高层建筑外文翻译.docx

高层建筑外文翻译.docx

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高层建筑外文翻译

土木工程

外文翻译

题目：

高层建筑

学院：

兰州交通大学博文学院

专业：

土木工程

班级：

08级土木5班

学号：

学生姓名：

指导教师：

完成日期：

2012年3月11号

一、外文原文：

TallBuildingStructure

Tallbuildingshavefascinatedmankindfromthebeginningofcivilization,theirconstructionbeinginitiallyfordefenseandsubsequentlyforecclesiasticalpurposes.Thegrowthinmoderntallbuildingconstruction,however,whichbeganinthe1880s,hasbeenlargelyforcommercialandresidentialpurposes.

Tallcommercialbuildingsareprimarilyaresponsetothedemandbybusinessactivitiestobeasclosetoeachother,andtothecitycenter,aspossible,therebyputtingintensepressureontheavailablelandspace.Also,becausetheyformdistinctivelandmarks,tallcommercialbuildingsarefrequentlydevelopedincitycentersasprestigesymbolsforcorporateorganizations.Further,thebusinessandtouristcommunity,withitsincreasingmobility,hasfuelledaneedformore,frequentlyhigh-rise,citycenterhotelaccommodations.

Therapidgrowthoftheurbanpopulationandtheconsequentpressureonlimitedspacehaveconsiderablyinfluencedcityresidentialdevelopment.Thehighcostofland,thedesiretoavoidacontinuousurbansprawl,andtheneedtopreserveimportantagriculturalproductionhaveallcontributedtodriveresidentialbuildingsupward.

Ideally,intheearlystagesofplanningabuilding,theentiredesignteam,includingthearchitect,structuralengineer,andservicesengineer,shouldcollaboratetoagreeonaformofstructuretosatisfytheirrespectiverequirementsoffunction,safetyandserviceability,andservicing.Acompromisebetweenconflictingdemandswillbealmostinevitable.Inallbuttheverytalleststructures,however,thestructuralarrangementwillbesubservienttothearchitecturalrequirementsofspacearrangementandaesthetics.

Thetwoprimarytypesofverticalload-resistingelementsoftallbuildingsarecolumnsandwalls,thelatteractingeitherindependentlyasshearwallsorinassembliesasshearwallcores.Thebuildingfunctionwillleadnaturallytotheprovisionofwallstodivideandenclosespace,andofcorestocontainandconveyservicessuchaselevators.Columnswillbeprovided,inotherwiseunsupportedregions,totransmitgravityloadsand,insometypesofstructure,horizontalloadsalso.

Theinevitableprimaryfunctionofthestructuralelementsistoresistthegravityloadingfromtheweightofthebuildinganditscontents.Sincetheloadingondifferentfloorstendstobesimilar,theweightofthefloorsystemperunitfloorareaisapproximatelyconstant,regardlessofthebuildingheight.Becausethegravityloadonthecolumnsincreasesdowntheheightofabuilding,theweightofcolumnsperunitareaincreasesapproximatelylinearlywiththebuildingheight.

Thehighlyprobablesecondfunctionoftheverticalstructuralelementsistoresistalsotheparasiticloadcausedbywindandpossiblyearthquakes,whosemagnitudeswillbeobtainedfromNationalBuildingCodesorwindtunnelstudies.Thebendingmomentsonthebuildingcausedbytheselateralforcesincreasewithatleastthesquareoftheheight,andtheireffectswillbecomeprogressivelymoreimportantasthebuildingheightincreases.

Oncethefunctionallayoutofthestructurehasbeendecided,thedesignprocessgenerallyfollowsawelldefinediterativeprocedure.Preliminarycalculationsformembersizesareusuallybasedongravityloadingaugmentedbyanarbitraryincrementtoaccountforwindforces.Thecross-sectionalareasoftheverticalmemberswillbebasedontheaccumulatedloadingsfromtheirassociatedtributaryareas,withreductionstoaccountfortheprobabilitythatnotallfloorswillbesubjectedsimultaneouslytotheirmaximumliveloading.Theinitialsizesofbeamsandslabsarenormallybasedonmomentsandshearsobtainedfromsomesimplemethodofgravityloadanalysis,orfromcodifiedmidandendspanvalues.Acheckisthenmadeonthemaximumhorizontaldeflection,andtheforcesinthemajorstructuralmembers,usingsomerapidapproximateanalysistechnique.Ifthedeflectionisexcessive,orsomeofthemembersareinadequate,adjustmentsaremadetothemembersizesorthestructuralarrangement.Ifcertainmembersattractexcessiveloads,theengineermayreducetheirstiffnesstoredistributetheloadtolessheavilystressedcomponents.Theprocedureofpreliminaryanalysis,checking,andadjustmentisrepeateduntilasatisfactorysolutionisobtained.

Invariably,alterationstotheinitiallayoutofthebuildingwillberequiredastheclient'sandarchitect'sideasofthebuildingevolve.Thiswillcallforstructuralmodifications,orperhapsaradicalrearrangement,whichnecessitatesacompletereviewofthestructuraldesign.Thevariouspreliminarystagesmaythereforehavetoberepeatedanumberoftimesbeforeafinalsolutionisreached.

Speedoferectionisavitalfactorinobtainingareturnontheinvestmentinvolvedinsuchlarge-scaleprojects.Mosttallbuildingsareconstructedincongestedcitysites,withdifficultaccess;thereforecarefulplanningandorganizationoftheconstructionsequencebecomeessential.Thestory-to-storyuniformityofmostmultistorybuildingsencouragesconstructionthroughrepetitiveoperationsandprefabricationtechniques.Progressintheabilitytobuildtallhasgonehandinhandwiththedevelopmentofmoreefficientequipmentandimprovedmethodsofconstruction.

EarthquakeFaults

Theoriginofanearthquake

Anearthquakeoriginatesonaplaneofweaknessorafractureintheearth'scrust,termeda"fault".Theearthononesideofthefaultslidesorslipshorizontallyand/orverticallywithrespecttotheearthontheoppositeside,andthisgeneratesavibrationthatistransmittedoutwardinalldirections.Thisvibrationconstitutestheearthquake.

Theearthquakegenerallyoriginatesdeepwithintheearthatapointonthefaultwherethestressthatproducestheslipisamaximum.Thispointiscalledthehypocenterorfocusandthepointontheearth'ssurfacedirectlyabovethispointiscalledtheepicenter.Themainorgreatestshockisusuallyfollowedbynumeroussmalleraftershocks.Theseaftershocksareproducedbyslippageatotherpointsonthefaultorinthefaultzone.

Typesofearthquakefaults

Faultsareclassifiedinaccordancewiththedirectionandnatureoftherelativedisplacementoftheearthatthefaultplane.Probablythemostcommontypeisthestrike-slipfaultinwhichtherelativefaultdisplacementismainlyhorizontalacrossanessentiallyverticalfaultplane.ThegreatSanAndreasfaultinCaliforniaisofthetype.Anothertypeistermedanormalfault—whentherelativemovementisinanupwardandownwarddirectiononanearlyverticalfaultplane.ThegreatAlaskanearthquakeof1964wasapparentlyofthistype.Alesscommontypeisthethrustfault—whentheearthisundercompressivestressacrossthefaultandtheslippageisinanupwardanddownwarddirectionalonganinclinedfaultplane.TheSanFernandoearthquakewasgeneratedonwhathasusuallybeenclassifiedasathrustfault,althoughtherewasaboutasmuchlateralslippageasupanddownslippageduetothrustacrosstheinclinedfaultplane.Someauthoritiesrefertothiscombinedactionaslateralthrustfaulting.ThecompressivestrainintheearthoftheSanFernandoValleyfloorjustsouthofthethrustfaultwasevidencedinmanyplacesbybuckledsidewalksandasphaltpaving.

Forcesexertedbyanearthquake

Slippagealongthefaultoccurssuddenly.Itisareleaseofstressthathasgraduallybuilt-upintherocksoftheearth'scrust.Althoughthevibrationalmovementoftheearthduringanearthquakeisinalldirections,thehorizontalcomponentsareofchiefimportancetothestructuralengineer.Thesemovementsexertforcesonastructurebecausetheyaccelerate.Thisaccelerationissimplyachangeinthevelocityoftheearthmovement.Sincethegroundmotioninanearthquakeisvibratory,theaccelerationandforcethatitexertsonastructurereversesindirectionperiodically,atshortintervalsoftime.

Thestructuralengineerisinterestedintheforceexertedonabodybythemovementoftheearth.ThismaybedeterminedfromNewton'ssecondlawofmotion'whichmaybestatedinthefollowingform:

F=Ma

InwhichFisaforcethatproducesanaccelerationawhenactingonabodyofmassM.Thisequationisnondimensional.ForcalculationsMissetequaltoW/g,then:

F=W/g*a

（1）

InwhichFisinpounds,aisinfeetpersecondpersecond,Wistheweightofthebodyalsoinpoundsandgistheaccelerationofgravity,whichis32.2feetpersecondpersecond.

Equation

（1）isempirical.ItsimplystatestheexperimentalfactthatforafreefallingbodytheaccelerationaisequaltogandtheaccelerationforceFisthenequaltotheweightW.

Forconvenience,theaccelerationofanearthquakeisgenerallyexpressedasaratiototheaccelerationofgravity.Thisratioiscalledaseismiccoefficient.Theadvantageofthissystemisthattheforceexertedonabodybyaccelerationissimplythecorrespondingseismiccoefficientmultipliedbytheweightofthebody.ThisisinaccordancewithEquation

（1）inwhicha/gistheseismiccoefficient.

Activityoffaults

Allfaultsarenotconsideredtopresentthesamehazard.Someareclassifiedas"active"sinceitisbelievedthatthesefaultsmayundergomovementfromtimetotimeintheimmediategeologicfuture.Unfortunatelyinthepresentstate-of-the-artthereisagooddealofuncertaintyintheidentificationofpotentiallyactivefaults.Forexample,thefaultthatgeneratedtheSanFernandoearthquakedidnotevenappearonanypublishedgeologicalmapsofthearea.Thisfaultwasdiscovere