Effects of Splice Configuration on Web Crippling of Lapped Cold-Formed Steel Channels Subjected to Interior Two-Flange Loading

Web crippling is a form of localized buckling that occurs at points of transverse concentrated loading or supports of thin-walled structural members. Cold-Formed Steel (CFS) channels that are unstiffened against this type of loading are susceptible to structural failure caused by web crippling. The theoretical computation of web crippling strength is quite complex as it involves a large number of factors such as initial imperfections, local yielding at load application and instability of web. Currently, the North American standards for the design of cold-formed steel structural members (S136) specify an empirical formula for web crippling strength of different joist geometries in case of exterior end and concentrated load locations. However, this formula does not permit an increase in web crippling capacity when lapped cold-formed steel channels are subjected to interior two-flange loading. This may be attributed to the lack of experimental data on web crippling strength at interior support locations. As such, the objective of the current research is to generate experimental data for CFS channels where both flanges of channel members are lapped at the interior support location and being loaded simultaneously. Previous experimental work published by the authors addressed the effects of the lap length of the spliced channels at the interior support, the presence of corrugated steel deck fastened to the top flange and the end support restraint condition. Based on those test results, the authors proposed modifications to the existing web crippling strength formula in North American standards S136. Herein, the experimental program has been extended to cover more related parameters such as the arrangement of fasteners splicing the channels, the bearing length at the interior support as compared to the lap length and the presence of lateral support at the channels splice (i.e clip angles). The details and findings of the extended experimental program are discussed in the present paper.

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