Ultimate uniaxial compressive resistance of S600E cold-formed stainless steel square tubes

Sorbite stainless steel (S600E, SSS) is a promising alternative for conventional metals in diverse engineering applications due to its exceptional mechanical properties, superior corrosion resistance, weldability, and cost-effectiveness. Nonetheless, its understudied mechanical behavior hinders its widespread employment as a prospective structural element. To enrich the mechanical understanding of SSS, tensile coupons, uniaxial compressive stubs, and long columns with cold-formed square hollow sections (SHS) were examined, elucidating the stress-strain graphs, failure mechanisms, and uniaxial resistance. The yield stress of S600E reaches 700 and 870 MPa in the flat and corner regions. Furthermore, local buckling occurs in all stubs featuring symmetrical bulges at one end, with a mean ultimate compressive resistance of 670 MPa. Conversely, most long columns fail due to global buckling. To determine an appropriate capability estimation, the experimental and finite element model (FEM) data were compared with the theoretical outcomes of presently available methods. The continuous strength method (CSM) and most specifications provide conservative assessments of the load-carrying capacity of stubs, where CECS 410:2015 produces a relatively accurate evaluation, displaying a 1% error. Regarding long columns, the improved direct strength method (DSM) accurately predicts the uniaxial resistance with a 1% error. This study illuminates the mechanical behavior of S600E, providing critical insights that enable more efficient use of this promising material in engineering and construction applications. © 2023 Institution of Structural Engineers