A plane or space load-bearing member composed of several straight bars, usually with triangular elements. Under load, truss members mainly bear axial pressure or tension to make full use of the strength of materials. When the span is large, they can save materials, reduce self-weight and increase stiffness compared with solid web beams, so they are suitable for long-span load-bearing structures (such as roof truss, supporting truss, floor truss beam, bridge and crane bridge) and high-rise structures (such as transmission line towers, radio towers and satellite launch towers). Others, such as hydraulic gates and crane frames, can also use trusses. The disadvantage is that the labor consumed in manufacturing and the structure itself occupy a lot of building space.

Trusses are divided into statically determinate trusses and statically indeterminate trusses according to their mechanical properties, and statically determinate trusses are generally used in construction. According to the mechanical characteristics, it can be divided into plane truss and space truss. The former means that members and loads are in the same plane, while the latter may not be in the same plane. According to the materials used, it can be divided into steel truss, reinforced concrete truss, prestressed concrete truss, wood truss, steel-wood composite truss and steel-concrete composite truss. Trusses are divided into triangular trusses, trapezoidal trusses, parallel chord trusses and polygonal trusses according to their shapes. According to the web forms adopted, it can be divided into inclined web truss and non-inclined web truss, that is, the vierendeel truss bridge is a kind of bridge, which is common in railways and expressway. Refers to the bridge with truss as the main load-bearing component of the superstructure. Truss bridge is an open-web structure, which has good adaptability to double deck. Truss is a plane or spatial structure composed of straight bars, generally with triangular elements. Truss members mainly bear axial tension or pressure, which can make full use of the strength of materials and save materials. When the span is large, compared with the solid web beam, it can save materials, reduce self-weight and increase stiffness.