Experimental and Numerical Study on the Load-Bearing Capacity of Cold-Formed Stiffened High-Strength Steel Box Columns

This paper reports a comprehensive experimental and numerical study on the load-bearing capacity of cold-formed stiffened high-strength steel box columns. A novel cold-formed stiffened section for box columns with width-to-thickness ratios exceeding design limits was presented. Column buckling tests were conducted, including precise measurements of initial geometric imperfections, material property tests, and axial compression tests. The results revealed that the stability factors of the stiffened specimens consistently surpassed those of the corresponding box section specimens within the same experimental group, with an average increase ratio of 19.9%. Finite element models were developed, validated, and used for parametric studies, considering variations in width-to-thickness ratios, slenderness ratios, and steel strengths. A total of 144 finite element models were analyzed to comprehensively investigate the effects of the selected parameters. The obtained parameter analysis results were compared with calculation methods and design codes, such as GB 50017–2017, EN 1993-1-1, ANSI/AISC 360–16, and AISI S100-16, to investigate their applicability. The Direct Strength Method (DSM) was found to overestimate the bearing capacity of these columns. Therefore, a modified DSM was proposed specifically for predicting the ultimate strength of cold-formed stiffened high-strength steel box columns. Extensive verification confirmed that the design strengths obtained using the modified DSM provide accurate and reliable predictions for the behavior of these columns.