The weight reduction of automotive body structure sometimes causes the issue of decreasing its strength by buckling on thin plates which constitute body frames. Therefore, the theoretical methods which estimate these phenomena are require for the initial design stage. In case of bending and compression, the effective width theory is proposed in general, there is no theory in case of torsion. In this paper, we try to derive theoretical solution concerned with shear buckling on a thin plate in case that torsional moment act on a frame. As a result, it is shown that the post-buckling behavior under shear load can be evaluated by taking into consideration the view of the effective width theory and the effect of tension field.
