Axial strength of slotted perforated cold-formed steel channels under pinned-pinned boundary conditions

Abstract

The use of cold-formed steel (CFS) channel sections is becoming popular as the load-carrying members in building structures, and such channel sections are often perforated for the ease of installation of services. However, limited experimental investigation has been reported in the literature for such channel sections under pinned-pinned boundary conditions. In this paper, a total of 16 CFS channel sections with and without slotted web holes were tested under pinned-pinned boundary conditions, and it was shown that all specimens with short lips failed by distortional-local buckling interaction controlled by distortional buckling and all specimens with long lips failed by local buckling. Moreover, the slotted web holes caused the axial capacities to decrease slightly by 2.4% on average for specimens failed mainly by distortional buckling and 6.4% on average for specimens failed by local buckling. A nonlinear elasto-plastic finite element (FE) model was also validated against the test results, a parametric study was conducted using the validated FE model. In addition, the results obtained from the tests and parametric study were compared against the results predicted by the current direct strength method (DSM) in AISI S100–16 for CFS channel sections with web holes. It indicates that the results predicted by the DSM are un-conservative for most CFS channel sections with web holes under pinned-pinned boundary conditions, especially un-conservative by 27.0% on average for CFS channel sections failed by local buckling. Therefore, new design formulas were developed based on the current DSM formulas for CFS channel sections with web holes.