Partial Stress Redistribution in Cold‐Formed Steel

Abstract

On the basis of the failure criteria developed in an earlier paper by the writers, the utilization of partial section plastification in cold‐formed steel flexural members is presented. As in the limit design procedures developed for reinforced concrete, failure is defined in terms of the strain capacity of stiffened compression flanges, for specified values of the width‐to‐thickness ratio of the flange and the yield stress of the structural steel. Accordingly, depending upon the slenderness of the compression flanges and the cross‐sectional shape, ultimate moment capacities in excess of yield moment become possible. As design and analysis aids, formulas to compute the ultimate moment capacity of commonly used cold‐formed steel shapes are derived. To illustrate the use of these equations and the economy gained by taking into account the inelastic reserve capacity due to stress redistribution, two example problems are solved. The findings are compared with test results and an elastic soluton.