| In recent years,the steel pipe structure has developed rapidly in China.The circular steel pipe structure with direct welded joints has obtained the advantages of high rigidity,light weight,beautiful appearance and good economy,which has made it available in many large public buildings at home and abroad.A large number of applications.The design of steel pipe truss roof and circular steel pipe welding joints is an important point in the steel pipe truss structure.Among them,the geometrical characteristics and material properties of the planar KN-shaped circular steel pipe welded joints are more complicated,the stress concentration is more serious,and the influencing factors are more serious.Many,and the form of destruction is diverse.Through the query of the existing literature,it is found that there are few studies on the axial force of such planar joints,which brings troubles to the structural design and the application of the intersecting joints.Therefore,the ultimate bearing capacity of such joint.The study of performance has become an urgent problem to be solved in the study of steel truss structures.At the same time,in view of the complex performance of the long-span steel truss roof structure,in order to facilitate the effective guidance of engineering structure design and its application,it is necessary to study and analyze the structural dynamic characteristics under different working conditions.Based on the actual engineering project,this paper uses the finite element method to study and analyze the welded joints of the KN-type circular steel pipe and the steel pipe truss roof structure of the Foshan Gymnasium.Firstly,theoretically,the theoretical analysis of the welding joints of the KN-type circular steel tubes under the cover of the Foshan Gymnasiumwas carried out.By changing the ratio of the wall thickness of the inclined branch pipe to the wall thickness of the main pipe,the axis between the main axis and the axis of the inclined branch pipe Four different parameters,such as the angle ?,the ratio of the outer diameter of the joint oblique branch pipe to the width of the outer diameter of the main pipe,and the ratio? of the outer diameter of the joint main pipe to the thickness ?,are used to study the variation of each parameter on the welding of the plane KN-shaped round steel pipe.The influence of the ultimate bearing capacity of the joint.Then,using the finite element software SAP2000,the modal analysis,deflection and displacement analysis of the steel pipe truss roof structure of Foshan Gymnasium and the stress ratio analysis of the main component sections were carried out.The main research work and conclusions are as follows:(1)Studying the modeling and calculation methods of finite element analysis by scholars at home and abroad,and establishing the finite element calculation model of the welded joint of KN-type circular steel tube under the roof of Foshan Gymnasium,and carrying out the design load on the joint.Safety check under the action.The results show that under the design load,the joint has good carrying capacity and the joint is safe and reliable.(2)The ultimate bearing capacity of the welded joints of the plane KN-shaped circular steel tubes is analyzed and analyzed.The load-displacement curve of the most unfavorable members of the joint is obtained,and the ultimate bearing capacity criterion is obtained by the joint.Ultimate bearing capacity value.(3)Parametric research and analysis on the joint joints of the KN-type circular steel pipe under the chord plane of the Foshan Gymnasium,and the wall-to-thickness ratio ? of the branch pipe and the main pipe,the angle ? between the main pipe and the branch pipe,and the branch pipe and the main pipe are studied respectively.The influence of four geometric parameters,such as the diameter ratio ? and the wall thickness ratio ?,on the ultimate bearing capacity of the joint.The results show that the effect of changing the wall thickness ratio ? of the branch and the ratio of the outer diameter of the branch to the ultimate bearing capacity of the KN-type joints is significant.The change of the diameter-to-thickness ratio ? and the main branch tube axis ? is similar.The influence of the ultimate bearing capacity of KN type joints is small;the influence degree of each influencing factor on the ultimate bearing capacity of the joints is ranked from large to small as follows: the outer diameter ratio of the supporting main pipe is ?> the main wall thickness ratio of the supporting branch ?> the main branch pipe clamping angle ?.(4)The finite element method was used to analyze the modal analysis,deflection and displacement value of the steel pipe truss roof structure of Foshan Gymnasium and the stress ratio analysis of the main component sections.The analysis results were compared with the specification limits.The results show that the design values of the control indexes of the roofstructure performance of Foshan Gymnasium meet the requirements of the specification limits,and the overall performance of the designed roof structure is good. |
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