Study On Post-Buckling Performance Of Composite Members Of Space Truss Structures

According to the current research situation,the design and calculation of composite members of long-span space truss are analyzed according to the simplified model of single member.It is unreasonable to treat composite members according to the general member.The combined effect between members and members is not considered in this way,and the effective length coefficient of composite members is usually 1.This will lead to inaccurate calculation and design of composite members.Furthermore,the study of the hysteretic behavior of composite members after buckling provides a good preparation for accurate collapse simulation analysis.Therefore,the analysis of post-buckling behavior of composite members lays a theoretical foundation for the study of collapse resistance of long-span space truss structures.In this paper,the combination of theory and practice is used to study the composite members.Firstly,ABAQUS finite element software is used to model and analyze the composite bar with sealing plate.Considering the influence of initial defects on the post-buckling performance of composite bar,the basic theory of contact and friction and non-linear analysis(including material non-linearity,material non-linearity)are used.The basic theory of geometrical nonlinearity and boundary condition nonlinearity is used to simulate the contact and friction between bolt ball and hexagonal sleeve,hexagonal sleeve and sealing plate,sealing plate and bolt,and to reflect the real situation of composite bar under stress.On the basis of numerical simulation,experimental study is carried out to test the composite members under compression,and the results are compared with those of numerical simulation.Finally,the effective length coefficient of composite members and the elastoplastic hysteretic model of composite members are obtained.The elastoplastic hysteretic model is applied to the collapse resistance analysis of long-span space trusses.Through experiments and simulation analysis,the following conclusions are drawn in this paper:(1)Due to the influence of sleeve and friction,the ultimate bearing capacity of composite members is reduced.The results show that the effective length coefficient of composite members is about 1.06.(2)The ultimate stability bearing capacity of composite members decreases with the increase of slenderness ratio,and the ultimate stability stress of composite members decreases with the increase of initial bending when the slenderness ratio is unchanged.(3)According to the deformation and stress nephogram of the composite bar simulated by ABAQUS,it can be found that due to the buckling deformation of the composite bar,one end far from the bending direction between the outer side of the sealing plate and the hexagonal sleeve is separated,while the other end is extruded.(4)When a composite member is subjected to cyclic loading,the buckling of the composite member results in its axial shortening.At the same time,the plasticity of the composite member develops rapidly along the cross section and the length of the member due to the existence of the P-? effect.With the development of buckling and plastic deformation of composite members,the bearing capacity of members decreases rapidly.(5)When a cyclic load is applied to the composite member,there are still residual stress,residual axial deformation and residual strain on the composite member at the end of a cycle,but the axial force is zero.