Dynamic Response And Buckling Mode Of C-section Cold-formed Thin-walled Steel Members Under Lateral Impact

Because of its light weight,high strength,simple fabrication,convenient installation,high recovery and suitable for industrial production,cold-formed thin-walled steel members are widely used in industrial plants,residential buildings,light steel villas and other buildings.However,such buildings can also be used in environments with high seismic intensity,heavy snow,or possible impact loads.which involves the relevant research of cold-formed thin-walled steel members under dynamic load.At present,the research on the closed section cold-formed thin-walled members under the impact load is more extensive,and the research on the common open-section cold-formed thin-walled steel members(C-section,Z-section,etc.)is mostly focused on the static load,and the buckling capacity of the cold-formed thin-walled steel under the axial compression has also been relatively mature calculation formula,but for the open section thin-walled members under the impact load of the relevant research is very rare.There are no clear terms for the design of this kind of structure under the impact load in the domestic and foreign design codes of cold-formed steel structure,which directly affects the design and construction of this kind of structure under the risk of impact load and the post-disaster safety assessment.Therefore,it is necessary to study the dynamic response and buckling instability mode of open-section cold-formed thin-walled steel members under impact load.In this paper,the dynamic response and buckling mode of C-section cold-formed thin-walled steel members under lateral impact is studied by numerical simulation and experimental study.The main research contents are as follows:(1)Theoretical analysis and numerical simulation of C-section cold-formed thin-walled steel members.Using the Cowper-symbols constitutive model in ANSYS/LS-DYNA material library as the material model of C-section cold-formed thin-walled steel members,a modeling method suitable for dynamic analysis of C-section cold-formed thin-walled steel members is proposed.(2)The impact test was carried out on the members by considering the directionof the impact load,the length of the members,and whether the flange is provided with battens.The change rules of the dynamic strain,displacement and acceleration of the members under different impact energy are analyzed.The buckling failure modes of components under different factors are compared.At the same time,using ANSYS /LS-DYNA to establish the refined model of the test component,through the comparison of the finite element results and the test results,the validity of the finite element analysis is verified.(3)The finite element model of C-section cold-formed thin-walled steel members is established.By changing the density,velocity and impact angle of the impactor,as well as the thickness,length and section height of the member,a large number of numerical comparisons are made on the dynamic response of the member,and the influence of various factors on the dynamic response of C-section cold-formed thin-walled steel members is analyzed.(4)According to the final deformation and flange depression of C-section cold-formed thin-walled steel members,the buckling mode of members under lateral impact is divided into three categories: slight depression in the impact area of component flange,local depression in the impact area of component flange,local failure of component flange and large area depression around the impact area.In this paper,the finite element models of common and web-reinforced C-section cold-formed thin-walled steel members are established,the dynamic response of C-section cold-formed thin-walled steel members under different modes is analyzed,and the displacement nephogram,impact force and stress at web reinforcement of the two members under each buckling mode are compared.