Shahadat Hossain Shakil (shshakil.buet@gmail.com)

BRIDGE

A bridge is a structure built to span a gorge, valley, road, railroad track, river, body of water, or

any other physical obstacle, for the purpose of providing passage over the obstacle. Designs of

bridges will vary depending on the function of the bridge and the nature of the terrain where the

bridge is to be constructed.

Types of bridges

There are six main types of bridges: beam bridges, cantilever bridges, arch bridges, suspension

bridges, cable-stayed bridges and truss bridges.

1. Beam Bridge

Beam Bridges are a direct descendant of the log bridge; now more commonly made from

shallow steel 'I' beams, box girders, reinforced concrete, or post-tensioned concrete. It is

frequently used in pedestrian bridges and for highway overpasses and flyovers. As is its ancestor,

this bridge is in structural terms the simplest of the many bridge types.

Bridge 1 A steel pedestrian footbridge over a busy road in Swansea, Wales (UK).

2. Cantilever bridge

A cantilever bridge is a bridge built using cantilevers, structures that project horizontally into

space, supported on only one end. For small footbridges, the cantilevers may be simple beams;

however, large cantilever bridges designed to handle road or rail traffic use trusses built from

structural steel, or box girders built from prestressed concrete. The steel truss cantilever bridge

was a major engineering breakthrough when first put into practice, as it can span distances of

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Shahadat Hossain Shakil (shshakil.buet@gmail.com)

over 1,500 feet (460 m), and can be more easily constructed at difficult crossings by virtue of

using little or no false work.

Bridge 2 Forth Bridge Edinburgh.

3. Arch bridge

An arch bridge is a bridge with abutments at each end shaped as a curved arch. Arch bridges

work by transferring the weight of the bridge and its loads partially into a horizontal thrust

restrained by the abutments at either side. A viaduct (a long bridge) may be made from a series

of arches, although other more economical structures are typically used today.

Bridge 3 Alcántara roman Bridge, Spain.

Types of Arch Bridge

Aqueducts and canal viaducts Supported deck arch bridge

Suspended deck arch bridge

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Tied arch bridge

4. Suspension bridge

A suspension bridge is a type of bridge where the main load-bearing elements are hung from

suspension cables. While modern suspension bridges with level decks date from the early

19th century, earlier types are reported from the 3rd century BC. Simple suspension bridges,

for use by pedestrians and livestock, are still constructed, based upon the ancient Inca rope

bridge.

Bridge 4 Tsing Yi-Ma Wan, Hong Kong

5. Cable-stayed bridges

A cable-stayed bridge is a bridge that consists of one or more columns (normally referred to as

towers or pylons), with cables supporting the bridge deck.

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Bridge 5 The Rio-Antirio bridge in Greece

Types

Side-spar cable-stayed bridge

Cantilever-spar cable-stayed bridge

Multiple span cable-stayed bridge

Extra dosed bridge

Cable-stayed cradle System Bridge

6. Truss bridge

A truss bridge is a bridge composed of connected elements (typically straight) which may be

stressed from tension, compression, or sometimes both in response to dynamic loads. Truss

bridges are one of the oldest types of modern bridges.

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Bridge 6 General Hertzog Bridge over the Orange River at Aliwal North

Use

A bridge is designed for trains, pedestrian or road traffic, a pipeline or waterway for water transport or barge traffic. An aqueduct is a bridge that carries water, resembling a viaduct, which is a bridge that connects points of equal height. A road-rail bridge carries both road and rail traffic.

Abuse

Bridges are subject to unplanned uses as well. The areas underneath some bridges have become

makeshift shelters and homes to homeless people, and the undersides of bridges all around the

world are spots of prevalent graffiti. Some bridges attract people attempting suicide, and become

known as suicide bridges.

Double-decker Bridge

Double-decker bridges have two levels, such as the San Francisco – Oakland Bay Bridge, with

two road levels. Tsing Ma Bridge and Kap Shui Mun Bridge in Hong Kong have six lanes on

their upper decks, and on their lower decks there are two lanes and a pair of tracks for MTR

metro trains. Some double-decker bridges only use one level for street traffic; the Washington

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Avenue Bridge in Minneapolis reserves its lower level for automobile traffic and its upper level

for pedestrian and bicycle traffic (predominantly students at the University of Minnesota.

Bridge 7 Moscow's Vorobyovy Gory metro station of Sokolnicheskaya Line (at night).

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