Modelling Fatigue Crack Propagation in a Corroded Reinforcement Bar Based on Equivalent Initial Flaw Size

Reinforced concrete structures in a corrosive environment degrade due to reduced reinforcement cross-sectional area and strength. Further, structures such as bridges are subjected to repetitive loading, resulting in fatigue damage. The corrosion pits in the reinforcement bar pave the way for fatigue crack initiation and crack growth development. In this work, a fatigue crack propagation model for the steel reinforcement bar is developed using fracture mechanics principles considering the corrosion rate. The degree of corrosion obtained from the mass lost is related to the depth of the corrosion pit. The effect of corrosion pitting on the stress intensity factor is taken into account. The proposed model relates the corrosion fatigue life of the reinforcement to its material and geometric properties, stress range and the equivalent initial flaw size (EIFS), which is the crack length corresponding to the threshold stress intensity factor. The fatigue life is obtained as the number of cycles required for the crack to grow from the EIFS to the critical value. The results are validated using experimental data available in the literature. The proposed model can be employed to predict the remaining life of the corroded RCC specimens.