  Citation: Mohan, M.; Ramachandran, A.; Amran, M.; Borovkov, A. Determination of Buckling Behavior of Web-Stiffened Cold-Formed Steel Built-Up Column under Axial Compression. Materials 2022, 15, 2968. https://doi.org/10.3390/ma15092968 Academic Editor: Alexander Yu Churyumov Received: 10 March 2022 Accepted: 12 April 2022 Published: 19 April 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). materials Article Determination of Buckling Behavior of Web-Stiffened Cold-Formed Steel Built-Up Column under Axial Compression Muthuraman Mohan 1, * , Anuradha Ramachandran 2 , Mugahed Amran 3,4 and Aleksey Borovkov 5 1 Department of Civil Engineering, University VOC College of Engineering, Thoothukudi 628008, India 2 Department of Civil Engineering, SNS College of Technology, Coimbatore 641035, India; anuradhastalin@gmail.com 3 Department of Civil Engineering, College of Engineering, Prince Sattam Bin Abdulaziz University, Alkharj 16273, Saudi Arabia; m.amran@psau.edu.sa 4 Department of Civil Engineering, Faculty of Engineering and IT, Amran University, Amran 9677, Yemen 5 Institute for Advanced Manufacturing Technologies, Peter the Great St. Petersburg Polytechnic University, 195251 St. Petersburg, Russia; borovkov@compmechlab.com * Correspondence: mraman44@gmail.com Abstract: The practice of utilizing cold-drawn steel for structural and non-structural elements has expanded nowadays due to it being lighter in weight, economic section, desirable in fabrication, and its preferred post-buckling behavior over hot rolled sections. The cold-drawn steel section back to the back-lipped channel section has a wide application as a structural member. The fasteners are provided at regular intervals for the long-span structure to prevent individual failures. This study is concerned with the inadequacy of research addressing the behavior of built-up columns. The relevant built-up column section is chosen based on the AISI-S100:2007 specification. Thirty- six specimens were designed and tested by varying web, flange, lip dimensions, spacing between the chords, and battened width experimentally subjected to an axial compression. Comparing 36 experimentally buckled specimens with the model generated by Finite Element Method accom- panied with ASI-recommended two direct strength methods (DSMs). The DSM comprises the step-by-step procedure incorporated with the elastic, critical, and global distortional interaction. Based on the performed reliability analysis, such as the experimental, analytical, and theoretical studies, the failure load, buckling mode, the economic section, and design rules were proposed. Four suitable sections were selected from the proposal, and the validation study was carried out. From the validation study, experimental values were found to be 1.072 times the FEM values, and DSM values were found to be 0.97 times the FEM values. Based on the significant findings of this study, the proposed design recommendation and the corrected value for DSM are suitable for designing back-to-back stiffened columns. Keywords: stiffened section lipped built-up columns; back-to-back battened section; DSM; FEM 1. Introduction In modern construction, the usage of cold-formed steel sections is needed. The cold- formed steel structural members such as beams, columns, and joists are widely used. The main advantage of the cold-formed steel (CFS) is the post-buckling behavior where the hot rolled steel section fails early during axial loading in the single section member. Hence, the area is modified by placing two-lipped chords at a certain distance. Those two chords are connected back-to-back by batten with bolted connection to perform like a single member during loading. The failure mode of the column was influenced predominantly by the local buckling mode. However, there are some limitations in predicting the column’s buckling mode by varying the specifications such as the size of the battened plate, dimensions of the section, and the slenderness ratio during the experimental investigation. There is a need for conducting a parametrical study. So that area chosen for our research was selected from Materials 2022, 15, 2968. https://doi.org/10.3390/ma15092968 https://www.mdpi.com/journal/materials