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Advantages and Disadvantages of Suspension Bridge
Ever heard of suspension bridge? and wonder what of its advantages and disadvantages of suspension bridge ? Suspension bridge is a type of bridge in which the deck (the load-bearing portion) is hung below suspension cables on vertical suspenders. The first modern examples of this type of bridge were built in the early 19th century.
Simple suspension bridges, which lack vertical suspenders, have a long history in many mountainous parts of the world. A suspension bridge is any type of bridge that makes significant use of tension rather than or in addition to compression. A suspension bridge usually has main cables (else ropes or chains), anchored at each end of the bridge.
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). Ignoring the possibility of pre-Columbian trans-oceanic contact, there were two independent inventions of the suspension bridge, in Eurasia (probably in China) and in Central and South America.
Advantages of Suspension Bridge
- Longer main spans are achievable than with any other type of bridge
- Less material may be required than other bridge types, even at spans they can achieve, leading to a reduced construction cost
- Except for installation of the initial temporary cables, little or no access from below is required during construction, for example allowing a waterway to remain open while the bridge is built above
- May be better able to withstand earthquake movements than heavier and more rigid bridges
- Bridge decks can have deck sections replaced in order to widen traffic lanes for larger vehicles or add additions width for separated cycling/pedestrian paths.
Disadvantages of Suspension Bridge
- Considerable stiffness or aerodynamic profiling may be required to prevent the bridge deck vibrating under high winds
- The relatively low deck stiffness compared to other (non-suspension) types of bridges makes it more difficult to carry heavy rail traffic where high concentrated live loads occur
- Some access below may be required during construction, to lift the initial cables or to lift deck units. This access can often be avoided in cable-stayed bridge construction
Types of Suspension Bridge
- Simple suspension bridge - the earliest known type of suspension bridge, and usually a footbridge. The deck is flexible and lies on the main cables, which are anchored to the earth.
- Underspanned suspension bridge - an early 19th century descendant of the simple suspension bridge. The deck is raised on posts above the main cables.
- Stressed ribbon bridge - a modern descendant of the simple suspension bridge. The deck lies on the main cables, but is stiff, not flexible.
- Suspension bridge - the most familiar type. Though technically all the types listed here are suspension bridges, when unqualified with adjectives the term commonly refers to a suspended-deck suspension bridge,. This type is suitable for use by heavy vehicles and light rail The main cables are anchored to the earth. The deck is carried below the main cables by "suspenders" and usually is stiff.
- Self-anchored suspension bridge - a modern descendant of the suspension bridge, combining elements of a cable-stayed bridge. The main cables are anchored to the ends of the decks.
