Design of Locally Slender Structural Steel Columns

Abstract

The primary objective of this paper is to evaluate and compare design methods for locally slender steel columns. Three design methods utilized for such columns in the United States are explored: (1) the Q-factor method; (2) the unified effective width method; and (3) the direct strength method. The design strength formulas for locally slender W-section columns for all methods are provided in a common notation. The expressions highlight the prominent role of elastic local (cross-section) slenderness. A nonlinear shell finite-element analysis parametric study on short, intermediate, and long columns is conducted to explore the divergence in the design methods as a function of local slenderness. Recommendations for advancing the design methods are offered. In particular, based on the parametric study, an effective width method alternative is provided.