Parametric study on the flexural behavior of steel fiber reinforced concrete beams utilizing nonlinear finite element analysis

Reinforced concrete beams undergo significant internal forces and deformations under extensive loading and have flexural or shear failure based on the reinforcement detailing and geometric properties. The addition of steel fibers increases the deformation and load carrying capacities that leads to ductile behavior. The main contribution of fibers is the improvement of the composite tensile capacity, which results in improved flexural and shear responses. This study numerically investigates the effect of fiber properties on the flexural behavior of steel fiber reinforced concrete (SFRC) beams for both compression and tension failure. First, three specimens from prior experimental studies are modeled using the nonlinear finite element program ABAQUS and the analytical results are verified by comparison with the test results. Contrary to prior nonlinear models, the developed model accurately predicts the damage pattern, descending portion of the load-displacement relationship, and ultimate displacement, which lead to a reliable estimation of energy dissipation capacity and ductility. A comprehensive parametric study is then conducted to examine the effect of tension reinforcement ratio, fiber volume fraction, and fiber aspect ratio on the flexural behavior of both reinforced concrete and SFRC beams. The influence of these key parameters is investigated by comparing the peak load, displacement ductility, peak stiffness, service stiffness, energy dissipation capacity, and damage pattern for both reinforced concrete and SFRC beams. The analytical results indicate that the addition of steel fibers up to 2.0 % leads to a slight increase in the load carrying capacity, while the displacement ductility and energy dissipation capacity are significantly improved. Furthermore, the utilization of 1.0 % steel fibers is observed to be sufficient to modify the failure mode of over reinforced concrete beams from brittle compression failure to tension failure.