In this paper, the role of shear failure in the seismic behaviour of reinforced concrete structures has been investigated. In current practice, the effects of shear on beams and columns are usually neglected in nonlinear analysis, which is carried out based on the flexural behaviour of each element. In such analyses, only the flexural behaviour of the member is considered, while the experimental results confirmed the possibility of other modes failure prior to ultimate flexural capacity. Also, it is now generally accepted that axial load plays a dominant role in evaluating the seismic behaviour of RC columns. However columns, especially the exterior ones, can be subjected to variable axial loads depending on the lateral loads. In this study, a numerical model including rotational springs, was developed to simulate the effects of shear for beams and columns based on the material failure mechanism. Moreover, a procedure was recommended to take into account the effects of the variations of axial load on RC columns. In order to verify the proposed model for columns, the obtained results of the analytical analysis were compared to experimental results. The results predicted by the proposed model were in good agreement with the experimental tests. In addition, to evaluate the performance of the proposed model at structural level, two RC frames with various failure modes have been investigated and the results confirmed the ability of the model in predicting the inelastic behaviour of the frame, which can provide an alternative method in current practice. Moreover, a parametric analysis were carried out in order to highlight the effect of the variations of axial load on nonlinear response of reinforced concrete columns.
