Locally Buckled Thin‐Walled Columns

Abstract

An effective section method is presented for analyzing the effects of local buckling on the overall modes of behavior of singly symmetric, thinwalled columns and beam‐columns. The post‐local buckling strength of the component plate elements is recognized through effective width concepts. A single effective width equation is developed to represent the subultimate behavior under service loads and the ultimate strength of uniformly compressed stiffened elements. Also, an effective width approach is.proposed for predicting the response of eccentrically compressed stiffened elements. An experimental investigation is reported on cold‐formed, lipped channel, steel columns with concentric or eccentric loading. Predictions obtained with the presented analysis method are in good correspondence with experimental subultimate deflections and ultimate strength. In contrast to this, current design methods are shown to be inadequate for predicting the experimental results. In certain cases, laterally unbraced (edge) stiffened elements are prone to an elastic local torsional failure mode. A limiting stress approach is proposed for this situation, which provides fair agreement with limited experimental data.