Research On Bending Bearing Capacity Of Q460 Cold Formed Thin-Wall Corrugated Corrugated Channel Steel

In recent years,cold-formed thin-wall steel has been widely used in the construction industry because of its uniform mechanical properties,easy processing,energy saving and environmental protection.With the development of structure to light and high strength,the application of high strength steel is gradually increasing.The cold-formed thin-wall members of hot-plated aluminum zinc high-strength steel commonly used in engineering are prone to buckling failure in the elastic stage due to the large width of the plates,which makes the strength of the materials unable to give full play.But the traditional high strength steel members are mostly welded section,heavy weight and inconvenient processing.At present,the research on high-strength cold-formed steel is not enough,and the thickness of the study is small,so this paper proposes to use hot-rolled Q460 high-strength steel plate,cold-formed through the bending machine,the thickness of 4mm and 6mm cold-formed thin-wall winding channel steel members.As a basic load-bearing member in building structure,it is necessary to study its bearing capacity.Therefore,this paper explores the bending bearing capacity of Q460 cold-formed thin-wall corrugated channel steel through experimental research and finite element simulation,and discusses the influence of different geometric parameters on its bearing capacity.For members with different buckling modes,The formulas for calculating the bearing capacity of the direct strength method under the modified global buckling and distorted buckling modes are presented respectively.The main research contents and conclusions of this paper are as follows:(1)Four point bending loading tests were carried out on 18 Q460 cold-formed thin-wall winding channel steel members.The buckling modes of specimens are mainly integrated flexural buckling and integrated flexural buckling and distortion related buckling.The deformation of mid-span section is the largest,and all specimens fail in pure flexural section.The flexural ultimate bearing capacity of specimens increases with the increase of section size.Under the same web height,the flexural ultimate bearing capacity of specimens increases linearly with the increase of flange width,and the increase amplitude is basically the same under different web height.The increase of flexural ultimate bearing capacity caused by the increase of web height is less severe than that caused by the change of flange width.The bearing capacity increases significantly with the increase of section thickness.The width of the flange has little effect on the ultimate bearing capacity of such specimens.(2)The finite element simulation and experimental loading of the components are in good agreement in the three aspects of ultimate bearing capacity,buckling mode and load-displacement curve,which proves the reliability and accuracy of the finite element simulation method adopted in this paper.When the initial geometrical defect amplitude is 1/1000 span,the influence of the defect is not enough to change the buckling mode of the member.Among various initial geometric defect modes under investigation,the shrinkage distortion defect bearing capacity of mid-span section is the lowest,which can be used as the initial geometric defect mode of parameter analysis,and the thousandth span is selected as the initial geometric defect amplitude of parameter analysis.(3)By using the verified finite element method and introducing the initial geometric defects,the parameters of the geometric size of the member are analyzed.The results show that the ultimate bearing capacity of the member increases with the increase of the height of the web,the increase amplitude of different section sizes is different,and the increase amplitude of the section with large flange width is larger.The influence law of flange width on the ultimate bearing capacity of member is not monotonous,and the influence trend of flange width on different sections is different.The ultimate bearing capacity of the member increases slightly with the increase of the width of the flange.The member with small section size only has the overall bending and torsional buckling,while the member with large section gradually changes the buckling mode from distorted buckling to local buckling of the web with the increase of the width of the flange.The ultimate bearing capacity of the member increases obviously with the increase of the thickness of the member,and increases slightly with the larger section size.The ultimate bearing capacity of the member decreases with the increase of the pure bending length of the member,and the reduction degree of the member with small section size is greater.(4)By comparing the calculation formula of the direct strength method in current specifications with the results of loading test and finite element parameter analysis,it is found that the prediction results of the ultimate bearing capacity of Q460 cold-formed thin-wall corrugated channel steel flexural members studied in this paper are generally unsafe.Combined with the current formula of direct strength method and the results of finite element simulation and experimental loading,the bearing capacity calculation formulas of the direct strength method under the modified global buckling mode and the distorted buckling mode were proposed respectively for the members under different buckling modes.By comparing the prediction results of the ultimate bearing capacity of the proposed formula and the original formula with the experimental loading results and the finite element simulation results of the corresponding buckling modes,it is found that the calculation results of the proposed formula in this paper are in good agreement with the research data,and the degree of dispersion is low.The suggested formula given in this paper can predict the ultimate bearing capacity of Q460cold-formed thin-wall wound channel steel flexural member more accurately.