年4月19日土木工程專業畢業設計外文翻譯文檔僅供參考High-RiseBuildingsIntroductionItisdifficulttodefineahigh-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”buildingscaneasilybeprovidedbyfillingcertainpanels(orevenallpanels)withoutincreasingthesizesofthecolumnsandgirdersotherwiserequiredforverticalloads.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.Increasetheeffectivewidthofthemoment-resistingsubsystems.Thisisveryusefulbecauseincreasingthewidthwillcutdowntheoverturnforcedirectlyandwillreducedeflectionbythethirdpowerofthewidthincrease,otherthingsremainingcinstant.However,thisdoesrequirethatverticalcomponentsofthewidenedsubsystembesuitablyconnectedtoactuallygainthisbenefit.Designsubsystemssuchthatthecomponentsaremadetointeractinthemostefficientmanner.Forexample,usetrusssystemswithchordsanddiagonalsefficientlystressed,placereinforcingforwallsatcriticallocations,andoptimizestiffnessratiosforrigidframes.Increasethematerialinthemosteffectiveresistingcomponents.Forexample,materialsaddedinthelowerfloorstotheflangesofcolumnsandconnectinggirderswilldirectlydecreasetheoveralldeflectionandincreasethemomentresistancewithoutcontributingmassintheupperfloorswheretheearthquakeproblemisaggravated.Arrangetohavethegreaterpartofverticalloadsbecarrieddirectlyontheprimarymoment-resistingcomponents.Thiswillhelpstabilizethebuildingsagainsttensileoverturningforcesbyprecompressingthemajoroverturn-resistingcomponents.Thelocalshearineachstorycanbebestresistedbystrategicplacementifsolidwallsortheuseofdiagonalmembersinaverticalsubsystem.Resistingtheseshearssolelybyverticalmembersinbendingisusuallylesseconomical,sinceachievingsufficientbendingresistanceinthecolumnsandconnectinggirderswillrequiremorematerialandconstructionenergythanusingwallsordiagonalmembers.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.外文資料翻譯（譯文）高層建筑前沿高層建筑的定義很難確定。能夠說2-3層的建筑物為底層建筑，而從3-4層地10層或20層的建筑物為中層建筑，高層建筑至少為10層或者更多。盡管在原理上，高層建筑的豎向和水平構件的設計同低層及多層建筑的設計沒什么區別，但使豎向構件的設計成為高層設計有兩個控制性的因素：首先，高層建筑需要較大的柱體、墻體和井筒；更重要的是側向里所產生的傾覆力矩和剪力變形要大的多，必要謹慎設計來保證。高層建筑的豎向構件從上到下逐層對累積的重力和荷載進行傳遞，這就要有較大尺寸的墻體或者柱體來進行承載。同時，這些構件還要將風荷載及地震荷載等側向荷載傳給基礎。可是，側向荷載的分布不同于豎向荷載，它們是非線性的，而且沿著建筑物高度的增加而迅速地增加。例如，在其它條件都相同時，風荷載在建筑物底部引起的傾覆力矩隨建筑物高度近似地成平方規律變化，而在頂部的側向位移與其高度的四次方成正比。地震荷載的效應更為明顯。對于低層和多層建筑物設計只需考慮恒荷載和部分動荷載時，建筑物的柱、墻、樓梯或電梯等就自然能承受大部分水平力。所考慮的問題主要是抗剪問題。對于現代的鋼架系統支撐設計，如無特殊承載需要，無需加大柱和梁的尺寸，而經過增加板就能夠實現。不幸的是，對于高層建筑首先要解決的不但僅是抗剪問題，還有抵抗力矩和抵抗變形問題。高層建筑中的柱、梁、墻及板等經常需要采用特殊的結構布置和特殊的材料，以抵抗相當高的側向荷載以及變形。如前所述，在高層建筑中每平方英尺建筑面積結構材料的用量要高于低層建筑。支撐重力荷載的豎向構件，如墻、柱及井筒，在沿建筑物整個高度方向上都應予以加強。用于抵抗側向荷載的材料要求更多。對于鋼筋混凝土建筑，雖著建筑物層數的增加，對材料的要求也隨著增加。應當注意的是，因混凝土材料的質量增加而帶來的建筑物自重增加，要比鋼結構增加得多，而為抵抗風荷載的能力而增加的材料用量卻不是呢么多，因為混凝土自身的重量能夠抵抗傾覆力矩。不過不利的一面是混凝土建筑自重的增加，將會加大抗震設計的難度。在地震荷載作用下，頂部質量的增加將會使側向荷載劇增。無論對于混凝土結構設計，還是對于鋼結構設計，下面這些基本的原則都有助于在不需要增加太多成本的前提下增強建筑物抵抗側向荷載的能力。增加抗彎構件的有效寬度。由于當其它條件不變時能夠直接減小扭矩，并以寬度增量的三次冪形式減小變形，因此這一措施非常有效。可是必須保證加寬后的豎向承重構件非常有效地連接。在設計構件時，盡可能有效地使其加強相互作用力。例如，能夠采用具有有效應力狀態的弦桿和桁架體系；也可在墻的關鍵位置加置鋼筋；以及最優化鋼架的剛度比等措施。增加最有效的抗彎構件的截面。例如，增加較低層柱以及連接大梁的翼緣截面，將可直接減少側向位移和增加抗彎能力，而不會加大上層樓面的質量，否則，地震問題將更加嚴重。經過設計使大部分豎向荷載，直接作用于主要的抗彎構件。這樣經過預壓主要的抗傾覆構件，能夠使建筑物在傾覆拉力的作用下保持穩定。經過合理地放置實心墻體及在豎向構件中使用斜撐構件，能夠有效地抵抗每層的局部剪力。但僅僅經過豎向構件進行抗剪是不經濟的，因為使柱及梁有足夠的抗彎能力，比用墻或斜撐需要更多材料和施工工作量。每層應加設充分的水平隔板。這樣就會使各種抗力構件更好地在一起工作，而不是單獨工作。在中間轉換層經過大型豎向和水平構件及重樓板形成大框架，或者采用深梁體系。應當注意的是，所有高層建筑的本質都是地面支撐的懸臂結構。如何合理地運用上面所提到的原則，就能夠利用合理地布置墻體、核心筒、框架、筒式結構和其它豎向結構分體系，使建筑物取得足夠的