Fracture mechanics-based model for the flexural behavior of steel fiber-reinforced concrete with longitudinal reinforcement

This study introduces an analytical model to evaluate the flexural strength of concrete sections with longitudinal reinforcement and steel fibers based on Fracture Mechanics principles.It combines the compressive behavior model from Eurocode 2 with the tensile softening model from Model Code 2010 to accurately simulate the compressive and tensile responses of concrete.The model adopts a parabolic-linear stress-strain relationship for compression and a linear softening law for tension under the flat crack hypothesis.By ensuring compatibility between crack openings and reinforcement elongation, it facilitates precise analyses of stress distribution and fracture depth.The results highlight significant size effects governed by the brittleness number, which accounts for element size, tensile softening, and residual flexural strength.This model provides a practical and reliable tool for predicting the flexural behavior of concrete configurations with low longitudinal reinforcement ratios.