Lateral-Torsional Stability of Steel Web-Tapered I-Beams

Abstract

This paper deals with the stability behavior of web-tapered beams subjected to bending loads. According to the current AISC specifications, a tapered member is treated as prismatic with modified length and cross section identical to that of the tapered member's smaller end. Modification factors are used to determine the modified length and also to account for the moment gradient within the unbraced length and the restraining effect for adjacent spans. In this paper, these factors are evaluated via a finite-element analysis and compared to the ones proposed by the current specifications. The current design specifications for steel tapered beams are reexamined, and modifications that cover a wider range of geometry and loading cases are proposed.