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

Abstract

The mechanical behavior of fiber-reinforced cementitious composites (FRCC) is strongly dependent on the bridging of cracks by fibers. While fiber bridging effect on the tensile behavior of FRCC has been widely studied, little attention has been paid to the effect of fibers on the shear transfer behavior of cracked FRCC. In this study, a micromechanics based theoretical model is proposed to describe the shear transfer mechanism on the crack surface of FRCC due to fiber bridging effect. The model focuses on flexible fibers that can be modeled as strings, 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 effect of various micromechanical parameters and fiber distribution can be investigated. The simulation results can provide insight on the behavior of FRCC under shear loading when cracks are propagating under mixed mode.