Buckling behavior of 420Â MPa HSSY columns: Test investigation and design approach

To meet the requirement of larger bearing capacity and better material economization than traditional main members in latticed transmission towers, a novel Y-section column is put forward in this paper. A series of full-scale tests is carried out to investigate the buckling behavior of 420 MPa high strength steel Y-section (HSSY) columns. 57 columns including three different sectional dimensions and nine slenderness ratios ranging from 30 to 80 are designed for axial compression tests. The width-to-thickness ratios, reduction factors accounting for the design stress or effective cross section area, material mechanical properties, initial geometric imperfections and longitudinal residual stresses are measured and discussed in detail. Based on the validated finite element results taking the initial imperfections into account, the buckling deformations and ultimate strengths are obtained and demonstrate a good agreement with the test results. The buckling factors are calculated and compared with different code results such as Eurocode 3, GB 50017-2003, ASCE 10-97, ANSI/AISC 360-10, CSA S16-09, AS4100-2012, BS 5950-1 and AIJ 2010. Related buckling curves and formulae are derived through nonlinear fittings and compared with the code design curves. It is concluded that the HSSY columns characterize very strong stability and high buckling strengths. Finally, the recommended buckling curves and design formulae are proposed to predict the buckling strengths of HSSY columns.