Study On Elastic Distortional Buckling Of Cold-formed Thin-walled Lipped Channel Steel Flexural Members

In recent years,with the continuous application and development of cold-formed thin-walled steel members,distortional buckling has become a common buckling instability mode,and its bearing capacity calculation is an important issue in the stability theory of components.In a series of studies on bearing capacity,the direct strength method has become the most common method for its design and calculation.The key problem in the calculation of this method is to determine the elastic buckling load of the component.In the construction project,some holes are opened on the structural web according to the demand,and these holes may have a negative effect on the buckling mode and strength of the structure.Therefore,it is particularly important to calculate the elastic distortional buckling load of perforated and unperforated members.However,the existing calculation methods at home and abroad are more complicated and not easy to apply.Therefore,based on the previous research results,this paper will derive a simpler method for calculating the elastic distortional buckling load of perforated and unperforated members respectively.For the calculation of elastic distortional buckling load of unperforated members,the existing methods are mainly based on Hancock ’s method.When calculating the load,the rotational restraint stiffness of the web to the flange must be determined first,and this process requires iteration and is more complicated.In order to simplify the solution process,based on the calculation method proposed by Hancock,combined with the previous research on the local buckling coefficient of web and flange when the member is bent,this paper deduces a simple method for solving the rotational restraint stiffness,and corrects it based on the calculation results of Hancock method.Finally,the elastic distortional buckling load obtained by using it is compared with the finite strip analysis value to prove the feasibility of the proposed method.For open-hole members,the existing common method for solving the elastic distortional buckling load is mainly the finite strip method proposed by Moen et al.,which reduces the thickness of the relevant section.However,it is necessary to analyze the distortional buckling half-wavelength of the solid-web section before reducing the thickness,and the analysis steps are cumbersome.In order to simplify the calculation process,two new methods without considering the buckling half-wave length are proposed based on the Moen method,that is,the finite strip method for the reduction of web thickness and full-section thickness.Based on the idea of reducing the full-section thickness,it is applied to the calculation formula.Finally,the obtained elastic distortional buckling load is compared with the finite element software analysis results to verify the feasibility of the proposed method.Finally,the above-mentioned elastic distortional buckling load solution method for perforated and unperforated members is applied to the direct strength method and the flexural capacity is calculated.At the same time,it is compared with the existing test and finite element analysis results,which further shows that the calculation method proposed in this paper is feasible.Figure [32] Table [10] Reference [76]...