Stress Concentration Analysis And Fatigue Strength Check Of Circular Tubular Long Span Space Truss Joints

In recent years,China's national economy has maintained a relatively rapid development.With the development of the economy,construction has also undergone rapid changes,and many large-span and large-space buildings have appeared one after another.Because the steel pipe structure has the advantages of good mechanical properties and building performance,it is widely used in various large-span structures.However,most of the structures used in industrial plant buildings are bolt-ball node grids and welded hollow-spherule node grid structures.There are few applications for the intersecting tubular truss structures of circular steel tubes,and the specifications for the joints of circular steel tubes are described.Few,and at the same time,the fatigue problem of the intersecting nodes has a great influence on the overall stress of the truss structure.There are many factors that affect the fatigue life of the intersecting nodes,and the stress concentration of the nodes is more significant.Therefore,the following research work has been done for the above problems.:1.Through reviewing the literature on the joints of circular steel tubes,we have come to the conclusion that in recent years,scholars at home and abroadhave mainly studied the joint stiffness and ultimate bearing capacity of circular steel tubular joints,and the stress concentration factor of the joints,which is an important factor causing joint fatigue.Less research,and then put forward the study of the stress concentration of circular steel tubular joints.2.Based on a circular steel pipe intersecting node space truss industrial factory building,Midas modeling analysis was carried out.By analyzing the equivalent stress,maximum displacement and stress ratio of the truss structure and the equivalent stress and maximum displacement of the truss structure under the effect of the crane,the equivalent stress of each member of the truss,the deflection of the truss,and the stress ratio checking are all satisfied.Specification requirements,so as to provide reference for future designers to design the space truss structure of circular steel tubular intersecting nodes.3.Using ABAQUS finite element software to analyze 120 finite element models of T-joints,Y-shapes,K-shapes,X-shapes,and TT-type joints of circular steel tubular joints,and change the geometry of the joints of circular steel tubes under the single factor effect.The parameters show that the change of the main wall thickness has a greater influence on the stress concentration of the T-shaped,Y-shaped,X-shaped and TT-type circular steel tubular intersecting nodes,and the main wall thickness has a negative correlation with the stress concentration of the above-mentioned nodes;The change of diameter has a greater influence on the stress concentration of the T-node,the outer diameter increases,and the stress concentration increases;the change of the geometric parameterscontributes to the stress concentration of the K-type node;finally,the analysis results are collated and various types are obtained.The formulae of stress concentration factor of single-factor and multi-factor are used for the joints of circular steel tubes.At the same time,the fatigue strength of structural key rods is verified.The fatigue strength of the truss structure meets the specification requirements within the design service life.