Numerical modeling of steel fiber reinforced concrete using cohesive elements

The quasi-brittle behavior of concrete can result in the formation of cracks in structures built with this material. However, the addition of steel fibers has been shown to be highly effective in improving the post-cracking behavior of concrete, increasing its energy absorption capacity, and reducing the probability of structural damage. As a result, steel fiber reinforced concrete (SFRC) can support higher loads, better withstand weather conditions and chemical aggression, and have a longer lifespan compared to conventional concrete. In this context, the present article presents a numerical approach to simulate the behavior of SFRC. The simulation of concrete behavior (including fracture) is performed using bulk finite elements combined with cohesive element. A linear elastic model is used for bulk elements, while the model for cohesive elements is based on the plasticity theory and fracture mechanics, allowing for the prediction of crack development and propagation. Steel fibers are modeled using two-node finite elements (truss elements) with a perfect one-dimensional elasto-plastic constitutive model. They are positioned using a uniform and isotropic random distribution, considering the effect of the mold wall. Special contact elements are used to model the complex and nonlinear behavior of the fiber-matrix interface, capable of predicting the relative displacements between concrete and steel fibers. Numerical examples involving a set of fibers are presented. In all cases, the load–displacement curves agree with experiments in the literature. Fracture patterns also correspond to failure modes. Finally, comparisons with experimental results show that the application of numerical strategy to model the behavior of SFRC is very promising and can be a valuable tool for better understanding the effects of different aspects involved in the failure process of this material. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.