Study On Local-overall Interaction Buckling Plane Of Q690 High Strength Steel Welded I-section Beam-columns

In recent years,High strength steel has been applied to modern engineering structure due to its superior performance.Compared with ordinary strength steel structure steel,high strength steel can not only meet the current span steel structure engineering and the demand of the continuous development of the height,can also reduce the section size of steel members and area,reduce weight,making the structure seismic action effects on structure also decreased accordingly.But at the same time,due to the component of the cross section area and the decrease of the thickness,panel is generous ratio,slenderness ratio of steel structure components have different degrees of increase,even beyond the relevant limit of existing specifications,high strength steel components which makes the local stability and global stability problem becomes more serious.At present,the study of local and whole stability more concentrated in the high strength steel and the yield strength is less than 690 MPa ordinary strength steel axial compression member,for the more common bending member in engineering research is relatively small.In view of this,this paper studies the buckling load performance of the flexural member of Q690 steel welded I-section with high thickness ratio of the web.The main research contents are as follows:(1)First of all,using the general finite element software ANSYS,considering initial geometric imperfection and residual stress components and the influence of geometrical and material dual nonlinear finite element model is established,and through the existing experimental data demonstrate the effectiveness of the model.After verification by a finite element model parameter analysis,to study high web thickness ratio,flange relatively generous ratio,load eccentricity and slenderness ratio changes related to bending in-plane local-overall buckling bearing capacity.(2)Through the results of finite element simulation analysis,the results show that the flange relatively high generous ratio,web plate thickness ratio,load eccentricity ratio and local bending member slenderness ratio on welded I-section components-overall buckling related the ultimate bearing capacity in different degree;With the increase of the thickness ratio of the flange and the thickness ratio of the web,the ultimate bearing capacity of the component is improved,but its dimensionless bearing capacity is gradually reduced.With the increase of the length of the component,the ultimate bearing capacity and the non-dimensional ultimate bearing capacity of the components are significantly reduced.(3)By comparing the design method of the ultimate capacity in the plane of the bending member,it is found that there are limitations.In the ultimate capacity of existing relevant buckling calculation formula on the basis of the introduction of relevant influence factor,and through the multi-parameter regression analysis is established and the coefficient flange relatively high generous ratio,web plate thickness ratio,load eccentricity and slenderness ratio of the component parts of the calculation formula.Revised formula and the result was compared with finite element calculation results,the results show that the modified formula can be applied to high web thickness than transfinite Q690 steel I-section section bending component buckling ultimate capacity calculation of high strength steel structure design and analysis of the results for our country to provide certain reference.