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A TYPICAL CABLE STAY BRIDGE
V. Ryan © 2006 - 2024
 

A scientific understanding of the properties of modern materials and the availability of computer software have made it possible to construct new types of bridges. A typical cable stay bridge can be seen below. These are modern bridges designed using computer aided design (CAD). Bridge designers are now able to design a bridge on computer, simulate its use and correct any faults before building begins. Modern materials, especially special steels are used to construct this type of bridge. This means that bridges can be made from lighter, stronger materials and engineered precisely. Today materials are used efficiently.
Older bridges (built in the 19th and early 20th century) such as suspension bridges were designed on paper and the design could not be simulated before being built. Consequently, designers ensured that early steel/stone/concrete bridges were constructed from more materials than were actually required - just in case the final bridge was too weak and collapsed.

   
 
 
 
 

Unlike suspension bridges, cable stay bridges do not need anchor blocks. The cables are fixed to either side of each tower - this means that the weight of each side of the bridge counter balances the opposite side.
The absence of anchor blocks substantially reduces the amount of materials needed and the cost of building the bridge.
Also, the towers tend to be positioned down the centre of the roadway and half as many towers are needed compared to suspension bridges.

   
 
   

Two well known cable stay bridges can be found in France. The ‘Le Pont de Normandie’, can be found in Normandy, Northern France. This was once the longest cable stay bridge in the world. However, this engineering feat has been surpassed in dramatic style by the opening of the Millau Bridge in Southern France. This cable stay bridge is the highest bridge in the world, with its deck almost at the same height as the Eiffel Tower.

 
THE FACTS
 
A Cable Stay Bridge has a deck that is directly supported by the cables, each fixed to the towers at a slightly different angle. Each cable transfers the vertical loads to the towers, produced when supporting the deck.
The weight of the deck is held initially by the towers, with the weight distributed through the cables. The ‘abutments’ at each end of the bridge hold the entire structure in position, transferring the ‘loads’ from the bridge to the ground.
Cable Stay Bridges are usually less expensive to manufacture and construct than suspension bridges. Their cantilever design requires less material, but it does have one disadvantage (see next point).
Due to the nature of their design, cable stay bridges are suited to small to medium spans, rather than long spans.
The Cable Stay design is regarded as more modern looking, due to its straight lines and angles.
 
FAMOUS CABLE STAY BRIDGES
 
Russky Bridge (Russia) - Spanning 1,104 metres.
Sutong Yangtze River Bridge (China) - With a main span of 1,088 metres
Stonecutters Bridge (Hong Kong) - This bridge has a main span of 1,018 metres
Tatara Bridge (Japan) - Spanning 890 metres,
Normandy Bridge (France) - With a main span of 856 metres.
 
 

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