Moment Capacities of Steel Angle Sections (No. R809)

Abstract

Steel angle sections are commonly used as beams to support distributed loads which cause biaxial bending and torsion. However, the recommendations of many design codes are unnecessarily conservative when applied to the bending of angle section beams, or are of limited application, or fail to consider some effects which are thought to be important. In this paper, consideration is given to the first-order elastic analysis of the biaxial bending of angle section beams including the effects of elastic restraints, and proposals are developed for the section moment capacities of angle sections under biaxial bending which approximate the effects of full plasticity in compact sections, first yield in semi-compact sections, and local buckling in slender sections. Proposals are developed for the bearing, shear, and uniform torsion capacities of angle section beams in a companion paper. The proposals in this and the companion paper can be used to design steel angle section beams which are laterally restrained so that lateral buckling or second-order effects are unimportant.