Innovative Bridge Types and Structural Systems

The Yanji Yangtze River Bridge in Hubei, under construction with a main span of 1860 m, is the world's first double-deck suspension bridge with four main cables of different sags. Its construction is of great significance forthe development of suspension bridges toward 3000 m or even larger spans.

The Furongjiang Bridge on the Daoweng Expressway in Guizhou, with a main span of 170 m, is the world's first single-inclined-pylon cable-stayed bridge with no side span and with ground anchors. It replaced the original arch bridge scheme, avoiding excavation of the cliff face and protecting the ecological environment.

The Yellow River Sanxia Bridge on the Jixin Expressway in Henan, under construction with a main span of 510 m, is the world's first single-pylon suspension bridge with a rotating cable. It adopts a composite anchorage suited to the terrain and routes the main cable through in a rotating anchorage manner, reducing mountain excavation.

The Wumengshan Grand Bridge on the Naqing Expressway in Guizhou, under construction with a main span of 270 m, is the world's first prefabricated and assembled steel truss-concrete composite arch bridge. It shifts a large amount of specialized high-altitude work to factory prefabrication beneath the bridge, greatly reducing safety risks and the difficulty of construction quality control.

Key Structural Details and Construction Methods

Relying on the Baiyang Yangtze River Bridge in Hubei, key technologies for the anchorage of a large shallow-foundation suspension bridge in strong-seepage strata with large water-level fluctuations were developed. For the first time, the anchorage foundation of a suspension bridge was placed on a shallow Quaternary pebble layer foundation, and construction was completed within a single dry season by open-cut shallow-pit spread foundation, saving more than 150 million yuan in cost.

Relying on the Zangkejiang Bridge on the Naqing Expressway in Guizhou, key technologies for the combined bearing mechanism and anti-sliding of gravity anchorages and foundations in limestone mountainous areas were developed, providing a theoretical basis for the stability design calculation formulas for gravity anchorages in codes, forming anti-sliding design criteria for composite gravity anchorages based on combined anchorage structure-foundation bearing in limestone mountainous areas, reducing project cost and protecting the environment.

Relying on the Zhuankou Yangtze River Bridge in Hubei, key technologies for the construction of long-span, heavy-load, wide steel box girder cable-stayed bridges were developed, a new theory and new method for fatigue-resistant design of steel structure bridges oriented toward fatigue performance were established, and a complete set of U-rib internal welding technology and an intelligent equipment production line were pioneered.

Relying on the Guanyinsi Yangtze River Bridge in Hubei, key technologies for steel-UHPC hybrid composite girders of cable-stayed bridges with spans exceeding 1000 m were developed, providing a main girder configuration for super-long-span cable-stayed bridges based on material performance. The mid-span main girder adopts a three-segment arrangement: the girder segments near the towers use steel-UHPC composite girders, while the mid-span uses steel box girders, giving full play to the compressive performance of concrete and the tensile performance of steel.

Relying on the Zongxihe Bridge on the Hangrui Expressway in Guizhou and the Daxiaojing Grand Bridge on the Pingluo Expressway in Guizhou, key technologies for super-long-span deck-type concrete-filled steel tubular arch bridges in deep mountains and gorges were developed; a reasonable new joint configuration for highway concrete-filled steel tubular arch bridges was proposed, calculation methods for the new joints were established, and the difficulties of component transportation and assembly for concrete-filled steel tubular arch bridges in deep mountains and gorges were solved; structural measures of installing internal studs at the joints of concrete-filled steel tubular truss arches and a theoretical calculation method for interface shear bearing capacity were proposed, solving the problem of force transfer at the joints.

Relying on the Guanyinsi Yangtze River Bridge in Hubei, key technologies for steel-shell composite cable towers and the composite effect in the anchorage zone of cable-stayed bridges with spans exceeding 1000 m were developed; the influence laws of key structural parameters of steel shell-high-performance concrete composite cable towers on the mechanical performance of composite cable towers were clarified, the dimensions of the cable tower anchorage zone were optimized, reducing the engineering quantity by about 10% at the same stress level, and relevant suggestions and basis were provided for compiling design codes for steel-concrete composite cable towers and cable tower anchorage zones.

Relying on the Siduhe Bridge on the Hurongxi Expressway in Hubei, key technologies for suspension bridges in deep-cut gorges were developed. For large gorges with a depth of up to 500 m, conventional traction of the pilot cable across the valley is difficult to implement; research on launching the pilot cable across the gorge using military obstacle-clearing rocket projectiles realized a new construction method and successfully solved the technical problem of crossing the gorge with the pilot cable of the bridge.

Relying on the Yachihe Bridge on the Guiqian Expressway in Guizhou, key technologies for the construction and design of super-long-span steel truss cable-stayed bridges in mountainous areas were developed; using cable tower support, a complete set of 800 m-span, 350 t-class cable crane equipment was developed for the first time, forming a new construction method for installing steel truss girders of cable-stayed bridges.

Industrialized Intelligent Construction

Relying on the Hubei Province general drawings for steel structures, the Wutangxun Expressway in Yunnan, the eastern extension section of the Jianli-Jiangling Expressway in Hubei, and the medium-span steel-concrete composite bridges (30-60 m) in projects such as the Chongzun section (Guizhou territory) expansion project of the Lanhai Expressway in Guizhou as research objects, comprehensive research was carried out through structural simulation analysis, model tests and other methods on the key mechanical properties, system adaptability, optimization and simulation analysis technology of steel-concrete composite structures, probabilistic seismic performance assessment and seismic mitigation measures for composite bridges in high-intensity areas, integrated transportation and erection technology for composite bridges, and maintenance technology. Reasonable structural systems, optimal structural layout forms, reasonable transportation and erection measures and standard construction techniques, probabilistic seismic performance assessment methods for high-intensity areas, and a complete set of key construction technologies for reasonable seismic resistance and mitigation and improved maintenance levels were proposed for steel-concrete composite structure bridges based on the single-bay integral installation process.

From the integral hoisting and docking technology for cable tower segment reinforcement of the Yachihe Bridge on the Guiqian Expressway in Guizhou to the integrated intelligent tower-building machine of the Yanji Yangtze River Bridge in Hubei, "assembly-line" production of bridge towers has been realized, improving construction quality.

Relying on the Daxiaojing Bridge on the Pingluo Expressway in Guizhou and the Shuangbao Grand Bridge on the Yuxiang double-track expressway in Chongqing, 3D laser scanning technology was used for 3D inspection, the BIM model was applied to on-site construction, construction inspection procedures were optimized, work efficiency was improved, and comprehensive digital inspection of workpieces was realized. Through 3D laser scanning pre-assembly, finished-product inspection of steel structures and optimization of offsets before and after welding were realized, achieving in-process quality control.

Research, Development and Application of High-Performance Materials and Equipment

The cross-embankment approach bridge of the Qingyuan Beijiang Fourth Bridge is a single-span 102 m UHPC simply supported girder bridge with a deck width of 37 m, and is currently the world's largest-span full-section UHPC simply supported girder bridge. In light of the material characteristics of UHPC and the construction technology level of UHPC structures at the time, the bridge carried out a series of structural innovations, providing experience for the large-scale application of UHPC materials in bridges and playing a leading role in the development of concrete bridges toward slenderness, lightness and durability.

The Zhijiang Bailizhou Yangtze River Bridge is a steel-UHPC composite hybrid girder cable-stayed bridge with a main span of 890 m, and will become the world's largest-span composite girder cable-stayed bridge upon completion. The composite girder deck adopts ultra-high-performance concrete with light self-weight, high strength and high durability, solving the technical difficulties of super-long-span composite girder cable-stayed bridges.

The Guanyinsi Yangtze River Bridge in Hubei is a steel-UHPC hybrid composite girder cable-stayed bridge with a main span of 1160 m, and will become the world's largest-span highway cable-stayed bridge upon completion. The mid-span main girder adopts steel-UHPC composite girders, while the side-span main girders adopt short-line-method prefabricated and assembled concrete box girders.

Relying on design projects, high-performance equipment such as dampers, expansion joints and bearings was developed, and numerous invention and utility model patents were obtained, including "a large-tonnage elastic-damping composite shock absorption device", "a seamless expansion joint device", "a combined spherical steel bearing", "a slope-adjusting plate-type damping rubber bearing", and "a plate-type damping rubber bearing".