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
1.37kn/m
6m
200
400
(a)plainconcretebeam
9.31kn/m
6m
200
400
(b)Reinfocedconcretebeam
2φ16
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.Finiteelementanalysisisextensivelyusedinthedesignofreinforcedconcretestruct