Suspension Bridges

Bridge is a structure built to span across a valley, road, body of water, or other physical resistance, for the purpose of providing passage over an obstacle. Bridges are those marvel in civil engineering tool kit which help in connecting the places located on other side of bank. Varieties of bridges have evolved from history. Of them one is suspension bridge. It is constructed to span across water body or valley. Nowadays these are the pioneers in bridge technology. Of all the bridge types in use today, the suspension bridge allows for the longest span ranging from 2,000 to 7,000 feet. Also they have quite attractive view which has added to the gloom of suspension bridges.

Suspension bridge is most commonly built to span across water body. It is built by suspending the roadway from cables attached to a master cable which runs above the length of the bridge. In addition to being strong and lightweight, suspension bridges are also beautiful. The design of a suspension bridge is simple and straightforward, and takes advantage of several techniques to distribute the weight of the bridge safely and evenly.

The main forces in a suspension bridge are tension in the main cables and compression in the pillars. Since almost all the force on the pillars is vertically downwards and they are also stabilized by the main cables, they can be made quite slender.

In a suspended deck bridge, cables suspended via towers hold up the road deck. The weight is transferred by the cables to the towers, which in turn transfer the weight to the ground.

Most of the weight or load of the bridge is transferred by the cables to the anchorage systems. These are imbedded in either solid rock or huge concrete blocks. Inside the anchorages, the cables are spread over a large area to evenly distribute the load and to prevent the cables from breaking free.

cables were replaced by iron which carried more load. Major bridges were still built using a truss design until 1808, when an American inventor named James Finley filed a patent on an early version of a suspension bridge. Finley's design involved stretching two strong chains over the top of several towers and anchoring them on either side of the bridge. He hung lesser chains from the two master chains and used them to suspend a rigid deck, and the modern incarnation of the suspension bridge was born. In 1830, French engineers realized that strongly woven cables were safer than chains, and began to use them in the construction of suspension bridges. Today all use this cabled design, but the basic form of the suspension bridge has remained the same, and engineers continue to push the limits of the spans that suspension bridges can cross.

The construction of bridge seems to be simple, but engineer’s quest for longer span suspension bridge makes the construction a challenge.