With its vast territory and large population, China's railways have always dominated the country's transportation system. In the 20th century, the design speed of newly built railway Bridges in China was always no more than 160km·h. In 1998, the maximum design speed of the qinhuangdao passenger dedicated line infrastructure started construction was increased to 250km·h, which was the first attempt of China to build a higher speed railway. At the beginning of the 21st century, with the construction of beijing-shanghai high-speed railway and wuhan-guangzhou special passenger line as the symbol, China started large-scale high-speed railway construction, with the highest design speed reaching 350km·h. By the end of 2016, the total mileage of high-speed railway has reached 22,000 km.

Bridges are an important part of high speed railway. In the 22000km high-speed railway built in China, the total length of Bridges is more than 50%, among which the length of beijing-shanghai high-speed railway Bridges is more than 85% of the total length of the line. Most of these Bridges adopt the prestressed concrete simply supported box girder with a span of 32m. In the west, there are dry plateaus, lofty mountains, deep canyons and fast rivers. Southeast on the sea, wide rivers. Large span Bridges must also be built to span wide waters and high mountain valleys. Up to now, China has built or under construction more than 60 long-span high-speed railway Bridges with a span of over 200m, including 2 Bridges with a span of over 1000m and about 10 Bridges with a span of over 500m. This paper lists some representative Chinese high-speed railway long-span Bridges.

In order to ensure the safety and comfort of high-speed trains on Bridges, the coupling dynamic analysis model of high-speed train-bridge must be established, and the dynamic design and evaluation of bridge structure must be carried out by taking bridge structure, running vehicles, track and other factors into consideration. From the perspective of bridge structure, the core is to require the bridge to have better stiffness to obtain better track smoothness.

With the increasing span of the bridge, especially the construction of multi-functional joint bridge, the internal force of the structure is getting larger and larger. The main span of dashengguan bridge is a 2 336m steel truss arch bridge, which can pass through 6 lines of railway, and the maximum rod force is 150MN. The hutong Yangtze river bridge is a cable-stayed bridge with a span of 1092m, with a maximum girder pressure of 750MN. Therefore, it is urgent to develop bridge steel with higher strength.

To this end, Q420q and Q500q bridge steel have been successfully developed.

Q420q was first applied in dashengguan bridge, and Q500 bridge steel has been applied in hutong bridge.

In order to maintain the reasonable stiffness and size of the structure, different strength grades of steel are used in different sections of the main girder of the same bridge. Q420 steel is used for the arch ribs of dashingguan bridge, and Q370 steel is used for the rest parts. The main girder of hutong bridge near the main tower and auxiliary piers is under high pressure, Q500 steel is used, the section with lower pressure is Q420 steel, and the section with lower pressure is Q370 steel.