Experimental and Analytical Study on Local Buckling Behavior of High Strength Steel Welded I-Section Beams

With the progress in metallurgical technique and steel production process, the strength of structural steels can be improved, along with other material properties, including higher toughness and better weldability. Meanwhile, there are numerous potential civil structural applications for high strength steel (HSS), such as large-span space frames, transfer truss in high-rise buildings, as well as truss bridges. The mechanical behavior of structural members made up from HSS must be closely investigated and quantified before HSS can be widely used in engineering structures. In this paper experiments on six Q550 HSS I-section beams under moment gradient (MG) and four Q550 HSS I-section beams under patch loading (PL) were carried out, to investigate the local buckling behavior of I-section beams subjected to different loading conditions. The failure modes, critical local buckling strengths, ultimate strengths, load–deformation curves, load–strain curves and moment–rotation curves of the specimens were obtained. The test results of ultimate strengths were further compared with the design results in accordance with the available design methods in current specifications, ANSI/AISC 360-16, Eurocode 3, AS 4100-1998, AIJ LSD 2010 and GB 50017-2003. Accounting for material nonlinearity, geometric imperfection and residual stress, finite element models were established and verified with the existing test results, which were used for the parametric analysis of two series of 240 beams. The parametric investigation focused on the effects of the material properties and component plate slenderness on the ultimate strengths of I-section beams under MG and the ones under PL. The comparisons between the parametric analysis results, test results and the design results from ANSI/AISC 360-16 and Eurocode 3 were also conducted.