Numerical and analytical modeling of concrete beams with steel, FRP and hybrid FRP-steel reinforcements

Abstract The paper presents the results obtained from a numerical and analytical analysis carried out on a set of concrete beams reinforced with steel bars, Fiber Reinforced Polymer (FRP) bars and hybrid combinations of FRP-steel bars. To this purpose a database of experimental results, available in literature, was collected. A simple and reliable two-dimensional Finite Element (FE) model was defined. In the numerical simulations, the linear and nonlinear behavior of all materials was adequately modeled by appropriate constitutive laws. To simulate the concrete post-cracking tensile behavior a specific tension stiffening model was used. In order to overcome convergence difficulties, to simulate the quasi-static response of RC beams, a dynamic approach was adopted. Furthermore, to assess the effectiveness of the current Italian guideline, on same set of RC beams, an analytical analysis was performed. The comparisons between numerical/analytical results and experimental data highlighted the reliability of both the proposed FE model and the analytical model. The results show that the tension stiffening model used in the FE analysis provides good results with low and normal reinforcement ratios, whereas the numerical predictions are not acceptable with high reinforcement ratios. The analytical results provided by the Italian guideline are satisfactory, compared to experimental data.