Trusses are widely used in steel structures, such as roofs (roof trusses). ) and crane beams (crane trusses), bridges and cranes (their towers, beams or suspenders, etc.) of industrial and civil buildings. ), hydraulic gates and offshore oil platforms. Steel trusses are often used as the main components of load-bearing structures. All kinds of steel grid structures widely used in roof structures of long-span public buildings belong to space steel trusses. Various types of towers, such as TV, power transmission, drilling, tower crane and mast tower, usually use space steel trusses composed of three, four or more plane trusses. Compared with solid web beams, steel trusses use sparse web members instead of full web members, and members mainly bear axial force, which can often save steel and reduce structural weight. This makes steel truss especially suitable for structures with large span or height. In addition, steel trusses can be made into various shapes according to different requirements. In addition, because the amount of steel used in the web member is less than the web of the solid web beam, the steel truss can usually be made to have a greater height and thus greater rigidity. However, the steel truss has many members, many joints, complex structure and labor-consuming manufacture.