Arch bridge DesignThrough arch bridgeCantilever bridgeArch bridge structural analysisTied-arch bridgeChenab bridgearch bridge中文NOVA Online | Super Bridge | Arch Bridges - PBS
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Arch bridges are one of the oldest types of bridges and have great natural strength. Instead of pushing straight down, the weight of an arch bridge is ... ArchBridge ArchBridge BixbyCreekBridge,Monterey,CA Archbridgesareoneoftheoldesttypesofbridgesandhavegreatnatural strength.Insteadofpushingstraightdown,theweightofanarchbridgeis carriedoutwardalongthecurveofthearchtothesupportsateachend.These supports,calledtheabutments,carrytheloadandkeeptheendsofthebridge fromspreadingout. TryIt! Howdotheabutmentssupportanarchbridge? Cutastripofcardboardthat'saboutoneinchby11inches.Gentlybendthe stripsothatithasacurve.Positionthecardboardonatablesothatit resemblesanarch.Pressdownonthecenterofthearch.Whathappenstothe endsofthecardboard? Next,placeastackofbooksateachendofthearch.Pressagain.Nowwhat happens?Noticehowthestacksofbooksactasabutments,keepingtheendsof thearchfromspreadingapart. Whensupportingitsownweightandtheweightofcrossingtraffic,everypart ofthearchisundercompression.Forthisreason,archbridgesmustbemadeof materialsthatarestrongundercompression. ThePontduGardaqueduct TheRomansusedstones.Oneofthemostfamousexamplesoftheirhandiworkis thePontduGardaqueductnearNîmes,France.Builtbeforethebirthof Christ,thebridgeisheldtogetherbymortaronlyinitstoptier;thestones intherestofthestructurestaytogetherbythesheerforceoftheirown weight. TheNewRiverbridge Todaymaterialslikesteelandpre-stressedconcretehavemadeitpossibleto buildlongerandmoreelegantarches,includingaspectacular1700footspanin NewRiverGorge,WestVirginia.(Moretypically,modernarchbridgesspan between200-800feet.) Centeringunderconstruction Constructinganarchbridgecanbetricky,sincethestructureiscompletely unstableuntilthetwospansmeetinthemiddle.Onetechniqueistobuild elaboratescaffolding,or"centering,"belowthespanstosupportthemuntil theymeet.Anewermethodsupportsthespansusingcablesanchoredtothe Archconstructionusingcablesupports groundoneithersideofthebridge.Insituationswherethereisanactive waterorroadwaybelow,thismethodallowscontractorstobuildwithout disruptingtraffic. TheNatchezTracebridge OneofthemostrevolutionaryarchbridgesinrecentyearsistheNatchezTrace BridgeinFranklin,Tennessee,whichwasopenedtotrafficin1994.It'sthe firstAmericanarchbridgetobeconstructedfromsegmentsofpre-cast concrete,ahighlyeconomicalmaterial.Twogracefularchessupportthe roadwayabove.Usuallyarchbridgesemployverticalsupportscalled "spandrels"todistributetheweightoftheroadwaytothearchbelow,butthe NatchezTraceBridgewasdesignedwithoutspandrelstocreateamoreopenand aestheticallypleasingappearance.Asaresult,mostoftheliveload isrestingonthecrownsofthetwoarches,whichhavebeenslightlyflattened tobettercarryit.Alreadythewinnerofmanyawards,thebridgeisexpected toinfluencebridgedesignforyearstocome. (backtointro) (nextbridgedescription:beambridge) Photos:(1)Caltrans;(2)©TimHauf/VisualsUnlimited;(3)DavidBowen/WVDOH;(4)Corbis-Bettmann;(5,6)Figg Engineering,Inc. BuildABridge| Resources| Guide| Transcript| BridgeHome Editor'sPicks| PreviousSites| JoinUs/E-mail| TV/WebSchedule AboutNOVA| Teachers| SiteMap| Shop| Jobs| Search| Toprint PBSOnline| NOVAOnline| WGBH ©|UpdatedOctober2000
延伸文章資訊
- 1Arch Bridges - an overview | ScienceDirect Topics
An arch bridge is a bridge shaped as an upward convex curved arch to sustain the vertical loads. ...
- 2Arch Bridge Facts: Lesson for Kids - Study.com
The arch allows the load to spread out instead of pushing straight down. The load spreads out to ...
- 3Facts and Types of Arch Bridges
Arch bridge is one of the most popular types of bridges, which came into use over 3000 years ago ...
- 4arch bridge - Encyclopedia Britannica
The arch bridge carries loads primarily by compression, which exerts on the foundation both verti...
- 5Arch Bridges - Solutions - midasBridge
An arch bridge is a bridge whose main structure is composed of arches or reinforced arches. Arch ...
