Direct Strength Method of Design for Channel Sections in Shear with Square and Circular Web Holes

The direct strength method (DSM) design rules for cold-formed steel members in shear have been incorporated recently into the North American specification for the design of cold-formed steel structural members and are being implemented in the Australian cold-formed steel structures standard. The method, which was calibrated for unperforated members only, requires two inputs including the buckling load V-cr and the shear yielding load V-y. For members with square web cutouts, V-cr can be computed by either the spline finite strip method or the tabulated values based on the shear buckling coefficients k(v) as in previous studies or the finite element method. However, V-y has not been accurately formulated including holes. This paper represents a practical model to obtain V-y for members with central openings subjected predominantly to shear. The model ranges from very small holes where traditional shear yielding predominates to large holes where Vierendeel action dominates. The model is verified with the DSM design formulas using the predominantly shear tests recently conducted at the University of Sydney and Queensland University of Technology with both square and circular web openings and for shear spans with aspect ratio of 1.0. (C) 2017 American Society of Civil Engineers.