Effective Lengths of Web-Tapered Columns in Rigid Metal Building Frames

Abstract

Current procedures for estimating effective length factors for web-tapered members rely heavily on the use of charts and graphs. This makes them difficult to implement using a computer. In addition, they are often based on unrealistic assumptions. In cases where these assumptions are not satisfied, design errors may result. This investigation proposes a modification to an effective length factor expression developed by Lui (1992). This modification allows the expression to be applied to web-tapered members with good accuracy.

A derivation of the proposed expression is presented, and the results obtained by applying the expression to a range of frames are compared to the results obtained from second-order finite element analyses. Calculations involved in using the expression are presented.