Cable-stayed type

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. The newest type of bridge is the cable-stayed bridge. They have great popularity in recent years because of their great beauty and economy.

These modern bridges are 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 stayed 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 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.

Suspension type	Cable-stayed type
http://commons.wikimedia.org/wiki/File:Bridge-harp-cable-stayed.svg

Source: http://www.aiacincinnati.org/community/abc/curriculum/fivebridgetypes.pdf