A suspension bridge usually has main cables (else ropes or chains), anchored at each end of the

bridge A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...

. Any load applied to the bridge is transformed into a tension in these main cables. The earliest suspension bridges had the cables anchored in the ground at either end of the bridge, but some modern suspension bridges anchor the cables to the ends of the bridge itself. The earliest suspension bridges had no towers or piers, but these are present in the majority of larger suspension bridges. Although the earlier types of suspension bridges are suitable only for relatively short spans, all of the 14 longest bridges in the world are suspension bridges (see

List of longest suspension bridge spans The world's longest suspension bridges are listed according to the length of their main span (i.e. the length of suspended roadway between the bridge's towers). The length of main span is the most common method of comparing the sizes of suspen ...

). Ignoring the possibility of

pre-Columbian trans-oceanic contact Pre-Columbian transoceanic contact theories are speculative theories which propose that possible visits to the Americas, possible interactions with the indigenous peoples of the Americas, or both, were made by people from Africa, Asia, Europe, ...

, there were two independent inventions of the suspension bridge, in

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...

(probably in China) and in Central and South America.

Types

Types of suspension bridge include the following: A pure suspension bridge is one without additional stay cables and in which the main cables are anchored in the ground. This includes most simple suspension bridges and suspended-deck suspension bridges, and excludes self-anchored suspension bridges.

Hybrid types

Some suspension bridges are of unusual hybrid types. Among these are suspension bridges that have an "intermediate deck". pages 517-520 These bridges have a portion of deck that resembles an underspanned suspension bridge. Some of the earliest suspended-deck suspension bridges were of this type, and they continue to be constructed. Examples constructed in the 20th century include a viaduct over the river Oberargen near Wangen, Germany. A

span Span may refer to: Science, technology and engineering * Span (unit), the width of a human hand * Span (engineering), a section between two intermediate supports * Wingspan, the distance between the wingtips of a bird or aircraft * Sorbitan ester ...

of the viaduct has a cable support below the deck, with one end of the cable anchored at a pier and the other end tied into a conventional cable stay. The underspanned portion of the span is long and has three vertical members. The

Akashi Kaikyō Bridge The is a suspension bridge which links the city of Kobe on the Japanese island of Honshu to Iwaya on Awaji Island. It is part of the Kobe-Awaji-Naruto Expressway, and crosses the busy and turbulent Akashi Strait (''Akashi Kaikyō'' in Japanese ...

, one of the longest suspension bridges in the world, is a suspended-deck suspension bridge with a stiff

truss girder A truss is an assembly of ''members'' such as beams, connected by ''nodes'', that creates a rigid structure. In engineering, a truss is a structure that "consists of two-force members only, where the members are organized so that the assembl ...

deck. Its main

is 1,991 meters long.

Construction

Unlike many other types of bridge, suspension bridges often can be built without use of

falsework Falsework consists of temporary structures used in construction to support a permanent structure until its construction is sufficiently advanced to support itself. For arches, this is specifically called centering. Falsework includes temporary s ...

. In many cases, the main cables are constructed first, then the deck is added. This often involves the use of a pilot cable. For details of their construction methods, see the articles about each type of bridge. Provided the cables are of sufficiently high quality, suspension bridges are suitable for the longest spans. However, their construction costs are high, so that usually they are economical only for spans in excess of 1000 feet. Shorter spans often are constructed for aesthetic reasons. The economy of longer span suspension bridges is due to their relatively low weight, but because of the greater flexibility that comes with low weight these bridges are more suitable as

road bridge A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...

s than railroad bridges. page 15.7

References

External links

"Suspension bridge"
''Encyclopædia Britannica'' {{Set index article + Bridges by structural type

Types

Hybrid types

Construction

See also

References

External links