Stress Concentration Analysis And Fatiue Check Calculation For Intersection Joints Of Square Steel Tubes In Large-span Industrial Plants

With the rapid development of China's economy since the reform and opening up,infrastructure construction is in the ascendant,and large-span steel structure industrial buildings are also growing.It has beautiful appearance,light weight,reasonable stress and high rigidity,and can be assembled in factories.To facilitate construction.In industrial buildings with large-span steel structures,industrial plants occupy a decisive position.In large-span industrial plants,hollow welded ball joints and bolted ball joints are used more frequently,but these node forms are susceptible to process and result in poor accuracy.It is difficult to meet the construction requirements.Therefore,it is urgent to improve the form of the nodes in large-span industrial plants.This paper proposes innovatively the use of square steel joints and applies it to large-span industrial plants to improve the deficiencies of previous node forms.The reason for adopting the intersecting nodes of the square steel pipe in this paper is that due to the continuous development of the steel pipe structurein recent years,the square steel pipe and the round steel pipe are widely used in various residential buildings and large-scale industrial maternities,in particular,the square steel pipe has flat cutting and good stress performance.The advantages are applied more widely in engineering.Therefore,through the modeling and analysis of large-span industrial plants,the applicability and feasibility of square-pipe joints are obtained.However,due to the curvature discontinuity of the geometric shape itself at the welding joint of the main pipe and the branch pipe of the pipe joint in this structure,the initial defects of the welding and the welding residual stress and other factors influence the high stress concentration around the weld.Under the action of random load cycles such as crane load,wind load,wave load,and earthquake load,the weld joint is prone to fatigue failure,which seriously affects its serviceability and even results in damage to the entire structure.Therefore,it is very necessary to study the stress concentration of different types of steel pipes in each other.By summarizing the research results of the previous joints of the other party's steel tubes,it is found that the research mainly focuses on the bending bearing capacity and stiffness of the pipe joints.At the same time,the formulae for the bearing capacity of pipe joints are only given in the steel pipe structural part of China's “ Code for Design of Steel Structures”(GB50017-2003),and the formulas for the calculation of therelevant hot spot stress or SCF are not given,so this article is not only for the large-span industry.This paper not only analyses the modeling of large-span industrial plants,but also gives reasonable suggestions for the size of square-pipe joints used in future large-span industrial plants.In this paper,not only the modeling and analysis of large-span industrial plants,but also reasonable suggestions for the size of the joints of the square steel tubes used in the future large-span industrial plants,and the fatigue of the joints of the steel pipe at the same time.The research content and research methods of this paper are as follows:1? through a large number of inquiries to understand the domestic and foreign references and research results,a detailed understanding of the development of domestic and foreign steel pipe structure and the scope of application,and the stress concentration of the pipe node collection.2? Through the use of square pipe joints and finite element analysis software Midas/gen,a large-span industrial plant in Datong City was designed and analyzed to demonstrate the rationality of the use of square pipe joints.3? Using ABAQUS software to perform finite element simulation analysis on plane X,Y,K,T,and N square tubular joints to obtain their hot spot stress values,and to change their different parameters to obtain the stress concentration factor.4? The above results were analyzed and fitted by origin software,and the stress concentration calculation formulas under different types of different parameters were proposed and finally provided reference for designers.