This paper investigates the cross-sectional warping of thin-walled rods at plane frame joints in the framework of the “semi-shear” theory of V. I. Slivker. Studied are the shell finite element models of rigid joints in bar structures, designed and calculated in the software package Ansys Workbench. The correlation of the geometric characteristics of thin-walled profiles and the connecting plate is considered toward the change in the value of normal stresses and bimoments when the cross-sectional axis is rotated. The obtained ratios of the bimoment stresses before and after the rotation of the cross-sectional axis of the rigid joint are presented. The study concentrates the distribution of the bimoments and warpings in the plane frame with and without the consideration of the coefficient of the cross-sectional axis rotation. The comparison of the obtained results for both cases is shown.