Design Expressions Based on a Finite Element Model of a Stiffened Cold-Formed Steel C-Section

Abstract

The design of cold-formed steel (CFS) C-sections that have bearing stiffeners installed between their flanges is a challenging task because complex interactions occur between the stiffener and the C-section when the assembly is loaded to failure. These interactions make it impractical to derive design expressions from first principles. Described in this paper is the application of a finite element (FE) model of a stiffened CFS C-section that was used to carry out parametric studies of the behavior of the stiffened joist assembly. Based on the results of these FE studies and experimental work, design expressions are proposed for the web crippling capacity of a stiffened C-section; the magnitude of the forces that develop in the fasteners connecting the joist to the stiffener; and the equivalent stiffness of the fasteners. These design expressions are fundamental components in the development of practical design expressions for the ultimate strength of stiffened C-sections.