Analytical Model for Fatigue Crack Propagation in Concrete

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Abstract A new approximate analytical model is presented for the fatigue crack propagation rate in concrete. The model considers fatigue cracking at all stress levels up to the modulus of rupture. As the bending stress increases, the size of the inelastic zone compared to the crack length increases, and the stress intensity factor no longer controls the stresses in the vicinity of the crack tip, necessitating the use of the path-independent J-integral. At high stress levels fatigue crack propagation becomes nonlinear, and fracture may occur by ultimate strength collapse. Recently Kharlab postulated a hypothesis that enables the prediction of fracture of concrete by a single criterion that considers failure at any stress level for any size beam. An approximate analytical method for fatigue crack propagation in concrete at any stress level is presented. It incorporates the size effect and uses the crack tip opening displacement as the primary criterion upon which the rate of crack propagation is dependent. The model is validated by the published experimental data on concrete fatigue.