Micromechanics of Fiber-Concrete Interaction: Numerical Modeling and Experimental Validation

To simulate the behavior of fiber-reinforced concrete, an accurate modeling of the concrete and fiber phases as well as the fiber-concrete interaction is required. This study proposes a new model to account for fiber-matrix interactions based on micromechanics. The concrete matrix is simulated using the lattice discrete particle model (LDPM), a mesoscale model for heterogeneous materials. The fiber is explicitly represented using elastoplastic beam elements. The fiber-concrete interaction algorithm features a slideline model and a constitutive model to describe the bond-slip relation. The slideline model includes a tie algorithm for interactions between concrete and slideline, and a penalty constraint between the slideline and the fiber. The proposed model is examined by simulating different types of fiber pullout tests. These simulations examine the model validity in capturing the fiber-concrete interaction both in the direction orthogonal to the fiber and in the direction of pullout. Also, the proposed model is calibrated and validated by comparing numerical simulations with experimental data from the literature, including fiber pullout under confinement, pullout of hooked fiber, and pullout of inclined fiber that leads to matrix spalling. The good agreement between the simulation results and the experimental data in terms of force versus displacement curve demonstrates the effectiveness of the proposed approach in simulating fiber-concrete interaction. In addition, using the proposed model, the contributions from different toughening mechanisms can be quantitatively compared.