The elastic stability of bent I-section beams

Abstract

The lateral buckling of an I-section beam bent by pure couples in the plane of its web is considered. The method of Reissner and Grober, who discussed beams of rectangular section, is combined with that of Timoshenko who gave approximate theory for an I-section. In this way, the critical moment of an I-section beam supported at its ends in the most general manner is obtained. The result shows that the critical moment depends upon the fixing of the individual flanges as well as of the whole beam at the ends, and has been verified by experiment. When the principal flexural rigidities of the section are of the same order, so that the curvature in the plane of bending is large, a modification of the end-conditions given by previous writers for both I-and rectangular-section beams is necessary. This modification is not important in practical cases.