土木工程毕业设计外文翻译建筑物的组成及高层结构.docx
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土木工程毕业设计外文翻译建筑物的组成及高层结构.docx
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土木工程毕业设计外文翻译建筑物的组成及高层结构
ComponentsofABuildingandTallBuildings
Materialsandstructuralformsarecombinedtomakeupthevariouspartsofabuilding,includingtheload-carryingframe,skin,floors,andpartitions.Thebuildingalsohasmechanicalandelectricalsystems,suchaselevators,heatingandcoolingsystems,andlightingsystems.Thesuperstructureisthatpartofabuildingaboveground,andthesubstructureandfoundationisthatpartofabuildingbelowground.
Theskyscraperowesitsexistencetotwodevelopmentsofthe19thcentury:
steelskeletonconstructionandthepassengerelevator.Steelasaconstructionmaterialdates
fromtheintroductionoftheBessemerconverterin1885.GustaveEiffel(1832-1932)introducedsteelconstructioninFrance.HisdesignsfortheGaleriedesMachinesandtheTowerfortheParisExpositionof1889expressedthelightnessofthesteelframework.TheEiffelTower,984feet(300meters)high,wasthetalleststructurebuiltbymanandwasnotsurpasseduntil40yearslaterbyaseriesofAmericanskyscrapers.
Thefirstelevator
wasinstalledbyElishaOtisinstalledthefirstelevatorinadepartmentstoreinNewYorkin1857.In1889;EiffelinstalledthefirstelevatorsonagrandscaleintheEiffelTower,whosehydraulicelevatorscouldtransport2,350passengerstothesummiteveryhour.
Load-CarryingFrame.Untilthelate19thcentury,theexteriorwallsofabuildingwereusedasbearingwallstosupportthefloors.Thisconstructionisessentiallyapostandlinteltype,anditisstillusedinframeconstructionforhouses.Bearing-wallconstructionlimitedtheheight
ofbuildingsbecauseoftheenormouswallthicknessrequired;Forinstance,the16-storyMonadnockBuildingbuiltinthe1880’sinChicagohadwalls5feet(1.5meters)thickatthelowerfloors.In1883,WilliamLeBaronJenney(1832-1907)supportedfloorsoncast-ironcolumnstoformacage-likeconstruction.Skeletonconstruction,consistingofsteelbeamsandcolumns,wasfirstusedin1889.Asaconsequenceofskeletonconstruction,theenclosingwallsbecomea“curtainwall”ratherthanservingasupportingfunction.Masonrywasthecurtainwallmaterialuntilthe1930’s,whenlightmetalandglasscurtainwallswereused.Aftertheintroductionofbuildingscontinuedtoincreaserapidly.
AlltallbuildingswerebuiltwithaskeletonofsteeluntilWorldWarⅡ.Afterthewar,theshortageofsteelandtheimprovedqualityofconcreteledtotallbuildingbeingbuiltofreinforcedconcrete.MarinaTower(1962)inChicagoisthetallestconcretebuildingintheUnitedStates;Itsheight—588feet(179meters)—isexceededbythe650-foot(198-meter)PostOfficeTowerinLondonandbyothertowers.
Achangeinattitudeaboutskyscraperconstructionhasbroughtareturntotheuseofthebearingwall.InNewYorkCity,theColumbiaBroadcastingSystemBuilding,designedbyEeroSaarinenin1962,hasaperimeterwallconsistingof5-foot(1.5meter)wideconcretecolumnsspaced10feet(3meters)fromcolumncentertocenter.Thisperimeterwall,ineffect,constitutesabearingwall.Onereasonforthis
trendisthatstiffnessagainsttheactionofwindcanbeeconomicallyobtainedbyusingthewallsofthebuildingasatube;theWorldTradeCenterbuildingisanotherexampleofthistubeapproach.Incontrast,rigidframesorverticaltrussesareusuallyprovidedtogivelateralstability.
Skin.The
skinofabuildingconsistsofbothtransparentelements(windows)andopaqueelements(walls).Windowsaretraditionallyglass,althoughplasticsarebeingused,especiallyinschoolswherebreakagecreatesamaintenanceproblem.Thewallelements,whichareusedtocoverthestructureandaresupportedbyit,arebuiltofavarietyofmaterials:
brick,precastconcrete,stone,opaqueglass,plastics,steel,andaluminum.Woodisusedmainlyinhouseconstruction;Itisnotgenerallyusedforcommercial,industrial,orpublicbuildingbecauseofthefirehazard.
Floors.Theconstructionofthefloorsinabuildingdependsonthebasicstructuralframethatisused.Insteelskeletonconstruction,floorsareeitherslabsofconcreterestingonsteelbeamsoradeckconsistingofcorrugatedsteelwithaconcretetopping.Inconcreteconstruction,thefloorsareeitherslabsofconcreteonconcretebeamsoraseriesofcloselyspacedconcretebeams(ribs)intwodirectionstoppedwithathinconcreteslab,givingtheappearanceofawaffleonitsunderside.Thekindoffloorthatisuseddepends
onthespanbetweensupportingcolumnsorwallsandthefunctionofthespace.Inanapartmentbuilding,forinstance,wherewallsandcolumnsarespacedat12to18feet(3.7to5.5meters),themostpopularconstructionisasolidconcreteslabwithnobeams.Theundersideoftheslabservesastheceilingforthespacebelowit.Corrugatedsteeldecksareoftenusedinofficebuildingsbecausethecorrugations,whenenclosedbyanothersheetofmetal,formductsfortelephoneandelectricallines.
MechanicalandElectricalSystems.Amodernbuildingnotonlycontainsthespaceforwhichitisintended(office,classroom,apartment)butalsocontainsancillaryspaceformechanicalandelectricalsystemsthathelptoprovideacomfortableenvironment.Theseancillaryspacesinaskyscraperofficebuildingmayconstitute25%ofthetotalbuildingarea.Theimportanceofheating,ventilating,electrical,andplumbingsystemsinanofficebuildingisshownbythefactthat40%oftheconstructionbudgetisallocatedtothem.Becauseoftheincreaseduseofsealedbuildingwithwindowsthatcannotbeopened,elaboratemechanicalsystemsareprovidedforventilationandairconditioning.Ductsandpipescarryfreshairfromcentralfanroomsandairconditioningmachinery.Theceiling,whichissuspendedbelowtheupperfloorconstruction,concealstheductworkandcontainsthelightingunits.Electricalwiringforpowerandfortelephonecommunicationmayalsobelocatedinthisceilingspaceormaybeburiedinthefloorconstructioninpipesorconduits.
Therehavebeenattemptstoincorporatethemechanicalandelectricalsystemsintothearchitectureofbuildingbyfranklyexpressingthem;Forexample,theAmericanRepublicInsuranceCompanyBuilding(1965)inDesMoines,Iowa,exposesboththeductsandthefloorstructureinanorganizedandelegantpatternand
dispenseswiththesuspendedceiling.Thistypeofapproachmakesitpossibletoreducethecostofthebuildingandpermitsinnovations,suchasinthespanofthestructure.
Soilsand
Foundations.Allbuildingaresupportedontheground,andthereforethenatureofthesoilbecomesanextremelyimportantconsiderationinthedesignofanybuilding.Thedesignofafoundationdependsonmanysoilfactors,suchastypeofsoil,soilstratification,thicknessofsoillaversandtheircompaction,andgroundwaterconditions.Soilsrarelyhavea
singlecomposition;Theygenerallyaremixturesinlayersofvaryingthickness.Forevaluation,soilsaregradedaccordingtoparticlesize,whichincreasesfromsilttoclaytosandtograveltorock.Ingeneral,thelargerparticlesoilswillsupportheavierloadsthanthesmallerones.Thehardestrockcansupportloadsupto100tonspersquarefoot(976.5metrictons/sqmeter),butthesoftestsiltcansupportaloadofonly0.25tonpersquarefoot(2.44metrictons/sqmeter).Allsoilsbeneaththesurfaceareinastateofcompaction;thatis,theyareunderapressurethatisequaltotheweightofthesoilcolumnaboveit.Manysoils(exceptformostsandsandgavels)exhibitelasticproperties—theydeformwhencompressedunderloadandreboundwhentheloadisremoved.Theelasticityofsoilsisoftentime-dependent,thatis,deformationsofthesoiloccuroveralengthoftimewhichmayvaryfromminutestoyearsafteraloadisimposed.Overaperiodoftime,abuildingmaysettleifitimposesaloadonthesoilgreaterthanthenaturalcompactionweightofthesoil.Conversely,abuildingmayheaveifitimposesloadsonthesoilsmallerthanthenaturalcompactionweight.Thesoilmayalsoflowundertheweightofabuilding;Thatis,ittendstobesqueezedout.
Duetoboththecompactionandfloweffects,buildingstendsettle.Unevensettlements,exemplifiedbytheleaningtowersinPisaandBologna,canhavedamagingeffects—thebuildingmaylean,walls
andpartitionsmaycrack,windowsanddoorsmaybecomeinoperative,and,intheextreme,abuildingmaycollapse.Uniformsettlementsarenotsoserious,althoughextremeconditions,suchasthoseinMexicoCity,canhaveseriousconsequences.Overthepast100years,achangeinthegroundwaterleveltherehascausedsomebuildingstosettlemorethan10feet(3meters).Becausesuchmovementscanoccurduringandafterconstruction,carefulanalysisofthebehaviorofsoilsunderabuildingisvital.
Thegreatvariabilityofsoilshasledtoavarietyofsolutionstothefoundationproblem.Wherefirmsoilexistsclosetothesurface,thesimplestsolutionistorestcolumnsonasmallslabofconcrete(spreadfooting).Wherethesoilissofter,itisnecessarytospreadthecolumnloadoveragreaterarea;inthiscase,acontinuousslabofconcrete(raftormat)underthewholebuildingisused.Incaseswherethesoilnearthesurfaceisunabletosupporttheweightofthebuilding,pilesofwood,steel,orconcretearedrivendowntofirmsoil.
Theconstructionofabuildingproceedsnaturallyfromthefoundationuptothesuperstructure.Thedesignprocess,however,proceedsfromtheroofdowntothefoundation(inthedirectionofgravity).Inthepast,thefoundationwasnotsubjectto
systematicinvestigation.Ascientificapproachtothedesignoffoundationshasbeendevelopedinthe20t
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- 土木工程 毕业设计 外文 翻译 建筑物 组成 高层 结构