Over the past 75 years since New China found, steel for bridge construction has gone through seven major stages of development.
1.The first generation of bridge steel: A3q
Wuhan Yangtze River Bridge was opened to traffic on October 15, 1957, a total length of 1670.4 meters, riveted structure, steel beams imported from the Soviet Union, A3q steel (Q235 carbon steel) construction. A3q steel yield strength ≥ 240 MPa, tensile strength ≥ 380 MPa. It is understood that the bridge used 24,805 tons of steel girders, millions of rivets, 16 tons of columns for each m-shaped steel girder, 4 diagonal rods of 9 tons each, steel girders under the suspension of the weight of 36 tons, the upper suspension weight of 35 tons.
2.The second generation of bridge steel: 16Mnq
16Mnq bridge steel has good overall mechanical properties, welding performance and low-temperature impact toughness, cold stamping and machinability are good, and A3q steel compared to the composition of only a little more manganese, with A3q steel with the same good plasticity and weldability at the same time, the yield strength has increased by about 50%, and its yield strength of ≥ 345 MPa, tensile strength ≥ 520 MPa. Anshan Iron and Steel production of 16Mnq high-strength bridge plate to fill the gaps in the country, in 1964 won the first prize of the National New Product, the
3.The third generation of bridge steel: 15MnVNq
Anshan Iron & Steel developed and produced 15MnVNq steel (Q420qE steel) for the Jiujiang Yangtze River Bridge, supplying 20,000 tons of 15MnVNq steel (Wuhan Iron & Steel supplied more than 10,000 tons of 16Mnq steel), which filled the gap of high-quality, high-strength steel for large-span bolted-welded steel bridges in China. Jiujiang Yangtze River Bridge is a double-decker double-lane dual-purpose bridge, the highway bridge is 4,460 meters long, the railroad bridge is 7,675 meters long, the project won the Luban Prize for National Quality Engineering and the first prize of the National Science and Technology Progress Award.
4.The fourth generation of bridge steel: 14MnNbq
Wuhu Yangtze River Bridge was the largest dual-purpose bridge in Asia at the time, March 22, 1997, Wuhu Yangtze River Bridge construction, September 30, 2000 opened to traffic. Wuhu Yangtze River Bridge highway bridge length of 6078.4 meters, railroad bridge length of 10624.4 meters.
In order to solve the problem of poor low-temperature toughness and weldability of 15MnVNq steel plate, WISCO and Wuhan Bridge Bureau jointly for the Wuhu Yangtze River Bridge research and development of large-span railroad bridge steel 14MnNbq (Q370qE steel), used in the main span of 312 meters of steel girders. 14MnNbq steel in the 16Mnq steel on the basis of the use of carbon-reducing niobium micro-alloying technology research and development, the yield strength of ≥ 370 MPa, tensile strength ≥ 550 MPa, and the steel is a good choice. Pa, tensile strength ≥ 530 MPa, with moderate strength, plate thickness effect is not obvious, good weldability, good toughness and crack resistance and other characteristics.
5.The fifth generation of bridge steel: Q420qE
Nanjing Dashengguan Yangtze River Bridge is one of the key projects of the Beijing-Shanghai high-speed railroad, the world’s first six-lane railroad bridge, and the world’s largest span, the world’s largest high-speed railroad bridge with the largest design load. The total length of Nanjing Dasheng Pass Yangtze River Bridge is 9,273 meters, of which the main bridge is 1,615 meters long and the main span is 336 meters. The Nanjing Dashengguan Yangtze River Bridge for the first time used the Q420qE (WNQ570) high-strength bridge steel developed by WISCO and rolled at Xiang Steel.
6.The sixth generation of bridge steel: Q500qE
The Shanghai-Suzhou-Nantong Yangtze River Public-Railway Bridge, with a total length of 11.072 kilometers (of which 6,989 meters are public-railway joint bridges), consists of the main channel bridge, Tiansheng Harbor Channel Bridge, Henggang Sandy Waters Bridge, bridges across the Yangtze River embankment, and approaches on both sides of the Yangtze River, and adopts the structure of double-tower, three-cable-surface steel truss girder cable-stayed bridges with a main span of 1,092 meters. The bridge is not only the world’s highest main tower (up to 330 meters) of the dual-purpose bridge. Anshan Iron and Steel supplied 12,000 tons of Q500qE bridge steel (and nearly 40,000 tons of Q420qE, Q370qE bridge steel), WISCO supplied 18,000 tons of Q500qE bridge steel. In addition, other steel enterprises also supplied different grades of high-strength bridge steel. The performance of Q500qE bridge steel is high strength, high toughness and high crack resistance. That means that each square meter of steel beams can withstand the maximum force of 5,000 tons, equivalent to the weight of about 2,500 cars. Compared with Q345qE, Q370qE, in the case of the same load, the use of Q500qE steel plate thickness can be reduced by about half, reducing the amount of steel used in the project, while greatly reducing the weight of the bridge.
7.The seventh generation of bridge steel: Q690qE
The total length of Hanjiang Bay Bridge is 2754 meters, of which the main bridge is 672 meters long, with a main span of 408 meters, which is a three-span continuous steel truss tie-arch bridge, with a standard design width of the bridge deck of 47 meters, making it the widest and largest span bridge on the Han River at the moment.
The high-performance bridge steel Q690qE developed by Baosteel WISCO for the Hanjiang Bay Bridge is currently the highest grade for bridge applications internationally. Compared with Q500qE steel, its yield strength level from 500 MPa significantly increased to 690 MPa, yield strength ratio, weldability, low temperature toughness and other key technical indicators are better than international standards, can greatly increase the length of the main span of the bridge, reduce the main body weight of the bridge. It is understood that, under the same conditions, the use of seventh-generation bridge steel bridge than the use of sixth-generation bridge steel bridge weight 15% to 20% lighter, can greatly reduce the construction difficulty and material usage.
