建筑结构设计及材料中英文对照外文翻译文献Word文件下载.docx
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Wehaveandthearchitectsmustdealwiththespatialaspectofactivity,physical,andsymbolicneedsinsuchawaythatoverallperformanceintegrityisassured.Hence,heorshewellwantstothinkofevolvingabuildingenvironmentasatotalsystemofinteractingandspaceformingsubsystems.Isrepresentsacomplexchallenge,andtomeetitthearchitectwillneedahierarchicdesignprocessthatprovidesatleastthreelevelsoffeedbackthinking:
schematic,
preliminary,andfinal.
Suchahierarchyisnecessaryifheorsheistoavoidbeingconfused,atconceptualstagesofdesignthinking,bythemyriaddetailissuesthatcandistractattentionfrommorebasicconsiderations.Infact,wecansaythatanarchitect’sabilitytodistinguishthemorebasicformthemoredetailedissuesisessentialtohissuccessasadesigner.
Theobjectoftheschematicfeedbacklevelistogenerateandevaluate overall site-plan, activity-interaction, andbuilding-configurationoptions.Todosothearchitectmustbeabletofocusontheinteractionofthebasicattributesofthesitecontext,thespatialorganization,andthesymbolismasdeterminantsofphysicalform.Thismeansthat,inschematicterms,thearchitectmayfirstconceiveandmodelabuildingdesignasanorganizationalabstractionofessentialperformance-spaceinteractions.Thenheorshemayexploretheoverallspace-formimplicationsoftheabstraction.Asanactualbuildingconfigurationoptionbeginstoemerge,itwillbemodifiedtoincludeconsiderationforbasicsiteconditions.
Attheschematicstage,itwouldalsobehelpfulifthedesignercouldvisualizehisorheroptionsforachievingoverallstructuralintegrityandconsidertheconstructivefeasibilityandeconomicof
hisorherscheme.Butthiswillrequirethatthearchitectand/oraconsultantbeabletoconceptualizetotal-systemstructuraloptionsintermsofelementaldetail.Suchoverallthinkingcanbeeasilyfedbacktoimprovethespace-formscheme.
Atthepreliminarylevel,thearchitect’semphasiswillshifttotheelaborationofhisorhermorepromisingschematicdesignoptions.Herethearchitect’sstructuralneedswillshifttoapproximatedesignofspecificsubsystemoptions.Atthisstagethetotalstructuralschemeisdevelopedtoamiddlelevelofspecificitybyfocusingonidentificationanddesignofmajorsubsystemstotheextentthattheirkeygeometric,component,andinteractivepropertiesareestablished.Basicsubsysteminteractionanddesignconflictscanthusbeidentifiedandresolvedinthecontextoftotal-systemobjectives.Consultantscanplayasignificantpartinthiseffort;
thesepreliminary-leveldecisionsmayalsoresultinfeedbackthatcallsforrefinementorevenmajorchangeinschematicconcepts.
Whenthedesignerandtheclientaresatisfiedwiththefeasibilityofadesignproposalatthepreliminarylevel,itmeansthatthebasicproblemsofoveralldesignaresolvedanddetailsarenotlikelytoproducemajorchange.Thefocusshiftsagain,andthedesignprocessmovesintothefinallevel.Atthisstagetheemphasis
willbeonthedetaileddevelopmentofallsubsystemspecifics.Heretheroleofspecialistsfromvariousfields,includingstructuralengineering,ismuchlarger,sincealldetailofthepreliminarydesignmustbeworkedout.DecisionsmadeatthislevelmayproducefeedbackintoLevelIIthatwillresultinchanges.However,ifLevels
IandIIarehandledwithinsight,therelationshipbetweentheoveralldecisions,madeattheschematicandpreliminarylevels,andthespecificsofthefinallevelshouldbesuchthatgrossredesignisnotinquestion,Rather,theentireprocessshouldbeoneofmovinginanevolutionaryfashionfromcreationandrefinement(ormodification)ofthemoregeneralpropertiesofatotal-systemdesignconcept,tothefleshingoutofrequisiteelementsanddetails.
Tosummarize:
AtLevelI,thearchitectmustfirstestablish,inconceptualterms,theoverallspace-formfeasibilityofbasicschematicoptions.Atthisstage,collaborationwithspecialistscanbehelpful,butonlyifintheformofoverallthinking.AtLevelII,thearchitectmustbeabletoidentifythemajorsubsystemrequirementsimpliedbytheschemeandsubstantialtheirinteractivefeasibilitybyapproximatingkeycomponentproperties.Thatis,thepropertiesofmajorsubsystemsneedbeworkedoutonlyinsufficientdepthtoverytheinherentcompatibilityoftheirbasicform-relatedandbehavioralinteraction.Thiswillmeanasomewhatmorespecific
formofcollaborationwithspecialiststhenthatinlevelI.AtlevelIII,thearchitectandthespecificformofcollaborationwithspecialiststhenthatprovidingforalloftheelementaldesignspecificsrequiredtoproducebiddableconstructiondocuments.
OfcoursethissuccesscomesfromthedevelopmentoftheStructuralMaterial.
Theprincipalconstructionmaterialsofearliertimeswerewoodandmasonrybrick,stone,ortile,andsimilarmaterials.Thecoursesorlayerswereboundtogetherwithmortarorbitumen,atarlikesubstance,orsomeotherbindingagent.TheGreeksandRomanssometimesusedironrodsorclapstostrengthentheirbuilding.ThecolumnsoftheParthenoninAthens,forexample,haveholesdrilledinthemforironbarsthathavenowrustedaway.TheRomansalsoused
anaturalcementcalledpuzzling,madefromvolcanicash,thatbecameashardasstoneunderwater.
Bothsteelandcement,thetwomostimportantconstructionmaterialsofmoderntimes,wereintroducedinthenineteenthcentury.Steel,basicallyanalloyofironandasmallamountofcarbonhadbeenmadeuptothattimebyalaboriousprocessthatrestrictedittosuchspecialusesasswordblades.AftertheinventionoftheBessemerprocessin1856,steelwasavailableinlargequantitiesatlowprices.Theenormousadvantageofsteelisitstensileforce
which,aswehaveseen,tendstopullapartmanymaterials.Newalloyshavefurther,whichisatendencyforittoweakenasaresultofcontinualchangesinstress.
Moderncement,calledPortlandcement,wasinventedin1824.It
isamixtureoflimestoneandclay,whichisheatedandthengroundintoapower.Itismixedatorneartheconstructionsitewithsand,aggregatesmallstones,crushedrock,orgravel,andwatertomakeconcrete.Differentproportionsoftheingredientsproduceconcretewithdifferentstrengthandweight.Concreteisveryversatile;
itcanbepoured,pumped,orevensprayedintoallkindsofshapes.Andwhereassteelhasgreattensilestrength,concretehasgreatstrengthundercompression.Thus,thetwosubstancescomplementeachother.
Theyalsocomplementeachotherinanotherway:
theyhavealmostthesamerateofcontractionandexpansion.Theythereforecanworktogetherinsituationswherebothcompressionandtensionarefactors.Steelrodsareembeddedinconcretetomakereinforcedconcreteinconcretebeamsorstructureswheretensionswilldevelop.Concreteandsteelalsoformsuchastrongbond─theforcethatunitesthem─thatthesteelcannotslipwithintheconcrete.Stillanotheradvantageisthatsteeldoesnotrustinconcrete.Acidcorrodessteel,whereasconcretehasanalkalinechemicalreaction,theoppositeofacid.
Theadoptionofstructuralsteelandreinforcedconcretecausedmajorchangesintraditionalconstructionpractices.Itwasnolongernecessarytousethickwallsofstoneorbrickformultistorybuildings,anditbecamemuchsimplertobuildfire-resistantfloors.Boththesechangesservedtoreducethecostofconstruction.Italsobecamepossibletoerectbuildingswithgreaterheightsandlongerspans.
Sincetheweightofmodernstructuresiscarriedbythesteelorconcreteframe,thewallsdonotsupportthebuilding.Theyhavebecomecurtainwalls,whichkeepouttheweatherandletinlight.Intheearliersteelorconcreteframebuilding,thecurtainwallsweregenerallymadeofmasonry;
theyhadthesolidlookofbearingwalls.Today,however,curtainwallsareoftenmadeoflightweightmaterialssuchasglass,aluminum,orplastic,invariouscombinations.
Anotheradvanceinsteelconstructionisthemethodoffasteningtogetherthebeams.Formanyyearsthestandardmethodwasriveting.
Arivetisaboltwithaheadthatlookslikeabluntscrewwithoutthreads.Itisheated,placedinholesthroughthepiecesofsteel,andasecondheadisformedattheotherendbyhammeringittoholditinplace.Rivetinghasnowlargelybeenreplacedbywelding,thejoiningtogetherofpiecesofsteelbymeltingasteelmaterial
betweenthemunderhighheat.
Priestess’sconcreteisanimprovedformofreinforcement.Steelrodsarebentintotheshapestogivethemthenecessarydegreeoftensilestrengths.Theyarethenusedtopriestessconcrete,usuallybyoneoftwodifferentmethods.Thefirstistoleavechannelsinaconcretebeamthatcorrespondtotheshapesofthesteelrods.Whentherodsarerunthroughthechannels,theyarethenbondedtotheconcretebyfillingthechannelswithgrout,athinmortarorbindingagent.Intheother(andmorecommon)method,thepriestessessteelrodsareplacedinthelowerpartofaformthatcorrespondstotheshapeofthefinishedstructure,andtheconcreteispouredaroundthem.Priestess’sconcreteuseslesssteelandlessconcrete.Becauseitisahighlydesirablematerial.
Progressedconcretehasmadeitpossibletodevelopbuildingswithunusualshapes,likesomeofthemodern,sportsarenas,withlargespacesunbrokenbyanyobstructingsupports.Theusesforthisrelativelynewstructuralmethodareconstant