Lateral Buckling of I-Section Column With Eccentric End Loads in Plane of the Web

Abstract

Abstract When a relatively slender column of the symmetrical I or WF shape is loaded eccentrically in the plane of the web by longitudinal end loads it may fail by elastic instability involving a combination of lateral bending and twisting. Timoshenko has shown that in the case of the solid rectangle a considerable end eccentricity causes the critical buckling load to be only slightly less than the Euler critical load for the same strip loaded axially. The corresponding solution for the WF or I-column, presented herein, shows that relatively small eccentricities of the longitudinal end load applied in the plane of the web cause a large falling off from the Euler critical load. For the ideally straight column, with a material perfectly elastic up to the yield point, there would be a critical l/r ratio for any given eccentricity, column length, and material. Below this critical ratio the column would fail by yielding, according to the secant or eccentricity formula. Above the critical ratio the failure would be by elastic instability with respect to lateral bending and twisting. Application of the equations is made to two structural wide-flange sections, of light and medium weight, and the results are presented in the form of diagrams.