The Local And Overall Interaction Buckling Study Of Q690 High Strength Steel Welded Box Section Biaxial Bending Beam-columns

In this paper,a refined finite element model considering the effects of initial geometric imperfections,residual stress,geometric nonlinearity and material nonlinearity is established by using ANSYS finite element software.The validity of the finite element model is verified based on the existing experimental data.On this basis,a large number of parameter analysis is carried out,focusing on the slenderness ratio of components,flange width-thickness ratio,web height-thickness ratio and load relative.The influence of eccentricity on ultimate bearing capacity of members is analyzed;the results of finite element calculation are compared with those of formulas in China,the United States and Europe;based on the analysis results,referring to the standard formulas of steel structure design in China and the effective yield strength method,it is proposed to calculate the integrity of Q690 steel welded box-section bidirectional compression-bending members by using the properties of the gross section of members.Suggested formulas for ultimate buckling capacity of body and local correlation.The results show that the finite element model considering various factors can well simulate the buckling behavior of Q690 steel welded box-section members under biaxial compression and bending;the dimensionless ultimate bearing capacity of members is approximately linearly related to the width-thickness ratio of flange,the height-thickness ratio of web,the slenderness ratio of members and the relative eccentricity of load;the dimensionless ultimate bearing capacity of members increases with the increase of flange width-thickness ratio.The trend of load reduction is slower and less affected by the change of load eccentricity;the increase of web height-thickness ratio will make the dimensionless ultimate bearing capacity of members decrease faster and slower with the increase of load relative eccentricity;the dimensionless ultimate bearing capacity of members will decrease with the increase of slenderness ratio and the trend of reduction will also decrease with the increase of load eccentricity;the increase of eccentricity along the two main axes will lead to the decrease of dimensionless ultimate bearing capacity of members,but the trend of the decline of the curve is different;the relationship between the axial force-moment correlation curve and the influencing parameters is approximately linear;the proposed formula can well predict the related ultimate buckling capacity of Q690 steel welded box-section bi-directional compression-bending members.