Bridge

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This article is about the edifice (including an index to articles on specific bridge types). For other uses, see Bridge (disambiguation).

A bridge is a structure built to span a gorge, valley, road, railroad track, river, body of water, or any other physical obstacle. Designs may be built higher than otherwise needed in order to allow other traffic (particularly ship traffic) beneath.

The purpose of a bridge is to allow people or cargo easy passage over an obstacle by providing a route that would otherwise be uneven or impossible.

Contents

[edit] History

Image:Ponrom.jpg
The Roman Bridge of Sertã was actually built during the Philippine Dynasty (1580-1640).

The first bridges were spans made of wooden logs or planks and eventually stones, using a simple support and crossbeam arrangement.

The arch was first used by the Roman Empire for bridges and aqueducts, some of which still stand today. The Romans also used cement, which reduced the variation of strength found in natural stone. Brick and mortar bridges were built after the Roman era, as the technology for cement was lost then later rediscovered.

Rope bridges, a simple type of suspension bridge, were used by the Inca civilization in the Andes mountains of South America, just prior to European colonization in the 1500s.

During the 18th century there were many innovations in the design of timber bridges by Hans Ulrich, Johannes Grubenmann, and others. The first engineering book on building bridges was written by Hubert Gautier in 1716.

With the Industrial Revolution in the 19th century, truss systems of wrought iron were developed for larger bridges, but iron did not have the tensile strength to support large loads. With the advent of steel, which has a high tensile strength, much larger bridges were built, many using the ideas of Gustave Eiffel.

[edit] Etymology

The Oxford English Dictionary traces the origin of the word bridge to an Old English word brycg, of the same meaning, derived from a hypothetical Proto-Germanic root brugjō. There are cognates in other Germanic languages (for instance Brücke in German, brug in Dutch or bro in Danish and Swedish).

The word for the Pope, pontiff, comes from the Latin word pontifex meaning "bridge builder".

[edit] Types of bridges

Image:Golden gate San-Francisco.jpg
The Golden Gate Bridge, a suspension bridge, connects the city of San Francisco with the south-facing Marin County. The bridge carries 6 lanes of traffic, pedestrians, and bicycles.

There are four main types of bridges: beam bridges, cantilever bridges, arch bridges and suspension bridges.

[edit] By use

A bridge is designed for trains, pedestrian or road traffic, a pipeline or waterway for water transport or barge traffic. In some cases there may be restrictions in use. For example, it may be a bridge carrying a highway and forbidden for pedestrians and bicycles, or a pedestrian bridge, possibly also for bicycles.

An aqueduct is a bridge that carries water, resembling a viaduct, which is a bridge that connects points of equal height.

[edit] Decorative and ceremonial bridges

To create a beautiful image, some bridges are built much taller than necessary. This type, often found in east-asian style gardens, is called a Moon bridge, evoking a rising full moon.

Other garden bridges may cross only a dry bed of stream washed pebbles, intended only to convey an impression of a stream.

Often in palaces a bridge will be built over an artificial waterway as symbolic of a passage to an important place or state of mind. A set of five bridges cross a sinuous waterway in an important courtyard of the Forbidden City in Beijing, the People's Republic of China. The central bridge was reserved exclusively for the use of the Emperor, Empress, and their attendants.

[edit] Index to types of bridges

[edit] Index to bridge related topics

[edit] Bridge structural and evolutionary taxonomy

Image:BridgeTaxonomyBW.png
A bridge taxonomy showing evolutionary relationships

Bridges may be classified by how the four forces of tension, compression, bending and shear are distributed through their structure. Most bridges will employ all of the principle forces to some degree, but only a few will predominate. The separation of forces may be quite clear. In a suspension or cable-stayed span, the elements in tension are distinct in shape and placement. In other cases the forces may be distributed among a large number of members, as in a truss, or not clearly discernible to a casual observer as in a box beam. Bridges can also be classified by their lineage, which is shown as the vertical axis on the diagram to the right.

[edit] Efficiency

A bridge's structural efficiency may be considered to be the ratio of load carried to bridge weight, given a specific set of material types. In one common challenge students are divided into groups and given a quantity of wood sticks, a distance to span, and glue, and then asked to construct a bridge that will be tested to destruction by the progressive addition of load at the center of the span. The bridge taking the greatest load is by this test the most structurally efficient. A more refined measure for this exercise is to weigh the completed bridge rather than measure against a fixed quantity of materials provided and determine the multiple of this weight that the bridge can carry, a test that emphasizes economy of materials and efficient glue joints (see balsa wood bridge).

A bridge's economic efficiency will be site and traffic dependent, the ratio of savings by having a bridge (instead of, for example, a ferry, or a longer road route) compared to its cost. The lifetime cost is composed of materials, labor, machinery, engineering, cost of money, insurance, maintenance, refurbishment, and ultimately, demolition and associated disposal, recycling, and reuse. Bridges employing only compression are relatively inefficient structurally, but may be highly cost efficient where suitable materials are available near the site and the cost of labor is low. For medium spans, trusses or box beams are usually most economical, while in some cases, the appearance of the bridge may be more important than its cost efficiency. The longest spans usually require suspension bridges.

[edit] Notable bridges

Brian MacQuarrie. "View from a bridge", The Boston Globe, October 8, 2006. Retrieved on 2006-10-08.</ref>,first bridge to use a nitrogen gas enclosed around each cable stay<ref> Tanya Mitchell. "Just the facts", VillageSoup, September 28, 2006. Retrieved on 2006-10-08.</ref>.

[edit] Special Installations

Some bridges carry special installations such as the tower of Nový Most bridge in Bratislava which carries a restaurant. On other suspension bridge towers transmission antennas are installed.

A bridge can carry overhead powerlines as the Storstrøm Bridge.

[edit] Catastrophic collapses

Bridge Town Country Date Construction type, use of bridge Reason Number death/injuries Damage Remarks
Stirling Bridge Stirling Scotland September 1297 Beam and trestle over the River Forth Overload by attackers during the Battle of Stirling Bridge Unknown, attacking forces defeated Bridge rendered unusable Collapse may have been assisted by defending forces.
Bridge of Angers (France) Angers France April 16 1850 Suspension bridge over Maine River Resonance of soldiers led to collapse 226/? Bridge total damage Marching columns now break step when crossing bridges.
Yarmouth Bridge Great Yarmouth England May 2 1845 Suspension People had crowded onto the bridge to see a circus clown go down the river in a barrel pulled by geese. The weight of people shifted as the barrel passed underneath, the suspension chains on the south side snapped and the bridge deck tipped over. 79 people drowned, mainly children. Suspension chains snapped due to overload. [1]
Tay Rail Bridge Dundee Scotland December 28 1879 Continuous girder bridge, steel framework on cast iron columns, railway bridge Insufficient consideration of the wind load, inadequate construction, collapsed because of the stresses caused by a storm 75/0 Bridge unusable, piers partly reused, train heavily damaged Locomotive was saved from the Tay and was still in use 19 years later known as "The Diver".
Québec Bridge Quebec Canada August 29 1907 Cantilever bridge, steel framework, railway bridge Collapsed during construction 74/11 Bridge completely destroyed  
Theodor-Heuss-Rhine River Bridge Ludwigshafen Germany March 1940 Bridge of concrete, Motorway bridge Collapsed during construction  ?/? Bridge totally destroyed Resulted in delay in completion of the motorway crossing of the Rhine until 1953
Tacoma Narrows Bridge Tacoma, WA USA November 7 1940 Road bridge, cable suspension with plate girder deck Aerodynamically poor form resulted in resonance No Bridge partially destroyed, one car lost, and one dog killed Became known as "Galloping Gertie", in the first 4 months after opening up until its collapse under a previously unseen resonant mode. Since that time all new bridges have been modelled in wind tunnels.
The bridge at Remagen Remagen Germany March 17 1945 Truss railroad and pedestrian bridge Collapse due to previous battle damage incurred March 7th, 1945 28 U.S. soldiers Total destruction Capture of intact bridge offered significant short term tactical advantage to Allied forces. Collapse was not strategically significant due to placement of parallel floating bridges during the previous week
Harrow and Wealdstone rail crash Wealdstone England October 8 1952 Pedestrian footbridge Struck by train(s) during accident 112 dead 340 injured Total destruction It is not recorded how many casualties were due to the bridge collapse
Tangiwai railway bridge Tangiwai New Zealand December 24 1953 Railway bridge Damaged by lahar minutes before passenger train passed over it. 134/151 Bridge destroyed
General Rafael Urdaneta Bridge Maracaibo Venezuela April 6 1964 Road bridge Ship collision 7 2 section collapsed Currently in Operation
Silver Bridge USA 15 December 1967 Road bridge, chain link suspension Material fault and Corrosion 46/9 Bridge and 37 vehicles destroyed  
West Gate Bridge Melbourne Australia October 15, 1970 Road Bridge Collapse during construction 35 112 metre span between piers 10 and 11 collapsed Section sprung back and collapse during attempts to remove a buckle cause by a difference in camber of 4.5 inches  
South Bridge Koblenz Koblenz Germany 10 November 1971 Road bridge Bridge bent into Rhine 13/? Bridge completely destroyed  
Reichsbrücke Vienna Austria August 1, 1976 Road bridge with Tram Column fractured 1/0 Bridge, one bus and a lorry destroyed, ships damaged Concrete of the column had never been examined, was internally totally destroyed; "higher force"
Tasman Bridge Hobart Tasmania, Australia January 5, 1975 Bridge of concrete, Motorway bridge Ore freighter Lake Illawarra collided with pylons. Section of bridge collapsed onto frieghter. Four cars fell into the river. 7 ship crewman and 5 motorists killed 2 pylons and three sections of bridge collapsed, ore freighter sank, 5 cars fell into river City of Hobart was split in two. Residents living in the east were forced to make a 50km trip to the CBD via the next bridge up north. Bridge was reconstructed and reopened on October 8, 1977
Almö Bridge Stenungsund Sweden January 18, 1980 Bridge with bow built of concrete Ship collision 8/? Bridge and several cars destroyed  
Sunshine Skyway Bridge USA 1980 Steel Cantilever Bridge Ship collision 35/? 1200 ft. of southbound span, several cars and a bus destroyed Demolished and replaced with cable-stayed bridge
Aschaffenburg Main River Freeway Bridge Aschaffenburg Germany 1988 Bridge of Motorway A 3 over River Main Error in construction 1/0 Bridge total damage Partial collapse at Repetitive sliding
Bridge over railway line at Eschede Eschede Germany June 3, 1998 Road bridge Train disaster 101/105   Destruction by train crashing on pillar, killed and injured people were train passengers
Loncomilla Bridge near San Javier Chile November 18, 2004 Concrete bridge for vehicle traffice over Maule River The structure was not build on rock, but rather on fluvial ground. 0/8 Partial collapse Bridge was later repaired
Motorway bridge at Almuñecar, Province of Granada, Spain (search correct name of bridge) Almuñecar Spain November 7 2005 Motorway bridge Construction, accident, reason unknown 6/3   A 60 metre long part fell 50 metre deep
Viaducto No.1 Caracas - La Guaira motorway Tacagua, Venezuela Tacagua Venezuela January 8 2006 Motorway bridge Various factors 0/0 Bridge rendered unusable Demolished, it will be replaced with a new one

[edit] References

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[edit] See also

Wikimedia Commons has media related to:

[edit] External links

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Bridge

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