Tension-softening constitutive relation and numerical simulation method for mode I fatigue crack propagation in concrete

This paper presents the investigations of the tension-softening constitutive relation of concrete and the numerical method for mode I fatigue crack propagation in concrete. Firstly, the static loading, fatigue loading, and fatigue–static loading were carried out on 191 notched three-point bending (TPB) beams. With the experimental results, the tension-softening constitutive relation of concrete under fatigue loading was proposed from the view of energy conservation, where the equilibrium relation between the energy dissipated by crack propagation and the external work was established. Secondly, by combining the constitutive relation with the stress intensity factor (SIF)-based crack propagation criterion, the numerical method for mode I fatigue crack propagation in concrete was developed. Finally, the applicability of the numerical method was validated by comparing the numerically derived fatigue life, fatigue crack propagation length, crack mouth opening displacement (CMOD), and SIF with the experimental results. It is concluded that the numerical method proposed in this paper is significantly helpful in evaluating the fatigue performance of concrete structures.