建筑外文翻译高层结构与钢结构.docx

建筑外文翻译高层结构与钢结构.docx

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建筑外文翻译高层结构与钢结构

TallingbuildingandSteelconstruction

Althoughtherehavebeenmanyadvancementsinbuildingconstructiontechnologyingeneral.Spectaculararchievementshavebeenmadeinthedesignandconstructionofultrahigh-risebuildings.

Theearlydevelopmentofhigh-risebuildingsbeganwithstructuralsteelframing.Reinforcedconcreteandstressed-skintubesystemshavesincebeeneconomicallyandcompetitivelyusedinanumberofstructuresforbothresidentialandcommercialpurposes.Thehigh-risebuildingsrangingfrom50to110storiesthatarebeingbuiltallovertheUnitedStatesaretheresultofinnovationsanddevelopmentofnewstructualsystems.

Greaterheightentailsincreasedcolumnandbeamsizestomakebuildingsmorerigidsothatunderwindloadtheywillnotswaybeyondanacceptablelimit.Excessivelateralswaymaycauseseriousrecurringdamagetopartitions,ceilings.andotherarchitecturaldetails.Inaddition,excessiveswaymaycausediscomforttotheoccupantsofthebuildingbecausetheirperceptionofsuchmotion.Structuralsystemsofreinforcedconcrete,aswellassteel,takefulladvantageofinherentpotentialstiffnessofthetotalbuildingandthereforerequireadditionalstiffeningtolimitthesway.

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,andarethuslighterandlessexpensive.Allthetypicalcolumnsandspandrelbeamsarestandardrolledshapes,minimizingtheuseandcostofspecialbuilt-upmembers.Thedepthrequirementfortheperimeterspandrelbeamsisalsoreduced,andtheneedforupsetbeamsabovefloors,whichwouldencroachonvaluablespace,isminimized.Thestructuralsystemhasbeenusedonthe54-storyOneMellonBankCenterinPittburgh.

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.

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,alsoknown