Steel bridge, the main load-bearing structure of steel bridge, that is, steel structure bridge, steel bridge. Precast steel bridges have been widely used throughout the world. Steel frame bridge is the main load-bearing structure of rigid frame bridge. The beam and leg or pier body form a rigid connection. The structure can be divided into portal rigid frame bridge, inclined leg rigid frame bridge, T-shaped rigid frame bridge and continuous rigid frame bridge. It is mainly used for various vehicles to cross rivers, valleys and other obstacles, and can be used to erection bridges on dangerous and broken bridges, as well as prefabricated metal parts for emergency maintenance during road maintenance. Has the following characteristics: 1. Simple structure and fast installation. 2. Good adaptability and interchangeability 3. High strength and durability, with good durability. 4. Large carrying capacity, good carrying capacity.