Browsing by Author "Francis, R."

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    Investigation of local buckling behavior of web perforated plain channel stub columns
    (Elsevier Ltd, 2024) Francis, R.; Shabhari, A.; Chandrasekar, D.; Vijaya Vengadesh Kumar, J.
    As a sustainable material, cold-formed steel (CFS) is increasingly popular in structural components of buildings and industrial storage racks. The plain channel sections having a flange stiffened web element and unstiffened flange elements are prominently used as compression members in CFS systems. These elements are likely to undergo local buckling under compressive loading. The openings or closely spaced perforations along the longitudinal direction of the web for serviceability requirements on buildings and beam level adjustment requirements on storage racks lead to additional complications to the local buckling. Although the Effective Width Method and Direct Strength Method rationally cover the buckling behavior of plain channel sections, the influence of height-to-width ratio with perforations is not effectively accounted for in the design. Limited research details are available in the literature for the web perforations of lipped channels or rack sections. However, these sections do not have unstiffened flanges, where the unstiffened flanges can be more vulnerable to local buckling, e.g., plain channels. The web perforations also make the web more vulnerable to local buckling. This article examines the local buckling behavior of plain channel sections with the influence of web perforations through systematic experimental and comprehensive numerical studies. The influencing parameters of the cross-section geometry are assessed through the principal component analysis (PCA) to understand its correlation with local buckling. The PCA results shed light on mandatory parameters for the elastic critical local buckling load calculation and/or nominal local buckling strength prediction of the plain channel section. © 2024
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    Local buckling strength enhancement due to non-slender flanges in web perforated plain channel columns
    (Elsevier Ltd, 2025) Francis, R.; Shabhari, A.; Jeyapragasam, V.V.K.; Chandrasekar, D.
    Cold-formed steel columns are the primary compression members in housing and industrial storage racks, with discrete holes or closely spaced web perforations. The element slenderness and web perforations influence the local buckling capacity. This study examines the local buckling capacity of slender web plain channel cross-sections with non-slender or slender flanges in the presence of web perforations. Fourteen plain channel stub column tests were conducted on two cross-section aspect ratios, two perforation shapes, with three perforation orientations. Further, a comprehensive parametric study was conducted using validated Finite Element models. The local buckling strength of unperforated and web-perforated cold-formed plain channel columns is evaluated using the Direct Strength Method (DSM) and Modified Direct Strength Method (MDSM). The increase in local buckling strength due to non-slender flanges becomes significant, depending on the aspect ratio and non-dimensional local buckling slenderness ratio of the plain channel cross-section. This research provides the scope to expand the applicability of DSM and MDSM design strength predictions from cold-formed steel design to general thin-walled steel sections, where the welded thin-walled steel sections can have different element thicknesses. As the element thickness plays a crucial role in element slenderness and inter-element interaction, the local buckling capacity prediction available for uniform cross-section thickness can be unduly conservative. This study highlights the significance of element slenderness and effective area reduction due to perforation shape and orientation in the local buckling strength of cold-formed plain channel sections. © 2025 Institution of Structural Engineers. Published by Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.