Micromechanical Modeling of Fracture Energy for Hooked-End Steel Fiber-Reinforced Cementitious Composites

Since pullout behaviors of fibers intersecting a fracture plane of cementitious composite are similar to those in a single-fiber pullout test, micromechanical model of fracture energy for hooked-end steel fiber-reinforced cementitious composite (HSFRCC) is developed on the basis of single hooked-end steel fiber pullout test. The hooked-ends of steel fibers intersecting a fracture plane have various deformations which can be generally classified into hooked-end total deformation, partial deformation, and nondeformation. The pullout energy of steel fiber with deformed hooked-end is significantly different from that with nondeformed one; derivations of pullout energies of hooked-end steel fibers with deformed/nondeformed hooked-ends are carried out first. The fracture energy model of HSFRCC is proposed using probabilistic method accounting for energy contributions from all steel fibers intersecting the fracture plane. Experimental validation of the proposed micromechanical model is performed, and excellent agreements are observed in comparison with experimental data from uniaxial tensile tests. As the proposed fracture energy model is a function of physical and micro-geometric properties of hooked-end steel fibers and cementitious matrix, it can guide optimal design of HSFRCC.