Effects of torsion on the flexural stiffness of the rectangular reinforced concrete sections

In this paper, in order to investigate the effect of torsion on the flexural stiffness, a progressive algorithm is presented for finding the response of the section under combined loadings. In the proposed method, it is proven that for finding the response of the section under combined loadings, there are always two independent variables and the other variables can be related to these two variables. In the method of this work, the bending curvature of the section, φ, and the torsion angle, ψ, are assumed to be known and the goal is finding the actions that produce such section response.At the end of the paper, the method is applied for an example section and the results are summarized in a table. Using information of the table the M -φ curves for different values of torsion at the section are plotted. The curves can be used in order to investigate the effect of torsion on the bending stiffness of the section.