The basic form of the truss roof structure is related to its use. Generally, its shape can be divided into a triangle, trapezoid, parallel chord, and arch, etc. The commonly used forms of truss web members are herringbone, cross and Funk.
Regarding the classification of truss structures, they can be divided into plane truss structures and space truss structures according to their force characteristics and the arrangement of members. The support ensures the lateral stability of the structure; the section of the space truss structure is usually triangular, and the triangular section is divided into two types: regular triangle and inverted triangle. The design, manufacture, and installation of the plane truss are relatively simple, but its out-of-plane stiffness is poor, and the amount of steel used is correspondingly large; while the space truss structure has rich shapes, simple and smooth lines, and relatively few, in exhibition halls and waiting halls. It is widely used in large public buildings such as gymnasiums and gymnasiums and is suitable for rectangular planes. Space trusses not only have the advantages of plane trusses but also have better spatial rigidity, better mechanical performance, and low steel consumption.
Under normal circumstances, the steel consumption of the space three-dimensional truss is about 85% of that of the plane truss, and the out-of-plane stiffness is much larger than that of the plane truss. The truss structure is classified according to the cross-sectional form of the connecting members and can be divided into a truss structure in which the main pipe and branch pipe are intersected by round pipes (C-C truss), and a truss structure in which the main pipe and branch pipe are intersected by square steel pipes or rectangular pipes (R-R truss), truss structure with rectangular section main pipe and circular section branch pipe directly welded (R-C truss), etc. Among them, the C-C truss has been the most widely used because of its higher inertia radius and effective torsional cross-section compared with the round steel pipe and other cross-section pipes, and the research and development is earlier, so it has been the most widely used; The outstanding advantages of steel pipes and rectangular sections in terms of compression and torsion resistance, as well as the advantages of simple and neat appearance, have been applied in buildings such as China Harbin Ice and Snow Art Exhibition Hall, Shanghai Oriental Pearl TV Tower; R-C trusses can make full use of circular The advantage of the tube section as an axial force member can also take advantage of the bending and compressive properties of the rectangular section.