Buckling resistance of HSS box section columns Part II: Analytical study

The accurate and economical consideration of the flexural buckling resistance of high strength steel (HSS) structures is highly important in the design. According to the previous research results the flexural buckling behaviour of HSS and NSS columns can be significantly different, which differences are not considered in the current design rules. The aim of the current study is to obtain a reliable design method for the flexural buckling resistance of HSS welded box section columns. The buckling resistance is previously determined by the authors based on an experimental research program and based on stochastic numerical simulations . The current paper focuses on the investigation of the theoretical background of the flexural buckling phenomena and on the implementation of the specialties regarding HSS materials into the buckling curve formulation. The analytically derived Ayrton-Perry type formulation is studied and modified based on the theoretical and numerical investigations implementing the effect of residual stresses and geometrical imperfections into the design method. Using the revised buckling curve, the flexural buckling resistance of welded box columns can be predicted with larger accuracy for steel grades between S420 - S960.