Local And Local-overall Buckling Behavior Of High Strength Steel Welded Box Section Under Eccentric Compression

With the improvement of steel production technology,the high strength steel is more and more used in the construction structure.As the yield strength increases,the bearing capacity of the compression member is controlled by the stability rather than the intensity control.At present,domestic studies on the local-overall stability of high-strength steels are mostly concentrated in Q460 steels,and there is a lack of research on higher-grade steels.Based on the differences in the constitutive relationship and material properties of higher-strength steels,this paper uses a combination of numerical simulation and theoretical analysis to comprehensively analyze Q550,Q620 and Q690 steels for welded box-shaped cross-section biased components,include their local stability performance and related stability performance,and proposed a proposed calculation method.This paper mainly completes the following aspects:(1)Considering the effects of initial geometric imperfections and residual stresses,the local-global buckling model of high strength steel was established by using finite element software ABAQUS,and the finite element model was validated by existing experimental data.(2)Finite element analysis of 510 welded box-section eccentrically loaded members is completed by using the verified local-global buckling finite element model.The influence of main factors on the stability of high-strength steel is studied.The results show that the N-M correlation curves of Q550,Q620 and Q690 high strength steels studied in this paper are basically straight lines and approximately parallel.With the increase of slenderness ratio,width-thickness ratio and section side-length ratio,the values of Pu/Py and Mu/My decrease continuously,but the decrease amplitude is different.The ultimate load-carrying capacity of high strength steel members can be improved obviously.The lifting amplitude decreases with the increase of slenderness ratio and width-thickness ratio,but increases with the increase of eccentricity.(3)On the basis of finite element analysis,the proposed formula for calculating the local-global correlation stability of welded box-section eccentric compression members of high strength steel is proposed,and the formula is validated.The numerical results of the model are in good agreement with the calculated values of the recommended formula in this paper,and the proposed formula can be deviated.The influence of local-global buckling on the ultimate bearing capacity of welded box-section eccentrically loaded members of high strength steel is considered safely.Based on the finite element analysis,a new formula for high strength steel welded box section eccentric compression members is put forward and verified.