Prediction of fatigue life of reinforced concrete bridges using Fracture Mechanics

With the occurrence of higher and more frequent axle loads, bridges are more solicited by fatigue loading. Bridge elements like deck slabs are subjected to a high number of stress cycles at relatively small stress magnitudes. The application of Fracture Mechanics as a useful tool for the analysis of fatigue crack growth in steel elements was demonstrated by Paris et al. in the early 1960s. With respect to reinforced concrete, the fatigue strength of the steel reinforcement is determinant. The fatigue behaviour of the steel reinforcement is similar to that of structural steel. The fatigue relevant parameters are the stress ranges, the number of fatigue cycles and stress concentrations. This paper presents a study to predict the fatigue life of steel reinforcement based on the Paris law. The method will be validated by a case study.