土木工程毕业设计 外文翻译.docx
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土木工程毕业设计 外文翻译.docx
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土木工程毕业设计外文翻译
外文原文
TallingBuildingAndSteelConstruction
Althoughtherehavebeenmanyadvancementsinbuildingconstructiontechnologyingeneral.Spectaculararchievementshavebeenmadeinthedesignandconstructionofultrahigh-risebuildings.Theearlydevelopmentofhigh-risebuildingsbeganwithstructuralsteelframing.Reinforcedconcreteandstressed-skintubesystemshavesincebeeneconomicallyandcompetitivelyusedinanumberofstructuresforbothresidentialandcommercialpurposes.Thehigh-risebuildingsrangingfrom50to110storiesthatarebeingbuiltallovertheUnitedStatesaretheresultofinnovationsanddevelopmentofnewstructualsystems.
Greaterheightentailsincreasedcolumnandbeamsizestomakebuildingsmorerigidsothatunderwindloadtheywillnotswaybeyondanacceptablelimit.Excessivelateralswaymaycauseseriousrecurringdamagetopartitions,ceilings.andotherarchitecturaldetails.Inaddition,excessiveswaymaycausediscomforttotheoccupantsofthebuildingbecausetheirperceptionofsuchmotion.Structuralsystemsofreinforcedconcrete,aswellassteel,takefulladvantageofinherentpotentialstiffnessofthetotalbuildingandthereforerequireadditionalstiffeningtolimitthesway.
Systemsinconcrete.Whiletallbuildingsconstructedofsteelhadanearlystart,developmentoftallbuildingsofreinforcedconcreteprogressedatafastenoughratetoprovideacompetitivechanllengetostructuralsteelsystemsforbothofficeandapartmentbuildings.
Framedtube.Asdiscussedabove,thefirstframedtubeconceptfortallbuildingswasusedforthe43-storyDeWittChestnutApartmentBuilding.Inthisbuilding,exteriorcolumnswerespacedat5.5ft(1.68m)centers,andinteriorcolumnswereusedasneededtosupportthe8-in.-thick(20-m)flat-plateconcreteslabs.
Tubeintube.Anothersysteminreinforcedconcreteforofficebuildingscombinesthetraditionalshearwallconstructionwithanexteriorframedtube.Thesystemconsistsofanouterframedtubeofverycloselyspacedcolumnsandaninteriorrigidshearwalltubeenclosingthecentralservicearea.Thesystem(Fig.2),knownasthetube-in-tubesystem,madeitpossibletodesigntheworld’spresenttallest(714ftor218m)lightweightconcretebuilding(the52-storyOneShellPlazaBuildinginHouston)fortheunitpriceofatraditionalshearwallstructureofonly35stories.
Systemscombiningbothconcreteandsteelhavealsobeendeveloped,anexamleofwhichisthecompositesystemdevelopedbyskidmore,Owings&Merrilinwhichanexteriorcloselyspacedframedtubeinconcreteenvelopsaninteriorsteelframing,therebycombiningtheadvantagesofbothreinforcedconcreteandstructuralsteelsystems.The52-storyOneShellSquareBuildinginNewOrleansisbasedonthissystem.
Inasteelstructure,forexample,theeconomycanbedefinedintermsofthetotalaveragequantityofsteelpersquarefootoffloorareaofthebuilding.CurveAinFig.1representstheaverageunitweightofaconventionalframewithincreasingnumbersofstories.CurveBrepresentstheaveragesteelweightiftheframeisprotectedfromalllateralloads.Thegapbetweentheupperboundaryandthelowerboundaryrepresentsthepremiumforheightforthetraditionalcolumn-and-beamframe.Structuralengineershavedevelopedstructuralsystemswithaviewtoeliminatingthispremium.Systemsinsteel.Tallbuildingsinsteeldevelopedasaresultofseveraltypesofstructuralinnovations.Theinnovationshavebeenappliedtotheconstructionofbothofficeandapartmentbuildings.
Framewithrigidbelttrusses.Inordertotietheexteriorcolumnsofaframestructuretotheinteriorverticaltrusses,asystemofrigidbelttrussesatmid-heightandatthetopofthebuildingmaybeused.AgoodexampleofthissystemistheFirstWisconsinBankBuilding(1974)inMilwaukee.
Framedtube.Themaximumefficiencyofthetotalstructureofatallbuilding,forbothstrengthandstiffness,toresistwindloadcanbeachievedonlyifallcolumnelementcanbeconnectedtoeachotherinsuchawaythattheentirebuildingactsasahollowtubeorrigidboxinprojectingoutoftheground.Thisparticularstructuralsystemwasprobablyusedforthefirsttimeinthe43-storyreinforcedconcreteDeWittChestnutApartmentBuildinginChicago.Themostsignificantuseofthissystemisinthetwinstructuralsteeltowersofthe110-storyWorldTradeCenterbuildinginNewYork.
Column-diagonaltrusstube.Theexteriorcolumnsofabuildingcanbespacedreasonablyfarapartandyetbemadetoworktogetherasatubebyconnectingthemwithdiagonalmembersinterestingatthecentrelineofthecolumnsandbeams.ThissimpleyetextremelyefficientsystemwasusedforthefirsttimeontheJohnHancockCentreinChicago,usingasmuchsteelasisnormallyneededforatraditional40-storybuilding.
Bundledtube.Withthecontinuingneedforlargerandtallerbuildings,theframedtubeorthecolumn-diagonaltrusstubemaybeusedinabundledformtocreatelargertubeenvelopeswhilemaintaininghighefficiency.The110-storySearsRoebuckHeadquartersBuildinginChicagohasninetube,bundledatthebaseofthebuildinginthreerows.Someoftheseindividualtubesterminateatdifferentheightsofthebuilding,demonstratingtheunlimitedarchitecturalpossibilitiesofthislateststructuralconcept.TheSearstower,ataheightof1450ft(442m),istheworld’stallestbuilding.
Stressed-skintubesystem.Thetubestructuralsystemwasdevelopedforimprovingtheresistancetolateralforces(windandearthquake)andthecontrolofdrift(lateralbuildingmovement)inhigh-risebuilding.Thestressed-skintubetakesthetubesystemastepfurther.Thedevelopmentofthestressed-skintubeutilizesthefaçadeofthebuildingasastructuralelementwhichactswiththeframedtube,thusprovidinganefficientwayofresistinglateralloadsinhigh-risebuildings,andresultingincost-effectivecolumn-freeinteriorspacewithahighratioofnettogrossfloorarea.Becauseofthecontributionofthestressed-skinfaçade,theframedmembersofthetuberequirelessmass,andarethuslighterandVlessexpensive.Allthetypicalcolumnsandspandrelbeamsarestandardrolledshapes,minimizingtheuseandcostofspecialbuilt-upmembers.Thedepthrequirementfortheperimeterspandrelbeamsisalsoreduced,andtheneedforupsetbeamsabovefloors,whichwouldencroachonvaluablespace,isminimized.Thestructuralsystemhasbeenusedonthe54-storyOneMellonBankCenterinPittburgh.
Steelconstructionreferstoabroadrangeofbuildingconstructioninwhichsteelplaystheleadingrole.Moststeelconstructionconsistsoflarge-scalebuildingsorengineeringworks,withthesteelgenerallyintheformofbeams,girders,bars,plates,andothermembersshapedthroughthehot-rolledprocess.Despitetheincreaseduseofothermaterials,steelconstructionremainedamajoroutletforthesteelindustriesoftheU.S,U.K,U.S.S.R,Japan,WestGerman,France,andothersteelproducersinthe1970s.
Earlyhistory.ThehistoryofsteelconstructionbeginsparadoxicallyseveraldecadesbeforetheintroductionoftheBessemerandtheSiemens-Martin(openj-hearth)processesmadeitpossibletoproducesteelinquantitiessufficientforstructureuse.Manyofproblemsofsteelconstructionwerestudiedearlierinconnectionwithironconstruction,whichbeganwiththeCoalbrookdaleBridge,builtincastironovertheSevernRiverinEnglandin1777.Thisandsubsequentironbridgework,inadditiontotheconstructionofsteamboilersandironshiphulls,spurredthedevelopmentoftechniquesforfabricating,designing,andjioning.Theadvantagesofironovermasonrylayinthemuchsmalleramountsofmaterialrequired.Thetrussform,basedontheresistanceofthetriangletodeformation,longusedintimber,wastranslatedeffectivelyintoiron,withcastironbeingusedforcompressionmembers-i.e,thosebearingtheweightofdirectloading-andwroughtironbeingusedfortensionmembers-i.e,thosebearingthepullofsuspendedloading.
Thetechniqueforpassingiron,heatedtotheplasticstate,betweenrollstoformflatandroundedbars,wasdevelopedasearlyas1800;by1819angleironswererolled;andin1849thefirstIbeams,17.7feet(5.4m)long,werefabricatedasroofgirdersforaParisrailroadstation.
TwoyearslaterJosephPaxtonofEnglandbuilttheCrystalPalacefortheLondonExpositionof1851.Heissaidtohaveconceivedtheideaofcageconstruction-usingrelativelyslenderironbeamsasaskeletonfortheglasswallsofalarge,openstructure.ResistancetowindforcesintheCrystalpalacewasprovidedbydiagonalironrods.Twofeatureareparticularlyimportantinthehistoryofmetalconstruction;first,theuseoflatticedgirder,whicharesmalltrusses,aformfirstdevelopedintimberbridgesandotherstructuresandtranslatedintometalbyPaxton;andsecond,thejoiningofwrought-irontensionmembersandcast-ironcompressionmembersbymeansofrivetsinsertedwhilehot.
In1853thefirstmetalfloorbeamswererolledfortheCooperUnionBuildinginNewYork.Inthelightoftheprincipalmarketdemandforironbeamsatthetime,itisnotsurprisingthattheCooperUnionbeamscloselyresembledrailroadrails.
ThedevelopmentoftheBessemerandSiemens-Martinprocessesinthe1850sand1860ssuddenlyopenthewaytotheuseofsteelforstructuralpurpose.Strongerthanironinbothtensionandcompression,thenewlyavailablemetalwasseizedonbyimaginativeengineers,notablybythoseinvolvedinbuildingthegreatnumberofheavyrailroadbridgesthenindemandinBritain,Europe,andtheU.S.
AnotableexamplewastheEadsBridge,alsok
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