外文翻译文档格式.docx
《外文翻译文档格式.docx》由会员分享,可在线阅读,更多相关《外文翻译文档格式.docx(8页珍藏版)》请在冰豆网上搜索。
题目:
桥梁工程和桥梁美学
Title:
:
BRIDGEENGINEERINGANDAESTHETICS
专业:
土木工程
班级:
土木111班
学号:
110711132
姓名:
傅明涛
指导教师:
庞传琴
完成日期:
2016年6月11日
EvolvementofbridgeEngineering,briefreview
AmongtheearlydocumentedreviewsofconstructionmaterialsandstructuretypesarethebooksofMarcusVitruviosPolliointhefirstcenturyB.C.ThebasicprinciplesofstaticsweredevelopedbytheGreeks,andwereexemplifiedinworksandapplicationsbyLeonardodaVinci,Cardeno,andGalileo.Inthefifteenthandsixteenthcentury,engineersseemedtobeunawareofthisrecord,andreliedsolelyonexperienceandtraditionforbuildingbridgesandaqueducts.ThestateoftheartchangedrapidlytowardtheendoftheseventeenthcenturywhenLeibnitz,Newton,andBernoulliintroducedmathematicalformulations.PublishedworksbyLahire(1695)andBelidor(1792)aboutthetheoreticalanalysisofstructuresprovidedthebasisinthefieldofmechanicsofmaterials.
Kuzmanovic(1977)focusesonstoneandwoodasthefirstbridge-buildingmaterials.Ironwasintroducedduringthetransitionalperiodfromwoodtosteel.Accordingtorecentrecords,concretewasusedinFranceasearlyas1840forabridge39feet(12m)longtospantheGaroyneCanalatGrisoles,butreinforcedconcretewasnotintroducedinbridgeconstructionuntilthebeginningofthiscentury.Prestressedconcretewasfirstusedin1927.
Stonebridgesofthearchtype(integratedsuperstructureandsubstructure)wereconstructedinRomeandotherEuropeancitiesinthemiddleages.Thesearcheswerehalf-circular,withflatarchesbeginningtodominatebridgeworkduringtheRenaissanceperiod.Thisconceptwasmarkedlyimprovedattheendoftheeighteenthcenturyandfoundstructurallyadequatetoaccommodatefuturerailroadloads.Intermsofanalysisanduseofmaterials,stonebridgeshavenotchangedmuch,butthetheoreticaltreatmentwasimprovedbyintroducingthepressure-lineconceptintheearly1670s(Lahire,1695).Thearchtheorywasdocumentedinmodeltestswheretypicalfailuremodeswereconsidered(Frezier,1739).Culmann(1851)introducedtheelasticcentermethodforfixed-endarches,andshowedthatthreeredundantparameterscanbefoundbytheuseofthreeequationsofcoMPatibility.
WoodentrusseswereusedinbridgesduringthesixteenthcenturywhenPalladiobuilttriangularframesforbridgespans10feetlong.Thiseffortalsofocusedonthethreebasicprinciplesogbridgedesign:
convenience(serviceability),appearance,andendurance(strength).severaltimbertrussbridgeswereconstructedinwesternEuropebeginninginthe1750swithspansupto200feet(61m)supportedonstonesubstructures.SignificantprogresswaspossibleintheUnitedStatesandRussiaduringthenineteenthcentury,promptedbytheneedtocrossmajorriversandbyanabundanceofsuitabletimber.Favorableeconomicconsiderationsincludedinitiallowcostandfastconstruction.
Thetransitionfromwoodenbridgestosteeltypesprobablydidnotbeginuntilabout1840,althoughthefirstdocumenteduseofironinbridgeswasthechainbridgebuiltin1734acrosstheOderRiverinPrussia.Thefirsttrusscompletelymadeofironwasin1840intheUnitedStates,followedbyEnglandin1845,Germanyin1853,andRussiain1857.In1840,thefirstironarchtrussbridgewasbuiltacrosstheErieCanalatUtica.
TheImpetusofAnalysis
Thetheoryofstructures,developedmainlyintheninetheenthcentury,focusedontrussanalysis,withthefirstbookonbridgeswrittenin1811.TheWarrentriangulartrusswasintroducedin1846,supplementedbyamethodforcalculatingthecorrecetforces.I-beamsfabricatedfromplatesbecamepopularinEnglandandwereusedinshort-spanbridges.
In1866,Culmannexplainedtheprinciplesofcantilevertrussbridges,andoneyearlaterthefirstcantileverbridgewasbuiltacrosstheMainRiverinHassfurt,Germany,withacenterspanof425feet(130m).ThefirstcantileverbridgeintheUnitedStateswasbuiltin1875acrosstheKentuckyRiver.AmostimpressiverailwaycantileverbridgeinthenineteenthcenturywastheFirstofForthbridge,builtbetween1883and1893,withspanmagnitudesof1711feet(521.5m).
Ataboutthesametime,structuralsteelwasintroducedasaprimematerialinbridgework,althoughitsqualitywasoftenpoor.SeveralearlyexamplesaretheEadsbridgeinSt.Louis;
theBrooklynbridgeinNewYork;
andtheGlasgowbridgeinMissouri,allcompletedbetween1874and1883.
AmongtheanalyticalanddesignprogresstobementionedarethecontributionsofMaxwell,particularlyforcertainstaticallyindeterminatetrusses;
thebooksbyCremona(1872)ongraphicalstatics;
theforcemethodredefinedbyMohr;
andtheworksbyClapeyronwhointroducedthethree-momentequations.
TheImpetusofNewMaterials
Sincethebeginningofthetwentiethcentury,concretehastakenitsplaceasoneofthemostusefulandimportantstructuralmaterials.BecauseofthecoMParativeeasewithwhichitcanbemoldedintoanydesiredshape,itsstructuralusesarealmostunlimited.WhereverPortlandcementandsuitableaggregatesareavailable,itcanreplaceothermaterialsforcertaintypesofstructures,suchasbridgesubstructureandfoundationelements.
Inaddition,theintroductionofreinforcedconcreteinmultispanframesatthebeginningofthiscenturyimposednewanalyticalrequirements.Structuresofahighorderofredundancycouldnotbeanalyzedwiththeclassicalmethodsofthenineteenthcentury.TheimportanceofjointrotationwasalreadydemonstratedbyManderla(1880)andBendixen(1914),whodevelopedrelationshipsbetweenjointmomentsandangularrotationsfromwhichtheunknownmomentscanbeobtained,thesocalledslope-deflectionmethod.MoresimplificationsinframeanalysisweremadepossiblebytheworkofCalisev(1923),whousedsuccessiveapproximationstoreducethesystemofequationstoonesimpleexpressionforeachiterationstep.ThisapproachwasfurtherrefinedandintegratedbyCross(1930)inwhatisknownasthemethodofmomentdistribution.
Oneofthemostimportimportantrecentdevelopmentsintheareaofanalyticalproceduresistheextensionofdesigntocovertheelastic-plasticrange,alsoknownasloadfactororultimatedesign.PlasticanalysiswasintroducedwithsomepracticalobservationsbyTresca(1846);
andwasformulatedbySaint-Venant(1870),TheconceptofplasticityattractedresearchersandengineersafterWorldWarⅠ,mainlyinGermany,withthecenterofactivityshiftingtoEnglandandtheUnitedStatesafterWorldWarⅡ.Theprobabilisticapproachisanewdesignconceptthatisexpectedtoreplacetheclassicaldeterministicmethodology.
Amainstepforwardwasthe1969additionoftheFederalHighwayAdiministration(FHWA)”CriteriaforReinforcedConcreteBridgeMembers“thatcoversstrengthandserviceabilityatultimatedesign.Thiswaspreparedforuseinconjunctionwiththe1969AmericanAssociationofStateHighwayOffficials(AASHO)StandardSpecification,andwaspresentedinaformatthatisreadilyadaptabletothedevelopmentofultimatedesignspecifications.Accordingtothisdocument,theproportioningofreinforcedconcretemembers(includingcolumns)maybelimitedbyvariousstagesofbehavior:
elastic,cracked,andultimate.Designaxialloads,ordesignshears.Structuralcapacityisthereactionphase,andallcalculatedmodifiedstrengthvaluesderivedfromtheoreticalstrengthsarethecapacityvalues,suchasmomentcapacity,axialloadcapacity,orshearcapacity.Atserviceabilitystates,investigationsmayalsobenecessaryfordeflections,maximumcrackwidth,andfatigue.
BridgeTypes
Anotablebridgetypeisthesuspensionbridge,withthefirstexamplebuiltintheUnitedStatesin1796.ProblemsofdynamicstabilitywereinvestigatedaftertheTacomabridgecollapse,andthisworkledtosignificanttheoreticalcontributionsSteinman(1929)summarizesabout250suspensionbridgesbuiltthroughouttheworldbetween1741and1928.
Withtheintroductionoftheinterstatesystemandtheneedtoprovidestructuresatgradeseparations,certainbridgetypeshavetakenastrongplaceinbridgepractice.Theseincludeconcretesuperstructures(slab,T-beams,concreteboxgirders),steelbeamandplategirders,steelboxgirders,compositeconstruction,orthotropicplates,segmentalconstruction,curvedgirders,andcable-stayedbridges.Prefabricatedmembersaregivenseriousconsideration,whileinterestinboxsectionsremainsstrong.
BridgeAppearanceandAesthetics
Grimm(1975)documentsthefirstrecordedlegislativeefforttocontroltheappearanceofthebuiltenvironment.Thisoccurredin1647whentheCouncilofNewAmsterdamappointedthreeofficials.In1954,theSupremeCourtoftheUnitedStatesheldthatitiswithinthepowerofthelegislaturetodeterminethatcommunitiesshouldbeattractiveaswellashealthy,spaciousaswellasclean,andbalancedaswellaspatrolled.TheEnvironmentalPolicyActof1969directsallagenciesofthefederalgovernmenttoidentifyanddevelopmethodsandprocedurestoensurethatpresentlyunquantifiedenvironmentalamentitiesandvaluesaregivenappropriateconsiderationindecisionmakingalongwitheconomicandtechnicalaspects.
Althoughinmanycivilengineeringworksaestheticshasbeenpracticedalmostintuitively,particularlyinthepast,bridgeengineershavenotignoredorneglectedtheaestheticdisciplines.Recentresearchonthesubjectappearstoleadtoarationalizedaestheticdesignmethodology(GrimmandPreiser,1976).Workhasbeendoneontheaest