Zagh-High Performance Concrete Repairs of Steel … · Ultra-High Performance Concrete for Steel...

Ultra-HighPerformanceConcreteforSteelBeamEndRepairs

NESMEA2017ConferenceOctober17-18,2017| Hartford,CT

ArashE.Zaghi,PhD,PE,SEAssociateProfessor,UniversityofConnecticut

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Outline

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IntroductiontotheProblem

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America’sCrumblingInfrastructureASCE Report Card

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Problem– CorrosionDamage§ 15%ofstructurallydeficientbridgesexperienceheavycorrosiondamage

§ $8.3billionisspentannuallytorepairorreplacehighwaybridgeswithcorrosion

§ Girderbridgesmainlysufferfromcorrosionatthegirderends

§ Themaincauseofcorrosiondamageisdeicingchemicals

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ImpactontheStructuralCapacity

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CurrentRepairMethod

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OverviewofProposedRepairMethod

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RepairConcept

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LoadTransferMechanism

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qDefinitionofUHPC(FHWA2011)•Materialconsistingofoptimizedgranularconstituents•MaximumW/Cratioof0.25• Compressivestrengthoflargerthan22ksi• Enhanceddurabilityviadiscontinuousporestructure

qSelfconsolidatingwithoutvibrationqConstituents:cement,silicafume,silicapowder,sand,water,admixtures,steelfibers

UltraHighPerformanceConcrete

Component MassFraction(%)

PremixPowder 86.6

Water 5.1

Premia 150(HRWR1) 0.7

Optima100(HRWR2) 0.5

Turbocast (Accelerator) 0.9

SteelFibers 6.2

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UltraHighPerformanceConcrete

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UltraHighPerformanceConcrete

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Phase1:LargeScaleGirderTests

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TestedthreeW21x55Girders1. Undamaged: Baselinetomeasurecapacity.

2. Damaged:Webandflangereductiontosimulatecorrosiondamage.

3. Repaired:SamesectionreductionasDamaged,butwithUHPCrepair.

Loading Point

Test Beam

Phase1:Large-ScaleGirderTests

24”

12”

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RepairedFlexuralYielding

DamagedLocalizedWebBuckling

UndamagedGlobalWebBuckling

Phase1:Large-ScaleGirderTests

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Phase1:Large-ScaleGirderTests

Undamaged

Damaged

Repaired

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Phase2:DevelopmentofDesignGuide

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Phase2:ProjectOverview

InvestigationofstudcapacityinUHPC

Experimentalstudyoffull-scaleplategirders

Highfidelityfiniteelementmodelingandparametricstudies

Developmentofdesignguideandstandarddetailsforfieldapplication

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BehaviorofshearstudsinUHPCisdifferentthaninregularconcrete.

Phase2:StudCapacity

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Phase2:StudCapacity

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Typicalfailureofpush-outSpecimens

Phase2:StudCapacity

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Phase2:StudCapacity

Slip (mm)

Forc

e (k

ip/s

tud)

0 1 2 3 4 5 60

10

20

30

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D = 1/2 in (UHPC)D = 5/8 in (UHPC)D = 3/4 in (UHPC)D = 1/2 in (RSC)

UHPC f'c (ksi)

P u /

Asc

Fu

15 18 21 24 27 300.9

0.95

1

1.05

1.1

1.15

1.2

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Phase2:DurabilityTesting

PriortocastingUHPC,thewebofthesteelsectionwassubmergedfor60hourstoachievesurfacerust.

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Phase2:DurabilityTesting

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Phase2:DurabilityTesting

Slip (mm)

Forc

e (k

ip/s

tud)

0 1 2 3 4 5 60

4

8

12

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BenchmarkCorrosion1Corrosion2

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Phase2:LargeScaleTesting§ 54”-Deepplategirders

§ Testdifferentrepairgeometries:

• FullHeight

• HalfHeight

§ SimulateLiveLoad

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Phase2:LargeScaleTesting

Full-HeightRepairHalf-HeightRepairDamagedGirder

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Phase2:LargeScaleTesting

Full-HeightRepairDamagedGirderIntactGirder

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Phase2:LargeScaleTestingFiniteElementResults

Forcevs.Displacement

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RepairDesignExample

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q Constructedin1965

q Foursimplysupportedspans

q Rolledsteelmulti-girdersuperstructure

PilotBridgeRepairDesign

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PilotBridgeRepairDesign

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CurrentCondition

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Demand(kip)

#of½”Studs

#of⅝”Studs

LoadDesign

LiveLoadOnly 116 9 6

StrengthI(AASHTO) 301 22 15

CapacityDesign

Bearing 640 48 32

Shear 568 42 28

DesignNumberofShearStuds

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PlanView CrossSection ElevationView

SampleRepairDesign

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ForstudsembeddedinUHPC(Cao2017)

ADT=67,000vehiclesperday

N=147millioncycles(50yeardesignlife)

Allowablestressrange(basedonfatigue)=7.9ksi

Stressrangedemandunderfatiguetruck=7.0ksi

FatigueControl

8 log ∆𝜏 + log𝑁 = 22.1131

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SummaryandConclusions

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§ AnovelmethodhasbeendevelopedtorehabilitategirderswithcorrosiondamagebyattachingUHPCpanelstothegirderusingshearstuds.

§ ThecompositeactionoftheUHPCrepairintroducedasecondaryloadpaththroughtheshearstudstotransferbearingandshearforces.

§ TheUHPCrepairdemonstratedtheabilitytorestorebearingcapacitylostduetocorrosionover5timesthatofadamagedgirder.

§ Thisrepairoffersflexibilityregardinglocationandnumberofstudstotacklecomplexgeometriesundervariouslimitstates

SummaryandConclusion

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§ TheConnecticutDepartmentofTransportation

§MikeCulmoofCMEAssociates§ConnecticutTransportationInstituteofUCONN§GraduateStudents:KevinZmetra,KevinMcMullen,DominicKruszewskiandAlexandraHain

§ RabihBarakat § Bradley Overturf § RichardHanley§ TimothyFields § Anne-Marie McDonnell § Mary Baker

Acknowledgements

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RepairforSteelBridgeGirderswithCorrosionDamageUtilizingUHPC

Thankyou!

UltraHighPerformanceConcreteWorkshopJune28,2017| Albany,NewYork

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PDHQuestions

Whatisthecurrentcommonmethodforrepairingdeterioratedsteelgirderendregions?(singleanswer)a) Applypost-tensioningalonglengthofgirdertensionflange,

b) Weldorboltnewsteelplatesoverdeterioratedsteel,

c) Encasetheend10’ofeachdeterioratedgirderinconventionalconcrete,

d) SelectivelyapplysteelstudsandUHPCinandneardeterioratedregions.

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PDHQuestions

WhataresomeadvantagesofusingUHPCtorepairdeterioratedsteelgirderendregions?(multipleanswer)

a) UHPCcaneasilyflowintotightspaces,

b) UHPCcancarryhighertensileandcompressivestressesthanconventionalconcrete,

c) UHPCcostslessthanconventionalconcrete,

d) UHPCisfarmoredurablethanconventionalconcrete.

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PDHQuestions

TheUHPCgirderendrepairoffersflexibilityregardinglocationandnumberofstudstotacklecomplexgeometriesundervariouslimitstates?(True/False)

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PDHQuestions

ThefullscalestructuraltestingoftheUHPCrepairsolutiondemonstratedthatthelostbearingandshearcapacitycanoftenberecoveredinaproperlydetailedUHPCrepair?(True/False)