Editing Bridge (section)

===Structure types===
Bridges may be classified by how the actions of [[Tension (mechanics)|tension]], [[compression (physical)|compression]], [[bending]], [[torsion (mechanics)|torsion]] and [[Shear stress|shear]] are distributed through their structure. Most bridges will employ all of these to some degree, but only a few will predominate. The separation of forces and moments may be quite clear. In a [[Suspension bridge|suspension]] or [[cable-stayed bridge]], 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.
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| style="text-align:center;"|[[File:BeamBridge-diagram.svg|200px]]'''Beam bridge'''
|[[Beam bridges]] are horizontal beams supported at each end by substructure units and can be either ''[[simply supported]]'' when the beams only connect across a single span, or ''continuous'' when the beams are connected across two or more spans. When there are multiple spans, the intermediate supports are known as [[bridge pier|piers]]. The earliest beam bridges were simple logs that sat across streams and similar simple structures. In modern times, beam bridges can range from small, wooden beams to large, steel boxes. The vertical force on the bridge becomes a [[Shear stress|shear]] and [[Bending|flexural]] load on the beam which is transferred down its length to the substructures on either side<ref name="beambridge">{{cite web | url=http://www.design-technology.org/beambridges.htm | title=Beam bridges | publisher=Design Technology | access-date=14 May 2008 | url-status=live | archive-url=https://web.archive.org/web/20080518121256/http://www.design-technology.org/beambridges.htm | archive-date=18 May 2008 | df=mdy-all }}</ref> They are typically made of steel, concrete or wood. [[Girder bridge]]s and [[plate girder bridge]]s, usually made from steel, are types of beam bridges. [[Box girder bridge]]s, made from steel, concrete, or both, are also beam bridges. Beam bridge spans rarely exceed {{convert|250|ft|m}} long, as the flexural stresses increase proportionally to the square of the length (and deflection increases proportionally to the 4th power of the length).<ref>[http://www.engineersedge.com/beam_bending/beam_bending1.htm Structural Beam Deflection Stress Bending Equations / Calculation Supported on Both Ends Uniform Loading] {{webarchive|url=https://archive.today/20130122060213/http://www.engineersedge.com/beam_bending/beam_bending1.htm |date=22 January 2013 }}. ''Engineers Edge''. Retrieved on 23 April 2013.</ref> However, the main span of the [[Rio–Niteroi Bridge]], a box girder bridge, is {{convert|300|m|ft}}.<ref>{{cite book |author1=de Vasconcelos, Augusto Carlos |title=Handbook of International Bridge Engineering |author2=Marchesini, Gilson L. |author3=Timerman, Júlio |date=2014 |publisher=CRC Press |isbn=978-1-4398-1029-3 |editor1=Chen, Wai-Fah |location=Boca Raton, Florida |pages=184–186 |chapter=4.4 Steel Box Bridges |editor2=Duan, Lian |chapter-url=https://books.google.com/books?id=fYcAAQAAQBAJ&pg=PA184 |accessdate=26 July 2015}}</ref>

The world's longest beam bridge is [[Lake Pontchartrain Causeway]] in southern [[Louisiana]] in the United States, at {{convert|23.83|mi|km}}, with individual spans of {{convert|56|ft|m}}.<ref>{{cite magazine|date=28 May 1956|title=A big prefabricated bridge|magazine=[[Life (magazine)|Life]]|volume=40|issue=22|pages=53–60}}</ref> Beam bridges are the simplest and oldest type of bridge in use today,<ref>{{cite web|url=http://www.asceville.org/cw_bridges_explore.html|title=Civil What?!: Explore Bridges|website=ASCEville |access-date=2 February 2017|url-status=live|archive-url=https://web.archive.org/web/20170203161112/http://www.asceville.org/cw_bridges_explore.html|archive-date=3 February 2017}}</ref> and are a popular type.<ref>{{Cite journal|title=Forensic Examination of a Noncomposite Adjacent Precast Prestressed Concrete Box Beam Bridge|journal=Journal of Bridge Engineering|volume=15|issue=4|doi=10.1061/(ASCE)BE.1943-5592.0000110|year=2010|pages=408–418 | last1 = Naito | first1 = Clay | last2 = Sause | first2 = Richard | last3 = Hodgson | first3 = Ian | last4 = Pessiki | first4 = Stephen | last5 = Macioce | first5 = Thomas|issn=1084-0702 }}</ref>
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| style="text-align:center;"|[[File:TrussBridge-diagram.svg|200px]]'''Truss bridge'''
| A [[truss bridge]] is a bridge whose load-bearing superstructure is composed of a truss. This truss is a structure of connected elements forming triangular units. The connected elements (typically straight) may be stressed from tension, compression, or sometimes both in response to dynamic loads.<ref>[https://books.google.com/books?id=A3oSAAAAYAAJ Science and Industry] {{Webarchive|url=https://web.archive.org/web/20170215092202/https://books.google.com/books?id=A3oSAAAAYAAJ |date=2017-02-15 }}, Members of a Truss Bridge by Benj. F. La Rue, Home Study Magazine, Published by the Colliery Engineer Company, Vol 3, No. 2, March 1898, pages 67–68.</ref> Truss bridges are one of the oldest types of modern bridges. The basic types of truss bridges shown in this article have simple designs which could be easily analyzed by nineteenth and early twentieth-century engineers. A truss bridge is economical to construct owing to its efficient use of materials.
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| style="text-align:center;"|[[File:CantileverBridge-diagram.svg|200px]]'''Cantilever bridge'''
|[[Cantilever bridge]]s are built using [[cantilever]]s—horizontal beams supported on only one end. Most cantilever bridges use a pair of [[continuous span]]s that extend from opposite sides of the supporting piers to meet at the center of the obstacle the bridge crosses. Cantilever bridges are constructed using much the same materials and techniques as beam bridges. The difference comes in the action of the forces through the bridge.

Some cantilever bridges also have a smaller beam connecting the two cantilevers, for extra strength.

The largest cantilever bridge is the {{convert|549|m|adj=on}} [[Quebec Bridge]] in Quebec, Canada.
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| style="text-align:center;"|[[File:ArchBridge-diagram.svg|200px]]'''Arch bridge'''
|[[Arch bridge]]s have [[abutments]] at each end. The weight of the bridge is thrust into the [[abutments]] at either side. The earliest known arch bridges were built by the Greeks, and include the [[Arkadiko Bridge]].

With the span of {{convert|220|m}}, the [[Solkan Bridge]] over the [[Soča]] River at [[Solkan]] in Slovenia is the second-largest stone bridge in the world and the longest railroad stone bridge. It was completed in 1905. Its arch, which was constructed from over {{convert|5000|t}} of stone blocks in just 18 days, is the second-largest stone arch in the world, surpassed only by the Friedensbrücke (Syratalviadukt) in [[Plauen]], and the largest railroad stone arch. The arch of the Friedensbrücke, which was built in the same year, has the span of {{convert|90|m|0|abbr=on}} and crosses the valley of the [[Syrabach]] River. The difference between the two is that the Solkan Bridge was built from stone blocks, whereas the Friedensbrücke was built from a mixture of crushed stone and cement mortar.<ref>{{cite conference |url=https://books.google.com/books?id=E7ywmb24EQMC&q=%22world+famous+arch+bridges+in+slovenia%22&pg=PA121 |title=World Famous Arch Bridges in Slovenia |language=en, fr |author=Gorazd Humar |date=September 2001 |publisher=Presses des Ponts |book-title=Arch'01: troisième Conférence internationale sur les ponts en arc Paris |editor=Charles Abdunur |pages=121–124 |location=Paris |isbn=2-85978-347-4 |url-status=live |archive-url=https://web.archive.org/web/20160730012023/https://books.google.com/books?id=E7ywmb24EQMC&lpg=PA121&dq=%22world%20famous%20arch%20bridges%20in%20slovenia%22&pg=PA121#v=onepage&q=%22world%20famous%20arch%20bridges%20in%20slovenia%22&f=false |archive-date=30 July 2016}}</ref>

The world's largest arch bridge is the [[Chaotianmen Bridge]] over the [[Yangtze River]] with a length of {{convert|1741|m|ft|0|abbr=on}} and a span of {{convert|552|m|ft|0|abbr=on}}. The bridge was opened 29 April 2009, in [[Chongqing]], China.<ref name=Chaotianmen>{{cite web | url=http://www.guinnessworldrecords.com/records-1/longest-bridge-steel-arch-bridge/# | publisher=Guinness World Records | access-date=18 February 2013 | title=Longest bridge, steel arch bridge | archive-url=https://web.archive.org/web/20131019124452/http://www.guinnessworldrecords.com/records-1/longest-bridge-steel-arch-bridge/ | archive-date=19 October 2013 | df=mdy-all }}</ref>
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| style="text-align:center;"|[[File:TiedarchBridge-diagram.svg|200px]]'''Tied&nbsp;arch bridge'''
|[[Tied-arch bridge]]s have an arch-shaped superstructure, but differ from conventional arch bridges. Instead of transferring the weight of the bridge and traffic loads into thrust forces into the abutments, the ends of the arches are restrained by tension in the bottom chord of the structure.<ref>{{cite web |url=http://www.bath.ac.uk/ace/uploads/StudentProjects/Bridgeconference2009/Papers/MASKELL.pdf |title=A Critical Analysis of North Shore Footbridge, Stockton-on-Tees, UK |first=Daniel |last=Maskell |work=Proceedings of Bridge Engineering 2 Conference 2009 |publisher=bath.ac.uk |year=2009 |access-date=11 December 2009 |quote=Under vertical  dead  loads  and  uniform  imposed  loads  the arches  support  the  loads  under  pure  axial compression with  the  deck  edge  cables  acting  as  horizontal  ties.}}</ref> They are also called bowstring arches.
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| style="text-align:center;"|[[File:SuspensionBridge-diagram.svg|200px]]'''Suspension bridge'''
|[[Suspension bridges]] are suspended from cables. The earliest suspension bridges were made of ropes or vines covered with pieces of bamboo. In modern bridges, the cables hang from towers that are attached to caissons or cofferdams. The caissons or cofferdams are implanted deep into the bed of the lake, river or sea. Sub-types include the [[simple suspension bridge]], the [[stressed ribbon bridge]], the [[underspanned suspension bridge]], the [[suspended-deck suspension bridge]], and the [[self-anchored suspension bridge]]. There is also what is sometimes called a "semi-suspension" bridge, of which the [[Ferry Bridge, Burton|Ferry Bridge]] in Burton-upon-Trent is the only one of its kind in Europe.<ref>''A.O.P. Guide to Burton-on-Trent'', 1911, p. 13{{full citation needed|date=November 2019}}</ref>

The longest suspension bridge in the world is the {{convert|4608|m|0|abbr=on}} [[1915 Çanakkale Bridge]] in Turkey.
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| style="text-align:center;"|[[File:CableStayedBridge-diagram.svg|200px]]'''Cable-stayed bridge'''
|[[Cable-stayed bridge]]s, like suspension bridges, are held up by cables. However, in a cable-stayed bridge, less cable is required and the towers holding the cables are proportionately higher.<ref name=cable>{{cite web | url=http://www.newton.dep.anl.gov/askasci/eng99/eng99373.htm | title=Cable Stay vs Suspension Bridges | first=Andy | last=Johnson | publisher=U.S. Department of Energy | url-status=live | archive-url=https://web.archive.org/web/20080518142005/http://www.newton.dep.anl.gov/askasci/eng99/eng99373.htm | archive-date=18 May 2008 | df=mdy-all }}</ref> The first known cable-stayed bridge was designed in 1784 by C. T. (or C. J.) Löscher.<ref>{{cite book|url = https://books.google.com/books?id=AhSgrMcT4sgC&q=loescher+cable-stayed&pg=PA5 |title = Cable Stayed Bridges|page = 7|url-status = live|first =René|date = 1999 |last=Walther | publisher=Thomas Telford |archive-url=https://web.archive.org/web/20161115132533/https://books.google.ca/books?id=AhSgrMcT4sgC&pg=PA5&lpg=PA5&dq=loescher+cable-stayed&source=bl&ots=Ldmb12QZ67&sig=Au-TF0YlWc2pQOrtw7CmDufITds&hl=en&sa=X&ei=LfenUZXOLqri0QGCtoFo&ved=0CCwQ6AEwAA |archive-date=15 November 2016 |isbn = 978-0-7277-2773-2}}</ref><ref>{{cite web|url = http://www.contech.co.nz/uploaded/Marcel%20Poser%20-%20Cable%20Stayed%20Structures%20and%20Stay%20Cable%20Technology.pdf |title = Cable Stayed Structures and Stay Cable Technology|last = Poser|first =Marcel |archive-url=https://web.archive.org/web/20130209123954/http://www.contech.co.nz/uploaded/Marcel%20Poser%20-%20Cable%20Stayed%20Structures%20and%20Stay%20Cable%20Technology.pdf |archive-date=9 February 2013 }}</ref>

The longest cable-stayed bridge since 2012 is the {{convert|1104|m|0|abbr=on}} [[Russky Bridge]] in [[Vladivostok]], Russia.<ref>{{cite news|work=The Guardian|date=2 July 2012|author=Elder, Miriam|location=London|title=Russian city of Vladivostok unveils record-breaking suspension bridge|url=https://www.theguardian.com/world/2012/jul/02/russian-vladivostok-record-suspension-bridge|access-date=3 February 2016|url-status=live|archive-url=https://web.archive.org/web/20160120162508/http://www.theguardian.com/world/2012/jul/02/russian-vladivostok-record-suspension-bridge|archive-date=20 January 2016}}</ref>
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Some Engineers sub-divide 'beam' bridges into slab, beam-and-slab and box girder on the basis of their cross-section.<ref name=":1" /> A slab can be solid or [[hollow-core slab|voided]] (though this is no longer favored for inspectability reasons) while beam-and-slab consists of concrete or steel girders connected by a concrete slab.<ref name=":2" /> A [[Box girder bridge|box-girder]] cross-section consists of a single-cell or multi-cellular box. In recent years, [[integral bridge]] construction has also become popular.