This paper presents an analytical study on the width-to-thickness requirements for flanges and webs of steel beams subjected to cyclic loading. Limit values are derived numerically for the combination of flange and web thickness that ensure sufficient beam rotation capacity. Interaction between lateral-torsional and local buckling was examined, and local buckling induced by lateral-torsional buckling was found to be the major source of strength reduction when the web is relatively thick. Restraining effect of top flanges (due to the presence of floor slabs) was found to be conspicuous and more pronounced for thick webs.
