Rafael Manzanarez：旧金山奥克兰海湾桥钢结构介绍

1TheNewSanFrancisco-OaklandBayBridgeSelf-AnchoredSuspensionSpanMarwanNader,PhD,P.E.–T.Y.LinInternationalRafaelManzanarez,P.E.,P.Eng–T.Y.LinInternationalCHONGQING,CHINAJune,20102PaulChinn,TheSanFranciscoChroniclePaulChinn,TheSanFranciscoChronicleAerialViewofBayBridge3ProjectLimitsProjectLimitsSanFrancisco-OaklandBayBridgeEastSpanProjectLimits4SFOBBSpanHistory•OpenedNovember12,1936for$77m•3years,4,months,&3daystoconstruct•Longestvehicularbridgeintheworldwiththelargesttunnelintheworld5ProjectSite&SeismicitySanAndreasFault(8.1M)HaywardFault(7.5M)6DamagetoBayBridgeEastSpanDuringthe1989LomaPrietaEarthquake(7.1M)7NewEastBayBridgeSpan8SkywaySuperstructureFirstPrecastSegmentalBridgeinCaliforniaFirstPrecastSegmentalBridgeinCaliforniaFirstPrecastSegmentalBridgeinCalifornia9SkywayBatteredPiles10HingeADetailsFuse11HingeADetails12SelfAnchoredSuspensionBridge13SelfAnchoredSuspensionBridge14TowerLayout–LookingEast15TowerShaftDetails16TowerShearLink17T1TowerFoundationvPileCap–6.5mdeepx22.5mwidex26mlongvSteelMomentResistingFrame(SMRF)EncasedinConcretevConnecttopilesbysheartabsv13–60mlong2.5mdiametervUpper30m–SteelShellPilesfilledwithConcretevLower30m–“rocksocket”embedintobedrockv424–7.5mlonganchorrods(388-75mmøand36-100mmø)v150–0.9mlongdowels(150mmø)vPileCap–6.5mdeepx22.5mwidex26mlongvSteelMomentResistingFrame(SMRF)EncasedinConcretevConnecttopilesbysheartabsv13–60mlong2.5mdiametervUpper30m–SteelShellPilesfilledwithConcretevLower30m–“rocksocket”embedintobedrockv424–7.5mlonganchorrods(388-75mmøand36-100mmø)v150–0.9mlongdowels(150mmø)18TypicalCrossSection19TypicalFloorbeamSection–“W”Line20DesignoftheOrthotropicDeckOrthotropicdeckdesignrequires:•Selectionofadeckconfiguration•Transversedistributionofwheelloads•Servicestressesanddeflections•Globalloadeffects21DesignoftheOrthotropicDeckClosedribsselected•Compactness•Torsionalrigidity•Simplicity.22DesignoftheOrthotropicDeckSelectedDetails•Bottomcutout:out-of-planedeflection•Transitionwelds:CJPwithgroundrunoffforstrengthandfatigueresistance•Ribwebtofloorbeam:lightPJPforshear•Decktofloorbeam:filletweldforshear•Ribtodeck:80%PJPbasedonAASHTOLRFDcode23CodeCriteriaforSteelOrthotropicDecksCaliforniaBridgeDesignSpecifications(BDS),Section10.41•Transverseliveloadstressindeckplatenottoexceed30ksi(200Mpa)•Longitudinalribstressesduetocombinedlocalandglobaleffectsdonotexceed125%ofallowable•Deflectionofdeckplatebetweenribs1/300ofribwebspacing•Deflectionoflongitudinalribs1/500ofspanAASHTOLRFD,Sections6.6.1.2.3,9.8.3•FatiguecategoryCatribtofloorbeamweldsandplates(35Mpa)•FatiguecategoryEfordeckplateatconnectiontofloorbeamweb(16Mpa)•Deflectionofdeckplatebetweenribs1/300ofribspacing•Deflectionoflongitudinalribs1/1000ofspan•Relativedeflectionbetweenadjacentribs2.5mm24RibandDeckDeflections•MaximumribdeflectionbyPelikan-Esslingermethod•2mmatmidspan,or1/2500ofspan•MeetsAASHTOrequirementof1/1000•ResultswereconfirmedindetailedFEM25RibandDeckDeflectionsDeckplatedeflection(AISCManual,eq.6.5):wm=(5/6)(1/384)(pa4/EI)Deflectionratioexpressedas:(a/wm)=(38.4)(E/p)(tP/a)3ForSF-OBB,deflectionis1/1890ofwebspacing26FatigueDesignLoad-Induced•Defineddetailtypes•Stressescanbedeterminedclearlybyanalysis•FatiguecategoriescontroldesignDistortion-Induced•Distortionandstressdistributionsaresubtle•Codescontrolfatigue•Limitsondeckdeflectionsandgeometry27FatigueDesignDistortion-Induced28FatigueDesignDistortion-Induced•AffectedweldsPJP•Actualstressesdifficulttodetermineanalytically•Experimentsshowcrackingavoided•Ribwebssufficientlyflexiblewithrespecttodeckplatewithoverlays•FlexibilityratiospecifiedAASHTO9.8.3.7.229FatigueDesignDistortion-Induced•DeflectionratiospecifiedAASHTO9.8.3•FatiguecategoryCforcombinedstressesAASHTOLRFD,Section6.6.1.2.330CombinedIn-planeandOut-of-planeStressesSpecialinterestinfloorbeamsabovecutouts.Effectsconsidered:•Compressionoftransversebeamaspartofglobaltransversetruss•GlobalInteractionshearsbetweendeckandbeamweb•Localbendingoftransversebeam•Localeffectsofdirectwheelpressureandribreactionstobeam•RibrotationscausingtwistingofbeamwebFatigueDesign31Localmodelcheckeddesignofgirdersandorthotropicdecks30-metersegmentofonegirderandhalfofonecrossbeamFiniteElementModelSubmodelingusedtodevelopfinemeshesinareasofinterest•orthotropicdeckribs•floorbeamwebcutouts32FiniteElementModelStressResults:Floorbeamsabovecutouts•GlobalCompression•GlobalShearInteractions•LocalShearInteractions•LocalWheelEffects•Floorbeamwebout-of-planedeflections33FiniteElementModelPracticalLimitationsonAnalyticalResults•HAZsubjecttotensilestressestoyieldstrength•Linearsuperpositionofstressnotvalidinplasticizedareas•Analyticalresultsnotaccurateincriticallocations34FiniteElementModelPracticalLimitationsonAnalyticalResults•Effectsofpermanentcompressivestressonfatigueresistanceunclear•Fatiguecracksfoundinorthotropicdecksinpredominantcompressionoftwiceliveloadstress•CurrentAASHTOLRFDSpecificationspermitdisregardingfatigueinsuchelements35FiniteElementModelPracticalLimitationsonAnalyticalResults•Theoreticalanalysisprovidesusefulpictureofnominalstresse