Performance Analysis Of Local Buckling And Distortional Buckling Of Thin-walled H-beam Flexural Members

In recent years,thin-walled steel has become more and more popular in China.All kinds of thin-walled steel sections are widely used in various projects.The state has also promulgated the corresponding norms to guide the engineering design and construction.But for Thin-Walled Steel,because of its relatively thin,once it is made into a certain length of the component,it is prone to buckling instability.Therefore,if we want to use the thin-walled steel more perfectly,we must control the buckling instability.For ordinary H-section steel,the flange and web is prone to local buckling.So we have to limit the width-thickness ratio of flange and the depth-thickness ratio of web.The most direct way is to increase the thickness of the flange and web,but the amount of steel will increase.In this case,a new type of thin-walled lipped H-section steel has been developed.Because of the effect of lipped stiffening or part stiffening,the post-buckling strength of flange can be improved.In this paper,the direct strength method and the effective width method for solving the local buckling and distortional buckling of thin-walled steel are introduced.Through the analysis of the advantages and disadvantages of these two methods,it is suggested to use more simple and feasible direct strength method.However,it is necessary to obtain the elastic buckling stress of the component by using the direct strength method to calculate the ultimate bearing capacity.Generally,the elastic buckling stress is solved by numerical method,but this method is complicated and inconvenient.So,the finite strip software CUFSM and the finite element software ABAQUS is used to analyze the local buckling and distortional buckling performance of thin-walled lipped H-section steel in this paper.The emphasis of the research is to analyze the influence of various parameters on the flexural members and establish the local buckling stress formula and distortional buckling stress formula.Among them,mainly completed the following innovative work:(1)A large number of thin-walled lipped H-section steel with different sizes were established by the finite strip software CUFSM.The buckling stress of the member is obtained and the flexural capacity of the member is obtained.The influence of crimping width-thickness ratio,sectional width-height ratio,the depth-thickness ratio of web,the width-thickness ratio of flange on the local and distortional buckling performance of thin-walled lipped H-section steel were analyzed.The optimal range of parameters is obtained and applied to engineering.(2)Based on the analysis of the influence of different parameters on the distortional buckling of thin-walled lipped H-section steel flexural members,a half wavelength formula for solving the distortional buckling of thin-walled lipped H-section steel flexural members is established,and the results show that the formula can be used to calculate the half wavelength of the distortional buckling of thin-walled lipped H-section steel flexural member.In order to provide support for the study of distortional buckling of thin-walled lipped H-section steel flexural members.(3)By using the finite strip software CUFSM,a large number of the local buckling stresses and the distortional buckling stresses of thin-walled lipped H-section steel flexural members are obtained.Then the buckling coefficient of member is calculated by using the buckling stress formula of golden plate.The buckling coefficient formula is obtained by fitting the local buckling coefficient and distortional buckling coefficient.Finally,the buckling coefficient formula is incorporated into the buckling stress formula of the Golden plate,so as to obtain the local buckling stress formula and the distortional buckling stress formula for the thin-walled lipped H-section steel flexural members,and the accuracy of the simplified formulas are verified by the ABAQUS.