Local buckling behavior of welded stub columns with normal and high strength steels

• A validated FE model is employed to undertake parametric analyses of welded stub columns.
• Section types include box section and I section. Steel strengths include 235 MPa, 460 MPa, 690 MPa and 960 MPa.
• Variation rules of post-buckling ultimate stress with steel yield strength and width-to-thickness ratio are clarified.
• Variation rules of local buckling stress with steel yield strength and width-to-thickness ratio are also clarified.
• The FE analysis results and existing test results are compared with the corresponding design methods in different codes.
• New design formulas for the local buckling behavior of welded stub columns under axial compression are proposed.

High strength steels (HSSs) are increasingly applied in structural engineering due to their benefits in terms of mechanical performance and economy. Compared with normal strength steel (NSS) axial compression members, HSS members possess more critical local buckling behavior since its component plates may be designed as being more slender, and different mechanical properties of HSS, in terms of increased yield strength and reduced ductility, may result in different local buckling behaviors. In this paper, finite element (FE) analysis is performed to investigate the local buckling behavior of welded box section and I-section stub columns under axial compression with both NSS and HSS being incorporated, where initial geometric imperfections and welding-induced residual stresses are accurately simulated. Through this work, variation rules of post-buckling ultimate stress and local buckling stress of the axial compression members with steel yield strength and width-to-thickness ratio are clarified. By comparing the FE analysis results and existing test results with the corresponding design methods in ANSI/AISC 360-10, Eurocode 3 and GB 50017-2003, it is confirmed that the design methods for the local buckling behavior of welded box section and I-section stub columns under axial compression need to be modified. New design formulas are proposed to take the influence of the steel strength into consideration.