1) The tensile, compressive and shear strength of steel is relatively high, and the cross-section of steel components is small and the deadweight is light. High strength makes it suitable for building bridges with heavy loads; light deadweight can reduce the load on the foundation, reduce the foundation cost, and also facilitate transportation and hoisting. 2) The good plasticity and toughness of steel make the seismic performance of steel structure bridges good. Because steel has good plasticity and toughness, it can absorb more energy through the deformation of the structure under the action of earthquake, and at the same time has the toughness that can act repeatedly, which greatly improves the seismic performance of steel structure. Earthquake resistance and wind resistance are the guarantee of bridge safety. The excellent seismic performance of steel structure bridges has expanded its scope of use, especially in high-intensity earthquake areas. 3) Short construction period. The materials of steel structure can be rolled into a variety of profiles, which are easy and quick to process; the transportation volume of building materials is small, and the construction site occupies a small area; sporadic parts can be made on site, which is easy to connect, easy to install, and has a short construction period. 4) The quality of steel bridges is easy to guarantee. Steel structure components are generally manufactured and processed in factories, with a high degree of industrialization and high precision.5) Steel structure bridges are easy to modify during use, such as reinforcement, heightening, and widening the road surface. Changes are relatively easy and flexible. 6) Steel structure is an environmentally friendly product. The old parts removed from the steel bridge can be re-melted, which can save energy and comply with the policy of sustainable development. 7) Pipeline layout is convenient. There are many holes and cavities in the structural space of the steel bridge, which makes the layout of the pipeline more convenient, and the replacement and repair of the pipeline are more convenient. 8) Steel structure bridges have a wide range of applications and are easy to make into large spans. Practice and research have shown that: steel concrete structures are suitable for arch bridges and cable-stayed bridges with a span of less than 500m, but not for suspension bridges; steel structure bridges are suitable for arch bridges, suspension bridges and cable-stayed bridges with a span of 100m, especially large-span cable bridges.