What Is a Rope Bridge?

Suspension bridges, also known as suspension bridges, refer to bridges that use cables (or steel chains) suspended by cable towers and anchored on both sides (or both ends of the bridge) as the main load-bearing components of the superstructure. The cable geometry is determined by the equilibrium conditions of the force and is generally close to a parabola. Many suspenders are suspended from the cable, and the bridge is suspended. A stiffening beam is often set between the bridge and the suspender to form a combined system with the cable to reduce the deformation caused by the load.

The greatest forces in a suspension bridge are the tension in the suspension and the pressure in the tower. Because the tower is basically not subject to lateral forces, its structure can be made quite slim, and in addition, the suspension cable has a certain stabilizing effect on the tower. If the weight of the suspension cable is ignored in the calculation, the suspension cable forms a parabola. In this way, the process of calculating the suspension bridge becomes very simple. The suspension cables of old suspension bridges are usually iron chains or iron bars connected together. Modern suspension cables are generally multiple strands of high-strength steel wire.

The construction of suspension bridges was invented in the early 19th century, and many bridges use this structure. Modern suspension bridges have evolved from cable bridges. The scope of application is mainly for long-span and extra-long-span highway bridges. Today, long-span bridges adopt this structure. It is the main form of long-span bridges.

Suspension bridges are bridges with tension-resistant cables or chains as the main load-bearing components.

Compared to other bridge structures, suspension bridges can use less material to cover longer distances. Suspension bridges can be made relatively high, allowing ships to pass underneath. It is not necessary to establish a temporary pier in the center of the bridge during bridge construction. Therefore, suspension bridges can be built on deeper or more rapid currents.

Suspension bridges are more flexible, so it is suitable for windy and seismic areas. More stable bridges must be stronger and heavier in these areas.

If the tower is to be built on water, it must first be used where the tower is to stand

Suspension bridges are one of the main forms of extra-long-span bridges.

Self-anchored suspension bridge

In general, the main cables of the main load-bearing components of cable bridges are anchored on anchors. In a few cases, in order to meet special design requirements, the main cables can also be directly anchored on the stiffening beams, thereby eliminating the large anchors and becoming A self-anchored suspension bridge.

Most of the self-anchored suspension bridges built in the past used steel structures, such as the Flower Bridge opened in Japan in 1990, the Yongzong suspension bridge in South Korea, the San Francisco-Oakland Bay new bridge, and the Muhu island pier in Estonia. In July 2002, the world s first self-anchored suspension bridge made of reinforced concrete material, Jinshitan Jinwan Pier, was completed in Dalian, providing valuable experience for the study of this type of pier. Since then, four more reinforced concrete self-anchored suspension bridges in Jilin, Hebei and Liaoning are being designed, designed and constructed.

The self-anchored suspension bridge has the following advantages: There is no need to build large-volume anchors, so it is especially suitable for areas with poor geological conditions.

Due to the small terrain limitation, it can be flexibly arranged in combination with the terrain. It can be made into a double-tower three-span suspension bridge or a single-tower double-span suspension bridge.

For stiffened beams made of reinforced concrete, due to the need to withstand the pressure transmitted by the main cable, the rigidity will be increased, a large number of prestressed structures and devices are saved, and the shortcomings of steel under the large axial force are easily overcome.

The use of concrete materials can overcome the shortcomings of the large amount of steel used in previous self-anchored suspension bridges and the high cost of construction and subsequent maintenance, and can achieve good economic and social benefits.

The shape of the traditional suspension bridge is retained, which is a very competitive solution in small and medium span bridges.

Because of the low cost of using reinforced concrete materials, the structure is reasonable, and the appearance of the bridge is beautiful, the injustice is limited to use in areas with poor foundations and difficult anchor construction.

Self-anchored suspension bridges inevitably have their own shortcomings: Because the main cable is directly anchored to the stiffening beam, the beam bears a large axial force. To this end, the cross section of the beam needs to be enlarged. For stiffening beams of steel structures, The cost is significantly increased, and the stiffening beams of concrete materials increase the weight of the main beam, thereby increasing the amount of steel used in the main cable. Therefore, the use of these two materials will be limited in span.

The construction steps are restricted. The main cables and slings must be hoisted after the stiffening beams and bridge towers are completed. Therefore, a large number of temporary supports are required to install the stiffening beams. Therefore, if the span of a self-anchored suspension bridge is increased, the additional construction cost will increase.

Local stresses in the anchoring area are complicated.

Compared to ground-anchored suspension bridges, due to the influence of the non-linearity of the main cable, the construction control when the boom is tensioned is more complicated.

The following data are as of 2017 ^[1]

Serial number Bridge name Main span span completion time location

1 Akashi Kaikyo Bridge 1991m Kobe ~ Awaji Island, 1998

2 Zhoushan West Jianmen Bridge 1650m Zhoushan 2009 Zhejiang China

3 large bridges 1624m Denmark 1998

4 Runyang Yangtze River Bridge 1490m Jiangsu, China 2005

5 Nanjing Yangtze River Fourth Bridge 1418m 2012 Jiangsu, China

6 Humber Bridge 1410m 1981 UK

7 Jiangyin Yangtze River Bridge 1385m Jiangsu, China 1999

8 Tsing Ma Bridge 1377m Hong Kong, China 1997

9 Verrazano Bridge 1298m 1964 United States

10 Golden Gate Bridge 1280m 1937 United States