土木工程专业英语教学课件 作者 鲁正Unit7 Introduction to Bridge Engineering

Unit7IntroductiontoBridgeEngineeringEnglishforCivilEngineering——Teacher:Prof.ZhengLuE-mail:luzheng111@tongji.edu.cn（SchoolofCivilEngineering,TONGJIUNIVERSITY）Unit7IntroductiontoBridgeEngineering7.1ReinforcedConcreteGirderBridges（钢筋混凝土梁式桥）(1)SlabBridges（板桥）(2)T-BeamBridges（T形梁桥）(3)Box-GirderBridges（箱梁桥）7.2ArchBridge（拱桥）7.3SteelBridges（钢桥）7.4TrussBridges（桁架桥）7.5PlateandBoxGirderBridges（板箱梁桥）7.6CableStayedBridges（斜拉桥）7.7SuspensionBridge（悬索桥）7.1ReinforcedConcreteGirderBridgesTherawmaterialsofconcrete,consistingofwater,fineaggregate,coarseaggregate,andcement,canbefoundinmostareasoftheworldandcanbemixedtoformavarietyofstructuralshapes.Thegreatavailabilityandflexibilityofconcretematerialandreinforcingbarshavemadethereinforcedconcretebridgeaverycompetitivealternative.Reinforcedconcretebridgesmayconsistofprecastconcreteelements,whicharefabricatedataproductionplantandthentransportedforerectionatthejobsite,orcast-in-placeconcrete,whichisformedandcastdirectlyinitssettinglocation.钢筋混凝土梁式桥材料搭配与建造过程fineaggregate细骨料；coarseaggregate粗骨料；cement水泥；precastconcreteelements预制混凝土构件；fabricated制造；cast-in-place现场浇筑7.1ReinforcedConcreteGirderBridgesCast-in-placeconcretestructuresareoftenconstructedmonolithicallyandcontinuously.Theyusuallyprovidearelativelylowmaintenancecostandbetterearthquake-resistanceperformance.Cast-in-placeconcretestructures,however,maynotbeagoodchoicewhentheprojectisonafast-trackconstructionscheduleorwhentheavailablefalseworkopeningclearanceislimited.Inthisunit,variousstructuraltypesanddesignconsiderationsforconventionalcast-in-place,reinforcedconcretehighwaygirderbridgearediscussed.钢筋混凝土梁式桥材料搭配与建造过程Monolithically整体地；maintenancecost维护费用；earthquake-resistanceperformance抗震性能；fast-track快速；falsework脚手架7.1ReinforcedConcreteGirderBridges1SlabBridges（板桥）Longitudinallyreinforcedslabbridgeshavethesimplestsuperstructureconfigurationandtheneatestappearance.Theygenerallyrequiremorereinforcingsteelandstructuralconcretethandogirder-typebridgesofthesamespan.However,thedesigndetailsandformworksareeasierandlessexpensive.Ithasbeenfoundeconomicalforsimplysupportedspansupto9mandforcontinuousspansupto12m.钢筋混凝土板桥Longitudinally纵向；superstructureconfiguration上部结构形状；girder-typebridges梁式桥7.1ReinforcedConcreteGirderBridges2T-BeamBridges（T形梁桥）TheT-beamconstructionconsistsofatransverselyreinforcedslabdeckwhichspansacrosstothelongitudinalsupportgirders.Theserequireamore-complicatedformwork,particularlyforskewedbridges,comparedtotheothersuperstructureforms.T-beambridgesaregenerallymoreeconomicalforspansof12to18m.Thegirderstemthicknessusuallyvariesfrom35to55cmandiscontrolledbytherequiredhorizontalspacingofthepositivemomentreinforcement.Optimumlateralspacingoflongitudinalgirdersistypicallybetween1.8and3.0mforaminimumcostofformworkandstructuralmaterials.However,whereverticalsupportsfortheformworkaredifficultandexpensive,girderspacingcanbeincreasedaccordingly.transverselyreinforcedslabdeck横向加筋板；formwork；skewedbridges斜交桥；girder大梁；horizontalspacing水平间距；positivemoment正弯矩7.1ReinforcedConcreteGirderBridges3Box-GirderBridges（箱梁桥）Box-girderbridgescontaintopdeck,verticalweb,andbottomslabandareoftenusedforspansof15to36mwithgirdersspacedat1.5timesthestructuredepth.Beyondthisrange,itisprobablymoreeconomicaltoconsideradifferenttypeofbridge,suchaspost-tensionedboxgirderorsteelgirdersuperstructure.Thisisbecauseofthemassiveincreaseinvolumeandmaterials.TheycanbeviewedasT-beamstructuresforbothpositiveandnegativemoments.Thehightorsionalstrengthoftheboxgirdermakesitparticularlysuitableforsharpcurvealignment,skewedpiersandabutments,superelevation,andtransitionssuchasinterchangerampstructures.topdeck顶面板；web腹板；post-tensioned后张法；torsionalstrength抗扭强度；skewedpiersandabutments倾斜支柱和台墩；interchangeramp立交匝道7.1ReinforcedConcreteGirderBridges7.2ArchBridgeEvenintheMiddleAges,itwasappreciatedthatmasonryarchesbehavedessentiallyasgravitystructures,forwhichgeometryandproportiondictatedaestheticappealandstability.Compressivestrengthcouldberelieduponwhilsttensilestrengthcouldnot.Baseduponexperience,manyempiricalrelationshipsbetweenthespanandarchthicknessweredevelopedandappliedsuccessfullytoproducemanyelegantstructuresthroughoutEurope.Theexpansionoftherailwayandcanalsystemsledtoanexplosionofbridgebuilding.Brickworkarchesbecameincreasinglypopular.WiththeconstructionoftheCoal-brookdaleBridge(1780)aneweraofarchbridgeconstructionbegan.Bytheendofthenineteenthcenturycastiron,wroughtironandfinallysteelbecameincreasinglypopular;onlytobechallengedbyferrocement(reinforcedconcrete)attheturnofthecentury.拱桥的历史发展masonry/Brickworkarches石/砖拱；aestheticappeal美学作用；empirical经验的；railwayandcanalsystems铁路和管道系统；cast/wroughtiron生/熟铁7.3SteelBridgesStructuralsteelisanextremelyversatilematerialeminentlysuitedfortheconstructionofallformsofbridges.Thematerial,whichhasahighstrength-to-weightratio,canbeusedtobridgearangeofspansfromshortthroughtoverylong(15–1500m),supportingtheimposedloadswiththeminimumofdeadweight.Steelbridgesnormallyresultinlightsuperstructureswhichinturnleadtosmaller,economicalfoundations.Theyarenormallyprefabricatedinsectionsinafactoryenvironmentunderstrictqualitycontrol,transportedtositeinmanageableunitsandboltedtogetherinsitutoformthecompletebridgestructure.Usingthisconstructionmethodtheerectionofasteelbridgeisusuallyrapid,resultinginminimaldisruptiontotraffic;averyimportantfactoriftrafficdelays,beitroadorrail,areproperlyassessedintheconstructionproject.钢桥的优势Versatile多面的；strength-to-weightratio强度质量比；imposedloads外荷载；foundations基础；prefabricated预制的；bolted螺栓连接；insitu现场；erection建立；trafficdelays交通延误7.3SteelBridgesForspansintherangeofabout25–100m,plategirders,againactingcompositelywiththedeck,provideaneconomicalsolution.Inordertooptimisetheconcretedeck,whichhastodistributewheelloadstransverselyacrossthebridge,itisusualtoarrangeforaplategirderspacingofaround3m.Forlongerspansexceeding100m,boxgirdersarethefavouredchoice.Althoughboxgirdershaveahigherfabricationcostthanplategirders,boxgirdershavesubstantiallygreatertorsionalstiffnessand,ifcarefullyprofiled,goodaerodynamicstability.Forverylongspansinexcessof250m,stiffenedsteelboxgirderswithanintegralorthotropicallystiffenedsteeltopplate,formingtheprimarysupportfortherunningsurface,provideaveryeconomicallightweightsolution.Fig.7-2givescross-sectionstakenthroughtypicalbridgestructuresusinghot-rolled,plategirderandboxgirdersections.钢桥的优势plategirders钢板梁；compositely复合；profiled外形设计；orthotropically各向正交异性；lightweight轻质7.4TrussBridgesLatticetrussstructureshavebeenusedverysuccessfullyforbothrailwayandhighwaybridgesthroughoutthelast150years.Therearethreemaintrussconfigurationsinusetoday,namelytheWarrentruss,theModifiedWarrentrussandthePratttruss,allofwhichcanbeusedasanunderslungtruss,asemi-throughtruss,orathroughtrussbridge.Fig.7-3givesdetailsofthethreetrusstypestogetherwithsectionsshowingthedifferencesbetweenanunderslung,semi-throughandthroughtruss.桁架桥梁的形式Latticetrussstructures格构式桁架；configurations结构；Warrentruss华伦式桁架；ModifiedWarrentruss改进华伦式桁架；Pratttruss普拉特桁架；underslungtruss低重心桁架7.4TrussBridges7.5PlateandBoxGirderBridgesAsdiscussedpreviouslyinthisunit,oneofthemostcommonformsofsteel(orcomposite)bridge,theplategirder,iscomprisedofsteelplateelementsweldedtogether,oftenofrelativelyslenderconstruction.Theseelementsarefoundinthewebsandflangesofplategirdersandalsointhestiffeners,althoughthelatterarenormallymadefromhot-rolledsections.Theboxgirder,somewhatlesscommon,isfoundinlonger-spanbridgeseitherasacompositeconstructionor,forverylongspans,asanall-steelstructurewithstiffenedsteeldecks.Suchlong-spangirdersmayhaveadditionalsupportprovidedbycablessuchasfoundincable-stayedorsuspensionbridges.Verylong-spanbridgescanhaveextremelycomplexcross-sectionsofaerodynamicshapewithcomplexstiffeningarrangements.板梁和箱梁桥Slender细长的；websandflanges腹板和翼缘；compositeconstruction组合结构；all-steelstructure全钢结构；cable-stayedbridges斜拉桥；suspensionbridges悬索桥；localbuckling局部屈曲7.6CableStayedBridgesTheuseofinclinedstaysasatensionsupporttoabridgedeckwasawell-knownconceptinthenineteenthcenturyandtherearemanyexamples,particularlyusingtheinclinedstayasaddedstiffnesstotheprimarydrapedcablesofthesuspensionbridge.Unfortunately,atthistime,theconceptwasnotwellunderstood.Asitwasnotpossibletotensionthestaystheywouldbecomeslackundervariousloadconditions.Thestructuresoftenhadinadequateresistancetowind-inducedoscillations.Therewereseveralnotablecollapsesofsuchbridges,forexamplethebridgeovertheTweedRiveratDryburgh(Drewry,1832),builtin1817,andcollapsedin1818duringagaleonlysixmonthsafterconstructionwascompleted.AsaresulttheuseofthestayconceptwasabandonedinEngland.Nevertheless,theseideaswereadaptedandimprovedbytheAmericanbridgeengineerRoeblingwhousedcablestaysinconjunctionwiththedrapedsuspensioncableforthedesignofhisbridges.（时间顺序介绍斜拉索历史）inclinedstays斜拉索；bridgedeck桥面板；Slack松弛；wind-inducedoscillations风振；gale狂风；inconjunctionwith连接7.6CableStayedBridgesThebestknownofRoebling’sbridgesistheBrooklynBridge,completedin1883.Themodernconceptofthecable-stayedbridgewasfirstproposedinpostwarGermany,intheearly1950s,forthereconstructionofanumberofbridgesovertheRiverRhine.Thesebridgesprovedmoreeconomic,formoderatespans,thaneitherthesuspensionorarchbridgeforms.Itprovedverydifficultandexpensiveintheprevailingsoilconditionsofanalluvialfloodplaintoprovidethegravityanchoragesrequiredforthecablesofsuspensionbridges.Similarlyforthearchstructure,whetherdesignedwiththearchthrustcarriedatfoundationlevelorcarriedasatiedarch,substantialfoundationswererequiredtocarrytheselargeheavyspans.Bycomparisonthecable-stayedalternativeshadlightdecksandthetensilecableforceswerepartofaclosedforcesystemwhichbalancedtheseforceswiththecompressionwithinthedeckandpylon.Thusexpensiveexternalgravityanchorageswerenotrequired.（时间顺序介绍斜拉索历史）moderatespans中等跨度；prevailingsoilconditions常见的土壤条件；alluvialfloodplain冲积平原；archthrust拱推力；pylon桥塔7.7SuspensionBridgeThescopeofthisunitisrestrictedtoconsiderationoftheclassicalthree-spansuspensionbridgeconfiguration(Fig.7-4),withastiffenedload-carryingdeckstructuresupportedbyearth-anchoredcables.Thebridgemayhavesidespansofdifferinglengthsand,dependingonthesitetopography,thebridgedeckmaybesuspendedeitherinallthreespansorinthemainspanonly,whenthesidespancablesactsimplyasbackstaystothetowers.Bridgeswithunusualspanorcableconfigurations,includingbridgeswithmultiplemainspans,mono-cablebridges,self-anchoredstructures,andhybridpartsuspension/partcable-stayedstructuresarenotconsidered.Evenwiththeabovelimitations,itisnotpossibleinarelativelyshortchaptertoconsiderindetailmanyimportantaspectsofsuspensionbridgedesign–inparticulartheanalysisofcablesandtheaerodynamicdesignrequirements.（悬索结构介绍）three-spansuspensionbridgeconfiguration三跨吊桥结构；earth-anchoredcables地锚；sidespans边跨；topography地形；mainspans主跨；mono-cable单索；self-anchored自锚式7.7SuspensionBridgeTwoormoremaincablesformedfromhigh-strengthsteelwires,withastrength-to-weightratioofaroundthreetimesthatofweldablestructuralsteels,andwhichsupportthetraffic-carryingdeckandtransferitsloadingbydirecttensionforcestothesupportingtowersandanchorages.Asthedeckdeadloadisentirelysupportedbythecable,towersandanchorages,aneconomicaloveralldesignrequiresthelightestpracticabledeckstructurewhichissupportedfromthemaincablesbyhangersofhigh-strengthwireropesorstrandthatarespacedatregularintervalsthroughoutthespans.悬索桥设计原则Weldable焊接的；traffic-carryingdeck桥面板；supportingtowersandanchorages支撑塔架和锚固；deadload恒载；overalldesign总体设计；wireropes钢丝绳；spacedatregularintervals等间隔放置7.7SuspensionBridgeWithcablesconstructedfromveryhigh-strengthsteelloadedindirecttensionastheirprimaryload-carryingmembers,suspensionbridgesareideallysuitedtolongerspans,andthisisthereforetheprimaryapplicationforthistypeofstructure.Althoughcable-stayedstructureshavemadeconsiderableinroadsintothespanrangepreviouslyconsideredtobethedomainofsuspensionbridges,theseremaintheunchallengedchoiceforspansover1200m.Whenwelldesignedandproportioned,suspensionbridgesarethemostbeautifulofbridges,asthesimplicityofthestructuralarrangement,thenaturalcurveofthemaincables,theslendersuspendeddeckandtowers,produceanaestheticallyattractivestructure.Thisnaturalgracecanalsomakesuspensionbridgesasuitablechoiceforrelativelyshort-spanfootbridgesinsituationswhereanattractiveappearanceisanimportantconsideration.（悬索结构的优势）Inroads侵入，损耗；directtension直接受拉；naturalcurve自然曲线；aestheticallyattractive美观，吸引人