Numerical investigation on the structural performance of octagonal hollow section columns

Abstract This study is initiated by the increasing use of steel tubular members with octagonal hollow sections (OctHSs) in civil structures. Previous studies primarily focused on the local buckling behaviour of cold-formed steel OctHSs. However, investigations on the global buckling behaviour of OctHS long columns remain scarce. Thus, the main objective of this paper is to numerically investigate the structural performance of the OctHS columns. A finite element method (FEM) was developed for tubular columns and validated against relevant experimental results reported in the literature. Subsequently, a parametric study on 239 OctHS columns was carried out. The applicability of design methods outlined in Eurocode 3, ANSI/AISC 360-16 and ASCE/SEI 48-19 was evaluated. The evaluation shows that the design method in Eurocode 3 provides conservative predictions for the load-bearing capacity of OctHS columns, while the ANSI/AISC 360-16 design method was slightly unconservative for the strength predictions. The design method in ASCE/SEI 48-19 gave inaccurate predictions for the load-bearing capacity of the OctHS columns. Modifications to the design methods in ANSI/AISC 360 and ASCE/SEI 48-19 were proposed to improve the accuracy of strength predictions and to obtain safe structural designs. The reliability of the design method in Eurocode 3 and the modified American design methods was assessed through the reliability analysis and found to satisfy the reliability requirements.