Avaliação de estratégias para a simulação de fibras de aço dispersas em matriz cimentícia via programa comercial de elementos finitos

Abstract

Advances in research on Steel Fiber Reinforced Concrete (SFRC) aim to enhance the understanding of its mechanical behavior under flexural and shear loading. In this context, numerical modeling based on the Finite Element Method (FEM) has become an essential tool. The literature identifies two main approaches: homogenization of the composite constitutive law and discrete modeling, in which individual fibers are explicitly represented and embedded within the cementitious matrix. Although the discrete approach enables a detailed description of fiber–matrix interactions, it presents significant challenges due to the large number of degrees of freedom and the inherent physical nonlinearities, leading to high computational costs. This study proposes a numerical strategy for simulating SFRC structures using the commercial software DIANA FEA®. To facilitate the analysis, an algorithm available in literature was modified to generate a random distribution of fibers in two- and three-dimensional domains. The investigation focused on the structural response under direct tension, flexure, and combined flexure–shear loading. It was observed that the native interface models available in the software were unable to adequately capture the degradation of composite strength associated with fiber pull-out. As an alternative, an indirect representation of the bond–slip behavior was implemented through modifications to the steel constitutive law. Furthermore, allowing fiber intersection during model generation resulted in post-peak responses that were more consistent with experimental observations. The results indicate that the proposed discrete modeling approach, when properly calibrated, is capable of accurately predicting the macroscopic behavior of Steel Fiber Reinforced Concrete.