Modeling the flexural behavior of concrete sections with longitudinal reinforcement and steel fibers using Fracture Mechanics concepts

Abstract

This study introduces an analytical model for assessing the flexural strength of concrete sections reinforced with both longitudinal bars and steel fibers, grounded in Fracture Mechanics principles. By combining the compressive behavior model from Eurocode 2 with the tensile softening model from Model Code 2010, the proposed approach enables precise simulations of the compressive and tensile responses in reinforced concrete. The model characterizes the compression zone with a parabolic-linear stress–strain relationship and applies a linear softening law in the tensile zone under the flat crack hypothesis. This framework ensures compatibility between crack openings and reinforcement elongation, facilitating accurate calculations of stress distribution and fracture depth. The model’s results align reasonably well with experimental data from the scientific literature. It highlights significant size effects related to the brittleness number, which accounts for element size, tensile softening, and residual flexural strength. As a practical tool for structural design, this model offers reliable predictions of flexural behavior for various reinforced concrete configurations.