Abstract：Fiber-reinforced concrete (FRC) is a composite material made up of concrete and fibers. FRC has higher tensile strength and toughness than conventional plain concrete because of the reinforcement of fibers. Understanding the fracture behavior of FRC is vital for its application and design in construction work. The size effect of the FRC experimental specimen affects the accuracy of predicting the mechanical properties because of the micro-structures. Most existing numerical methods are unable to reproduce the complex fracture patterns of FRC, due to the lack of methods to characterize the FRC’s micro-structure. This paper proposes a numerical model of FRC based on the Cosserat peridynamic model and analyzes the crack propagation of FRC. The material points in Cosserat peridynamic model have independent rotational degrees of freedom and have the internal length to represent the size of micro-structure, which is appropriate for describing the mechanical behavior of FRC. The full-discrete method is applied in fiber modeling, and the relation of pullout displacement and shear stress is applied to obtain the peridynamic force between the fibers and the concrete matrix. And a fabric tensor of fiber distribution is defined to represent the local reinforcement and its direction. The proposed model is validated by simulating the single fiber pullout test and the numerical results show consistent with the experimental data and existing numerical results. The tension test of the notched plate and the three-point bending beam test with randomly distributed fibers are simulated to analyze the influences from the micro-structure and the fibers on crack propagation. The results indicate that the influence from micro-structure on the load-displacement curve mainly exists at the post-peak stage and has little impact on the peak value and pre-peak stage. And the micro-structure mainly influences the local damage and has little impact on the main direction of the crack path.
2022, Vol. 43 
