Asraf Uzzaman

Design of cold-formed stainless steel lipped channel sections with web openings subjected to web crippling under end-one-flange loading condition:

This article presents a numerical investigation on the web crippling strength of cold-formed stainless steel lipped channel sections with circular web openings under end-one-flange loading condition. In order to take into account the influence of the circular web openings, a parametric study involving 1992 finite element analyses was performed, covering duplex EN1.4462, austenitic EN1.4404 and ferritic EN1.4003 stainless steel grades; from the results of the parametric study, strength reduction factor equations are proposed. The web crippling strengths predicted by the reduction factor equations are first compared to the strengths calculated using the equations recently proposed for cold-formed carbon steel lipped channel sections. It is demonstrated that the strength reduction factor equations proposed for cold-formed carbon steel are unconservative for the stainless steel grades by up to 7%. Unified strength reduction factor equations are then proposed that can be applied to all three stainless steel grades.

Web crippling strength of cold-formed stainless steel lipped channels with web perforations under end-two-flange loading

This article presents a finite element investigation into the web crippling strength of cold-formed stainless-steel lipped channels with circular web perforations under end-two-flange loading. The cases of web openings located both centred and offset to the load bearing plates are considered. In order to take into account the influence of the circular web openings, a parametric study involving 2190 finite element analyses was performed, covering duplex EN 1.4462, austenitic EN 1.4404 and ferritic EN 1.4003 stainless-steel grades; from the results of the parametric study, strength reduction factor equations are determined. The strength reduction factor equations are first compared to equations recently proposed for cold-formed carbon-steel lipped channels. It is demonstrated that the strength reduction factor equations proposed for cold-formed carbon steel are conservative for the stainless-steel grades by up to 10%. New coefficients for web crippling strength reduction factor equations are then proposed that can be applied to all three stainless-steel grades.

The effects of web opening on web crippling strength of cold-formed steel channels under interior-two-flange loading condition

Cold-formed steel sections are increasingly used in residential and commercial construction as both the primary as well as the secondary framing members. Web crippling at points of concentrated load or reaction is well known to be a significant problem, particularly in thin walled beams. To improve the buildability of buildings composed of cold-formed steel channel-sections, openings in the web are often required, for ease of installation of electrical or plumbing services. In this paper, a combination of experimental tests and non-linear elasto-plastic finite element analyses are used to investigate the effect of such holes on web crippling under the interior-two-flange (ITF) loading condition. In the case of the tests with web openings, the web holes located at the mid-depth of the webs. A non-linear elasto-plastic finite element model is described, and the results compared against the laboratory test results; a good agreement was obtained in terms of both strength and failure modes.