LATERAL BUCKLING ANALYSIS OF ANGLED FRAMES WITH THIN-WALLED I-BEAMS

Abstract

With the inclusion of warping deformations, lateral buckling behavior for angled frames with I-beams under the action of in-plan bending moments will be conducted in this paper. By adopting the joint equilibrium for the angled frame and the force-displacement relations for the members defined at the buckled position (rather than the initial position), the analytical solutions for buckling moments of an angled frame with simply supported ends are presented in closed form. The computed results indicate that for symmetric buckling, the buckling resistance to resist positive moments can be strengthened along with the increase of inclined angle of the member of an angled frame, but the buckling resistance against negative moments is reduced. On the other hand, for anti-symmetric buckled modes, the buckling strength to carry positive moments generally rises with the increase of inclined angles. However, an interesting phenomenon indicates that the buckling capacity to resist negative moments may reach its minimum at certain inclined angles. It means that the rotational restraints of torsion and bending at the joint of such a critical angled frame are situated in a minimum state to resist the anti-symmetric buckled modes.