桥梁评测_桥梁工程.pdf_第1页
桥梁评测_桥梁工程.pdf_第2页
桥梁评测_桥梁工程.pdf_第3页
桥梁评测_桥梁工程.pdf_第4页
桥梁评测_桥梁工程.pdf_第5页
已阅读5页，还剩4页未读， 继续免费阅读

下载本文档

版权说明：本文档由用户提供并上传，收益归属内容提供方，若内容存在侵权，请进行举报或认领

文档简介

BRIDGERATINGUSINGSYSTEMRELIABILITYASSESSMENTIIIMPROVEMENTSTOBRIDGERATINGPRACTICESNAIYUWANG,MASCE1BRUCERELLINGWOOD,DISTMASCE2ANDABDULHAMIDZUREICK,MASCE3ABSTRACTTHECURRENTBRIDGERATINGPROCESSDESCRIBEDINAASHTOMANUALFORBRIDGEEVALUATION,FIRSTEDITIONPERMITSRATINGSTOBEDETERMINEDBYALLOWABLESTRESS,LOADFACTOR,ORLOADANDRESISTANCEFACTORMETHODSTHESETHREERATINGMETHODSMAYLEADTODIFFERENTRATEDCAPACITIESANDPOSTINGLIMITSFORTHESAMEBRIDGE,ASITUATIONTHATHASSERIOUSIMPLICATIONSWITHREGARDTOPUBLICSAFETYANDTHEECONOMICWELLBEINGOFCOMMUNITIESTHATMAYBEAFFECTEDBYBRIDGEPOSTINGSORCLOSURESTHISPAPERISTHESECONDOFTWOPAPERSTHATSUMMARIZEARESEARCHPROGRAMTODEVELOPIMPROVEMENTSTOTHEBRIDGERATINGPROCESSBYUSINGSTRUCTURALRELIABILITYMETHODSTHEFIRSTPAPERPROVIDEDBACKGROUNDONTHERESEARCHPROGRAMANDSUMMARIZEDACOORDINATEDPROGRAMOFLOADTESTINGANDANALYSISTOSUPPORTTHERELIABILITYASSESSMENTLEADINGTOTHERECOMMENDEDIMPROVEMENTSTHISSECONDPAPERPRESENTSTHERELIABILITYBASISFORTHERECOMMENDEDLOADRATING,DEVELOPSMETHODSTHATCLOSELYCOUPLETHERATINGPROCESSTOTHERESULTSOFINSITUINSPECTIONANDEVALUATION,ANDRECOMMENDSSPECIFICIMPROVEMENTSTOCURRENTBRIDGERATINGMETHODSINAFORMATTHATISCONSISTENTWITHTHELOADANDRESISTANCEFACTORRATINGLRFROPTIONINTHEAASHTOMANUALFORBRIDGEEVALUATIONDOI101061/ASCEBE1943559200001712011AMERICANSOCIETYOFCIVILENGINEERSCEDATABASESUBJECTHEADINGSCONCRETEBRIDGESREINFORCEDCONCRETEPRESTRESSEDCONCRETELOADFACTORSRELIABILITYSTEELRATINGSAUTHORKEYWORDSBRIDGESRATINGCONCRETEREINFORCEDCONCRETEPRESTRESSEDCONDITIONASSESSMENTLOADSFORCESRELIABILITYSTEELSTRUCTURALENGINEERINGINTRODUCTIONTHEAASHTOMANUALFORBRIDGEEVALUATIONMBE,FIRSTEDITIONAASHTO2008ALLOWSBRIDGERATINGSTOBEDETERMINEDTHROUGHTHETRADITIONALALLOWABLESTRESSRATINGASRORLOADFACTORRATINGLFRMETHODSORBYTHEMORERECENTLOADANDRESISTANCEFACTORRATINGLRFRMETHOD,WHICHISCONSISTENTWITHTHEAASHTOLRFDBRIDGEDESIGNSPECIFICATIONS2007THESETHREERATINGMETHODSMAYLEADTODIFFERENTRATEDCAPACITIESANDPOSTEDLIMITSFORTHESAMEBRIDGENCHRP2001WANGETAL2009,ASITUATIONTHATCANNOTBEJUSTIFIEDFROMAPROFESSIONALENGINEERINGVIEWPOINTANDHASIMPLICATIONSFORTHESAFETYANDECONOMICWELLBEINGOFTHOSEAFFECTEDBYBRIDGEPOSTINGSORCLOSURESTOADDRESSTHISISSUE,THEGEORGIAINSTITUTEOFTECHNOLOGYHASCONDUCTEDAMULTIYEARRESEARCHPROGRAMAIMEDATMAKINGIMPROVEMENTSTOTHEPROCESSBYWHICHTHECONDITIONOFEXISTINGBRIDGESTRUCTURESINGEORGIAAREASSESSEDTHEENDPRODUCTOFTHISRESEARCHPROGRAMISSETOFRECOMMENDEDGUIDELINESFORTHEEVALUATIONOFEXISTINGBRIDGESELLINGWOODETAL2009THESEGUIDELINESAREESTABLISHEDBYACOORDINATEDPROGRAMOFLOADTESTINGANDADVANCEDFINITEELEMENTMODELING,WHICHHAVEBEENINTEGRATEDWITHINASTRUCTURALRELIABILITYFRAMEWORKTODETERMINEPRACTICALBRIDGERATINGMETHODSTHATARECONSISTENTWITHTHOSEUSEDTODEVELOPTHEAASHTOLRFDBRIDGEDESIGNSPECIFICATIONSAASHTO2007ITISBELIEVEDTHATBRIDGECONSTRUCTIONANDRATINGPRACTICESARESIMILARENOUGHINOTHERNONSEISMICAREASTOMAKETHEINFERENCES,CONCLUSIONS,ANDRECOMMENDATIONSVALIDFORLARGEREGIONSINTHECENTRALANDEASTERNUNITEDSTATESCEUSTHERECENTIMPLEMENTATIONOFLRFDANDITSCOMPANIONRATINGMETHOD,LRFR,BOTHOFWHICHHAVEBEENSUPPORTEDBYSTRUCTURALRELIABILITYMETHODS,ENABLEBRIDGEDESIGNANDCONDITIONASSESSMENTTOBEPLACEDONAMORERATIONALBASISNOTWITHSTANDINGTHESEADVANCES,IMPROVEDTECHNIQUESFOREVALUATINGTHEBRIDGEINITSINSITUCONDITIONWOULDMINIMIZETHELIKELIHOODOFUNNECESSARYPOSTINGFOREXAMPLE,MATERIALSTRENGTHSINSITUMAYBEVASTLYDIFFERENTFROMTHESTANDARDIZEDORNOMINALVALUESASSUMEDINDESIGNANDCURRENTRATINGPRACTICESATTRIBUTABLETOSTRENGTHGAINOFCONCRETEONONEHANDANDDETERIORATIONATTRIBUTABLETOAGGRESSIVEATTACKFROMPHYSICALORCHEMICALMECHANISMSONTHEOTHERSATISFACTORYPERFORMANCEOFAWELLMAINTAINEDBRIDGEOVERAPERIODOFYEARSOFSERVICEPROVIDESADDITIONALINFORMATIONNOTAVAILABLEATTHEDESIGNSTAGETHATMIGHTBETAKENINTOACCOUNTINMAKINGDECISIONSREGARDINGPOSTINGORUPGRADINGINVESTIGATINGBRIDGESYSTEMRELIABILITYRATHERTHANSOLELYRELYINGONCOMPONENTBASEDRATINGMETHODSMAYALSOBEOFSIGNIFICANTBENEFITPROPERCONSIDERATIONOFTHESEFACTORSISLIKELYTOCONTRIBUTETOAMOREREALISTICCAPACITYRATINGOFEXISTINGBRIDGESTHISPAPERISTHESECONDOFTWOCOMPANIONPAPERSTHATPROVIDETHETECHNICALBASESFORPROPOSEDIMPROVEMENTSTOTHECURRENTLRFRPRACTICETHEFIRSTPAPERWANGETAL2011SUMMARIZEDTHECURRENTBRIDGERATINGPROCESSANDPRACTICESINTHEUNITEDSTATES,ANDPRESENTEDTHERESULTSOFACOORDINATEDBRIDGETESTINGANDANALYSISPROGRAMCONDUCTEDTOSUPPORTREVISIONSTOTHECURRENTRATINGPROCEDURESTHISPAPERDESCRIBESTHERELIABILITYANALYSISFRAMEWORKTHATPROVIDESTHEBASISFORRECOMMENDEDIMPROVEMENTSTOTHEMBEANDRECOMMENDSSPECIFICIMPROVEMENTSTOTHEMBETHATADDRESSTHEPRECEDINGFACTORS1SENIORSTRUCTURALENGINEER,SIMPSON,GUMPERTZ,ANDHEGER,INC,41SEYONST,WALTHAM,MA02453FORMERLY,GRADUATERESEARCHASSISTANT,SCHOOLOFCIVILANDENVIRONMENTALENGINEERING,GEORGIAINSTITUTEOFTECHNOLOGY2PROFESSOR,SCHOOLOFCIVILANDENVIRONMENTALENGINEERING,GEORGIAINSTITUTEOFTECHNOLOGY,790ATLANTICDR,ATLANTA,GA303320355CORRESPONDINGAUTHOREMAILELLINGWOODGATECHEDU3PROFESSOR,SCHOOLOFCIVILANDENVIRONMENTALENGINEERING,GEORGIAINSTITUTEOFTECHNOLOGY,790ATLANTICDR,ATLANTA,GA303320355NOTETHISMANUSCRIPTWASSUBMITTEDONMARCH19,2010APPROVEDONAUGUST2,2010PUBLISHEDONLINEONOCTOBER14,2011DISCUSSIONPERIODOPENUNTILAPRIL1,2012SEPARATEDISCUSSIONSMUSTBESUBMITTEDFORINDIVIDUALPAPERSTHISPAPERISPARTOFTHEJOURNALOFBRIDGEENGINEERING,VOL16,NO6,NOVEMBER1,2011ASCE,ISSN10840702/2011/6863871/2500JOURNALOFBRIDGEENGINEERINGASCE/NOVEMBER/DECEMBER2011/863DOWNLOADED21MAR2012TO1809522453REDISTRIBUTIONSUBJECTTOASCELICENSEORCOPYRIGHTVISITHTTP/WWWASCELIBRARYORGRELIABILITYBASESFORBRIDGELOADRATINGBRIDGEDESIGN,ASCODIFIEDINTHEAASHTOLRFDSPECIFICATIONS2007,ISESTABLISHEDBYMODERNPRINCIPLESOFSTRUCTURALRELIABILITYANALYSISTHEPROCESSBYWHICHEXISTINGBRIDGESARERATEDMUSTBECONSISTENTWITHTHOSEPRINCIPLESUNCERTAINTIESINTHEPERFORMANCEOFANEXISTINGBRIDGEARISEFROMVARIATIONSINLOADS,MATERIALSTRENGTHPROPERTIES,DIMENSIONS,NATURALANDARTIFICIALHAZARDS,INSUFFICIENTKNOWLEDGE,ANDHUMANERRORSINDESIGNANDCONSTRUCTIONELLINGWOODETAL1982GALAMBOSETAL1982NOWAK1999PROBABILITYBASEDLIMITSTATESDESIGN/EVALUATIONCONCEPTSPROVIDEARATIONALANDPOWERFULTHEORETICALBASISFORHANDLINGTHESEUNCERTAINTIESINBRIDGEEVALUATIONTHELIMITSTATESFORBRIDGEDESIGNANDEVALUATIONCANBEDEFINEDINTHEGENERALFORMGX01WHEREXX1X2X3XNLOADANDRESISTANCERANDOMVARIABLESONTHEBASISOFBRIDGEPERFORMANCEOBJECTIVES,THESELIMITSTATESMAYRELATETOSTRENGTHFORPUBLICSAFETYORTOEXCESSIVEDEFORMATION,CRACKING,WEAROFTHETRAFFICSURFACE,OROTHERSOURCESOFFUNCTIONALIMPAIRMENTASTATEOFUNSATISFACTORYPERFORMANCEISDEFINED,BYCONVENTION,WHENGX0THUS,THEPROBABILITYOFFAILURECANBEESTIMATEDASPFPGX0C138ZFXXDX2WHEREFXXJOINTDENSITYFUNCTIONOFXANDFAILUREDOMAININWHICHGX0INMODERNFIRSTORDERFORELIABILITYANALYSISMELCHERS1999,EQ2ISOFTENAPPROXIMATEDBYPFC03WHERESTANDARDNORMALDISTRIBUTIONFUNCTIONANDRELIABILITYINDEXFORWELLBEHAVEDLIMITSTATES,EQ3USUALLYISANEXCELLENTAPPROXIMATIONTOEQ2,ANDANDPFCANBEUSEDINTERCHANGEABLYASRELIABILITYMEASURESELLINGWOOD2000WHENTHEFAILURESURFACEINEQ1ISCOMPLEXORWHENTHERELIABILITYOFASTRUCTURALSYSTEM,INWHICHTHESTRUCTURALBEHAVIORISMODELEDTHROUGHFINITEELEMENTANALYSIS,ISOFINTEREST,EQ2CANBEEVALUATEDEFFICIENTLYBYMONTECARLOMCSIMULATIONTHEAASHTOLRFDBRIDGEDESIGNSPECIFICATIONS2007AREESTABLISHEDONFORELIABILITYANALYSIS,APPLIEDTOINDIVIDUALGIRDERSNOWAK1999KIMANDNOWAK1997TABSHANDNOWAK1991WITHTHESUPPORTINGPROBABILISTICMODELINGOFRESISTANCEANDLOADTERMSNOWAK1993BARTLETTANDMCGREGOR1996MOSESANDVERMA1987,ANEXAMINATIONOFEXISTINGBRIDGEDESIGNPRACTICESLEDTOATARGETRELIABILITYINDEX,EQUALTO35BASEDONA75YEARSERVICEPERIODNOWAK1999,MOSES2001CONSISTENTWITHSUCHRELIABILITYBASEDPERFORMANCEOBJECTIVE,THEAASHTOLRFDSPECIFICATIONSSTIPULATETHATINTHEDESIGNOFNEWBRIDGES125D15DA175LIRN4WHEREDDEADLOADEXCLUDINGWEIGHTOFTHEWEARINGSURFACEDAWEIGHTOFTHEWEARINGSURFACEASPHALTLIREPRESENTSLIVELOADINCLUDINGIMPACTRNDESIGNSTRENGTH,INWHICHRNNOMINALRESISTANCEANDRESISTANCEFACTORWHICHDEPENDSONTHEPARTICULARLIMITSTATEOFINTERESTTHISEQUATIONISFAMILIARTOMOSTDESIGNERSWHENTHERELIABILITYOFANEXISTINGBRIDGEISCONSIDERED,ALLOWANCESHOULDBEMADEFORTHESPECIFICKNOWLEDGEREGARDINGITSSTRUCTURALDETAILSANDPASTPERFORMANCEFIELDINSPECTIONDATA,LOADTESTING,MATERIALTESTS,ORTRAFFICSURVEYS,IFAVAILABLE,CANBEUTILIZEDTOMODIFYTHEPROBABILITYDISTRIBUTIONSDESCRIBINGTHESTRUCTURALBEHAVIORANDRESPONSEINEQ2THEMETRICFORACCEPTABLEPERFORMANCEISOBTAINEDBYMODIFYINGEQ2TOREFLECTTHEADDITIONALINFORMATIONGATHEREDPFPGX0JHC138PT5WHEREHREPRESENTSWHATISLEARNEDFROMPREVIOUSSUCCESSFULPERFORMANCE,INSERVICEINSPECTION,ANDSUPPORTINGINSITUTESTING,IFANYTHETARGETPROBABILITY,PT,SHOULDDEPENDONTHEECONOMICSOFREHABILITATION/REPAIR,CONSEQUENCESOFFUTUREOUTAGES,ANDTHEBRIDGERATINGSOUGHTINTHEAASHTOLRFRMETHOD2007,THETARGETFORDESIGNLEVELCHECKINGBYUSINGHL93LOADMODELATINVENTORYLEVELIS35,WHICHISCOMPARABLETOTHERELIABILITYFORNEWBRIDGES,WHEREASTHETARGETFORHL93OPERATINGLEVELANDFORLEGAL,ANDPERMITLOADSISREDUCEDTO25OWINGTOTHEREDUCEDLOADMODELANDREDUCEDEXPOSUREPERIOD5YEARSMOSES2001THEPRESENCEOFHINEQ5ISACONCEPTUALDEPARTUREFROMEQS2AND3,WHICHPROVIDETHEBASISFORLRFDFOREXAMPLE,TRAFFICDEMANDSONBRIDGESLOCATEDINDIFFERENTPLACESINTHEHIGHWAYSYSTEMMAYBEDIFFERENTTOTAKETHISSITUATIONINTOACCOUNT,LRFRINTRODUCESASETOFLIVELOADFACTORSFORTHELEGALLOADRATING,WHICHDEPENDONTHEINSITUTRAFFICDESCRIBEDBYTHEAVERAGEDAILYTRUCKTRAFFICADTTFURTHERMORE,THECOMPONENTNOMINALRESISTANCEINLRFRISFACTOREDBYASYSTEMFACTORSANDAMEMBERCONDITIONFACTORCINADDITIONTOTHEBASICRESISTANCEFACTORFORAPARTICULARCOMPONENTLIMITSTATETHESYSTEMFACTORDEPENDSONTHEPERCEIVEDREDUNDANCYLEVELOFAGIVENBRIDGEINITSRATING,WHEREASTHECONDITIONFACTORISTOACCOUNTFORTHEBRIDGESSITESPECIFICDETERIORATIONCONDITION,ANDPURPORTSTOINCLUDETHEADDITIONALUNCERTAINTYBECAUSEOFANYDETERIORATIONTHATMAYBEPRESENTTHEBASISFORTHELRFRTABULATEDVALUESFORCWILLBEFURTHEREXAMINEDLATERINTHISPAPERTHELRFROPTIONINTHEAASHTOMBEEXTENDSTHELIMITSTATEDESIGNPHILOSOPHYTOTHEBRIDGEEVALUATIONPROCESSINANATTEMPTTOACHIEVEAUNIFORMTARGETLEVELOFSAFETYFOREXISTINGHIGHWAYBRIDGESYSTEMSHOWEVER,THEUNCERTAINTYMODELSOFLOADANDRESISTANCEEMBEDDEDINTHELRFRRATINGFORMATREPRESENTTYPICALVALUESFORALARGEPOPULATIONOFBRIDGESINVOLVINGDIFFERENTMATERIALS,CONSTRUCTIONPRACTICES,ANDSITESPECIFICTRAFFICCONDITIONSALTHOUGHTHELRFRLIVELOADMODELHASBEENMODIFIEDFORSOMEOFTHESPECIFICCASESASDISCUSSEDPREVIOUSLY,THEBRIDGERESISTANCEMODELSHOULDALSOBE“CUSTOMIZED”FORANINDIVIDUALBRIDGEBYINCORPORATINGAVAILABLESITESPECIFICKNOWLEDGETOREFLECTTHEFACTTHATEACHBRIDGEISUNIQUEINITSASBUILTCONDITIONARATINGPROCEDURETHATDOESNOTINCORPORATEINSITUDATAPROPERLYMAYRESULTININACCURATERATINGSANDCONSEQUENTUNNECESSARYREHABILITATIONORPOSTINGCOSTSFOROTHERWISEWELLMAINTAINEDBRIDGES,ASINDICATEDBYMANYLOADTESTSNOWAKANDTHARMABALA1988BAKHTANDJAEGER1990MOSESETAL1994FUANDTANG1995FABERETAL2000BARKER2001BHATTACHARYAETAL2005IMPROVEMENTSINPRACTICALGUIDANCEWOULDPERMITTHEBRIDGEENGINEERTOINCLUDEMORESITESPECIFICKNOWLEDGEINTHEBRIDGERATINGPROCESSTOACHIEVEREALISTICEVALUATIONSOFTHEBRIDGEPERFORMANCETHISGUIDANCEMUSTHAVEASTRUCTURALRELIABILITYBASISIMPROVEMENTSINBRIDGERATINGBYUSINGRELIABILITYBASEDMETHODSINTHISSECTION,THEBRIDGERATINGSINLIGHTOFTHERELIABILITYBASEDUPDATINGOFINSERVICESTRENGTHDESCRIBEDINTHEPREVIOUSSECTIONAREEXAMINEDTHEPOSSIBILITIESOFINCORPORATINGAVAILABLESITESPECIFICDATAOBTAINEDFROMMATERIALTESTS,LOADTESTS,ADVANCED864/JOURNALOFBRIDGEENGINEERINGASCE/NOVEMBER/DECEMBER2011DOWNLOADED21MAR2012TO1809522453REDISTRIBUTIONSUBJECTTOASCELICENSEORCOPYRIGHTVISITHTTP/WWWASCELIBRARYORGSTRUCTURALANALYSIS,ANDSUCCESSFULSERVICEPERFORMANCETOMAKEFURTHERRECOMMENDATIONSFORIMPROVINGRATINGANALYSISAREEXPLOREDINCORPORATIONOFINSITUMATERIALTESTINGTHECOMPANIONPAPERSUMMARIZEDTHELOADTESTOFBRIDGEID1290045,AREINFORCEDCONCRETETBEAMBRIDGETHATWASDESIGNEDACCORDINGTOTHEAASHTO1953DESIGNSPECIFICATIONFORH15LOADINGANDWASCONSTRUCTEDIN1957THESPECIFIED28DAYCOMPRESSIONSTRENGTHOFTHECONCRETEWAS172MPA2,500PSI,WHEREASTHEYIELDSTRENGTHOFTHEREINFORCEMENTWAS276MPA40KSITHESCHEDULEDDEMOLITIONOFTHISBRIDGEPROVIDEDANOPPORTUNITYTOSECUREDRILLEDCORESTODETERMINETHESTATISTICALPROPERTIESOFTHEINSITUSTRENGTHOFTHE51YEAROLDCONCRETEINTHEBRIDGEFOURINCHDIAMETERDRILLEDCORESWERETAKENFROMTHESLABOFTHEBRIDGEBEFOREITSDEMOLITIONSEVENCORESWERETAKENFROMTHESLABATSEVENDIFFERENTLOCATIONSALONGBOTHTHELENGTHANDWIDTHOFTHEBRIDGECORESALSOWERETAKENFROMTHREEOFTHEGIRDERSTHATWEREINGOODCONDITIONAFTERDEMOLITIONTHESEWERECUTINTO203MM8INLENGTHSANDTHEJAGGEDENDSWERESMOOTHEDANDCAPPED,RESULTINGINATOTALOF14GIRDERTESTCYLINDERSTESTSOFTHESE102203MM48INCYLINDERSCONFORMEDTOASTMSTANDARDC42ASTM1995ANDTHERESULTSAREPRESENTEDINTABLE1ANANALYSISOFTHESEDATAINDICATEDNOSTATISTICALLYSIGNIFICANTDIFFERENCEINTHECONCRETECOMPRESSIONSTRENGTHINTHEGIRDERSANDSLAB,ANDTHEDATAWERETHEREFORECOMBINEDFORFURTHERANALYSISTHEMEANAVERAGECOMPRESSIONSTRENGTHOFTHECONCRETEIS33MPA4,820PSIANDTHECOEFFICIENTOFVARIATIONCOVIS12,WHICHISREPRESENTATIVEOFGOODQUALITYCONCRETEBARTLETTANDMACGREGOR1996THEMEANSTRENGTHIS193TIMESTHESPECIFIEDCOMPRESSIONSTRENGTHOFTHECONCRETETHISINCREASEINCOMPRESSIONSTRENGTHOVERAPERIODOFMORETHAN50YEARSISTYPICALOFTHEINCREASESFOUNDFORGOODQUALITYCONCRETEBYOTHERINVESTIGATORSWASHAANDWENDT1975IFTHESERESULTSARETYPICALOFWELLMAINTAINEDOLDERCONCRETEBRIDGES,THEINSITUCONCRETESTRENGTHISLIKELYTOBESUBSTANTIALLYGREATERTHANTHE28DAYSTRENGTHTHATISCUSTOMARILYSPECIFIEDFORBRIDGEDESIGNORCONDITIONEVALUATIONACCORDINGLY,THEBRIDGEENGINEERSHOULDBEPROVIDEDINCENTIVESINTHERATINGCRITERIATORATEABRIDGEBYUSINGTHEBESTPOSSIBLEINFORMATIONFROMINSITUMATERIALSTRENGTHTESTINGWHENEVERFEASIBLEELLINGWOODETAL2009ITISCUSTOMARYTOBASETHESPECIFIEDCOMPRESSIONSTRENGTHOFCONCRETEONTHE10THPERCENTILEOFANORMALDISTRIBUTIONOFCYLINDERSTRENGTHSSTANDARD31805ACI2005ASUITABLEESTIMATEFORTHIS10THPERCENTILEBASEDONASMALLSAMPLEOFDATAISPROVIDEDBYFCC22X1C0KV6WHEREC22XSAMPLEMEANVSAMPLECOEFFICIENTOFVARIATIONANDKPLOWERCONFIDENCEINTERVALONTHE10THPERCENTILECOMPRESSIONSTRENGTHBYUSINGTHE21TESTSFROMBRIDGEID1290045WITHP75ASANEXAMPLE,K1520MONTGOMERY1996ANDFCCANBEEXPRESSEDASFC1152001248203941PSI2717MPA,AVALUETHATIS58HIGHERTHANTHE172MPA2,500PSITHATOTHERWISEWOULDBEUSEDINTHERATINGCALCULATIONSINTHEFEMODELINGOFTHISBRIDGETHATPRECEDEDTHESESTRENGTHTESTS,THECONCRETECOMPRESSIONSTRENGTHWASSETAT172MPA2,500PSI,WHICHWASTHEONLYINFORMATIONAVAILABLEBEFORETHEMATERIALTESTTODETERMINETHEIMPACTOFUSINGTHEACTUALCONCRETESTRENGTHINANOLDERBRIDGEONTHERATINGPROCESS,THEFINITEELEMENTMODELWASREVISEDTOACCOUNTFORTHEINCREASEDCONCRETECOMPRESSIONSTRENGTHANDTHECORRESPONDINGINCREASEINSTIFFNESSINTOTHEANALYSISOFTHEBRIDGEONLYAMODESTENHANCEMENTINTHEESTIMATEDBRIDGECAPACITYINFLEXUREWASOBTAINED,BUTA34INCREASEWASACHIEVEDINTHESHEARCAPACITYRATINGSFORTHEGIRDERSBYUSINGTHERESULTSOFTABLE1BRIDGESYSTEMRELIABILITYASSESSMENTONTHEBASISOFSTATICPUSHDOWNANALYSISALTHOUGHCOMPONENTBASEDDESIGNOFANEWBRIDGEPROVIDESADEQUATESAFETYATREASONABLECOST,COMPONENTBASEDEVALUATIONOFANEXISTINGBRIDGEFORRATINGPURPOSESMAYBEOVERLYCONSERVATIVEANDRESULTINUNNECESSARYREPAIRORPOSTINGCOSTSITISPREFERABLETOPERFORMLOADRATINGREGARDINGBRIDGEPOSTINGORROADCLOSURETHROUGHASYSTEMLEVELANALYSISAPROPERLYCONDUCTEDPROOFLOADTESTCANBEANEFFECTIVEWAYTOLEARNTHEBRIDGESSTRUCTURALPERFORMANCEASASYSTEMANDTOUPDATETHEBRIDGELOADCAPACITYASSESSMENTINSITUATIONSINWHICHTHEANALYTICALAPPROACHPRODUCESLOWRATINGS,ORSTRUCTURALANALYSISISDIFFICULTTOPERFORMBECAUSEOFDETERIORATIONORLACKOFDOCUMENTATIONSARAFANDNOWAK1998HOWEVER,APROOFLOADTESTREPRESENTSASIGNIFICANTINVESTMENTINCAPITAL,TIME,ANDPERSONNEL,ANDTHETRADEOFFBETWEENTHEINFORMATIONGAINANDTHERISKOFDAMAGINGTHEBRIDGEDURINGTHETESTMUSTBECONSIDEREDPROOFTESTSARERARELYCONDUCTEDBYTHESTATEDOTSWANGETAL2009FORRATINGPURPOSESONEOFTHEKEYCONCLUSIONSFROMTHECOMPANIONPAPERWANGETAL2011,INWHICHBRIDGERESPONSEMEASUREMENTSOBTAINEDFROMTHELOADTESTSOFTHEFOURBRIDGESWERECOMPAREDWITHTHERESULTSOFFINITEELEMENTANALYSESOFTHOSEBRIDGESWITHABAQUS2006,WASTHATTHEFINITEELEMENTMODELINGPROCEDUREWASSUFFICIENTFORCONDUCTINGVIRTUALLOADTESTSOFSIMILARBRIDGESTHESEVIRTUALLOADTESTSCANPROVIDETHEBASISFORDEVELOPINGRECOMMENDATIONSFORIMPROVINGGUIDELINESFORBRIDGERATINGSBYUSINGSTRUCTURALRELIABILITYPRINCIPLESASNOTEDINTHEINTRODUCTORYSECTION,SUCHGUIDELINESREQUIRETHEBRIDGETOBEMODELEDASASTRUCTURALSYSTEMTOPROPERLYIDENTIFYTHEPERFORMANCELIMITSTATESONWHICHSUCHGUIDELINESARETOBEBASEDTOIDENTIFYSUCHPERFORMANCELIMITSTATESANDTOGAINAREALISTICAPPRAISALOFTHECONSERVATISMINHERENTINCURRENTBRIDGEDESIGNANDCONDITIONRATINGPROCEDURES,ASERIESOFSTATICPUSHDOWNANALYSESOFTHEFOURBRIDGESWASPERFORMEDTHESEANALYSESAREAIMEDATDETERMININGTHEACTUALSTRUCTURALBEHAVIOROFTYPICALBRIDGESWHENLOADEDWELLBEYONDTHEIRDESIGNLIMITASASIDELIGHT,THEYPROVIDEADDITIONALINFORMATIONTOSUPPORTRATIONALEVALUATIONOFPERMITLOADAPPLICATIONSSECTION6A45INTHEMANUALOFBRIDGEEVALUATIONINAPUSHDOWNANALYSIS,TWORATINGVEHICLESAREPLACEDSIDEBYSIDEONTHEBRIDGEINAPOSITIONTHATMAXIMIZESTHERESPONSEQUANTITYOFINTERESTINTHEEVALUATIONEG,MAXIMUMMOMENT,SHEAR,ANDDEFLECTIONTHELOADSARETHENSCALEDUPWARDSTATICALLYANDTHEPERFORMANCEOFTHEBRIDGESYSTEMISMONITOREDTHEDEADWEIGHTOFTHEBRIDGESTRUCTUREISINCLUDEDINTHEANALYSISTHERESPONSEISINITIALLYELASTICASTHESTATICLOADINCREASES,HOWEVER,ELEMENTSOFTHEBRIDGESTRUCTUREBEGINTOYIELD,CRACK,ORBUCKLE,ANDTHEGENERALIZEDLOADDEFLECTIONBEHAVIORBECOMESNONLINEARIFTHEBRIDGESTRUCTUREISREDUNDANTANDTHESTRUCTURALELEMENTBEHAVIORSAREDUCTILE,SUBSTANTIALLOADREDISTRIBUTIONMAYOCCURATSOMEPOINT,HOWEVER,ASMALLINCREMENTINSTATICLOADLEADSTOALARGEINCREMENTINDISPLACEMENTATTHATPOINT,THEBRIDGEHASREACHEDITSPRACTICALLOADCARRYINGLIMIT,ANDISATASTATEOFINCIPIENTCOLLAPSETABLE1COMPRESSIONTESTSOF48INCORESDRILLEDFROMRCCONCRETEBRIDGEID1290045SOURCENUMBERAVERAGEPSISTANDARDDEVIATIONPSICOEFFICIENTOFVARIATIONGIRDER144,880603012SLAB74,698573012OVERALL214,820586012NOTE1PSI69PAJOURNALOFBRIDGEENGINEERINGASCE/NOVEMBER/DECEMBER2011/865DOWNLOADED21MAR2012TO1809522453REDISTRIBUTIONSUBJECTTOASCELICENSEORCOPYRIGHTVISITHTTP/WWWASCELIBRARYORGTHESTATICPUSHDOWNANALYSISISILLUSTRATEDINFIG1FORTHERCTBEAMBRIDGEID1290045THEFEMODELINGWASPERFORMEDWITHABAQUS2006,WITHRANDOMMATERIALPROPERTIESDETERMINEDBYTHEIRRESPECTIVEMEANVALUESTHEPOINTOFINITIALYIELDINGOCCURSATAPPROXIMATELY431TIMESTHEHS2044DESIGNLOADCONFIGURATION,ATADEFLECTIONOFAPPROXIMATELY36MM14IN,WHICHISEQUALTOAPPROXIMATELY1345TIMESTHESPANTHEULTIMATELIVELOADCAPACITYOFTHEBRIDGEISAPPROXIMATELY48TIMESTHEAPPLIEDHS2044LOADSFROMFIG1,THIS52YEAROLDBRIDGESHOWSACONSIDERABLEDEGREEOFDUCTILITYINBEHAVIORTHELEVELOFLOADIMPOSEDBYTHEFOURFULLYLOADEDTRUCKSDURINGTHELOADTESTDESCRIBEDINTHECOMPANIONPAPERISALSOSHOWNINFIG1THETESTLOADINMAXIMUMGIRDERMOMENTWASAPPROXIMATELY13TIMESTHETWOSIDEBYSIDEHS2044LOADSTHEC
人人文库> 全部分类> 教育资料 > 幼儿教育

温馨提示

  • 1. 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
  • 2. 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
  • 3. 本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
  • 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
  • 5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
  • 6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
  • 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。

最新文档

评论

0/150

提交评论