DOC-土建畢業(yè)設(shè)計(jì)外文翻譯-一個(gè)未完工的二層預(yù)制混凝土結(jié)構(gòu)物的抗震測試-建筑結(jié)構(gòu)

TestsonaHalf-ScaleTwo-StorySeismic-ResistingPrecastConcreteThispaperdescribesexperimentalstudiesontheseismicbehavioranddesignofprecastconcretebuildings.Ahalf-scaletwo-storyprecastconcretebuildingincorporatingadualsystemandrepresentingaparkingstructureinMexicoCitywasinvestigated.Thestructurewastesteduptofailureinalaboratoryundersimulatedseismicloading.Insomeofthebeam-to-columnjoints,thebottomlongitudinalbarsofthebeamwerepurposelyundevelopedduetodimensionalconstraints.Emphasisisgiveninthestudyontheevaluationoftheobservedglobalbehavioroftheteststructure.Thisbehaviorshowedthatthewallsoftheteststructurecontrolledtheforcepathmechanismandsignificantlyreducedthelateraldeformationdemandsintheprecastframes.Seismicdesigncriteriaandcodeimplicationsforprecastconcretestructuresresultingfromthisresearcharediscussed.TheendresultofthisresearchisthatabetterunderstandingofthestructuralbehaviorofthistypeofbuildinghasbeengainedresultsofsimulatedseismicloadtestsofatwostoryprecastconcretebuildingconstructedwithprecastconcreteelementsthatareusedinMexicoaredescribedherein.Thestructuralsystemchosenintheteststructureisthesocalleddualtype,definedasthecombinationofstructuralwallsandbeam-to-columnframes.Connectionsbetweenprecastbeamsandcolumnsintheteststructureareofthe"window"type.Thistypeofconstructionistypicallyusedinlow-andmediumrisebuildingsinwhichcolumnsareconnectedwith"windows"ateachstorylevel.These"windows"containthetopandbottomreinforcement.Fig.1showsthistypeofconstructionforacommercialbuildinginMexicoCity.InmostprecastconcreteframessuchasthoseshowninFig,1,longitudinalbeambottombarsarenotfullydevelopedduetoconstraintsimposedbythedimensionsoffilecolumnsinbeam-to-columnjoints.Inanefforttoovercomethisdeficiency,andasdescribedlater,somepracticingengineersinMexicodesignthesejointsbyprovidinghoopsaroundthehooksofthatreinforcementinordertoachieveitsrequiredcontinuity.However,thispracticeisnotcoveredintheACIBuildingCode(ACI318-02),norintheMexicoCityBuildingCode(MCBC,1993).Partofthisresearchwasdonetoaddressthisissue.TheobjectivesofthisresearchwereIoevaluatetheobservedbehaviorofaprecastconcretestructuresinthelaboratoryandtoproposetheuseofprecaststructuralelementsorprecaststructureswithbothanacceptablelevelofexpectedseismicperformanceandappealingfeaturesfromtheviewpointofconstructionEmphasisisgiveninthispaperontheglobalbehavioroftheteststructure.Inthesecondpartofthisresearchwhichgillbepresentedinacompanionpaper,theobservedbehaviorofconnectionsbetweenprecastelementsintheteststructure,aswellasthebehavioroftheprecastfloorsystemwillbediscussedindetail.Structuralandnonstructuraldamagesobservedinbuildingsduringpastearthquakesthroughouttheworldhaveshowntheimportanceofcontrollinglateraldisplacementinstructurestoreducebuildingdamageduringearth-quakes.Itisalsorelevanttomentionthatthereareseveralcasesofstructuresinmoderateearthquakesinwhichtheobserveddamageinnon-structuralelementsinbuildingswasconsiderableeventhoughthestructuralelementsshowedlittleornodamage.ThisbehaviorisalsorelatedIoexcessivelateraldisplacementdemandsinthestructure.Tominimizeseismicdamageduringearthquakes,theabovediscussionsuggeststheconvenienceofusingastructuralsystemcapableofcontrollinglateraldisplacementsinstructures.Asolutionofthistypeistheso-calleddualsystem.StudiesbyPaulayandPriestley4ontheseismicresponseofdualsystemshaveshownthatthepresenceofwallsreducethedynamicmomentdemandsinstructuralelementsintheframesubsystem.Alsoinconjunctionwithshaketabletestsconductedonacast-in-placereinforcedconcretedualsystem.Bertero5hasshownthepotentialofthedualsystem,inachievingexcellentseismicbehavior[nthisinvestigation,thedualsystemisappliedtothecaseofprecastconcretestructures.DUCTILITYDEMANDINDUALSYSTEMSInordertodevelopabaseforalateranalysisoftheobservedseismicresponseoftheteststructurestudiedinthisprojectasimpleanalyticalmodelisusedtoevaluatethemainfeaturesofductilitydemandsindualsystems.Fig2showstheresultsofasimpleapproachtoanalyzethelateralloadresponseiiiadualsystem.Thelateralloadhasbeennormalizedinsuchamannerthatthecombinationofmaximumlateralresistanceinbothsubsysterni.e.wallsandframes--leadstoalateralresistanceoftheglobalsystemequaltounitybisalsoassumedthatbothsubsystemshavethesamemaximumlateralresistance.Inthefirstcase(Fig2a),itisassumedthatthewallandframesubsystemshaveglobaldisplacementductilitycapacitiesequalto4and2respectively.Inthesecondcase(Fig.2b),theframesubsystemresponseisassumedtobeelastic,andthelateralstiffnessofthewallsubsystemistakentobe4timesthatoftheframesubsystem.AsshowninFig2,thelateraldeformationcompatibilityofthecombinedsystemiscontrolledbythelateraldeformationcapacityofthewallsubsystem.InthefirstcaseFig2akanelastic-plasticenvelopeforthelateralglobalresponseofthedualsystemisassumed,andthecorrespondingdisplacementductility(u)isequalto33.Forthesecondcase(Fig.2b)withanelasticbehavioroftheframesubsystem,thisductilityisequalto25.Thesesimpleexamplesillustratethatintheanalyzedcases,duetothehigherflexibilityintheframesubsystemsascomparedtothoseofthewallsubsystern,inadualsystem,theductilitydemandsintheframesubsystemresultinsmallerductilityvaluesthanthoseofthewallsubsystem.Thisanalyticalfindingwasverifiedinthisstudyfromtheexperimentalstudiesconductedontheteststructure.ThisverificationislaterdiscussedinthepaperItisofinteresttonotethatresultsofthetypeshowninFig.2havebeenalsofoundbyBertero'inshaketabletestsofadualsystem.DESCRIPTIONOFTESTSTRUCTURETheteststructureusedinthisinvestigationisatwo-storyprecastconcretebuilding,representativeofalow-riseparkingstructurelocatedinthehighestseismiczoneofMexicoCity.Theprototypewasconstructedatone-halfscale.Forthesakeofsimplicity,rampsrequiredinaparkingstructurehavenotbeenconsideredintheselectedprototypestructure.Theiruse,requiringlargeopeningsinthefloorsystem,wouldhaverequiredaverycomplexmodelofthefloorsystemforbothlinearandnonlinearanalysisofthestructure.Adetaileddescriptionofthedimensions,materials,designprocedures,andconstructionoftheteststructurecanbefoundelsewhere.6Asummaryofthisinformationisgivenbelow.ThedimensionsandsomecharacteristicsoftheteststructureareshowninFig.3.ThelongitudinalandtransverseareshowninFig3a.Also,theexterior(longitudinal)framecontainingthewall(ColumnLines1and3)aretermedthelateralframe(seeFig,3b),andtheinternal(longitudinal)framewiththesingletee(ColumnLine2)aretermedthecentralframe.DoableteesspanninginthelongitudinaldirectionaresupportedbyL-shapedprecastbeamsinthetransversedirectionasshowninFig3a.Thestructureusesprecastframesandprecaststructuralwalls,thelatterelementsfunctioningasthemainlateralloadresistingsystem.Fig.4showsanearlyphaseoftheconstructionoftheteststructure.Ascanbeseen,the"windows''inthecolumnsandwallsareleftintheseelementsforalaterassemblagewiththeprecastbeams.TheunfasteneddesignbaseshearrequiredbytheMexicoCityBuildingCode(MCBC,1993)2is0.2WT,whereWTisthetotalweightoftheprototypestructure,assumingadeadloadof5,15KPa(108psi)andaliveloadof0.98KPa(20.5psi).TheprototypestructurewasdesignedusingproceduresofelasticanalysesandproportioningrequirementsoftheMCBC,Intheseanalyses,thegrossmomentofinertiaofthemembersinthestructurewasconsideredandrigidoffsets(distancesfromthejointstothefaceofthesupports)wereassumedforallbeamsinthestructureexceptforbeamsinthecentralframe,whichhadsubstandarddetailingaswillbedescribedlatch.Resultsfromtheseanalysesindicatedthatthestructuralwallsintheteststructurewouldtakeabout65percentofthedesignlateralloads.AreviewofthenominallateralresistanceofthestructureusingtheMCBCproceduresshowedthatthisresistingforcewasabout1.3timestherequiredcodelateralresistance(0,2Wr),Thisisoneofseveralfactors,laterdiscussed,thatcontributedtotheover-strengthofthestructure.ThelongitudinalreinforcementinallthestructuralelementsoftheteststructorewasdeformedbarsfromGrade420steel.Table1liststheconcretecompressivecylinderstrengthsfordifferentmembersoftheprototypestructure.Fig.5showstypicalreinforcingdetailsforprecastbeamsspanninginthedirectionoftheappliedlateralload(seeFig.3).Figs.6and7showreinforcingdetailsforthecolumns,andforthestructuralwailsandtheirfoundation,respectively.ItshouldbementionedthattheteststructurewasdesignedwiththerequirementsformoderatelyductilestructuresspecifiedbytheMCBC.Accordingtotheseprovisions,theteststructuredidnotrequirespecialstructuralwallswithboundaryelementssuchasthosespecifiedinChapter21ofAC131802.Theprecasttwo-storycolumnswereconnectedtotheprecastfoundationbyunthreadingtheminagroutedsockettypeconnection.Thereinforcingdetailsofthefoundation,aswellasitsdesignprocedureandbehaviorintheteststructurearediscussedinthecompanionpaper?Taebeam-to-cadmiumjointsinfileteststructurewerecast-in-placetoenablepositioningthelongitudinalreinforcementoftheframingbeams.Thebeamtopreinforcementwasplacedinsumontopoftheprecastbeams.Fig.8showstypicalreinforcingdetailsforthejointsinthedoubleteesofthecentralframe.SincetheseteesandtheirsupportingL-shapedbeamsinAxesAorC(seeFig.3)hadthesamedepth,thehookedbottomlongitudinalbarsinthedoubleteescouldnotpassthroughthefulldepthofthecolumnbecauseofinterferencewiththebottombarsfromfiletransversebeam(seeFig.g).Asaresult,thesehookedbarspossessedonlyabout55percentofthedevelopmentlengthrequiredbyChapter21ofACI318-02.Inanattempttoanchorthesehookedbars,somedesignersinMexicoprovideclosedhoopsaroundthehooks,asshowninFig.8.Theeffectivenessofthisapproachwasalsostudiedinthecompanionpaper.3Beamto-columnjointsinthelateralframesoftheteststructurehadtransversebeamsthatweredeeperthanthelongitudinalbeams.Thismadeitpossibleforthetopandbottombarsofthelongitudinalbeamstopassthroughthefulljoint,and,therefore,thesebarsachievedtheirrequireddevelopmentlength.Cast-in-placetoppingslabsintheteststructurewere30mm(1.18in.)thickandformedthediaphragmsinJanuary-February2005Fig.3.Planandelevationofteststructure:(a)Plan;(b)Lateralframe;(c)Transverseframe.Dimensionsinmm.Note:1mm-0.0394in.thestructuralsystem.Weldedwirereinforcement(WWR)wasusedasreinforcementforthetoppingslabs.TheamountofWWRillthetoppingslabswascontrolledbythetemperatureandshrinkageprovisionsoftheMCBC.whicharesimilartothoseofAC[318-02.Itisofinteresttomentionthattherequirementsforshearstrengthinthediaphragmsgivenbytheseprovisions,whicharesimilartothoseofACI318-89,didnotcontrolthedesign.Awiresizeof6x6in.10/10ledtoareinforcingratioof0.002inthetoppingslab.ThestrengthoftheWWRatyieldandfractureobtainedfromtestswere400and720MPa(58and104ksi),respectively.外文翻譯一個(gè)未完工的二層預(yù)制混凝土結(jié)構(gòu)物的抗震測試這篇文章是關(guān)于地震和預(yù)制混凝土建筑物設(shè)計(jì)的試驗(yàn)性的研究。墨西哥市里一個(gè)帶有雙重系統(tǒng)和代表了一個(gè)停車場結(jié)構(gòu)的未完工的兩層的預(yù)制混凝土建筑物被調(diào)查研究。這個(gè)結(jié)構(gòu)物在實(shí)驗(yàn)室里用模擬地震荷載測試，結(jié)果失敗了。在一些梁和柱的接頭處，粱底部的縱筋由于尺寸的限制不能屈服。這項(xiàng)研究所強(qiáng)調(diào)的是提高所測試結(jié)構(gòu)物的可觀察的綜合性能。這種性能表現(xiàn)為所測試結(jié)構(gòu)物的墻控制傳力途徑而且能顯著地減少預(yù)制結(jié)構(gòu)所要求的側(cè)向變形。源自于這項(xiàng)研究的預(yù)制混凝土結(jié)構(gòu)抗震設(shè)計(jì)標(biāo)準(zhǔn)和規(guī)范細(xì)節(jié)被討論。這項(xiàng)研究的最終結(jié)果是能更好地理解這種類型的建筑物的已得知的性能。在墨西哥，一個(gè)兩層的預(yù)制混凝土構(gòu)件建成的預(yù)制混凝土建筑物，在其上加上模擬的地震荷載。在這里描述的是其結(jié)果。在測試結(jié)構(gòu)物中所選擇的結(jié)構(gòu)系統(tǒng)是所謂的雙重類型，其定義就是構(gòu)造墻的結(jié)合點(diǎn)以及梁-柱框架。測試結(jié)構(gòu)物中預(yù)制梁柱之間的結(jié)合是窗型的。這種類型的建設(shè)顯著地用在低的或中等高建筑物中，在這種建筑中在每一樓層中柱子和窗子連在一起。這些“窗”包含頂部和底部的鋼筋。圖1所示的是在墨西哥市中這種類型的一個(gè)商業(yè)建筑物。大多數(shù)的預(yù)制混凝土結(jié)構(gòu)如圖1中所示，縱梁底部的鋼筋不能完全屈服。這是由于在梁-柱接頭中柱的尺寸限制所造成的。為了盡力克服這種缺陷，正如在后面所描述的，在墨西哥一些工程師嘗試著這樣設(shè)計(jì)這些接頭，就是通過用箍筋圈住這些鋼筋，這樣做是為了達(dá)到所要求的連續(xù)性。然而，這種嘗試在ACI建筑規(guī)范和MCBC中都沒有提到。這些研究的一部分是為了闡述這個(gè)觀點(diǎn)。這項(xiàng)研究的目的是為了提高在實(shí)驗(yàn)室里的預(yù)制混凝土結(jié)構(gòu)屋的可觀察的性能以及為利用諭旨構(gòu)件或預(yù)制結(jié)構(gòu)建議了一個(gè)可接受的期望的抗震性能以及從建設(shè)能力的觀點(diǎn)所得出的有吸引力的特征。這篇文章中強(qiáng)調(diào)的所測試結(jié)構(gòu)物中預(yù)制構(gòu)件間的連接處的可觀察的性能以及預(yù)制樓層系統(tǒng)的性能將會(huì)詳細(xì)講述。在過去的地震中，在建筑物中造成的可觀察的構(gòu)造和非構(gòu)造的破壞顯示了通過控制結(jié)構(gòu)的側(cè)向位移來降低由地震造成的建筑物的破壞的重要性。在這里還要提到的是，在中等程度的地震中有一些情況下非結(jié)構(gòu)構(gòu)件的破壞相當(dāng)大，盡管構(gòu)造構(gòu)件只有一點(diǎn)破壞或根本就沒有破壞。這種性能和結(jié)構(gòu)物中所要求的過多的側(cè)向位移有關(guān)。為了減少地震所造成的破壞，以上的討論建議了在結(jié)構(gòu)物中可以方便地使用能控制惻向位移的構(gòu)造系統(tǒng)。這種類型的解決方法就是所謂的雙重系統(tǒng)。Paulay和priestly的關(guān)于雙重系統(tǒng)的地震反映的研究表明墻的出現(xiàn)降低了框架微系統(tǒng)中結(jié)構(gòu)構(gòu)件的動(dòng)力要求。同時(shí)，在一個(gè)現(xiàn)澆的鋼筋混凝土雙重系統(tǒng)上所做的搖擺測試顯示了雙重系統(tǒng)能達(dá)到良好的抗震性能的潛力。在這次調(diào)查研究中，雙重系統(tǒng)應(yīng)用在預(yù)制混凝土構(gòu)件上。雙重系統(tǒng)的柔性要求為了使這個(gè)工程所研究的被測試結(jié)構(gòu)物的能觀測到的抗震反應(yīng)的以后的分析打好基礎(chǔ)，一個(gè)簡單的分析模式被用來提高雙重系統(tǒng)中主要柔性特征要求。圖2所示的是一個(gè)簡單的分析作用在雙重系統(tǒng)側(cè)向荷載反映的結(jié)果。側(cè)向荷載從這種方式標(biāo)準(zhǔn)化，將任一系統(tǒng)中最大的側(cè)向抵抗力聯(lián)合起來。比如，墻和框架導(dǎo)致綜合系統(tǒng)的側(cè)向抵抗力。假設(shè)任一微系統(tǒng)的總的位移量為4和2。在第二種情況下，框架系統(tǒng)假設(shè)為彈性，墻微系統(tǒng)的剛度為框架微系統(tǒng)的4倍。圖2所示，聯(lián)合系統(tǒng)的側(cè)向變形兼容性由墻微系統(tǒng)的側(cè)向變形量控制，在第一種情況下，假設(shè)雙重系統(tǒng)的總側(cè)向反應(yīng)有一個(gè)塑料封套，相應(yīng)的位移系數(shù)是3.3在第二種情況下，框架微系統(tǒng)在彈性力下，起位移系數(shù)是2.5。這些簡