Eccentrically-compressed High-strength Steel Welded Box Columns Undergoing Buckling Interaction

Recently, high strength steel (HSS, fy≥460MPa) welded box sections have beensuccessfully used in many steel structures, and better economic profit have beenobtained. As a consequence, HSS members is easier to be locally buckled, it becomeshardly take advantages of the HSS if the currently adopted design method, limitingslenderness of plate elements, extend to HSS box sections. Appropriate release of thelimiting width-thickness ratio, make use of the post-buckling strength can eithersteel-saving or lowering cost. However, previous researches on the local-overallinteraction buckling are mainly focused on the welded box sections subjected to purecompression, the sections under combined compression and bending which are widelyused in structural engineering are seldom been studied. This paper presents thepost-buckling performance and design method of eccentrically-compressed welded boxcolumns with slender plates, which are fabricated from steel with nominal yield strengthof460MPa.A finite element model (FEM) is established by ANSYS, the initial geometricimperfections (both the global and local deflections) and residual stresses, as well as thegeometrical and material nonlinearities were be considered and the reliability of theFEM was validated by experimental results. The influence of various parameters,namely local and global slenderness as well as section aspect ratio, on the local-overallinteraction ultimate capacity was studied by the verified FEM.Based on the numerical results, referring to the effective yield strength method and the direct strength method, the design formulas which used for predicting the interactivebuckling ultimate capacity of Q460high strength steel beam-columns with largewidth-to-thickness ratios were proposed directly use of the geometric parameters and ofthe gross section properties, the influencing factors of the capacity are also consideredin the formula. Get a set of data through varying model parameters, in order to verifythe effectiveness of the recommended formula.