土木工程英语翻译2

第第页土木工程英语翻译2Anotheradvanceinsteelconstruction〔结构〕isthemethodoffasteningtogether〔连在一起〕thebeams.Formanyyearsthestandardmethodwasriveting.Arivetisaboltwithaheadthatlookslikeabluntscrew〔圆头螺丝钉〕withoutthreads〔螺纹〕.Itisheated,placedinholesthroughthepiecesofsteel〔钢构件〕,andasecondheadisformedattheotherendbyhammering〔锤击〕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〔砖层〕wereboundtogetherwithmortarorbitumen,atarlikesubstance,orsomeotherbindingagent.TheGreeksandRomanssometimesusedironrodsorclampstostrengthentheirbuilding.ThecolumnsoftheParthenoninAthens〔雅典的帕台农神庙〕,forexample,haveholesdrilled〔钻孔〕inthemforironbarsthathavenowrustedaway〔锈蚀殆尽〕.TheRomansalsousedanaturalcementcalledpozzolana,madefromvolcanicash,thatbecameashardasstoneunderwater.Bothsteelandcement,thetwomostimportantconstructionmaterialsofmoderntimes,wereintroduced〔推广〕inthenineteenthcentury.Steel,basicallyanalloyofiron〔铁合金〕andasmallamountofcarbon,hadbeenmadeuptothattime〔到那个时候〕byalaborious〔繁复的〕processthatrestrictedittosuchspecialusesasswordblades〔刀刃〕.AftertheinventionoftheBessemerprocess〔贝塞麦炼钢法〕in1856,steelwasavailableinlargequantitiesatlowprices.Theenormousadvantageofsteelisitstensilestrength;thatis,itdoesnotloseitsstrengthwhenitisunderacalculateddegree(适当的)oftension,aforcewhich,aswehaveseen,tendsto〔往往〕pullapartmanymaterials.Newalloyshavefurtherincreasedthestrengthofsteelandeliminatedsomeofitsproblems,suchasfatigue,whichisatendencyforittoweakenasaresultofcontinualchangesinstress〔连续的'应力改变〕.Moderncement,calledPortlandcement,wasinventedin1824.Itisamixtureoflimestone〔石灰石〕andclay,whichisheatedandthengroundintoapowder〔磨成粉末〕.Itismixedatorneartheconstructionsite〔施工现场〕withsand,aggregate(smallstones,crushedrock,orgravel),andwatertomakeconcrete.Differentproportionsoftheingredients〔配料〕produceconcretewithdifferentstrengthandweight.Concreteisveryversatile;itcanbepoured,pumped,orevensprayedinto〔喷射成〕allkindsofshapes.Andwhereassteelhasgreattensilestrength,concretehasgreatstrengthundercompression.Thus,thetwosubstancescomplementeachother〔互补〕.Theyalsocomplementeachotherinanotherway:theyhavealmostthesamerateofcontractionandexpansion.Theythereforecanworktogetherinsituationswhere〔在…状况下〕bothcompressionandtensionarefactors〔主要因素〕.Steelrods〔钢筋〕areembeddedin〔埋入〕concretetomakereinforcedconcreteinconcretebeamsorstructureswheretensionwilldevelop〔消失〕.Concreteandsteelalsoformsuchastrongbond-theforcethatunites〔粘合〕them-thatthesteelcannot

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

Theadoptionofstructuralsteelandreinforcedconcretecausedmajorchangesintraditionalconstructionpractices〔施工作业〕.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〔承重墙〕.Today,however,curtainwallsareoftenmadeoflightweightmaterialssuchasglass,aluminum,orplastic,invariouscombinations.

elbymelting〔熔化〕asteelmaterialbetweenthemunderhighheat.

Prestressedconcreteisanimprovedformofreinforcement〔加强方法〕.Steelrodsarebentintotheshapestogivethemthenecessarydegreeoftensilestrength.Theyarethenusedtoprestress〔对..预加应力〕concrete,usuallybyoneoftwodifferentmethods.Thefirstistoleavechannelsinaconcretebeamthatcorrespondto〔相应于〕theshapesofthesteelrods.Whentherodsarerunthroughthechannels,theyarethenbondedtotheconcretebyfillingthechannelswithgrout,athinmortarorbindingagent.Intheother(andmorecommon)method,theprestressedsteelrodsareplacedinthelowerpartofaform〔模板〕thatcorrespondstotheshapeofthefinishedstructure〔成品结构〕,andtheconcreteis

pouredaroundthem.Prestressedconcreteuseslesssteelandlessconcrete.Becauseitissoeconomical,itisahighlydesirable〔特别抱负〕material.Prestressedconcretehasmadeitpossibletodevelop〔建筑〕buildingswithunusualshapes,likesomeofthemodernsportsarenas,withlargespaceunbrokenbyanyobstructingsupports〔阻碍的支撑物〕.Theusesforthisrelativelynewstructuralmethodareconstantlybeingdeveloped〔不断地扩大〕.Thecurrenttendencyistodevelop〔采纳〕lightermaterials,aluminum,forexample,weighsmuchlessthansteelbuthasmanyofthesameproperties.Aluminumbeamshavealreadybeenusedforbridgeconstructionandfortheframeworkofafewbuildings.

Lightweightconcretes,anotherexample,arenowrapidlydeveloping〔进展〕throughouttheworld.Theyareusedfortheirthermalinsulation(绝热性).Thethreetypesareillustratedbelow〔举例说明如下〕:(a)Concretesmadewithlightweightaggregates;(b)Aeratedconcretes(USgasconcretes)foamed〔起泡〕bywhisking〔搅拌〕orbysomechemicalprocessduringcasting;(c)No-finesconcretes.

Allthreetypesareusedfortheirinsulatingproperties〔绝热性〕,mainlyinhousing,wheretheygivehigh〔特别〕comfortincoldclimatesandalowcostofcooling〔降温本钱〕inhotclimates.Inhousing,therelativeweaknessoflightweightconcretewallsisunimportant,butitmatters〔有重大关系〕inroofslabs,floorslabsandbeams.

Insomelocations,somelightweightaggregatescostlittlemorethan〔几乎等于〕thebestdense〔致密〕aggregatesandalargenumberof〔大量〕floorslabshavethereforebeenbuiltoflightweightaggregateconcretepurelyforitsweightsaving,withnothoughtof〔没考虑〕itsinsulationvalue.

Thelightweightaggregatereducesthefloordeadload〔恒载〕byabout20percentresultingin〔导致〕considerablesavingsinthefloor〔楼盖结构〕steelineveryfloorandtheroof,aswellasinthecolumnsteeland(less)inthefoundations.OneLondoncontractor〔承包商〕preferstouselightweightaggregatebecauseitgiveshimthesameweightreductioninthefloorslabastheuseofhollowtiles,withsimplerorganizationandthereforehigherspeedandprofit.Theinsulationvalueofthelightweightaggregateisonlyimportantintheroofinsulation,whichisgreatlyimproved〔改良〕.

StructuralAnalysis

Astructureconsistsof〔由..组成〕aseriesofconnectedpartsusedtosupportloads.Notable〔显著的〕examplesincludebuildings,bridges,towers,tanks,anddams.Theprocess〔过程〕ofcreatinganyofthesestructuresrequiresplanning〔规划〕,analysis,design,andconstruction〔施工〕.Structuralanalysisconsistsof〔包括〕avarietyofmathematicalprocedures〔数学程序〕fordeterminingsuchquantitiesasthememberforcesandvariousstructuraldisplacements〔位移〕asastructurerespondstoitsloads.Estimatingrealisticloadsforthestructureconsidering〔依据〕itsuseandlocationisoftenapartofstructuralanalysis.Onlytwoassumptionsaremaderegarding〔关于〕thematerialsusedinthestructuresofthischapter.First,thematerialhasalinearstress-strainrelationship〔线性的应力-应变关系〕.Second,thereisnodifferenceinthematerialbehaviorwhenstressedintensionvis-a-vis〔与..相比〕compression.Theframesandtrussesstudiedareplanestructuralsystems〔平面结构体系〕.Itwillbeassumedthatthereisadequatebracingperpendicularto〔垂直于〕theplanesothatnomemberwillfailduetoanelasticinstability〔弹性失稳〕.Theveryimportantconsiderationregardingsuchinstabilitywillbeleftforthespecific〔详细的〕designcourse.

Allstructuresareassumedtoundergoonlysmalldeformationsastheyareloaded.Asaconsequence〔因此〕weassumenochangeinthepositionordirectionofaforceasaresultof〔由于〕structuraldeflections〔变位〕.Finally,sincelinearelasticmaterialsandsmalldisplacementareassumed,theprincipleofsuperpositionwillapplyinallcases.Thusthedisplacementsorinternalforcesthatarisefromtwodifferentforcessystemsappliedoneatatime〔一次一个〕maybeaddedalgebraically〔几何相加〕todeterminethestructure’sresponsewhenbothsystem(s)areappliedsimultaneously.Intherealsense〔真正意义上〕anexactanalysisofastructurecanneverbecarriedoutsinceestimatesalwayshavetobemadeoftheloadingsandthestrengthofthematerialscomposing〔构成〕thestructure.Furthermore,pointsofapplication〔作用点〕fortheloadingsmustalsobeestimated.Itisimportant,therefore,thatthestructuralengineersdevelop〔形成〕theabilitytomodel〔模拟〕oridealize〔使..抱负化〕astructuresothatheorshecanperformapracticalforceanalysisofthemembers.

Structuralmembersarejoinedtogetherinvariouswaysdependingontheintent〔意图〕ofthedesigner.Thetwotypesofjointsmostoftenspecified〔规定的〕arethepinconnectionandthefixedjoint〔节点〕.Apin-connectedjointallowssomefreedomforslight〔稍微〕rotation,whereasthefixedjointallowsnorelativerotationbetweentheconnectedmembers.Inreality,however,allconnectionsexhibit〔显现〕somestiffnesstowardjointrotations,owingtofriction〔摩擦〕andmaterialbehavior.Whenselectingaparticularmodelforeachsupport

〔支座〕orjoint,theengineermustbeawareofhowtheassumptionswillaffecttheactualperformance〔运行〕ofthememberandwhethertheassumptionsarereasonableforthestructuraldesign.Inreality,allstructuralsupportsactuallyexert〔产生〕distributedsurfaceloads〔面荷载〕ontheircontactingmembers.Theresultants〔合力〕oftheseloaddistributionsareoftenidealizedastheconcentratedforces〔集中力〕andmoments,sincethesurfacearea〔外表积〕overwhichthedistributedloadactsisconsiderablysmallerthanthetotalsurfaceareaoftheconnectingmembers.Theabilitytoreduceanactualstructureto〔将..简化为〕anidealizedformcanonlybegainedbyexperience.Inengineeringpractice,ifitbecomesdoubtful〔不明确〕astohowtomodelastructureortransfertheloadstothemembers,itisbesttoconsiderseveralidealizedstructuresandloadingsandthendesigntheactualstructuresothatitcanresist〔反抗〕theloadingsinalltheidealizedmodels.

Almostalltrusssystemsareconfigured〔装配〕sothatanalysisusingthemethodofjointsmustbeginatoneendandproceed〔连续〕jointbyjointtowardtheotherend.Ifitisnecessarytoevaluatetheforcescarriedbyamemberlocated〔位于〕somedistancefromtheends,themethodofjointsrequiresthecalculationoftheforcesinmanymembersbeforethedesiredoneisreached.Themethodofsectionsprovidesameans〔方法〕foradirectcalculationinthesecases.Afterthesupportreactionshavebeencalculatedthetrussiscutthrough〔切开〕(analytically分析上)sothatonepartofthetrussiscompletelyseveredfromtherest.Whenthisisdone,nomorethanthreeunknownmembersshouldbecut.Ifpossible〔假如可能〕thecut〔切口〕shouldpassthroughthememberormemberswhoseinternalforcesaretobefound.Afree-bodydiagramofthepartofthetrussononesideof〔在..一边〕thissectionisdrawn,andtheinternalforcesarefoundthroughtheequilibriumequations.Sincethesystemofforces〔力系〕onthefree-bodydiagramisaplanenon-concurrent〔非共点〕forcesystem,threeequilibriumequationsmaybewrittenandsolvedforthethreeunknowns.

Influencelines〔影响线〕haveimportantapplicationfor〔应用〕thedesignofstructuresthatresistlargeliveloads〔活荷载〕.Aninfluencelinerepresents〔代表〕thevariationofeitherthereaction,shear,moment,ordeflectionataspecific〔特定的〕pointinamemberasconcentratedforcemovesoverthemember.Oncethislineisconstructed〔作图〕,onecantellataglance〔一眼便知〕wherealiveloadshouldbeplacedonthestructuresothatitcreates〔引起〕thegreatestinfluenceatthespecifiedpoint.Furthermore,themagnitude〔大小〕oftheassociated〔相关的〕reaction,shear,moment,ordeflectionatthepointcanthenbecalculatedfromtheordinates〔纵坐标〕oftheinfluence-linediagram.Forthesereasons〔因此〕,influencelinesplayanimportantpartinthedesignofbridges,industrialcranerails〔吊车轨道〕,conveyors,andotherstructureswhereloadsmoveacrosstheirspan〔全长〕.Althoughtheprocedure〔步骤〕forconstructinganinfluencelineisratherbasic〔基本的〕,oneshouldclearlybeawareofthedifferencebetweenconstructinganinfluencelineandconstructingashearormomentdiagram.Influencelinesrepresenttheeffectofamovingloadonlyataspecifiedpointonamember,whereasshearandmomentdiagramsrepresenttheeffectoffixedloadsatallpointsalongtheaxisofthemember.

Deflectionsofstructurescanoccurfromvarioussources〔缘由〕,suchasloads,temperature,fabricationerrors,orsettlement.Indesign,deflectionsmustbelimitedinordertopreventcrackingofattached〔附属的〕brittlematerialssuchasconcreteorplaster(石膏).Furthermore,astructuremustnotvibrateordeflect〔变位〕severelyinorderto“appear”safe

foritsoccupants〔居住者〕.Moreimportant,though〔然而〕,deflectionsatspecifiedpointsinastructuremustbecomputedifoneistoanalyzestaticallyindeterminatestructures.Weoftendeterminetheelasticdeflectionsofastructureusingbothgeometricalandenergymethods.Also,themethodsofdoubleintegration〔双重积分〕areused.Thegeometricalmethodsincludethemoment-areatheorems〔弯矩图面积定理〕andtheconjugate-beammethod〔共轭梁法〕,andtheenergymethodstobeconsideredarebasedonvirtualwork〔虚功〕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〔归因于〕thewideavailabilityofreinforcingbars〔钢筋〕andtheconstituents〔组成部分〕ofconcrete,gravel,sand,andcement,therelativelysimpleskillsrequiredinconcreteconstruction〔施工〕,andtheeconomy〔经济性〕ofreinforcedconcretecomparedtootherformofconstruction.Concreteandreinforcedconcreteareusedinbridges,buildingsofallsorts〔各种各样〕,undergroundstructures,watertanks,televisiontowers,offshoreoilexplorationandproductionstructures〔近海石油开采和生产结构〕,dams,andeveninships.

valueofReinforcedConcrete

Concreteisstrongincompressionbutweakintension.Asaresult,cracksdevelop〔形成〕whenever〔每当〕loads,orrestrainedshrinkage〔收缩限制〕ortemperaturechanges,giveriseto〔导致〕tensilestressesinexcessof〔超过〕thetensilestrengthoftheconcrete.Intheplainconcrete〔素混凝土〕beam,themomentsduetoappliedloadsareresistedbyaninternaltension-compressioncouple〔拉压力偶〕involvingtensionintheconcrete.Suchabeamfailsverysuddenlyandcompletelywhenthefirstcrackforms.Inareinforcedconcretebeam,steelbars〔钢筋〕areembeddedintheconcreteinsuchawaythatthetensionforcesneededformomentequilibriumaftertheconcretecrackscanbedevelopedinthebars.

EconomyFrequently,theforemost〔最重要的〕considerationistheoverallcost〔总费用〕ofthestructure.Thisis,ofcourse,afunctionofthecosts〔费用函数〕ofthematerialsandthelabornecessarytoerectthem.Frequently,however,theoverallcostisaffectedasmuchormorebytheoverallconstructiontime〔总的建筑时间〕sincethecontractorandownermustallocate〔安排〕money〔资金〕tocarryouttheconstructionandwillnotreceiveareturnonthisinvestment〔收回投资〕untilthebuildingisreadyforoccupancy〔居住〕.Asaresult,financialsavings〔财务的节省〕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〔价值推断〕.

EconomyFrequently,theforemost〔最重要的〕considerationistheoverallcost〔总费用〕ofthestructure.Thisis,ofcourse,afunctionofthecosts〔费用函数〕ofthematerialsandthelabornecessarytoerectthem.Frequently,however,theoverallcostisaffectedasmuchormorebytheoverallconstructiontime〔总的建筑时间〕sincethecontractorandownermustallocate〔安排〕money〔资金〕tocarryouttheconstructionandwillnotreceive

areturnonthisinvestment〔收回投资〕untilthebuildingisreadyforoccupancy〔居住〕.Asaresult,financialsavings〔财务的节省〕duetorapidconstructionmaymorethanoffset〔足以抵消〕increasedmaterialcosts.Anymeasuresdesignercantaketostandardizethedesignandforming〔加工〕willgenerallypayoff〔使人得益〕inreducedoverallcosts.Inmanycasesthelong-termeconomy〔长期的经济性〕ofthestructuremaybemoreimportantthanthefirstcost.Asaresult,maintenance〔维护〕anddurability〔耐久性〕areimportantconsiderations.

SuitabilityofMaterialforArchitecturalandStructuralFunctionAreinforcedconcretesystemfrequentlyallowsthedesignertocombinethearchitecturalandstructuralfunctions〔功能〕.Concretehastheadvantagethatitisplacedinaplasticcondition〔塑性状态〕andisgiventhedesiredshapeandtexture〔密度〕bymeansoftheformsandthefinishingtechniques〔加工技术〕.Thisallowssuchelements〔构件〕asflatplatesorothertypesofslabstoserveasload-bearingelementswhileprovidingthefinishedfloorandceilingsurface〔楼面和顶棚面〕.Similarly,reinforcedconcretewallscanprovidearchitecturallyattractivesurfacesinadditiontohavingtheabilitytoresistgravity,