Numerical modelling on degradation of mechanical behaviour for engineered cementitious composites under fatigue tensile loading

A multiscale modelling framework is developed in this paper for analysing the degradation of mechanical behaviour of Engineered Cementitious Composites (ECCs) under fatigue tensile loading. Degradation models for calibrating fatigue-induced deterioration of the fibre-matrix interface and fibre fatigue rupture are proposed at the microscale. Based on these, the cycle-dependent crack bridging relation is derived at the mesoscale. At the macroscale, the degradation behaviour of the bridging stress in ECC with presence of multiple cracks is modelled using extended finite element method. This multiscale characterisation method is validated by comparing the computed degradation relation of the bridging stress to that obtained from the experiment. Good agreement is obtained, which demonstrates the effectiveness of the developed multiscale modelling framework for the analysis of fatigue behaviour of ECCs. In addition, the deterioration of the fibre-matrix interface is found to be responsible for a steady decreasing bridging stress, while the fibre fatigue rupture is found to contribute to an accelerated loss of bridging stress