土木毕业设计外文翻译.docx

土木毕业设计外文翻译.docx

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土木毕业设计外文翻译

毕业设计（论文）外文参考

资料及译文

译文题目：

DESIGNOFREINFORCEDCONCRETESTRUCTURES

学生姓名：

杨涛学号：

专业：

土木工程

所在学院：

建筑工程学院

指导教师：

蒋跃南

职称：

讲师

2014年12月31日

原文：

DESIGNOFREINFORCEDCONCRETESTRUCTURES

1.BASICCONCERPTSANDCHARACERACTERISTICSOFREINFORCEDCONCRETE

Plainconcreteisformedfromhardenedmixtureofcement,water,fineaggregate,coarseaggregate（crushedstoneorgravel）,airandoftenotheradmixtures.Theplasticmixisplacedandconsolidatedintheformwork,thencuredtoaccelerateofthechemicalhydrationofhencementmixandresultsinahardenedconcrete.Itisgenerallyknownthatconcretehashighcompressivestrengthandlowresistancetotension.Itstensilestrengthisapproximatelyone-tenthofitscompressivestrength.Consequently,tensilereinforcementinthetensionzonehastobeprovidedtosupplementthetensilestrengthofthereinforcedconcretesection.

Forexample,aplainconcretebeamunderauniformlydistributedloadqisshowninFig.1.1（a）,whenthedistributedloadincreasesandreachesavalueq=1.37KN/m,thetensileregionatthemid-spanwillbecrackedandthebeamwillfailsuddenly.Areinforcedconcretebeamifthesamesizebuthastosteelreinforcingbars（2φ16）embeddedatthebottomunderauniformlydistributedloadqisshowninFig.1.1（b）.Thereinforcingbarstakeupthetensionthereaftertheconcreteiscracked.Whentheloadqisincreased,thewidthofthecracks,thedeflectionandthestressofsteelbarswillincrease.Whenthesteelapproachestheyieldingstressƒy,thedeflectionandthecrackedwidtharesolargeofferingsomewarningthatthecompressionzone.Thefailureloadq=9.31KN/m,isapproximately6.8timesthatfortheplainconcretebeam.

Concreteandreinforcementcanworktogetherbecausethereisasufficientlystrongbondbetweenthetwomaterials,therearenorelativemovementsofthebarsandthesurroundingconcretecracking.Thethermalexpansioncoefficientsofthetwomaterialsare1.2×10-5K-1forsteeland1.0×10-5~1.5×10-5K-1forconcrete.

Generallyspeaking,reinforcedstructurepossessfollowingfeatures:

Durability.Withthereinforcingsteelprotectedbytheconcrete,reinforcedconcrete

Fig.1.1Plainconcretebeamandreinforcedconcretebeam

Isperhapsoneofthemostdurablematerialsforconstruction.Itdoesnotrotrust,andisnotvulnerabletoefflorescence.

（2）Fireresistance.Bothconcreteansteelarenotinflammablematerials.Theywouldnotbeaffectedbyfirebelowthetemperatureof200℃whenthereisamoderateamountofconcretecovergivingsufficientthermalinsulationtotheembeddedreinforcementbars.

（3）Highstiffness.Mostreinforcedconcretestructureshavecomparativelylargecrosssections.Asconcretehashighmodulusofelasticity,reinforcedconcretestructuresareusuallystifferthanstructuresofothermaterials,thustheyarelesspronetolargedeformations,Thispropertyalsomakesthereinforcedconcretelessadaptabletosituationsrequiringcertainflexibility,suchashigh-risebuildingsunderseismicload,andparticularprovisionshavetobemadeifreinforcedconcreteisused.

（4）Locallyavailableresources.Itisalwayspossibletomakeuseofthelocalresourcesoflabourandmaterialssuchasfineandcoarseaggregates.Onlycementandreinforcementneedtobebroughtinfromoutsideprovinces.

（5）Costeffective.Comparingwithsteelstructures,reinforcedconcretestructuresarecheaper.

（6）Largedeadmass,Thedensityofreinforcedconcretemayreach2400~2500kg/m3.Comparewithstructuresofothermaterials,reinforcedconcretestructuresgenerallyhaveaheavydeadmass.However,thismaybenotalwaysdisadvantageous,particularlyforthosestructureswhichrelyonheavydeadweighttomaintainstability,suchasgravitydamandotherretainingstructure.Thedevelopmentanduseoflightweightaggregatehavetoacertainextentmakeconcretestructurelighter.

（7）Longcuringperiod..Itnormallytakesacuringperiodof28dayunderspecifiedconditionsforconcretetoacquireitsfullnominalstrength.Thismakestheprogressofreinforcedconcretestructureconstructionsubjecttoseasonalclimate.Thedevelopmentoffactoryprefabricatedmembersandinvestmentinmetalformworkalsoreducetheconsumptionoftimberformworkmaterials.

（8）Easilycracked.Concreteisweakintensionandiseasilycrackedinthetensionzone.Reinforcingbarsareprovidednottopreventtheconcretefromcrackingbuttotakeupthetensileforce.Somostofthereinforcedconcretestructureinserviceisbehavinginacrackedstate.Thisisaninherentissubjectedtoacompressiveforcebeforeworkingloadisapplied.Thusthecompressedconcretecantakeupsometensionfromtheload.

2.HISTOEICALDEVELPPMENTOFCONCRETESTRUCTURE

Althoughconcreteanditscementitious（volcanic）constituents,suchaspozzolanicash,havebeenusedsincethedaysofGreek,theRomans,andpossiblyearlierancientcivilization,theuseofreinforcedconcreteforconstructionpurposeisarelativelyrecentevent,In1801,F.Concretepublishedhisstatementofprinciplesofconstruction,recognizingtheweaknessifconcreteintension,ThebeginningofreinforcedconcreteisgenerallyattributedtoFrenchmanJ.L.Lambot,whoin1850constructed,forthefirsttime,asmallboatwithconcreteforexhibitioninthe1855World’sFairinParis.InEngland,W.B.Wilkinsonregisteredapatentforreinforcedconcretel=floorslabin1854.J.Monier,aFrenchgardenerusedmetalframesasreinforcementtomakegardenplantcontainersin1867.Before1870,Monierhadtakenaseriesofpatentstomakereinforcedconcretepipes,slabs,andarches.ButMonierhadnoknowledgeoftheworkingprincipleofthisnewmaterial,heplacedthereinforcementatthemid-depthofhiswares.Thenlittleconstructionwasdoneinreinforcedconcrete.Itisuntil1887,whentheGermanengineersWayssandBauschingerproposedtoplacethereinforcementinthetensionzone,theuseofreinforcedconcreteasamaterialofconstructionbegantospreadrapidly.In1906,C.A.P.Turnerdevelopedthefirstflatslabwithoutbeams.

Beforetheearlytwentiesof20thcentury,reinforcedconcretewentthroughtheinitialstageofitsdevelopment,Considerableprogressoccurredinthefieldsuchthatby1910theGermanCommitteeforReinforcedConcrete,theAustrianConcreteCommittee,theAmericanConcreteInstitute,andtheBritishConcreteInstitutewereestablished.Variousstructuralelements,suchasbeams,slabs,columns,frames,arches,footings,etc.weredevelopedusingthismaterial.However,thestrengthofconcreteandthatofreinforcingbarswerestillverylow.Thecommonstrengthofconcreteatthebeginningof20thcenturywasabout15MPaincompression,andthetensilestrengthofsteelbarswasabout200MPa.Theelementsweredesignedalongtheallowablestresseswhichwasanextensionoftheprinciplesinstrengthofmaterials.

Bythelatetwenties,reinforcedconcreteenteredanewstageofdevelopment.Manybuildings,bridges,liquidcontainers,thinshellsandprefabricatedmembersofreinforcedconcretewereconcretewereconstructedby1920.Theeraoflinearandcircularprestressingbegan..Reinforcedconcrete,becauseofitslowcostandeasyavailability,hasbecomethestaplematerialofconstructionallovertheworld.Uptonow,thequalityofconcretehasbeengreatlyimprovedandtherangeofitsutilityhasbeenexpanded.Thedesignapproachhasalsobeeninnovativetogivingthenewroleforreinforcedconcreteistoplayintheworldofconstruction.

Theconcretecommonlyusedtodayhasacompressivestrengthof20~40MPa.Forconcreteusedinpre-stressedconcretethecompressivestrengthmaybeashighas60~80MPa.Thereinforcingbarscommonlyusedtodayhasatensilestrengthof400MPa,andtheultimatetensilestrengthofprestressingwiremayreach1570~1860Pa.Thedevelopmentofhighstrengthconcretemakesitpossibleforreinforcedconcretetobeusedinhigh-risebuildings,off-shorestructures,pressurevessels,etc.Inordertoreducethedeadweightofconcretestructures,variouskindsoflightconcretehavebeendevelopedwithadensityof1400~1800kg/m3.Withacompressivestrengthof50MPa,lightweightconcretemaybeusedinloadbearingstructures.OneofthebestexamplesisthegymnasiumoftheUniversityofIllinoiswhichhasaspanof122mandisconstructedofconcretewithadensityof1700kg/m3.Anotherexampleisthetwo20-storyapartmenthousesattheXi-Bian-MeninBeijing.Thewallsofthesetwobuildingsarelightweightconcretewithadensityof1800kg/m3.

Thetallestreinforcedconcretebuildingintheworldtodayisthe76-storyWaterTowerBuildinginChicagowithaheightof262m.ThetallestreinforcedconcretebuildinginChinatodayisthe63-storyInternationalTradeCenterinGuangZhouwithaheightaheightof200m.Thetallestreinforcedconcreteconstructionintheworldisthe549mhighInternationalTelevisionTowerinToronto,Canada.HeprestressedconcreteT-sectionsimplysupportedbeambridgeovertheYellowRiverinLuoyanghas67spansandthestandardspanlengthis50m.

Inthedesignofreinforcedconcretestructures,limitstatedesignconcepthasreplacedtheoldallowablestressesprinciple.Reliabilityanalysisbasedontheprobabilitytheoryhasveryrecentlybeenintroducedputtingthelimitstatedesignonasoundtheoreticalfoundation.Elastic-plasticanalysisofcontinuousbeamsisestablishedandisacceptedinmostofthedesigncodes.Finiteelementanalysisisextensivelyusedinthedesignofreinforcedconcretestructuresandnon-linearbehaviorofconcreteistakenintoconsideration.Recentearthquakedisasterspromptedtherese