Analysis of Nonlinear Behavior and Highlight of Local and Global Ductility of Reinforced Concrete Beam

We are interested in modeling the nonlinear behavior of reinforced concrete framed structures. Computer tools are proposed for modeling the nonlinear behavior of deflection sections and reinforced concrete structural elements, subjected to increasing load until failure. This is done using the theory of nonlinear elasticity, which takes account of actual stress-strain curves of concrete and steel. The aim is to study the behavior in terms of local and global ductility of reinforced concrete structural elements. The analysis is carried out in the case of bent cross-sections, this enabled the moment curvature curves to be plotted and the local ductility factor to be deduced. By plotting the load displacement curves of the elements analyzed, it is possible to deduce the global ductility factor. The application of the analysis tools enabled a parametric study to be carried out into the influence of both the percentage of longitudinal reinforcement and the compressive strength of the concrete on the local and global ductility of the beam studied. The results of the validation of the « 3n beam » program are very satisfactory, confirming our results with the experimental results obtained by other authors. The parametric study shows that the global and local ductility’s can vary considerably as a function of the applied stress and the percentage of longitudinal reinforcement, in particular at ω levels of 0.5 and 1%, and stresses of 25, 35 and 45 MPa, they show significant increases compared with percentages of 3 and 4% and stress 15 MPa.