Investigation on the Buckling Behavior of Normal Steel CHS Beam–Columns: A Revised Design Approach with Reliability Analysis

This paper focuses on the buckling behavior of circular hollow section (CHS) beam–columns. The literature review highlights the need for further investigations to improve the accuracy of structural performance predictions and optimize the design guidelines for CHS beam–columns. A comprehensive parametric study was conducted using the developed finite element model, which included a total of 1400 simulations, including sections made from cold-formed and hot-finished steel. An assessment of the existing design provisions in Eurocode 3 is presented. Based on the results, a revised buckling design approach is proposed. The existing design provisions in Eurocode 3 provide conservative predictions on the buckling resistance of CHS beam–columns for both cold-formed and hot-finished sections. The proposed design approach demonstrated improved accuracy in predicting the buckling resistance, with mean predicted-to-test ratios and RMSE values of 0.99 and 8.1 kN for Class 1–2 sections, and 1.00 and 6.4 kN for Class 3–4 sections. Finally, a reliability analysis was conducted to assess the safety and reliability of the proposed design approach, resulting in a partial safety factor of 1.12 compared to 1.14 for Eurocode 3, indicating slightly reduced conservatism, while maintaining adequate safety levels.