Shear tests and design of cold-formed steel channels with central square holes

In the latest North American Specification S100:2016 Edition and the most up-to-date Australian/New Zealand Standard AS/NZS 4600:2018, the Direct Strength Method (DSM) shear design rules for unperforated channel sections have been adopted. To date, for perforated sections, there is no DSM design rule for shear in the current Specification/Standard while the conventional reduction factor method is still in use to calculate shear strengths for these sections. This paper summarises the test results in an experimental program aiming to determine the ultimate shear strengths of high strength cold-formed C-sections with square holes centrally cut from the webs. A total number of 24 tests were performed using lipped channel sections in which 18 tests were conducted with central square holes of variable thicknesses and sizes, and the remaining 6 were tested with no holes in the webs. Three different section thicknesses and square hole sizes were chosen for investigation in this study. In addition, Finite Element Method (FEM) analysis was initially developed to validate against test results, and the accurate results from the FEM were then employed in a parametric study for the extension of test data by varying the section thicknesses and the hole sizes. In the DSM shear design equations, two inputs namely the shear buckling load, Vcr, and the shear yielding load, Vy, are required. The numerical solutions for Vcr for whole sections with central square holes have been proposed by first author in previous research studies. For Vy in this paper, a new and simplified model is proposed based on net web areas. Recommendations for an extension to the DSM shear design rules for channel sections with square holes up to certain hole size limit are given. •An experimental program of high strength cold-formed steel channels with square holes in shear is carried out.•Numerical simulation using Finite Element Method (FEM) program is performed for test validation and parametric study.•Elastic shear buckling loads of channel sections with square holes are computed using numerical solutions.•A new simple and simplified equation based on net web area of the channel to calculate shear yield loads is proposed.•Extension of the DSM shear design rules is proposed for cold-formed channels with square openings up to hole size limit.