土木毕业论文英文翻译部分.doc

第五篇 英文翻译部分TallBuildingStructureTallbuildingshavefascinatedmankindfromthebeginningofcivilization,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.Itisdifficulttodefineahigh-risebuilding.Onemaysaythatalow-risebuildingrangesfrom1to2stories.Amedium-risebuildingprobablyrangesbetween3or4storiesupto10or20storiesormore.Althoughthebasicprinciplesofverticalandhorizontalsubsystemdesignremainthesameforlow-,medium-,orhigh-risebuildings,whenabuildinggetshightheverticalsubsystemsbecomeacontrollingproblemfortworeasons.Higherverticalloadswillrequirelargercolumns,walls,andshafts.But,moresignificantly,theoverturningmomentandthesheardeflectionsproducedbylateralforcesaremuchlargerandmustbecarefullyprovidedfor.Theverticalsubsystemsinahigh-risebuildingtransmitaccumulatedgravityloadfromstorytostory,thusrequiringlargercolumnorwallsectionstosupportsuchloading.Inadditionthesesameverticalsubsystemsmusttransmitlateralloads,suchaswindorseismicloads,tothefoundations.However,incontrasttoverticalload,lateralloadeffectsonbuildingsarenotlinearandincreaserapidlywithincreaseinheight.Forexampleunderwindload,theoverturningmomentatthebaseofbuildingsvariesapproximatelyasthesquareofabuildingsmayvaryasthefourthpowerofbuildingsheight,otherthingsbeingequal.Earthquakeproducesanevenmorepronouncedeffect.Whenthestructureforalow-ormedium-risebuildingisdesignedfordeadandliveload,itisalmostaninherentpropertythatthecolumns,walls,andstairorelevatorshaftscancarrymostofthehorizontalforces.Theproblemisprimarilyoneofshearresistance.Moderateadditionbracingforrigidframesin“short”buildingscaneasilybeprovidedbyfillingcertainpanelswithoutincreasingthesizesofthecolumnsandgirdersotherwiserequiredforverticalloads.Unfortunately,thisisnotisforhigh-risebuildingsbecausetheproblemisprimarilyresistancetomomentanddeflectionratherthanshearalone.Specialstructuralarrangementswilloftenhavetobemadeandadditionalstructuralmaterialisalwaysrequiredforthecolumns,girders,walls,andslabsinordertomadeahigh-risebuildingssufficientlyresistanttomuchhigherlateraldeformations.Aspreviouslymentioned,thequantityofstructuralmaterialrequiredpersquarefootoffloorofahigh-risebuildingsisinexcessofthatrequiredforlow-risebuildings.Theverticalcomponentscarryingthegravityload,suchaswalls,columns,andshafts,willneedtobestrengthenedoverthefullheightofthebuildings.Butquantityofmaterialrequiredforresistinglateralforcesisevenmoresignificant.Withreinforcedconcrete,thequantityofmaterialalsoincreasesasthenumberofstoriesincreases.Buthereitshouldbenotedthattheincreaseintheweightofmaterialaddedforgravityloadismuchmoresizablethansteel,whereasforwindloadtheincreaseforlateralforceresistanceisnotthatmuchmoresincetheweightofaconcretebuildingshelpstoresistoverturn.Ontheotherhand,theproblemofdesignforearthquakeforces.Additionalmassintheupperfloorswillgiverisetoagreateroveralllateralforceundertheofseismiceffects.Inthecaseofeitherconcreteorsteeldesign,therearecertainbasicprinciplesforprovidingadditionalresistancetolateraltolateralforcesanddeflectionsinhigh-risebuildingswithouttoomuchsacrifireineconomy.1.Increasetheeffectivewidthofthemoment-resistingsubsystems.Thisisveryusefulbecauseincreasingthewidthwillcutdowntheoverturnforcedirectlyandwillreducedeflectionbythethirdpowerofthewidthincrease,otherthingsremainingcinstant.However,thisdoesrequirethatverticalcomponentsofthewidenedsubsystembesuitablyconnectedtoactuallygainthisbenefit.2.Designsubsystemssuchthatthecomponentsaremadetointeractinthemostefficientmanner.Forexample,usetrusssystemswithchordsanddiagonalsefficientlystressed,placereinforcingforwallsatcriticallocations,andoptimizestiffnessratiosforrigidframes.3.Increasethematerialinthemosteffectiveresistingcomponents.Forexample,materialsaddedinthelowerfloorstotheflangesofcolumnsandconnectinggirderswilldirectlydecreasetheoveralldeflectionandincreasethemomentresistancewithoutcontributingmassintheupperfloorswheretheearthquakeproblemisaggravated.4.Arrangetohavethegreaterpartofverticalloadsbecarrieddirectlyontheprimarymoment-resistingcomponents.Thiswillhelpstabilizethebuildingsagainsttensileoverturningforcesbyprecompressingthemajoroverturn-resistingcomponents.5.Thelocalshearineachstorycanbebestresistedbystrategicplacementifsolidwallsortheuseofdiagonalmembersinaverticalsubsystem.Resistingtheseshearssolelybyverticalmembersinbendingisusuallylesseconomical,sinceachievingsufficientbendingresistanceinthecolumnsandconnectinggirderswillrequiremorematerialandconstructionenergythanusingwallsordiagonalmembers. 6.Sufficienthorizontaldiaphragmactionshouldbeprovidedfloor.Thiswillhelptobringthevariousresistingelementstoworktogetherinsteadofseparately.Createmega-framesbyjoininglargeverticalandhorizontalcomponentssuchastwoormoreelevatorshaftsatmultistoryintervalswithaheavyfloorsubsystems,orbyuseofverydeepgirdertrusses.Rememberthatallhigh-risebuildingsareessentiallyverticalcantileverswhicharesupportedattheground.Whentheaboveprinciplesarejudiciouslyapplied,structurallydesirableschemescanbeobtainedbywalls,cores,rigidframes,tubularconstruction,andotherverticalsubsystemstoachievehorizontalstrengthandrigidity.Someoftheseapplicationswillnowbedescribedinsubsequentsectionsinthefollowing.Shear-WallSystemsWhenshearwallsarecompatiblewithotherfunctionalrequirements,theycanbeeconomicallyutilizedtoresistlateralforcesinhigh-risebuildings.Forexample,apartmentbuildingsnaturallyrequiremanyseparationwalls.Whensomeofthesearedesignedtobesolid,theycanactasshearwallstoresistlateralforcesandtocarrytheverticalloadaswell.Forbuildingsuptosome20storise,theuseofshearwallsiscommon.Ifgivensufficientlength,suchwallscaneconomicallyresistlateralforcesupto30to40storiesormore.However,shearwallscanresistlateralloadonlytheplaneofthewalls(i.e.notinadiretionperpendiculartothem).Therefore,itisalwaysnecessarytoprovideshearwallsintwoperpendiculardirectionscanbeatleastinsufficientorientationsothatlateralforceinanydirectioncanberesisted.Inaddition,thatwalllayoutshouldreflectconsiderationofanytorsionaleffect.Indesignprogress,twoormoreshearwallscanbeconnectedtofromL-shapedorchannel-shapedsubsystems.Indeed,internalshearwallscanbeconnectedtofromarectangularshaftthatwillresistlateralforcesveryefficiently.Ifallexternalshearwallsarecontinuouslyconnected,thenthewholebuildingsactsastube,andconnected,thenthewholebuildingsactsasatube,andisexcellentShear-WallSeystemsresistinglateralloadsandtorsion.Whereasconcreteshearwallsaregenerallyofsolidtypewithopeningswhennecessary,steelshearwallsareusuallymadeoftrusses.Thesetrussescanhavesinglediagonals,“X”diagonals,or“K”arrangements.Atrussedwallwillhaveitsmembersactessentiallyindirecttensionorcompressionundertheactionofview,andtheyoffersomeopportunityanddeflection-limitationpointofview,andtheyoffersomeopportunityforpenetrationbetweenmembers.Ofcourse,theinclinedmembersoftrussesmustbesuitableplacedsoasnottointerferewithrequirementsforwiondowsandforcirculationservicepenetrationsthoughthesewalls.Asstatedabove,thewallsofelevator,staircase,andutilityshaftsformnaturaltubesandarecommonlyemployedtoresistbothverticalandlateralforces.Sincetheseshaftsarenormallyrectangularorcircularincross-section,theycanofferanefficientmeansforresistingmomentsandshearinalldirectionsduetotubestructuralaction.Butaprobleminthedesignoftheseshaftsisprovidedsufficientstrengtharounddooropeningsandotherpenetrationsthroughtheseelements.Forreinforcedconcreteconstruction,specialsteelreinforcementsareplacedaroundsuchopening.Insteelconstruction,heavierandmorerigidconnectionsarerequiredtoresistrackingattheopenings.Inmanyhigh-risebuildings,acombinationofwallsandshaftscanofferexcellentresistancetolateralforceswhentheyaresuitablylocatedantconnectedtooneanother.Itisalsodesirablethatthestiffnessofferedthesesubsystemsbemore-or-lesssymmertricalinalldirections.Rigid-FrameSystemsInthedesignofarchitecturalbuildings,rigid-framesystemsforresistingverticalandlateralloadshavelongbeenacceptedasanimportantandstandardmeansfordesigningbuilding.Theyareemployedforlow-andmediummeansfordesigningbuildings.Theyareemployedforlow-andmediumuptohigh-risebuildingperhaps70or100storieshigh.Whencomparedtoshear-wallsystems,theserigidframesbothwithinandattheoutsideofabuildings.Theyalsomakeuseofthestiffnessinbeamsandcolumnsthatarerequiredforthebuildingsinanycase,butthecolumnsaremadestrongerwhenrigidlyconnectedtoresistthelateralaswellasverticalforcesthoughframebending.Frequently,rigidframeswillnotbeasstiffasshear-wallconstruction,andthereforemayproduceexcessivedeflectionsforthemoreslenderhigh-risebuildingsdesigns.Butbecauseofthisflexibility,theyareoftenconsideredasbeingmoreductileandthuslesssusceptibletocatastrophicearthquakefailurewhencomparedwith(some)shear-walldesigns.Forexample,ifoverstressingoccursatcertainportionsofasteelrigidframe(i.e.,nearthejoint),ductilitywillallowthestructureasawholetodeflectalittlemore,butitwillbynomeanscollapseevenunderamuchlargerforcethanexpectedonthestructure.Forthisreason,rigid-frameconstructionisconsideredbysometobea“best”seismic-resistingtypeforhigh-risesteelbuildings.Ontheotherhand,itisalsounlikelythatawell-designedshare-wallsystemwouldcollapse.Inthecaseofconcreterigidframes,thereisadivergenceofopinion.Ittruethatifaconcreterigidframeisdesignedintheconventionalmanner,withoutspecialcaretoproducehigherductility,itwillnotbeabletowithstandacatastrophicearthquakethatcanproduceforcesseveraltimeslergerthanthecodedesignearthquakeforces.therefore,somebelievethatitmaynothaveadditionalcapacitypossessedbysteelrigidframes.Butmodernresearchandexperiencehasindicatedthatconcreteframescanbedesignedtobeductile,whensufficientstirrupsandjoineryreinforcementaredesignedintotheframe.Modernbuildingscodeshavespecificationsfortheso-calledductileconcreteframes.However,atpresent,thesecodesoftenrequireexcessivereinforcementatcertainpointsintheframesoastocausecongestionandresultinconstructiondifficulties。Evenso,concreteframedesigncanbebotheffectiveandeconomical。Ofcourse,itisalsopossibletocombinerigid-frameconstructionwithshear-wallsystemsinonebuildings，Forexample,thebuildingsgeometrymaybesuchthatrigidframescanbeusedinonedirectionwhileshearwallsmaybeusedintheotherdirection。SummaryAbovestatesisthehigh-riseconstructionordinarieststructuralstyle.Inthedesignprocess,shouldtheeconomypracticalchoosethereasonableformasfaraspossible. BuildingconstructionconcretecrackofpreventionandprocessingAbstractThecrackproblemofconcreteisawidespreadexistencebutagaindifficultinsolveofengineeringactualproblem,thistextcarriedonastudyanalysistoalittlebitfamiliarcrackproblemintheconcreteengineering,andaimatconcretethecircumstanceputforwardsomeprevention,processingmeasure.Keyword:ConcretecrackpreventionprocessingForewordConcretesising1kindisanticipatebythefreestonebone,cement,waterandothermixturebutformationoftheinadditionmaterialofqualitybrittlenessnotandallmaterial.Becausetheconcreteconstructiontransformwithoneself,controletc.aseriesproblem,hardenmodelofintheconcreteexistencenumeroustinyhole,spiritcaveandtinycrack,isexactlybecausethesebeginningstartblemishofexistencejustmaketheconcretepresentonesomenotandallthecharacteristicofquality.Thetinycrackisakindofharmlesscrackandacceptconcreteheavy,defendShenandalittlebitotherusefunctionnotacreationtoendanger.Butaftertheconcretebesubjectedtolotuscarry,differenceintemperatureetc.function,tinycrackwouldcontinuouslyofexpandwithconnect,endformationwecanseewithouttheaidofinstrumentsofmacroviewthecrackbealsothecrackthattheconcreteoftensayintheengineering.ConcretebuildingandGoupieceusuallyalltakesewertomakeof,becauseofcrackofexistenceanddevelopmentusuallymakeinnerpartofreinforcingbaretc.materialcreationdecay,lowerreinforcedconcretematerialofloadingability,durableandanti-Shenability,influencebuildingofexternalappearance,servicelife,severitywillthreatarrivepeopleslifeandpropertysafety.Alotofallofcrashofengineeringsisbecauseoftheunsteadydevelopmentofthecrackwiththeresultthat.Modernagescienceresearchwithagreatdealofoftheconcreteengineeringpracticecertificate,intheconcreteengineeringcrackproblemisineluctable,alsoacceptableincertainlyofthescopejustneedtoadoptvalidofmeasurewillitendangerdegreecontrolatcertainofscopeinside.Thereinforcedconcretenormisalsoexplicitprovision:Somestructureatplaceofdissimilarityundertheconditionallowexistencecertainthecrackofwidth.Butatunderconstructionshouldasfaraspossibleadoptavalidmeasurecontrolcrackcreation,makethestructuredontappearcrackpossiblyorasfaraspossibledecreasecrackofamountandwidth,particularlywanttoasfaraspossibleavoidharmfulcrackofemergence,insureengineeringqualitythus.Concretecrackcreationofthereasonbealotofandhavealreadytransformedtocauseofcrack:Suchastemperaturevariety,constringency,inflation,theasymmetrysinktosinketc.reasoncauseofcrack;Haveoutsidecarrythecrackthatthefunctioncause;Protectedenvironmentnotappropriatethecracketc.causedwithchemicaleffect.Wantdifferentiationtotreatintheactualengineering,workoutaproblemaccordingtotheactualcircumstance.Intheconcreteengineeringthefamiliarcrackandtheprevention1.StemSuocrackandpreventionStemtheSuocrackmuchappearaftertheconcreteprotectbeoverofaperiodoftimeorconcretesprinkletobuildtocompletebehindofaroundaweek.InthecementsyruphumidityofevaporatewouldcreationstemSuo,andthiskindofconstringencyiscantnegative.StemSuocrackofthecreationbemainisbecauseofconcreteinsideoutsidehumidityevaporatedegreedissimilaritybutcausetotransformdissimilarityofresult:Theconcreteissubjectedtoexteriorconditionofinfluence,surfacehumiditylossleadquick,transformbigger,innerpartdegreeofhumidityvarietysmallertransformsmaller,biggersurfacestemtheSuotransformtobesubjectedtoconcreteinnerpartcontrol,creationmorebigpullshoulddintbutcreationcrack.Therelativehumidityismorelow,cementsyrupbodystemSuomorebig,stemtheSuocrackbemoreeasycreation.StemtheSuocrackismuchsurfaceparallellinesformorthenetshallowthincrack,widthmanybetween0.05-0.2mm,theflatsurfacepartmuchseeinthebigphysicalvolumeconcreteandfollowitmoreinthinnerbeamplankshorttodistribute.StemSuocrackusu