Web crippling capacity of cold-formed channel sections with and without longitudinal web stiffeners subject to two flange load cases

Cold-formed steel channel sections are increasingly used as flexural members in the construction industry. Improved section profiles such as SupaCee sections are also available for use instead of the conventional lipped channel beam (LCB) sections. They contain additional longitudinal web stiffeners and special return lips that enhance their bending and shear capacities. Web crippling capacities of these innovative sections are different from those of LCBs due to the difference in section geometry. However, no investigation has been conducted into the web crippling behaviour and strength of these high strength SupaCee sections. Current design equations (AISI S100 and AS/NZS 4600) do not include any design procedures for such sections with special longitudinal web stiffeners and lips. Hence an experimental study was first conducted to assess the web crippling behaviour and strengths of conventional LCBs and SupaCees under different loading conditions. Seventy two tests of LCB and SupaCee sections were conducted under two flange load cases (ETF and ITF load cases). Comparison of ultimate web crippling capacities showed that the web crippling capacities of SupaCee sections are reduced in comparison to LCB sections. Therefore suitable modifications to the current AS/NZS 4600 and AISI S100 design equations were made by proposing different web crippling coefficients for SupeCee sections. Numerical models were also developed and validated using the experimental results, and were then used in numerical parametric studies. This paper presents the details of the experimental and numerical studies of LCBs and SupaCees subject to web crippling under ETF and ITF load cases. Suitable web crippling design rules were also developed under the direct strength method format