Partial factor for local buckling of welded box sections

The accurate consideration of the local (plate) buckling resistance and the determination of the effective width is highly important in the design of civil engineering structures. The current effective width calculation method provided by the EN 1993-1-5 is mainly developed for I-sections subjected to bending. Several previous studies proved that the current design rules can overestimate the plate buckling resistance especially in case of square box sections subjected to pure compression. The purpose of the current study is (1) to investigate the local buckling resistance of welded square box section columns loaded by pure compression and pure bending moment separately, (2) to investigate the applicability of the Winter curve for these worst cases and (3) to provide the necessary partial factor to the application of the Winter curve according to the safety requirements of Eurocode. Another aim of the current study is to investigate the differences between normal strength steel (NSS: S235 – S355) and high strength steel (HSS: S420 – S960) structures on the local buckling resistance. Deterministic and stochastic numerical and experimental research programs are conducted to investigate the effect of residual stresses and geometric imperfections on the local buckling resistance of welded square box sections and the necessary partial factor is determined.