土木工程英語翻譯2

第第頁土木工程英語翻譯2Anotheradvanceinsteelconstruction〔結(jié)構(gòu)〕isthemethodoffasteningtogether〔連在一起〕thebeams.Formanyyearsthestandardmethodwasriveting.Arivetisaboltwithaheadthatlookslikeabluntscrew〔圓頭螺絲釘〕withoutthreads〔螺紋〕.Itisheated,placedinholesthroughthepiecesofsteel〔鋼構(gòu)件〕,andasecondheadisformedattheotherendbyhammering〔錘擊〕ittoholditinplace〔固定就位〕.Rivetinghasnowlargelybeenreplacedbywelding,thejoiningtogetherofpiecesofsteFundamentally,engineeringisanend-product-orienteddisciplinethatisinnovative,cost-consciousandmindfulofhumanfactors.Itisconcernedwiththecreationofnewentities,devicesormethodsofsolution:anewprocess,anewmaterial,animprovedpowersource,amoreefficientarrangementoftaskstoaccomplishadesiredgoaloranewstructure.Engineeringisalsomoreoftenthannotconcernedwithobtainingeconomicalsolutions.And,finally,humansafetyisalwaysakeyconsideration.Engineeringisconcernedwiththeuseofabstractscientificwaysofthinkingandofdefiningrealworldproblems.Theuseofidealizationsanddevelopmentofproceduresforestablishingboundswithinwhichbehaviorcanbeascertainedarepartoftheprocess.

Manyproblems,bytheirverynature,can’tbefullydescribed—evenafterthefact,muchlessattheoutset.Yetacceptableengineeringsolutionstotheseproblemsmustbefoundwhichsatisfythedefinedneeds.Engineering,then,frequentlyconcernsthedeterminationofpossiblesolutionswithinacontextoflimiteddata.Intuitionorjudgmentisakeyfactorinestablishingpossiblealternativestrategies,processes,orsolutions.Andthis,too,isallapartofengineering.

Civilengineeringisoneofthemostdiversebranchesofengineering.Thecivilengineerplans,designs,constructs,andmaintainsalargevarietyofstructuresandfacilitiesforpublic,commercialandindustrialuse.Thesestructuresincluderesidential,office,andfactorybuildings;highways,railways,airports,tunnels,bridges,harbors,channels,andpipelines.Theyalsoincludemanyotherfacilitiesthatareapartofthetransportationsystemsofmostcountries,aswellassewageandwastedisposalsystemsthataddtoourconvenienceandsafeguardourhealth.Theterm“civilengineer”didnotcomeintouseuntilabout1750,whenJohnSmeaton,thebuilderoffamousEddystonelighthousenearPlymouth,England,issaidtohavebeguncallinghimselfa“civilengineer”todistinguishhimselffromthemilitaryengineersofhistime.However,theprofessionisasoldascivilization.

InancientEgyptthesimplestmechanicalprinciplesanddeviceswereusedtoconstructmanytemplesandpyramidsthatarestillstanding,includingthegreatpyramidatGizaandthetempleofAmon-RaatKarnak.Thegreatpyramid,481feet(146.6meters)high,ismadeof2.25millionstoneblockshavinganaverageweightofmorethan1.5tons(1.4metrictons).Greatnumbersofmenwereusedintheconstructionofsuchmonuments.TheEgyptiansalsomadeobelisksbycuttinghugeblocksofstone,someweighingasmuchas1000tons(900metrictons).Cuttingtoolsofhardbronzewereused.TheEgyptiansbuiltcausewaysandroadsfortransportingstonefromthequarriestotheNile.Thelargeblocksofstonethat

wereerectedbytheEgyptiansweremovedbyusinglevers,inclinedplanes,rollers,andsledges.TheEgyptianswereprimarilyinterestedintheknow-howofconstruction;Theyhadverylittleinterestinwhy-forofuse.Incontrast,theGreeksmadegreatstridesinintroducingtheoryintoengineeringproblemsduringthe6thto3rdcenturiesB.C.Theydevelopedanabstractknowledgeoflines,angles,surfaces,andsolidsratherthanreferringtospecificobjects.ThegeometricbaseforGreekbuildingconstructionincludedfiguressuchasthesquare,rectangle,andtriangle.

TheGreekarchitektonwasusuallythedesigner,aswellasthebuilder,ofarchitecturalandengineeringmasterpieces.Hewasanarchitectandengineer.Craftsmen,masons,andsculptorsworkedunderhissupervision.IntheclassicalperiodofGreeceallimportantbuildingswerebuiltoflimestoneormarble;theParthenon,forexample,wasbuiltofmarble.

Theprincipalconstructionmaterials

Theprincipalconstructionmaterialsofearliertimeswerewoodandmasonry-brick,stone,ortile,andsimilarmaterials.Thecoursesorlayers〔磚層〕wereboundtogetherwithmortarorbitumen,atarlikesubstance,orsomeotherbindingagent.TheGreeksandRomanssometimesusedironrodsorclampstostrengthentheirbuilding.ThecolumnsoftheParthenoninAthens〔雅典的帕臺農(nóng)神廟〕,forexample,haveholesdrilled〔鉆孔〕inthemforironbarsthathavenowrustedaway〔銹蝕殆盡〕.TheRomansalsousedanaturalcementcalledpozzolana,madefromvolcanicash,thatbecameashardasstoneunderwater.Bothsteelandcement,thetwomostimportantconstructionmaterialsofmoderntimes,wereintroduced〔推廣〕inthenineteenthcentury.Steel,basicallyanalloyofiron〔鐵合金〕andasmallamountofcarbon,hadbeenmadeuptothattime〔到那個(gè)時(shí)候〕byalaborious〔繁復(fù)的〕processthatrestrictedittosuchspecialusesasswordblades〔刀刃〕.AftertheinventionoftheBessemerprocess〔貝塞麥煉鋼法〕in1856,steelwasavailableinlargequantitiesatlowprices.Theenormousadvantageofsteelisitstensilestrength;thatis,itdoesnotloseitsstrengthwhenitisunderacalculateddegree(適當(dāng)?shù)?oftension,aforcewhich,aswehaveseen,tendsto〔往往〕pullapartmanymaterials.Newalloyshavefurtherincreasedthestrengthofsteelandeliminatedsomeofitsproblems,suchasfatigue,whichisatendencyforittoweakenasaresultofcontinualchangesinstress〔連續(xù)的'應(yīng)力改變〕.Moderncement,calledPortlandcement,wasinventedin1824.Itisamixtureoflimestone〔石灰石〕andclay,whichisheatedandthengroundintoapowder〔磨成粉末〕.Itismixedatorneartheconstructionsite〔施工現(xiàn)場〕withsand,aggregate(smallstones,crushedrock,orgravel),andwatertomakeconcrete.Differentproportionsoftheingredients〔配料〕produceconcretewithdifferentstrengthandweight.Concreteisveryversatile;itcanbepoured,pumped,orevensprayedinto〔噴射成〕allkindsofshapes.Andwhereassteelhasgreattensilestrength,concretehasgreatstrengthundercompression.Thus,thetwosubstancescomplementeachother〔互補(bǔ)〕.Theyalsocomplementeachotherinanotherway:theyhavealmostthesamerateofcontractionandexpansion.Theythereforecanworktogetherinsituationswhere〔在…狀況下〕bothcompressionandtensionarefactors〔主要因素〕.Steelrods〔鋼筋〕areembeddedin〔埋入〕concretetomakereinforcedconcreteinconcretebeamsorstructureswheretensionwilldevelop〔消失〕.Concreteandsteelalsoformsuchastrongbond-theforcethatunites〔粘合〕them-thatthesteelcannot

slip〔滑移〕withtheconcrete.Still〔還有〕anotheradvantageisthatsteeldoesnotrustinconcrete.Acid〔酸〕corrodessteel,whereasconcretehasanalkalinechemicalreaction,theoppositeofacid.

Theadoptionofstructuralsteelandreinforcedconcretecausedmajorchangesintraditionalconstructionpractices〔施工作業(yè)〕.Itwasnolongernecessarytousethickwallsofstoneorbrickformultistorybuildings,anditbecamemuchsimplertobuildfire-resistantfloors〔防火地面〕.Boththesechangesservedto〔有利于〕reducethecostofconstruction.Italsobecamepossibletoerect〔建筑〕buildingswithgreaterheightsandlongerspans.Sincetheweightofmodernstructuresiscarried〔承受〕bythesteelorconcreteframe,thewallsdonotsupportthebuilding.Theyhavebecomecurtainwalls,whichkeepouttheweatherandletinlight.Intheearliersteelorconcreteframebuilding,thecurtainwallsweregenerallymadeofmasonry;theyhadthesolidlookofbearingwalls〔承重墻〕.Today,however,curtainwallsareoftenmadeoflightweightmaterialssuchasglass,aluminum,orplastic,invariouscombinations.

elbymelting〔熔化〕asteelmaterialbetweenthemunderhighheat.

Prestressedconcreteisanimprovedformofreinforcement〔加強(qiáng)方法〕.Steelrodsarebentintotheshapestogivethemthenecessarydegreeoftensilestrength.Theyarethenusedtoprestress〔對..預(yù)加應(yīng)力〕concrete,usuallybyoneoftwodifferentmethods.Thefirstistoleavechannelsinaconcretebeamthatcorrespondto〔相應(yīng)于〕theshapesofthesteelrods.Whentherodsarerunthroughthechannels,theyarethenbondedtotheconcretebyfillingthechannelswithgrout,athinmortarorbindingagent.Intheother(andmorecommon)method,theprestressedsteelrodsareplacedinthelowerpartofaform〔模板〕thatcorrespondstotheshapeofthefinishedstructure〔成品結(jié)構(gòu)〕,andtheconcreteis

pouredaroundthem.Prestressedconcreteuseslesssteelandlessconcrete.Becauseitissoeconomical,itisahighlydesirable〔特別抱負(fù)〕material.Prestressedconcretehasmadeitpossibletodevelop〔建筑〕buildingswithunusualshapes,likesomeofthemodernsportsarenas,withlargespaceunbrokenbyanyobstructingsupports〔阻礙的支撐物〕.Theusesforthisrelativelynewstructuralmethodareconstantlybeingdeveloped〔不斷地?cái)U(kuò)大〕.Thecurrenttendencyistodevelop〔采納〕lightermaterials,aluminum,forexample,weighsmuchlessthansteelbuthasmanyofthesameproperties.Aluminumbeamshavealreadybeenusedforbridgeconstructionandfortheframeworkofafewbuildings.

Lightweightconcretes,anotherexample,arenowrapidlydeveloping〔進(jìn)展〕throughouttheworld.Theyareusedfortheirthermalinsulation(絕熱性).Thethreetypesareillustratedbelow〔舉例說明如下〕:(a)Concretesmadewithlightweightaggregates;(b)Aeratedconcretes(USgasconcretes)foamed〔起泡〕bywhisking〔攪拌〕orbysomechemicalprocessduringcasting;(c)No-finesconcretes.

Allthreetypesareusedfortheirinsulatingproperties〔絕熱性〕,mainlyinhousing,wheretheygivehigh〔特別〕comfortincoldclimatesandalowcostofcooling〔降溫本錢〕inhotclimates.Inhousing,therelativeweaknessoflightweightconcretewallsisunimportant,butitmatters〔有重大關(guān)系〕inroofslabs,floorslabsandbeams.

Insomelocations,somelightweightaggregatescostlittlemorethan〔幾乎等于〕thebestdense〔致密〕aggregatesandalargenumberof〔大量〕floorslabshavethereforebeenbuiltoflightweightaggregateconcretepurelyforitsweightsaving,withnothoughtof〔沒考慮〕itsinsulationvalue.

Thelightweightaggregatereducesthefloordeadload〔恒載〕byabout20percentresultingin〔導(dǎo)致〕considerablesavingsinthefloor〔樓蓋結(jié)構(gòu)〕steelineveryfloorandtheroof,aswellasinthecolumnsteeland(less)inthefoundations.OneLondoncontractor〔承包商〕preferstouselightweightaggregatebecauseitgiveshimthesameweightreductioninthefloorslabastheuseofhollowtiles,withsimplerorganizationandthereforehigherspeedandprofit.Theinsulationvalueofthelightweightaggregateisonlyimportantintheroofinsulation,whichisgreatlyimproved〔改良〕.

StructuralAnalysis

Astructureconsistsof〔由..組成〕aseriesofconnectedpartsusedtosupportloads.Notable〔顯著的〕examplesincludebuildings,bridges,towers,tanks,anddams.Theprocess〔過程〕ofcreatinganyofthesestructuresrequiresplanning〔規(guī)劃〕,analysis,design,andconstruction〔施工〕.Structuralanalysisconsistsof〔包括〕avarietyofmathematicalprocedures〔數(shù)學(xué)程序〕fordeterminingsuchquantitiesasthememberforcesandvariousstructuraldisplacements〔位移〕asastructurerespondstoitsloads.Estimatingrealisticloadsforthestructureconsidering〔依據(jù)〕itsuseandlocationisoftenapartofstructuralanalysis.Onlytwoassumptionsaremaderegarding〔關(guān)于〕thematerialsusedinthestructuresofthischapter.First,thematerialhasalinearstress-strainrelationship〔線性的應(yīng)力-應(yīng)變關(guān)系〕.Second,thereisnodifferenceinthematerialbehaviorwhenstressedintensionvis-a-vis〔與..相比〕compression.Theframesandtrussesstudiedareplanestructuralsystems〔平面結(jié)構(gòu)體系〕.Itwillbeassumedthatthereisadequatebracingperpendicularto〔垂直于〕theplanesothatnomemberwillfailduetoanelasticinstability〔彈性失穩(wěn)〕.Theveryimportantconsiderationregardingsuchinstabilitywillbeleftforthespecific〔詳細(xì)的〕designcourse.

Allstructuresareassumedtoundergoonlysmalldeformationsastheyareloaded.Asaconsequence〔因此〕weassumenochangeinthepositionordirectionofaforceasaresultof〔由于〕structuraldeflections〔變位〕.Finally,sincelinearelasticmaterialsandsmalldisplacementareassumed,theprincipleofsuperpositionwillapplyinallcases.Thusthedisplacementsorinternalforcesthatarisefromtwodifferentforcessystemsappliedoneatatime〔一次一個(gè)〕maybeaddedalgebraically〔幾何相加〕todeterminethestructure’sresponsewhenbothsystem(s)areappliedsimultaneously.Intherealsense〔真正意義上〕anexactanalysisofastructurecanneverbecarriedoutsinceestimatesalwayshavetobemadeoftheloadingsandthestrengthofthematerialscomposing〔構(gòu)成〕thestructure.Furthermore,pointsofapplication〔作用點(diǎn)〕fortheloadingsmustalsobeestimated.Itisimportant,therefore,thatthestructuralengineersdevelop〔形成〕theabilitytomodel〔模擬〕oridealize〔使..抱負(fù)化〕astructuresothatheorshecanperformapracticalforceanalysisofthemembers.

Structuralmembersarejoinedtogetherinvariouswaysdependingontheintent〔意圖〕ofthedesigner.Thetwotypesofjointsmostoftenspecified〔規(guī)定的〕arethepinconnectionandthefixedjoint〔節(jié)點(diǎn)〕.Apin-connectedjointallowssomefreedomforslight〔稍微〕rotation,whereasthefixedjointallowsnorelativerotationbetweentheconnectedmembers.Inreality,however,allconnectionsexhibit〔顯現(xiàn)〕somestiffnesstowardjointrotations,owingtofriction〔摩擦〕andmaterialbehavior.Whenselectingaparticularmodelforeachsupport

〔支座〕orjoint,theengineermustbeawareofhowtheassumptionswillaffecttheactualperformance〔運(yùn)行〕ofthememberandwhethertheassumptionsarereasonableforthestructuraldesign.Inreality,allstructuralsupportsactuallyexert〔產(chǎn)生〕distributedsurfaceloads〔面荷載〕ontheircontactingmembers.Theresultants〔合力〕oftheseloaddistributionsareoftenidealizedastheconcentratedforces〔集中力〕andmoments,sincethesurfacearea〔外表積〕overwhichthedistributedloadactsisconsiderablysmallerthanthetotalsurfaceareaoftheconnectingmembers.Theabilitytoreduceanactualstructureto〔將..簡化為〕anidealizedformcanonlybegainedbyexperience.Inengineeringpractice,ifitbecomesdoubtful〔不明確〕astohowtomodelastructureortransfertheloadstothemembers,itisbesttoconsiderseveralidealizedstructuresandloadingsandthendesigntheactualstructuresothatitcanresist〔反抗〕theloadingsinalltheidealizedmodels.

Almostalltrusssystemsareconfigured〔裝配〕sothatanalysisusingthemethodofjointsmustbeginatoneendandproceed〔連續(xù)〕jointbyjointtowardtheotherend.Ifitisnecessarytoevaluatetheforcescarriedbyamemberlocated〔位于〕somedistancefromtheends,themethodofjointsrequiresthecalculationoftheforcesinmanymembersbeforethedesiredoneisreached.Themethodofsectionsprovidesameans〔方法〕foradirectcalculationinthesecases.Afterthesupportreactionshavebeencalculatedthetrussiscutthrough〔切開〕(analytically分析上)sothatonepartofthetrussiscompletelyseveredfromtherest.Whenthisisdone,nomorethanthreeunknownmembersshouldbecut.Ifpossible〔假如可能〕thecut〔切口〕shouldpassthroughthememberormemberswhoseinternalforcesaretobefound.Afree-bodydiagramofthepartofthetrussononesideof〔在..一邊〕thissectionisdrawn,andtheinternalforcesarefoundthroughtheequilibriumequations.Sincethesystemofforces〔力系〕onthefree-bodydiagramisaplanenon-concurrent〔非共點(diǎn)〕forcesystem,threeequilibriumequationsmaybewrittenandsolvedforthethreeunknowns.

Influencelines〔影響線〕haveimportantapplicationfor〔應(yīng)用〕thedesignofstructuresthatresistlargeliveloads〔活荷載〕.Aninfluencelinerepresents〔代表〕thevariationofeitherthereaction,shear,moment,ordeflectionataspecific〔特定的〕pointinamemberasconcentratedforcemovesoverthemember.Oncethislineisconstructed〔作圖〕,onecantellataglance〔一眼便知〕wherealiveloadshouldbeplacedonthestructuresothatitcreates〔引起〕thegreatestinfluenceatthespecifiedpoint.Furthermore,themagnitude〔大小〕oftheassociated〔相關(guān)的〕reaction,shear,moment,ordeflectionatthepointcanthenbecalculatedfromtheordinates〔縱坐標(biāo)〕oftheinfluence-linediagram.Forthesereasons〔因此〕,influencelinesplayanimportantpartinthedesignofbridges,industrialcranerails〔吊車軌道〕,conveyors,andotherstructureswhereloadsmoveacrosstheirspan〔全長〕.Althoughtheprocedure〔步驟〕forconstructinganinfluencelineisratherbasic〔基本的〕,oneshouldclearlybeawareofthedifferencebetweenconstructinganinfluencelineandconstructingashearormomentdiagram.Influencelinesrepresenttheeffectofamovingloadonlyataspecifiedpointonamember,whereasshearandmomentdiagramsrepresenttheeffectoffixedloadsatallpointsalongtheaxisofthemember.

Deflectionsofstructurescanoccurfromvarioussources〔緣由〕,suchasloads,temperature,fabricationerrors,orsettlement.Indesign,deflectionsmustbelimitedinordertopreventcrackingofattached〔附屬的〕brittlematerialssuchasconcreteorplaster(石膏).Furthermore,astructuremustnotvibrateordeflect〔變位〕severelyinorderto“appear”safe

foritsoccupants〔居住者〕.Moreimportant,though〔然而〕,deflectionsatspecifiedpointsinastructuremustbecomputedifoneistoanalyzestaticallyindeterminatestructures.Weoftendeterminetheelasticdeflectionsofastructureusingbothgeometricalandenergymethods.Also,themethodsofdoubleintegration〔雙重積分〕areused.Thegeometricalmethodsincludethemoment-areatheorems〔彎矩圖面積定理〕andtheconjugate-beammethod〔共軛梁法〕,andtheenergymethodstobeconsideredarebasedonvirtualwork〔虛功〕andCastigliano’stheorem〔卡氏最小功定理〕.Eachofthesemethodshasparticularadvantagesordisadvantages.

Concreteandreinforcedconcreteareusedasbuildingmaterialsineverycountry.Inmany,includingtheUnitedStatesandCanada,reinforcedconcreteisadominant〔主要的〕structuralmaterialinengineeredconstruction〔建筑的建筑物〕.Theuniversal〔通用的〕natureofreinforcedconcreteconstructionstemsfrom〔歸因于〕thewideavailabilityofreinforcingbars〔鋼筋〕andtheconstituents〔組成部分〕ofconcrete,gravel,sand,andcement,therelativelysimpleskillsrequiredinconcreteconstruction〔施工〕,andtheeconomy〔經(jīng)濟(jì)性〕ofreinforcedconcretecomparedtootherformofconstruction.Concreteandreinforcedconcreteareusedinbridges,buildingsofallsorts〔各種各樣〕,undergroundstructures,watertanks,televisiontowers,offshoreoilexplorationandproductionstructures〔近海石油開采和生產(chǎn)結(jié)構(gòu)〕,dams,andeveninships.

valueofReinforcedConcrete

Concreteisstrongincompressionbutweakintension.Asaresult,cracksdevelop〔形成〕whenever〔每當(dāng)〕loads,orrestrainedshrinkage〔收縮限制〕ortemperaturechanges,giveriseto〔導(dǎo)致〕tensilestressesinexcessof〔超過〕thetensilestrengthoftheconcrete.Intheplainconcrete〔素混凝土〕beam,themomentsduetoappliedloadsareresistedbyaninternaltension-compressioncouple〔拉壓力偶〕involvingtensionintheconcrete.Suchabeamfailsverysuddenlyandcompletelywhenthefirstcrackforms.Inareinforcedconcretebeam,steelbars〔鋼筋〕areembeddedintheconcreteinsuchawaythatthetensionforcesneededformomentequilibriumaftertheconcretecrackscanbedevelopedinthebars.

EconomyFrequently,theforemost〔最重要的〕considerationistheoverallcost〔總費(fèi)用〕ofthestructure.Thisis,ofcourse,afunctionofthecosts〔費(fèi)用函數(shù)〕ofthematerialsandthelabornecessarytoerectthem.Frequently,however,theoverallcostisaffectedasmuchormorebytheoverallconstructiontime〔總的建筑時(shí)間〕sincethecontractorandownermustallocate〔安排〕money〔資金〕tocarryouttheconstructionandwillnotreceiveareturnonthisinvestment〔收回投資〕untilthebuildingisreadyforoccupancy〔居住〕.Asaresult,financialsavings〔財(cái)務(wù)的節(jié)省〕duetorapidconstructionmaymorethanoffset〔足以抵消〕increasedmaterialcosts.Anymeasuresdesignercantaketostandardizethedesignandforming〔加工〕willgenerallypayoff〔使人得益〕inreducedoverallcosts.

Thechoiceofwhetherastructureshouldbebuiltofconcrete,steel,masonry,ortimber〔木材〕dependsontheavailability〔可得性〕ofmaterialsandonanumberof〔很多〕valuedecisions〔價(jià)值推斷〕.

EconomyFrequently,theforemost〔最重要的〕considerationistheoverallcost〔總費(fèi)用〕ofthestructure.Thisis,ofcourse,afunctionofthecosts〔費(fèi)用函數(shù)〕ofthematerialsandthelabornecessarytoerectthem.Frequently,however,theoverallcostisaffectedasmuchormorebytheoverallconstructiontime〔總的建筑時(shí)間〕sincethecontractorandownermustallocate〔安排〕money〔資金〕tocarryouttheconstructionandwillnotreceive

areturnonthisinvestment〔收回投資〕untilthebuildingisreadyforoccupancy〔居住〕.Asaresult,financialsavings〔財(cái)務(wù)的節(jié)省〕duetorapidconstructionmaymorethanoffset〔足以抵消〕increasedmaterialcosts.Anymeasuresdesignercantaketostandardizethedesignandforming〔加工〕willgenerallypayoff〔使人得益〕inreducedoverallcosts.Inmanycasesthelong-termeconomy〔長期的經(jīng)濟(jì)性〕ofthestructuremaybemoreimportantthanthefirstcost.Asaresult,maintenance〔維護(hù)〕anddurability〔耐久性〕areimportantconsiderations.

SuitabilityofMaterialforArchitecturalandStructuralFunctionAreinforcedconcretesystemfrequentlyallowsthedesignertocombinethearchitecturalandstructuralfunctions〔功能〕.Concretehastheadvantagethatitisplacedinaplasticcondition〔塑性狀態(tài)〕andisgiventhedesiredshapeandtexture〔密度〕bymeansoftheformsandthefinishingtechniques〔加工技術(shù)〕.Thisallowssuchelements〔構(gòu)件〕asflatplatesorothertypesofslabstoserveasload-bearingelementswhileprovidingthefinishedfloorandceilingsurface〔樓面和頂棚面〕.Similarly,reinforcedconcretewallscanprovidearchitecturallyattractivesurfacesinadditiontohavingtheabilitytoresistgravity,