建筑模型外文翻譯文獻(xiàn)

外文翻譯PAGEPAGE1建筑模型外文翻譯文獻(xiàn)建筑模型外文翻譯文獻(xiàn)(文檔含中英文對(duì)照即英文原文和中文翻譯)原文：LateralstiffnessestimationinframesanditsimplementationtocontinuummodelsforlinearandnonlinearstaticanalysisAbstractContinuummodelisausefultoolforapproximateanalysisoftallstructuresincludingmoment-resistingframesandshearwall-framesystems.Incontinuummodel,discretebuildingsaresimplifiedsuchthattheiroverallbehaviorisdescribedthroughthecontributionsofflexuralandshearstiffnessesatthestorylevels.Therefore,accuratedeterminationoftheselateralstiffnesscomponentsconstitutesoneofthemajorissuesinestablishingreliablecontinuummodelseveniftheproposedsolutionisanapproximationtoactualstructuralbehavior.Thisstudyfirstexaminesthepreviousliteratureonthecalculationoflateralstiffnesscomponents(i.e.flexuralandshearstiffnesses)throughcomparisonswithexactresultsobtainedfromdiscretemodels.Anewmethodologyforadaptingtheheightwisevariationoflateralstiffnesstocontinuummodelispresentedbasedonthesecomparisons.Theproposedmethodologyisthenextendedforestimatingthenonlinearglobalcapacityofmomentresistingframes.Theverificationsthatcomparethenonlinearbehaviorofrealsystemswiththoseestimatedfromtheproposedproceduresuggestitseffectiveusefortheperformanceassessmentoflargebuildingstocksthatexhibitsimilarstructuralfeatures.Thisconclusionisfurtherjustifiedbycomparingnonlinearresponsehistoryanalysesofsingle-degree-of-freedom(sdof)systemsthatareobtainedfromtheglobalcapacitycurvesofactualsystemsandtheirapproximationscomputedbytheproposedprocedure.KeywordsApproximatenonlinearmethods·Continuummodel·Globalcapacity·Nonlinearresponse·Framesanddualsystems1IntroductionReliableestimationofstructuralresponseisessentialintheseismicperformanceassessmentanddesignbecauseitprovidesthemajorinputwhiledescribingtheglobalcapacityofstructuresunderstronggroundmotions.Withtheadventofcomputertechnologyandsophisticatedstructuralanalysisprograms,theanalystsarenowabletorefinetheirstructuralmodelstocomputemoreaccuratestructuralresponse.However,attheexpenseofcapturingdetailedstructuralbehavior,theincreasedunknownsinmodelingparameters,whencombinedwiththeuncertaintyingroundmotions,maketheinterpretationsofanalysisresultscumbersomeandtimeconsuming.Complexstructuralmodelingandresponsehistoryanalysiscanalsobeoverwhelmingforperformanceassessmentoflargebuildingstocksorthepreliminarydesignofnewbuildings.Thecontinuummodel,inthissense,isanaccomplishedapproximatetoolforestimatingtheoveralldynamicbehaviorofmomentresistingframes(MRFs)andshearwall-frame(dual)systems.Continuummodel,asanapproximationtocomplexdiscretemodels,hasbeenusedextensivelyintheliterature.Westergaard(1933)usedequivalentundampedshearbeamconceptformodelingtallbuildingsunderearthquakeinducedshocksthroughtheimplementationofshearwavespropagatinginthecontinuummedia.Later,thecontinuousshearbeammodelhasbeenimplementedbymanyresearchers(e.g.Iwan1997;GülkanandAkkar2002;Akkaretal.2005;ChopraandChintanapakdee2001)toapproximatetheearthquakeinduceddeformationdemandsonframesystems.TheideaofusingequivalentshearbeamswasextendedtothecombinationofcontinuousshearandflexuralbeamsbyKhanandSbarounis(1964).HeidebrechtandStaffordSmith(1973)definedacontinuummodel(hereinafterHS73)forapproximatingtallshearwall-frametypestructuresthatisbasedonthesolutionofafourthorderpartialdifferentialequation(PDE).Miranda(1999)presentedthesolutionofthisPDEunderasetoflateralstaticloadingcasestoapproximatethemaximumroofandinterstorydriftdemandsonfirst-modedominantstructures.Later,HeidebrechtandRutenberg(2000)showedadifferentversionofHS73methodtodrawtheupperandlowerboundsofinterstorydriftdemandsonframesystems.MirandaandTaghavi(2005)usedtheHS73modeltoacquiretheapproximatestructuralbehaviorupto3modes.Asafollowupstudy,MirandaandAkkar(2006)extendedtheuseofHS73tocomputegeneralizeddriftspectrumwithhighermodeeffects.Continuummodelisalsousedforestimatingthefundamentalperiodsofhigh-risebuildings(e.g.DymandWilliams2007).Morerecently,Gengshuetal.(2008)studiedthesecondorderandbucklingeffectsonbuildingsthroughtheclosedformsolutionsofcontinuoussystems.Whilethetheoreticalapplicationsofcontinuummodelareabundantasbrieflyaddressedabove,itspracticalimplementationisratherlimitedasthedeterminationofequivalentflexural(EI)andshear(GA)stiffnessestorepresenttheactuallateralstiffnessvariationindiscretesystemshavenotbeenfullyaddressedintheliterature.ThisflawhasalsorestrictedtheefficientuseofcontinuummodelbeyondelasticlimitsbecausethenonlinearbehaviorofcontinuummodelsisdictatedbythechangesinEIandGAinthepost-yieldingstageThispaperfocusesontherealisticdeterminationoflateralstiffnessforcontinuummodels.EIandGAdefinedindiscretesystemsareadaptedtocontinuummodelsthroughananalyticalexpressionthatconsiderstheheightwisevariationofboundaryconditionsindiscretesystems.TheHS73modelisusedasthebasecontinuummodelsinceitiscapableofrepresentingthestructuralresponsebetweenpureflexureandshearbehavior.Theproposedanalyticalexpressionisevaluatedbycomparingthedeformationpatternsofcontinuummodelandactualdiscretesystemsunderthefirst-modecompatibleloadingpattern.TheimprovementsonthedeterminationofEIandGAarecombinedwithasecondprocedurethatisbasedonlimitstateanalysistodescribetheglobalcapacityofstructuresrespondingbeyondtheirelasticlimits.Illustrativecasestudiesindicatethatthecontinuummodel,whenusedtogetherwiththeproposedmethodologies,canbeausefultoolforlinearandnonlinearstaticanalysis.2ContinuummodelcharacteristicsTheHS73modeliscomposedofaflexuralandshearbeamtodefinetheflexural(EI)andshear(GA)stiffnesscontributionstotheoveralllateralstiffness.ThemajormodelparametersEIandGAarerelatedtoeachotherthroughthecoefficientα(Eq.1).Asαgoestoinfinitythemodelwouldexhibitpuresheardeformationwhereasα=0indicatespureflexuraldeformation.NotethatitisessentialtoidentifythestructuralmembersofdiscretebuildingsfortheirflexuralandshearbeamcontributionsbecausetheoverallbehaviorofcontinuummodelisgovernedbythechangesinEIandGA.Equation2showsthecomputationofGAforasinglecolumnmemberinHS73.ThevariablesIcandhdenotethecolumnmomentofinertiaandstoryheight,respectively.TheinertiatermsIb1andIb2thataredividedbythetotallengthsl1andl2,respectively,definetherelativerigiditiesofbeamsadjoiningtothecolumnfromtop(seeFig.3inthereferredpaper).Equation2indicatesthatGA(shearcomponentoftotallateralstiffness)iscomputedasafractionofflexuralstiffnessofframesorientedinthelateralloadingdirection.Accordingly,theflexuralpart(EI)oftotalstiffnessiscomputedeitherbyconsideringtheshear-wallmembersintheloadingdirectionand/orothercolumnsthatdonotspanintoaframeinthedirectionofloading.Thisassumptionworksfairlywellfordualsystems.However,itmayfailinMRFsbecauseitwilldiscardtheflexuralcontributionsofcolumnsalongtheloadingdirectionandwilllumptotallateralstiffnessintoGA.Essentially,thisapproximationwillreducetheentireMRFtoashearbeamthatwouldbeaninaccuratewayofdescribingMRFbehaviorunlessallbeamsareassumedtoberigid.Tothebestofauthors’knowledge,studiesthatuseHS73modeldonotdescribethecomputationofαindepthwhilerepresentingdiscretebuildingsystemsascontinuummodels.Inmostcasesthesestudiesassigngenericαvaluesfordescribingdifferentstructuralbehaviorspanningfrompureflexuretopureshear1.Thisapproachisdeemedtoberationaltorepresenttheoreticalbehaviorofdifferentstructures.However,theabovehighlightedfactsaboutthecomputationoflateralstiffnessrequirefurtherinvestigationtoimprovetheperformanceofHS73modelwhilesimplifyinganactualMRFasacontinuummodel.Inthatsense,itisworthwhiletodiscusssomeimportantstudiesonthelateralstiffnessestimationofframes.ThesecouldbeusefulfortheenhancedcalculationsofEIandGAtodescribethetotallateralstiffnessincontinuumsystems.3LateralstiffnessapproximationsforMRFsTherearenumerousstudiesonthedeterminationoflateralstiffnessinMRFs.ThemethodsproposedinMuto(1974)andHosseiniandImagh-e-Naiini(1999)(hereinafterM74andHI99,respectively)arepresentedinthispaperandtheyarecomparedwiththeHS73approachforitsenhancementindescribingthelateraldeformationbehaviorofstructuralsystems.Equation3showsthetotallateralstiffness,k,definitionofM74foracolumnatanintermediatestory.TheparametersIc,h,Ib1,Ib2,l1andl2havethesamemeaningsasinEq.(2).NotethatEq.(2)proposedinHS73isasimplifiedversionofEq.(3)foraunitrotation.Theformerexpressionassumesthatthedimensionsofbeamsspanningintothecolumnfromtoparethesameasthosespanningintothecolumnfrombottom.However,Eqs.(2)and(3)exhibitasignificantconceptualdifference:theHS73approachinterpretstheresultingstiffnesstermastheshearcontributionwhereasM74considersitasthetotallateralstiffness.TheHI99methoddefinesthelateralstiffnessofMRFsthroughanequivalentsimplesystemthatconsistsofsub-modulesofone-bay/one-storyframes.Eachsub-modulerepresentsastoryintheoriginalstructureandthecolumninertia(Ic)ofasub-moduleiscalculatedbytakinghalfofthetotalmomentofinertiaofallcolumnsintheoriginalstory.Therelativerigiditiesofupper(ku)andlower(kl)beamsinasub-modulearecalculatedbysummingalltherelativebeamrigiditiesatthetopandbottomoftheoriginalstory,respectively.ThetotallateralstiffnessofastorybyHI99isgiveninEq.(5)Theparameterkcandhdenotetherelativerigidityandlengthofthecolumninthesubmodule,respectively.Thetotallateralstiffnessatgroundstoryiscomputedbyassigningrelativelylargestiffnessvaluestokltorepresentthefixed-baseconditions.Equation(5)hasasimilarfunctionalformatasEqs.(2)and(3).Sincethelateralstiffnesscomputedstandsforthetotallateralstiffness,itexhibitsamoresimilartheoreticalframeworktoM74.DiscussionspresentedaboveindicatethatbothM74andHI99considerthevariationsinlateralstiffnessatthegroundstoryduetofixed-baseboundaryconditions.However,theyignorethefreeendconditionsatthetopstory.Asamatteroffact,Schultz(1992)pointedthatlateralstiffnesschangesalongthebuildingheightmightbeabruptatboundarystories.TheboundarystoriesdefinedbySchultz(1992)notonlyconsistofgroundandtopfloorsbutalsothe2ndstorybecausethepropagationoffixed-baseconditionsabovethegroundstorylevelisprominentatthe2ndstoryaswell.AlthoughSchultz(1992)proposedcorrectionfactorsforboundarystoriesofsomespecificcases,hedoesnotgiveageneralexpressionthataccountsforthestiffnesschangesatboundarystories.References1、AkkarS,YazganU,GülkanP(2005)Driftestimatesinframebuildingssubjectedtonear-faultgroundmotions.JStructEngASCE131(7):1014–10242、AmericanSocietyofCivilEngineers(ASCE)(2007)Seismicrehabilitationofexistingbuildings:ASCEstandard,reportno.ASCE/SEI41-06.Reston,Virginia3、AppliedTechnologyCouncil(ATC)(2004)FEMA-440Improvementofnonlinearstaticseismicanalysisprocedures,ATC-55projectreport.preparedbytheAppliedTechnologyCouncilfortheFeeralEmergencyManagementAgency,Washington,DC4、BlumeJA(1968)Dynamiccharacteristicsofmulti-storybuildings.JStructDivASCE94(2):377–4025、BorziB,PinhoR,CrowleyH(2008)Simplifiedpushover-basedvulnerabilityanalysisforlarge-scaleassessmentofRCbuildings.EngStruct30:804–820翻譯：框架橫向剛度估計(jì)和橫向剛度線性與非線性的連續(xù)模型的靜力分析吐哈埃爾奧盧?思南阿卡爾收到日期：2010年4月23日/發(fā)表日期：2010年11月17日?施普林格科學(xué)商業(yè)媒體B.V.2010+摘要：連續(xù)模型是高層結(jié)構(gòu)的近似分析，包括抗彎框架剪力墻系統(tǒng)都是非常有用的工具。在連續(xù)介質(zhì)模型，離散的建筑物被簡(jiǎn)化，這樣他們的整體性能可以通過(guò)樓層層面的彎曲和剪切剛度來(lái)描述。因此，這些組件橫向剛度的準(zhǔn)確測(cè)定，是建立可靠的連續(xù)模型的主要問(wèn)題之一，即提出的解決方案是一個(gè)實(shí)際的近似結(jié)構(gòu)。本研究首先探討通過(guò)與精確結(jié)果的比較，通過(guò)對(duì)橫向剛度組件（即彎曲和剪切剛度）以往文獻(xiàn)的計(jì)算來(lái)獲得離散模型?；谶@些比較，一種適用于橫向剛度連續(xù)模型變化的新方法被提出來(lái)。建議的方法是進(jìn)行延伸來(lái)估計(jì)非線性抗彎矩框架的整體能力。該核查是比較與建議的過(guò)程，而估計(jì)的實(shí)際系統(tǒng)的非線性特性表明其對(duì)大型建筑表現(xiàn)出類似的結(jié)構(gòu)特征，并被有效利用。這一結(jié)論是通過(guò)比較，來(lái)進(jìn)一步說(shuō)明單自由度的非線性特性歷史分析（單自由度），它們從實(shí)際系統(tǒng)和擬議的程序的近似計(jì)算來(lái)得到系統(tǒng)的整體能力曲線。關(guān)鍵詞：近似非線性方法、連續(xù)模型、整體能力、非線性特性、框架和雙系統(tǒng)吐哈埃爾奧盧目前留在中東技術(shù)大學(xué)研究生學(xué)院。介紹結(jié)構(gòu)特性的可靠估計(jì)是抗震性能評(píng)估和設(shè)計(jì)必不可少，因?yàn)樗峁┲饕獢?shù)據(jù)在描述在強(qiáng)地震時(shí)結(jié)構(gòu)的整體能力。隨著計(jì)算機(jī)技術(shù)和先進(jìn)的結(jié)構(gòu)分析程序的出現(xiàn)，分析家現(xiàn)在能夠改進(jìn)其結(jié)構(gòu)模型來(lái)計(jì)算更準(zhǔn)確的結(jié)構(gòu)反應(yīng)。然而，在捕捉詳細(xì)的結(jié)構(gòu)性能為前提，模型參數(shù)未知的增加與地面運(yùn)動(dòng)相結(jié)合的不確定性，會(huì)使分析結(jié)果繁瑣與解釋費(fèi)時(shí)。復(fù)雜的結(jié)構(gòu)模型和反應(yīng)歷史分析，也可用于大型建筑群性能評(píng)估或新建筑物的初步設(shè)計(jì)的確定。連續(xù)模型，在這個(gè)意義上，是估計(jì)抗彎矩框架（MRFs）和剪力墻框架（dual）系統(tǒng)近似整體動(dòng)態(tài)反應(yīng)的工具。連續(xù)模型，近似的作為一種復(fù)雜的離散模型，已被廣泛使用在文獻(xiàn)中。Westergaard（1933）是用于地震引起的沖擊下，高層建筑模型通過(guò)連續(xù)介質(zhì)傳播橫波方式的等效阻尼剪切梁的概念。后來(lái)，連續(xù)剪切梁模型由許多研究者實(shí)現(xiàn)了（如伊萬(wàn)1997年古坎和阿卡爾2002;阿卡爾等人，2005年。普拉和柴可珀達(dá)2001）模擬地震引起的變形對(duì)框架體系的作用。可翰和貝冉斯(1964)采用等效剪切梁的理念擴(kuò)展到連續(xù)剪切和彎曲梁的組合。黑布瑞去和斯塔福德史密斯（1973）所界定連續(xù)的結(jié)構(gòu)模型（以下簡(jiǎn)稱HS73），是用一個(gè)四階偏微分方程（PDE）來(lái)解決高層剪力墻框架模型，雖然連續(xù)介質(zhì)模型的理論應(yīng)用建立在簡(jiǎn)要討論上，其實(shí)際執(zhí)行情況是相當(dāng)有限，因?yàn)榈刃澢鷾y(cè)定和剪剛度測(cè)定，代表的實(shí)際離散系統(tǒng)橫向剛度變化在文獻(xiàn)里沒(méi)有得到充分處理。這一缺陷也限制了，因?yàn)槌鰪椥詷O限的非線性行為的連續(xù)模型的有效利用，連續(xù)模型是取決于在后階段EI和GA的變化。本文的重點(diǎn)是橫向剛度連續(xù)模型的定義。EI和GA在離散系統(tǒng)中的定義，是邊界條件下離散系統(tǒng)的變化模型的解析表達(dá)式。該HS73模型作為基礎(chǔ)連續(xù)模型，是因?yàn)樗憩F(xiàn)了純彎曲和剪切行為，能代表結(jié)構(gòu)反應(yīng)的能力。建議的解析表達(dá)式是通過(guò)比較在第一個(gè)模式兼容加載模式下的，連續(xù)模型和實(shí)際離散系統(tǒng)的變形模式。在EI和GA測(cè)定的改善，在結(jié)合了第二個(gè)過(guò)程的極限狀態(tài)分析的基礎(chǔ)上，描述了結(jié)構(gòu)承載超出其彈性極限后的整體能力。說(shuō)明案例研究表明，連續(xù)模型，使用時(shí)與所建議的方法一起，可以成為線性和非線性靜力分析的有用工具。連續(xù)模型的特點(diǎn)該HS73模型是由彎曲和剪切梁組成，來(lái)定義彎曲（EI）及剪切（GA）剛度的，從而確定整體剛度橫向剛度。主要的模型參數(shù)EI和GA有關(guān)，通過(guò)彼此的（公式1）系數(shù)α相互聯(lián)系。以α趨于無(wú)窮模型將展出純剪切變形而α=0表示純彎曲變形。注意的事，必須查明離散建筑物的結(jié)構(gòu)構(gòu)件的彎曲和剪切，因?yàn)檫B續(xù)模型的整體行為是受在EI和GA的變化而決定。公式2表示在HS73的一系列計(jì)算。變量Ic和H分別表示的慣性和層高。Ib1的慣性和由L1和L2，分別確定相對(duì)僵化的總長(zhǎng)度除以Ib2，梁毗鄰自頂柱（見(jiàn)圖。在3提到文件）。公式2表明，GA（占總數(shù)的橫向剛度剪切組件）是一個(gè)橫向載荷方向框架抗彎剛度的計(jì)算分?jǐn)?shù)。彎曲部分（EI）的總剛度計(jì)算或者考慮在剪力墻加載方向/或不成為一個(gè)框架中其它柱跨度方向的負(fù)荷載。這個(gè)假設(shè)對(duì)雙系統(tǒng)效果非常好。但是，它可能會(huì)失敗，因?yàn)樗鼤?huì)在抗彎矩框架上沿載荷方向，將柱并到GA橫向剛度。事實(shí)上，這種近似將減少整個(gè)抗彎矩框架到剪力梁，將會(huì)不準(zhǔn)確的描述抗彎矩框架反應(yīng)，除非所有的梁被認(rèn)為是剛性的。就作者的所知，研究使用HS73模型不僅詳細(xì)描述了α的計(jì)算，而且把離散建筑系統(tǒng)作為連續(xù)模型。在大多數(shù)情況下，這些研究不同結(jié)構(gòu)分配過(guò)程，從純彎曲跨越到純剪通用的α值。這種方法被認(rèn)為是合理的，是代表不同結(jié)構(gòu)理論的行為。不過(guò)，以上強(qiáng)調(diào)的事實(shí)，即有關(guān)的橫向剛度計(jì)算需要進(jìn)一步調(diào)查，以提高模型的性能，同時(shí)簡(jiǎn)化HS73實(shí)際抗彎矩框架作為一個(gè)連續(xù)模型。在這個(gè)意義上說(shuō)，的關(guān)于框架側(cè)向剛度估計(jì)的一些重要研究是值得討論的。這可能是關(guān)于GA和EI有用的增強(qiáng)計(jì)算方法，用于描述連續(xù)系統(tǒng)的總橫向剛度。抗彎矩框架的近似橫向剛度這里有很多研究關(guān)于抗彎矩框架橫向剛度的測(cè)定。Muto(1974)和Hosseini和Imagh-e-Naiini(1999)所提出的方法（以下分別簡(jiǎn)稱M74和HI99）基于本文件和他們相對(duì)于HS73途徑提高了其在描述系統(tǒng)結(jié)構(gòu)的側(cè)向變形。公式3顯示總橫向剛度K的M74，是一根柱在一個(gè)中間樓層的值。參數(shù)lchIb1，Ib2，L1和L2在公式2中的具相同涵義。公式（2）是在HS73提出的一個(gè)關(guān)于公式（3）的簡(jiǎn)化版本。前者表達(dá)假定頂部柱之間梁的跨度和底部柱之間梁的跨度相同。不過(guò)，公式（2）及（3）表現(xiàn)出一個(gè)重大的概念區(qū)別：M74認(rèn)為它為總計(jì)的橫向剛度，HS73同樣地解釋為剪切作用的術(shù)語(yǔ)。該方法HI99通過(guò)一個(gè)簡(jiǎn)單的系統(tǒng)把抗彎框架的橫向剛度，定義為是由一層樓高的框架的子模板組成。每個(gè)子模塊表現(xiàn)為原結(jié)構(gòu)的一個(gè)樓層，而且子模塊的柱剛度，由最初的層所有柱的總計(jì)剛度的一半來(lái)計(jì)算。在一個(gè)子模塊的上面的（ku）、比較低的（kl）梁的相對(duì)剛度，由最初層的頂和底部梁的剛度計(jì)算而得來(lái)。樓層總的橫向剛度在公式5中由HI99給出。參數(shù)架KC和h分別表示了柱在子模塊中的相對(duì)剛性和長(zhǎng)度。第一層總橫向剛度的計(jì)算方法是用較大的那個(gè)剛度值，分配到kl來(lái)表示固定的基礎(chǔ)條件。具有類似功能的公式（2）及公式（3）。由橫向剛度計(jì)算的總橫向剛度，它表現(xiàn)出一種更類似于M74的理論框架。上面介紹的討論表明，這兩個(gè)M74和HI99考慮橫向剛度從第一層到固定基地邊界的變化。但是，他們忽視了在頂層自由端的條件。由于事實(shí)上，舒爾茨（1992）指出，建筑物的橫向剛度沿高度變化可能發(fā)生在邊界層。根據(jù)上述情況，舒爾茨（1992）的邊界層定義不僅包括地面和頂層也包括第二層。雖然舒爾茨（1992）為某些特定情況下提出了邊界層的修正系數(shù)。他不用一般表達(dá)式來(lái)計(jì)算邊界層上剛度的變化。參考文獻(xiàn)AkkarS,YazganU,GülkanP(2005)Driftestimatesinframebuildingssubjectedtonear-faultgroundmotions.JStructEngASCE131(7):1014–1024AmericanSocietyofCivilEngineers(ASCE)(2007)Seismicrehabilitationofexistingbuildings:ASCEstandard,reportno.ASCE/SEI41-06.Reston,VirginiaAppliedTechnologyCouncil(ATC)(2004)FEMA-440Improvementofnonlinearstaticseismicanalysispro-cedures,ATC-55projectreport.preparedbytheAppliedtechnologyCouncilfortheFederalEmergencyManagementAgency,Washington,DC.4、BlumeJA(1968)Dynamiccharacteristicsofmulti-storybuildings.JStructDivASCE94(2):377–402BorziB,PinhoR,CrowleyH(2008)Simpli?edpushover-basedvulnerabilityanalysisforlarge-scaleassessmentofRCbuildings.EngStruct30:804–820外文原文：TheeffectsofsupplementarycementingmaterialsinmodifyingtheheatofhydrationofconcreteYunusBallimPeterC.GrahamReceived:23February2008/Accepted:17September2008/Publishedonline:23September2008AbstractThispaperisintendedtoprovideguidanceontheformandextenttowhichsupplementarycementingmaterials,incombinationwithPortlandcement,modifiestherateofheatevolutionduringtheearlystagesofhydrationinconcrete.Inthisinvestigation,concreteswerepreparedwithflyash,condensedsilicafumeandgroundgranulatedblastfurnaceslag,blendedwithPortlandcementinproportionsrangingfrom5%to80%.Theseconcretesweresubjectedtoheatofhydrationtestsunderadiabaticconditionsandtheresultswereusedtoassessandquantifytheeffectsofthesupplementarycementingmaterialsinalteringtheheatrateprofilesofconcrete.Thepaperalsoproposesasimplifiedmathematicalformoftheheatratecurveforblendedcementbindersinconcretetoallowadesignstageassessmentofthelikelyearly-agetime–temperatureprofilesinlargeconcretestructures.Suchanassessmentwouldbeessentialinthecaseofconcretestructureswherethepotentialforthermallyinducedcrackingisofconcern.Keywords:Heatofhydration_Flyash_Silicafume_Slag_Concrete1IntroductionSupplementarycementingmaterials,suchasgroundgranulatedblastfurnaceslag(GGBS),flyash(FA)andcondensedsilicafume(CSF),arenowroutinelyusedinstructuralconcrete.Usedjudiciously,thesematerialsareabletoprovideimprovementsintheeconomy,microstructureofcementpasteaswellastheengineeringpropertiesanddurabilityofconcrete.Theyalsoaltertherateofhydrationandcaninfluencethetime–temperatureprofileinlargeconcreteelements.Thispaperisaimedatanimprovedunderstandingofthewayinwhichtheearly-ageheatofhydrationcharacteristicsofconcretearealteredbytheadditionofsupplementarycementingmaterials(SCM),incombinationwithPortlandcement,asapartofthebinder.Importantly,inthedesignandconstructionoflargeconcreteelements,wheretheextentoftemperatureriseisofconcern,ourabilitytoreliablypredicttheearly-agetemperaturedifferentialsintheconcreterequiresacarefulunderstandingoftheratesatwhichheatisevolvedduringhydration[1–3].Inessence,theintentionofthispaperistoprovideguidanceontheformoftheheat-ratefunctionforconcretescontainingsupplementarycementingmaterials.Thisisessentialinputinformationinthedesignandconstructionoflargedimensionand/orhighstrengthstructureswherethermalstrainsarelikelytoleadtodeleteriouscrackingand/orlossofdurability.Intheinvestigationreportedhere,concretesamplescontainingcombinationsofPortlandcementwithGGBS,FAorCSFweretestedinanadiabaticcalorimeterinordertodeterminetheirheatofhydrationcharacteristics.Thetestprogrammewaslimitedtobinaryblendsofthematerials,i.e.,eachtestwaslimitedtoacombinationofPortlandcementandonesupplementarymaterialandallconcreteswerepreparedatthesamewater:binder(w/b)ratio.Foreachtypeofsupplementarymaterial,concreteswerepreparedwithsupplementarymaterialreplacingbetween5%and80%ofthePortlandcement,dependingonthetypeofSCM.Concretesampleswithavolumeofapproximately1lweretestedintheadiabaticcalorimeter.Theadiabaticcalorimeterthatwasusedinthetestprogrammeisbasedontheprincipleofsurroundingaconcretesamplewithanenvironmentinwhichthetemperatureiscontrolledtomatchthetemperatureofthehydratingconcreteitself,thusensuringthatnoheatistransferredtoorfromthesampleandtheriseintemperaturemeasuredissolelyduetotheheatMevolvedbythehydrationprocess.ThiscalorimeterhasbeendescribedindetailbyGibbonetal.[4].SincetherateofevolutionofheatduringtheMhydrationofcementitiousmaterialsisinfluencedbyMthetemperatureatwhichthereactiontakesplace,thereisnouniqueadiabaticheatratecurveforaparticularcementorcombinationofcementitiousmaterials.Comparisonsoftheheatrateperformancesofmaterialsmust,therefore,bemadeonthebasisofthedegreeofhydrationormaturity.Inthispaper,theresultsareexpressedintermsofmaturityort20h,whichreferstotheequivalenttimeofhydrationat20_C.Thisformofexpressionoftheheatratefunctionandthejustificationforitsuse,isdescribedbyBallimandGraham[1].2ConcretematerialsandmixturesConcretematerialswhicharecommonlyusedandreadilyavailableinSouthAfricawereusedinthesetests.ThePortlandcementcompliedwithSABSEN197-1,typeCEMIclass42.5[5]andtheGGBS,flyashandsilicafumecompliedwithSABS1491Parts1,2and3[6–8],respectively.TheoxidecontentsofthebindermaterialsweredeterminedbyXRFanalysisandtheresultsareshowninTable1.Therangeofreplacementlevelsbyeachofthethreesupplementarymaterialsused,togetherwiththeconcretemixtureproportions.Theconcretemixtureproportionswerekeptthesamethroughout,exceptthatthecompositionandrelativeproportionofthebinderwaschangedasrequired.Alltheconcretesthereforehadaw/bratioofapproximately0.67andthewatercontentwassufficienttocompacttheconcretebymanuallystampingthesampleholder.Allthemixturecomponents,includingthewater,werestoredinthesameroomasthecalorimeteratleast24hbeforemixing.Thisallowedthetemperatureofthematerialstoequilibratetotheroomtemperature,whichwascontrolledat19±1_C.A1.2lsampleofeachconcretewaspreparedbymanualmixinginasteelbowlandtheadiabatictestwasstartedwithin15minafterthewaterwasaddedtothemixture.Allthetestswerestartedattemperaturesbetween18and20_Candtemperaturemeasurementinthecalorimeterwascontinuedforapproximately4days.Thesilicasandusedintheconcreteswasobtainedinthreesizefractionsandthesewererecombinedasneededforthemixingoperationtoensureauniformsandgradingforeachconcrete.Thestoneusedintheconcretewasawashedsilica,largelysingle-sizedand9.5mminnominaldimension.3ConclusionsTheintentionoftheprojectreportedinthispaperwasNtoquantifytheeffectsofsupplementarycementingmaterialsontherateofheatevolutioninPortlandcementconcretes.Inparticular,thefocuswasonprovidinginformationontherateofheatevolutioninawaythatwouldallowimprovedpredictionoftheinternalconcretetemperatureprofilesduringconstructionoflargeorhigh-strengthconcreteelements.Inthisregardandgiventheparametersoftheconcretesused,thestudyhasshownthat:ThepeakrateofheatevolutioninGGBSorFAblendedbindersdecreaseslinearlywithincreasingadditionofGGBSorFA;ExceptforFAreplacementsashighas80%,thetimetoreachpeakratesofheatevolutionisreducedwithincreasedproportionsofGGBSorFAinthebinders.Iftheproportionofflyashisincreasedto80%,thereisasignificantincreaseinthetimerequiredtoreachthepeakrateofheatevolution.Uptoareplacementlevelof15%,theadditionofCSFinPortlandcementbindersdoesnotsignificantlyaltertheheat-rateprofileofconcrete.Themostsignificanteffectnotedwasanapproximately9%increaseinthepeakrateofhydrationwhen15%ofthePortlandcementwasreplacedbyCSF.However,theadditionof10%and15%CSFhadamarkedeffectinreducingthetimetoreachthepeakrateofhydration.ThepresenceoftheSCM’sassessedinthisinvestigationhavetheeffectofstimulatingthehydrationoftheCEMIintheblendedbinderThisstimulatedhydrationresultsfromtheconsumptionofcalciumhydroxide,thedilutioneffectandhydrationnucleationsiteeffect.ThisstimulationofhydrationisstrongestwiththeadditionofCSF,moderateinthecaseofGGBSandweakinthecaseofFA.Intheabsenceofamorereliableheat-ratecurveforconcretecontainingsupplementarycementitiousmaterials,themodelproposedinEqs.6–8canbeusedtoprovideafirst-estimateofthetemperatureprofilesatthedesignstageofatemperature-sensitiveconcretestructure.References1.BallimY,GrahamPC(2003)Amaturityapproachtotherateofheatevolutioninconcrete.MagConcrRes55(3).doi:10.1680/macr.75712.KoendersEAB,vanBreugelK(1994)Numericalandexperimentaladiabatichydrationcurvedetermination.In:SpringenschmidR(ed)Thermalcrackinginconcreteatearlyages.E&FNSpon,London3.MaekawaK,ChaubeR,KishiT(1999)Modellingofconcreteperformance.SponPress,London4.GibbonGJ,BallimY,GrieveGRH(1997)Alowcost,computer-controlledadiabaticcalorimeterfordeterminingtheheatofhydr