Flexural resistance of steel cellular beams subject to global-local buckling interaction: Direct strength method approach

• Published in: Thin-walled structures Vol. 213; p. 113266
• Main Authors: Berti, Flávia Gimenez, de Carvalho, Adriano Silva, Rossi, Alexandre, de Oliveira, Vinicius Moura, Martins, João Pedro, Simões da Silva, Luís Alberto P., Martins, Carlos Humberto
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2025
• Subjects: Cellular beams; Direct strength method; Lateral-torsional buckling; Web-post buckling; Lateral-torsional buckling; Direct strength method; Web-post buckling; Cellular beams
• ISSN: 0263-8231
• DOI: 10.1016/j.tws.2025.113266

•Buckling and post buckling numerical analyses are performed.•Interaction between LTB and WPB were the mainly failure mode observed.•Novel Design Curve based on Direct Strength Method was proposed.•The proposed equations accurately predict the load-bearing capacity of beams where failure is governed by local instabilities like WPB, as well as interactions between WPB and LTB.•The proposed equations offer a simplified yet precise method for designing cellular steel beams. Steel cellular beams are considerably more susceptible to stability-governed failure modes than I-section beams without perforations, particularly to local instabilities caused by the presence of the web openings. These openings result from the cutting and welding of the I-section, increasing its height and second moment of area about the strong axis. However, the beam's torsional stiffness reduces and other failure modes may arise. Lateral-torsional buckling (LTB), a widely studied type of global stability failure mode, is more likely to occur in these beam models due to the expansion of the section after cutting and welding to form openings in the web. On the other hand, web-post buckling (WPB), a type of local stability mode, occurs in the web region between the openings, and this is a failure mode exclusive to perforated cross-sections. While both failure modes have been extensively addressed in the literature individually, limited attention has been given to their interaction, underscoring the need for further investigation of cellular beams under these conditions. Therefore, this paper aims to assess the interaction between LTB and WPB exclusively in cellular beams. The proposed approach involves developing a design curve using the Direct Strength Method (DSM). Based on the analyses of 120 models, results indicate that a significant set of the studied members fail only due to LTB, while others fail due to WPB or due to the interaction between the two failure modes. Thus, a DSM-based curve was proposed to obtain the normalized ultimate bending moment of beams susceptible to interaction-driven failure modes with respect to the LTB resistance moment. The capacity is determined using the global-local slenderness of these steel profiles.