A Theoretical and Experimental Investigation of Torsional-Flexural Buckling in Thin-Walled Prismatic Members

In a previous paper [1]the authors presented a general solution to the problem of thin-walled prismatic members of doubly symmetric open cross section loaded by end forces only. Deep sections, in which the second moment of area about the major principal axis is much greater than that about the minor principal axis, were considered. Thus deflections due to major axis bending could be ignored. The end forces included an axial thrust and unequal major axis moment, both of which were considered constant. Force-deflection equations for the member were derived and the influence of the axial thrust and major axis moments upon these was considered.

In the present paper the general solution is applied to the problem of buck-ling in such members. Three sets o f end conditions-pinned, fixed. and mini-mum restraint-are considered. Formal and finite difference solutions are presented for each of these so that an independent check on all the theoretical results is obtained. A major portion of the paper is devoted to reporting an extensive series of tests cvried out on members of I and rectangular cross section. These are concerned with investigating all the major theoretical results o f this and the previous paper. Ageement is found to be good.