Derivation of crack bridging stresses in engineered cementitious composites under combined opening and shear displacements

The mechanical behavior of Engineered Cementitious Composites (ECC) is strongly dependent on the bridging of cracks by fibers. Due to the bridging action of fibers, tensile and shear stresses can be transferred through cracks in ECC members. In this study, a micromechanics based theoretical model is proposed to describe the shear transfer mechanism on the crack surface due to fiber bridging effect. The model focuses on flexible fibers and both the normal stress along the crack opening direction and the shear stress transferred across the crack surfaces are derived under the coupled effect of crack opening displacement (COD) and shear sliding. With the proposed model, the mechanism of fibers contributing to the shear transfer can be understood and the effect of various micromechanical parameters can be investigated. The simulation results can provide insight on the behavior of ECC under shear loading when cracks are propagating under mixed mode.