Design and optimization of 420Â MPa large-section HSSY columns

A new type of large-section high strength steel Y-shaped (HSSY) column was presented. 24 specimens in total were designed and subject to experiment in order to investigate the overall buckling behavior. The columns including two commonly-used slenderness ratios of 35 and 40 were divided into two groups for axial and eccentric compression, respectively. Prior to the buckling test, the material properties, initial geometric imperfections and longitudinal residual stresses were measured. The buckling deformations and ultimate strengths were obtained by test and compared with numerical results, which were based on validated finite element models taking the real initial imperfections and boundary conditions into account. A good agreement was reached between the test and numerical approaches. Buckling factors and column curves of axial compression specimens were obtained and compared with existing code design curves. To accurately predict the overall buckling strengths of HSSY columns, recommended column curves and their formulae corresponding to different codes were proposed through nonlinear regression method. In addition, the influence of loading eccentricity on ultimate buckling capacity was analyzed. Furthermore, the cross section efficiency was formulated and criteria for section optimal selection were concluded for making the best use of the column. Finally, a variety of large-section and medium-section columns with potentially high utilization ratios were recommended for engineering application.