decreases the fatigue life of reinforced concrete bridges. A critical issue in the corrosion-fatigue life prediction is to deal with the relationship between fatigue crack and corrosion propagation. This paper proposes two modelling methods for fatigue life prediction of reinforced concrete bridges subjected to coupled corrosion-fatigue effect model I considers the corrosion pit as a notch and model II treats the corrosion pit as a surface crack. The chloride ingress, cyclic load, corrosion pit growth, fatigue crack growth and concrete severe cracking are systematically considered. Following that, a probabilistic analysis is also performed to include various uncertainties in the two models, and the effects of environment aggressiveness level and traffic frequency on the prediction results are investigated. The results show that corrosion pit-induced stress concentration has a significant effect on the fatigue behavior, and modelling the corrosion pit as a notch is the preferred method for theoretical prediction. For the extreme aggressiveness environment and low traffic frequency conditions, considering the corrosion pit as a crack is an alternative modelling method for the fast assessment of aging reinforced concrete bridges due to its simplicity.