In the past 20 years, steel tube structures have developed rapidly at home and abroad. It has been widely used in modern industrial buildings, warehouses, gymnasiums, exhibition halls, venues, wharfs, stations and office buildings, hotels and other buildings. Because of its good performance, it has been more and more widely used at home and abroad. Pipe structure can be divided into beam structure and arch structure. From the layout, it can be divided into plane pipe structure and space pipe structure. Mainly used for two cross sections of pipes: pipes and square pipes. The pipe is connected to the pipe through cross welds, because the treatment makes the structure more neat and beautiful. The hybrid structure system formed by pipeline structure and cable combination, such as the beam-column structure mentioned above, can give full play to the advantages of different materials or components, which is a direction of future structural development. Tube truss has been widely used in large span facilities, such as gymnasiums, terminal buildings, conference centers and entertainment centers.


Tube joints are very important problems in pipe structures, including local stress and strain analysis of pipe joints, failure mechanism research, elastic-plastic analysis, design parameters research, load and branching effects, etc. Restraint and fatigue life. Because of the different positions of joints and the different shapes of connecting parts, the stress conditions and structural requirements are also different. There are many structures of pipeline joints, and new structural forms constantly produce new joints. Current research results are still unable to cover all types of tubular joints. For example, the ASTM A500 square pipe is in charge, and the pressure bearing capacity of the branch pipe seldom involves personnel