Local buckling behaviour of high strength steel welded box-section columns under axial compression

High strength steel (HSS) with superior strength and remarkable toughness has been widely utilised in large-scale structures. The application of HSS in engineering may result in slender plates in compression members, which are susceptible to local buckling. To investigate the local buckling behaviour of HSS columns, experiments are carried out on 800 MPa HSS welded box-section columns under axial compression in this study. Finite element analysis is performed to investigate the local buckling behaviour of welded box-section columns. Several parameters such as initial geometric imperfections, residual stresses of plates, and steel grade are considered in the analysis. The influences of the initial geometric imperfections and residual stresses on the local buckling of HSS welded box-section column are less effective than that for normal strength steel (NSS) welded box-section columns. The difference between the local buckling and post-buckling strengths of HSS increases compared with that for NSS. Present specifications for estimating the local buckling load and ultimate load of HSS welded box-section columns are evaluated. GB50017-2017 is a little overestimated for predicting the local buckling load. AISC360-16 is slightly overestimated for predicting the ultimate load. GB50017-2017 and Eurocode 3 are marginally underestimated for predicting the ultimate load of box-section columns. More accurate empirical formulas are recommended for determining the local buckling load and ultimate load of HSS welded box-columns under axial compression. Reliability analysis of various formulas for estimating the local buckling load and ultimate load of HSS welded box-section columns is performed. •Local buckling behaviour of HSS welded box-section columns is investigated.•Current design guidance are evaluated, and more accurate models are then developed.•Reliability analysis of various models is performed.