Study On In-plane Stability Of Steel Tube Lattice Frame

With the promotion of steel structure assembly building and the continuous pursuit of building economy and the gradual improvement of safety requirements,the form of steel structure frame structure system is gradually changing.With the invention of lattice-type beam-column connection joints,space steel tube lattice-type frame system came into being.Like other steel structures,stability is the main consideration of bearing capacity.At present,the study on the overall stability of the frame is mainly aimed at the solid-belly type,but very few studies on the overall stability of the frame structure or the rigid frame structure of the steel tube lattice in the same section space.Therefore,it is meaningful and necessary to study the overall stability of lattice frame:1.The theoretical derivation of compressive stiffness,flexural stiffness and shear stiffness of two-leg lattice members is described.and on this basis,the bending stiffness and shear stiffness of equal-section three-limb,limb lattice structural members are derived from a simple single joint hinge model,and then the equivalent bending stiffness formula is verified by finite element ABAQUS software.By means of finite element ABAQUS software,the shear stiffness of lattice members with different lengths is compared and analyzed by using virtual work principle method and lattice members buckling critical load formula inverse algorithm.The comparative findings indicate that:1)The flexural stiffness and compressive stiffness are only related to the limb columns of lattice members;2)The shear stiffness of lattice members increases with the increase of the length of members;3)The traditional idea of the shear stiffness derivation of lattice members does not take into account the influence of different constraints and different loads on the members,and ignores the relationship between the joints and the joints and the difference between the hinge models and the actual ones,which leads to a large deviation between the calculation results and the actual ones.2.The advantages and disadvantages of various methods for calculating lateral displacement of lattice members are briefly introduced.This paper tries to calculate the lateral displacement of lattice members by applying the linear displacement angle equation which considers the influence of shear deformation and comparing the displacement with finite element analysis.3.finite element ABAQUS software buckling analysis of lattice frame with different constraints,different column length,different beam-column line stiffness ratio and different layers was carried out to obtain a large amount of data.By analyzing and comparing the calculation coefficients of the frame column length of the solid web frame and the lattice frame in the same case,the variation curves of the shear deformation on the stability of the lattice frame are obtained considering the above four factors.The upper and lower limits of calculating coefficient of lattice frame column length are found according to the data chart.