Elastic and Plastic Effective Width Equations for Unstiffened Elements (No. R819)

Abstract

Current American design provisions treat unstiffened elements under stress gradients as if they were uniformly compressed for effective width calculations. Australian, British and European design provisions allow accurate calculation of the elastic buckling coefficient, however the same effective width equation for compressed elements is used for elements with stress gradients. In all cases, the design provisions produce conservative bending capacities for sections containing unstiffened elements under stress gradients. This report presents a design method for calculating the effective width of these elements, based on plate test results of unstiffened elements under strain gradients varying from pure compression to pure bending. It is shown that both elastic and plastic effective widths may be derived from the test results, and effective width methods based on both principles may be used for design.