Analytical Study of Torsional Moment Induced by Shifting of Shear Center of RC Cross Sections

This paper describes how, for members with symmetric cross-sections, the geometric centroid and shear center are coincident. Thus, if lateral load is applied through the geometric centroid, a torsional moment is not induced. However, a reinforced concrete (RC) cross section typically develops an asymmetric resistance mechanisms, resulting in progressive movement of the shear center away from the geometric centroid as nonlinearity increases and the section responds to bi-axial loading. In this paper, the mechanism causing shifting of the shear center for RC cross sections was investigated using frame elements with a fiber-type discretization of the member cross-section. Then, the effects of the torsional moment induced by the shifting of the shear center were discussed, and it was shown that the effect in not negligible in practical design.