Direct Strength Design of Cold-Formed Channels with Web Openings in Shear

In the current standards/specifications for cold-formed steel structures, the direct strength method (DSM) has not been developed for the shear strengths of perforated members, which is currently based on an empirical design approach using a $q_s$ factor. To extend the DSM design to members in shear with various hole shapes and sizes, new design procedures have been developed to determine shear loads including the elastic shear buckling load ($V_{crh}$), shear yield load ($V_{yh}$), and ultimate shear strength ($V_n$). $V_{crh}$ can be calculated via a linear approximation for buckling coefficients ($k_v$) based on the hole and section dimensions. $V_{yh}$ can be computed based on a theoretical Vierendeel mechanism or a proposed alternative simplified model to permit an easier implementation in design checks. $V_n$ can be determined using proposed DSM shear curves for members with and without full-transversely stiffened webs. To validate the new DSM approach, a collection of reliable historical experiments in perforated sections under shear was used for strength comparison. The experimental shear strengths were also further used for the calibration of the DSM-based proposal to determine the resistance factor ($\varphi$) for shear design, which is traditionally based on the LRFD methodology.