Buckling Strength of Cold-Formed Austenitic Stainless Steel SHS Columns Subjected to Concentric Axial Load

A study on austenitic stainless steel (STS304 TKC and STS316 TKC) square hollow section(SHS) columns subjected to centrally axial compression has been conducted to investigate the buckling behaviors of the compression members with both fixed ends. Main variables are steel type, column length and width-thickness ratio. Buckling modes at ultimate state were classified into two such as local buckling and global buckling. Compressive material properties of SHS members was also investigated through stub column tests in addition to tensile material properties. Stub columns showed local buckling mode. A finite element (FE) analysis model of a stainless steel SHS column considering initial geometric imperfection and compressive material properties was developed, and the validity of the FE analysis procedure was verified through comparison with test results. The test buckling strengths were compared with the strengths predicted by current stainless steel design specifications (American Society of Civil Engineers (ASCE 8–22) and Eurocode (EC3)). As a result, it is found that design strengths with compressive material test data of stub column than those of tensile coupon were close to test buckling strength. The global buckling coefficients of ASCE 8–22 was the values presented for the compression members of open sections, and since it did not sufficiently reflect the buckling characteristics of the closed-section SHS members, some of the buckling coefficients were adjusted upward referring to the AISC 370–21 specification. The EC3 standard presented a value with the adjusted initial imperfection coefficient. It was confirmed that the predicted strength by the design equations with the modified coefficient was close to the test and analysis buckling strength.