design, construction and testing of the neal bridge in

Design, Construction and Testing of the

Neal Bridge in Pittsfield, Maine

Final Report October 2009

A Publication from the Maine Department of Transportation’s Research Division

Technical Report Documentation Page 1. Report No. 09-07 2. 3. Recipient’s Accession No.

4. Title and Subtitle 5. Report Date October 2009

6.

Design, Construction & Testing of the Neal Bridge in Pittsfield Maine – Final Report

7. Author(s) 8. Performing Organization Report No. Edwin Nagy, PE, Keenan Goslin, Dan Bannon Melissa Landon, PhD, Larry Parent, PE

09-043

9. Performing Organization Name and Address 10. Project/Task/Work Unit No.

11. Contract © or Grant (G) No.

The AEWC Center University of Maine 5793 AEWC Center Orono, ME 04469

12. Sponsoring Organization Name and Address 13. Type of Report and Period Covered

14. Sponsoring Agency Code

Maine DOT 16 State House Station Augusta, ME 04333-0016

15. Supplementary Notes

16. Abstract (Limit 200 words)

Highway bridges in the US are quickly becoming deficient due to increasing traffic volumes, rapid deterioration, extended service life, and increasing load requirements. Repair or replacement of deficient structures is expensive, time and labor intensive, and typically results in lengthy road closures during construction. Researchers at the University of Maine’s AEWC Advanced Structures & Composites Center have developed a lightweight, corrosion resistant system for short to medium span bridge construction using FRP composite arch tubes that act as reinforcement and formwork for cast-in-place concrete. They are lightweight, easily transportable, rapidly deployable and do not require the heavy equipment or large crews needed to handle the weight of traditional construction materials. This report describes the design, construction and testing of the Neal Bridge in Pittsfield Maine, the first FRP arch bridge.

17. Document Analysis/Descriptors 18. Availability Statement FRP composite arch

19. Security Class (this report) 20. Security Class (this page) 21. No. of Pages 22. Price 55

AEWC Advanced Structures & Composites Center

Design,Construction&TestingOftheNealBridge,Pittsfield,Maine

AEWCReportProject622

October19,2009

Submittedby:

EdwinNagy,PEKeenanGoslinDanBannon MelissaLandon,PhDLarryParent,PE

AEWCReport09‐43Project622

TableofContents

1 Introduction...................................................................................................................... 1

2 BridgeFiles ....................................................................................................................... 12.1 General................................................................................................................................... 12.2 ComponentsofBridgeRecords ............................................................................................... 1

2.2.1 Plans ........................................................................................................................................12.2.2 Specifications.........................................................................................................................102.2.3 Correspondence–Thissectionnotincluded. .......................................................................142.2.4 Photographs–Thissectionnotincluded. .............................................................................142.2.5 MaterialsandTests ...............................................................................................................142.2.6 MaintenanceandRepairHistory–Thissectionnotincluded. ..............................................322.2.7 CoatingHistory–Thissectionnotincluded. .........................................................................322.2.8 AccidentRecords–Thissectionnotincluded. ......................................................................322.2.9 Posting–Thissectionnotincluded. ......................................................................................322.2.10 PermitLoads–Thissectionnotincluded. ...........................................................................322.2.11 FloodData–Thissectionnotincluded................................................................................322.2.12 TrafficData–Thissectionnotincluded. .............................................................................322.2.13 InspectionHistory–Thissectionnotincluded....................................................................322.2.14 InspectionRequirements ....................................................................................................322.2.15 StructureInventoryandAppraisalSheets–Thissectionnotincluded. ..............................362.2.16 InventoriesandInspections–Thissectionnotincluded.....................................................362.2.17 RatingRecords–Thissectionnotincluded .........................................................................36

2.3 InventoryData–Thissectionnotincluded............................................................................ 362.4 InspectionData–Thissectionnotincluded .......................................................................... 362.5 ConditionandLoadRatingData............................................................................................ 36

2.5.1 General ..................................................................................................................................362.5.2 RevisedConditionandLoadRatingData...............................................................................36

2.6 LocalRequirements–Thissectionnotincluded .................................................................... 402.7 References............................................................................................................................ 41

AppendixA.MaterialDataSheets ....................................................................................... 42

AppendixB.LessonsLearned ............................................................................................... 47

AppendixC.ConstructionoftheNealBridge........................................................................ 50

AppendixD.InspectionNotebook–HeadwallMeasurements ............................................. 53


AEWCAdvancedStructures&CompositesCenter Page1of55www.aewc.umaine.edu

1 IntroductionThis report isorganizedusingthesamesectionheadingsas theManual forBridgeEvaluation[AASHTO 2008]. Section 2 contains relevant information for the bridge files. Although theManualcontainsSections3through8,theyarenotreferencedhere.

2 BridgeFiles2.1 GeneralThisreportcompilesthedatafromAEWCforthestructural testinganddesignworkdonefortheNealBridgeinPittsfield,Maine.ItfollowsthesectionsoftheManualforBridgeEvaluationthatareapplicabletoAEWC’sresponsibilities.Thisincludesplans,testdata,anddesignofarchstructuralmembers,deckingandtheheadwall.ThosesectionswheretheworkwascompletedordesignedbytheMaineDOTarenotincludedinthisreport.

2.2 ComponentsofBridgeRecordsSeethefollowingsectionsforthecomponentsincludedinthebridgerecords.

2.2.1 PlansPlansincludedinthisreportaredesigndrawingsprovidedbyAEWC.Theydonotincludeshopdrawingsbycontractororas‐builtdrawings.



2.2.2 SpecificationsSpecificationsareincludedhereforthosesectionsthatAEWCwasresponsiblefor.Theyincludetheexpansiveself‐consolidatingconcretemixusedtofillthearchesandthecorrugatedFRPdeckingmaterial.

SPECIAL PROVISION SECTION 502

STRUCTURAL CONCRETE (Carbon Fiber Tube Fill)

Description:Thisworkshallconsistoffurnishingandplacingaportlandcementconcretefillasshownontheplans,orasdirectedbytheResident.ExceptasotherwisespecifiedinthisSpecialProvision,allworkshallbeinconformitywiththeapplicableprovisionsofSection502‐StructuralConcrete

MATERIALS Concrete:Concreteshallbeasspecifiedbelow.

Table1:ArchFillConcreteMix

ITEM WEIGHTPERYD3 NOTESWATER 378.2LBS TYPEIICEMENT 755.3LBS 3/8”COURSEAGGREGATE 1263.3LBS ShallsatisfySection703.02SANDFINEAGGREGATE 1391.7LBS ADVA530 98.2floz. 1/4Addedtoinitialmixwith

Remainder added on site as neededtoobtain10”slump

DARATARD17 22.7floz. AddedtoinitialmixCONEX 113.3LBS AddedtoinitialmixEntrainedAir 0%to3% Targetshallbe0%Min.CompressiveStrength 5500psi(38MPa) At28days

CONSTRUCTION REQUIREMENTS

PlacementofConcrete:Theconcretemixshallbeplacedinacontinuousplacementoperation.

A.GeneralConcreteshallnotbeplaceduntilarcheshavebeenplumbedandcheckedandapprovedbytheResident.Themethodandsequenceofplacingtheconcreteshallbeapprovedbeforeanyconcreteisplaced.Allconcreteshallbeplacedbeforeithastakenitsinitialsetand,inanycase,asspecifiedinSection502.0701.Concreteshallbeplacedinsuchamannerastoavoidseparationandsegregation.Asufficientnumberofworkersfortheproperhandlingoftheconcreteisrequired.Careshallbetakentopreventmortarfromspatteringontubemembersandsheathing.Followingtheplacingoftheconcrete,allexposedsurfacesshallbethoroughlycleanedasrequired,withcarenottoinjureanysurfaces.



B.PumpTruckPumptruckwillbetheonlymethodofconcreteplacementallowed.Payment,forPumptruckwithoperator,willbeincidentaltothisitem.

C. Vibrating shall not be allowed when placing concrete into the composite arches. The mix is self-consolidating and separation will occur if vibrated.

Method of MeasurementStructuralconcrete,CarbonFiberTubeFill,satisfactorilyplacedandaccepted,willbemeasuredforpaymentbythecubicyard,inaccordancewiththedimensionsshownontheplans.

BasisofPaymentTheacceptedquantityofStructuralConcrete,CarbonFiberTubeFill,willbepaidforbythecubicyardprice.

Payment will be made under: Pay Item Pay Unit 502.38StructuralConcrete,ArchType CubicYard

SPECIALPROVISION

SECTION509.60

FRPPanels(Sheathing)

Description. ThisworkshallconsistofthefurnishingtheFRPpanelsfortheCarbonFiberTubeArchinaccordancewiththeplans,specificationsandinconformitywithinstructionssuppliedbythemanufacturer.

Materials. Thematerialsincludethepanels,andhardware.

FRPPanels

FiberglassReinforcedPlastic(FRP)panelsandthefastenersrequiredtosecurethepanels.

PanelsshallbeTuffSpan®8.0RoofDeckSeries700oranapprovedequalthatconformstothesespecifications.

ResinType

Resinshallbepremiumgrade,chemicallyresistantVinylEster.

GlassReinforcement

Reinforcementshallbestraightandcontinuous,withfibersorientedintwodirections(alongthelengthandwidthofunit).Glasscontentshallbeaminimumof47%byweight.



FlameSpread

PanelsshallhaveaClass1flamespreadrating(25orlesswhentestedinaccordancewithASTME‐84),shallbelistedbyULandbeartheULlabel.

UVResistance

PanelmaterialshallbemadefromaUVstabilizedresinmodifiedwithacrylicmonomers.AdditionalUVresistanceshallcomefromsurfacingmatsandasurfacecoatingofanacrylicpolymer.

Color

WhiteorothercolorapprovedbyOwner.

Lengths

Use16’‐0”minimumlengths.Panelsshallnotbecut;lappanelstofitlength.Contractoroptiontohavefullwidth(~45’‐0”)panelssuppliedanddelivered.

StructuralFastenerswithWashers

Fastenersshallbestainlesssteel(300/316series),spacedandinstalledpermanufacturer'srecommendations.

SideLapFasteners

SB2grommets,installedpermanufacturer'sspecifications.

StructuralParametersPerformanceCriteria

Panelsshallmeettheperformancecriteriadescribedbelowforthespansindicatedonthedrawings(2’‐0”).Productcompliancewithcriteriashallbeestablishedbyfull‐scaletestsforpositiveandnegativeloadingperASTMTestMethodE‐72.

Loads

Deckingshallmeetthefollowinginsingleormultiplelayers.Dead(includessoil): 550psfLive(truck&lane): 2000psf

AllowableDeflections

Decking:L/240

FactorsofSafety

Decking

Liveloads:FOS=2.5



Execution

HandlingandStorage

Handling

ProtectthesurfaceofFRPpanelsfromcuts,scratches,gouges,abrasions,andimpacts.Donotusewireslingsunlessmaterialisfullyprotected.UsespreaderbarswhenliftingFRP.

Storage

Storepanelsundercover.Keeppanelsdry.Stackpanelsoffgroundwithoneendelevatedtopermitdrainingofincidentalwaterthatcanpermanentlystainpanels.

InstallationofFRPPanels

3.02.01InstallationInstructions

Installermustfollowmanufacturer'sinstallationinstructionsandtheshopdrawings.

PilotHolesinPanels

Pilotholesmustbedrilledinpanelsforallfasteners.Drillholeswithasharpcarbidetippedsheeter'sbit.Pilotholesinpanelsshouldbesizedsothatthefastenerthreadsjustcleartheedgesofthehole.

PilotHolesinCarbonFiberTubes

PilotholesmustbedrilledinsupportsforTypeAandBstainlesssteelself‐tappingatdrillspeedsof500RPMorless.Pilotholesincarbonfibertubesshallbesizedappropriatelyforfasteners.

EndLaps

Endlapsforpanelsshalloccuratsupportsandbe6inchesminimum.

ApprovedVendors:

EnduroComposites

16602CentralGreenBlvd.

Houston,TX77032

(713)358‐4000–Phone

(713)358‐4100–Fax

OrEqual,approvedbyUniversityofMaine



Submittals ShopDrawingssubmittedforreviewinaccordancewithSection105.7oftheStandardSpecifications.

Method of Measurement TheFRPPanelswillbemeasuredasonelumpsumpriceinaccordancewiththeplansandspecifications.

Basis of Payment TheacceptedFRPpanelswillbepaidforatthecontractlumpsumprice,completeandinplace.

Paymentwillbemadeunder:509.60FRPPanels(Sheathing)LumpSum

Othermaterialswerecalledoutonthedrawingsforitemsontheheadwall.Seethedrawingsforthisinformationonthesematerials.

2.2.3 Correspondence–Thissectionnotincluded.

2.2.4 Photographs–Thissectionnotincluded.

2.2.5 MaterialsandTestsThissectiongivestheresultsofmaterialandstructuralleveltestingforthematerialsusedintheNealBridgeinPittsfield,Maine.Coupontensiontestingofthelaminateusedinthearchshelliscoveredaswellaspreliminaryconcretemixtestingconductedinthedevelopmentofthetechnology.MaterialdatasheetsareattachedinAppendixAofthisreport.

2.2.5.1 MaterialTestData

2.2.5.1.1 CouponTestingMechanicaltestingwasperformedinaccordancewithASTMD3039onspecimensfortensilestiffnessandwithmodifiednotchedspecimensfortensilestrength.CompressivestrengthisequatedtothetensilestrengthbecauselocalbucklingoftheFRPispreventedduetotheexpansiveconcretefillingthetubes.AcomprehensiveanalysiswascarriedoutusingClassicalLaminationTheorytovalidatetheresultsofthesetests.Resultsofcoupontestswereingoodagreementwiththeoreticallypredictedvalues.

ThetestmethodASTMD3039determinesthein‐planetensilepropertiesofpolymermatrixcompositematerialsreinforcedbyhigh‐modulusfibers.ASTMD3039wasdesignedtoproducetensilepropertydataformaterialspecifications,researchanddevelopment,qualityassurance,andstructuraldesignandanalysis.TheresultsofthetestingaregiveninTable2.



Table2:ASTMD3039TestResults

Specimen TestedMOE(ksi)

Poisson'sRatio

Strength(kip/inwidth)

Strength(ksi)

Thickness(in)

PredictedMOE(ksi)

PercentDifference(MOE)

1 5872.8 0.477 2.831 28.26 0.1002 6722.7 12.64%3 6558.4 0.435 3.066 30.46 0.1007 6722.7 2.44%4 5956.1 0.473 2.698 27.30 0.0988 6722.7 11.40%5 6473.9 0.433 2.996 29.81 0.1005 6722.7 3.70%6 6373.0 0.352 2.773 27.55 0.1007 6722.7 5.20%7 6650.5 0.448 2.913 28.29 0.1030 6722.7 1.07%8 5938.3 0.411 2.572 25.63 0.1003 6722.7 11.67%9 5739.1 0.404 2.625 27.98 0.0938 6722.7 14.63%

Mean 6195.3 0.429 2.809 28.161 0.0998 7.85%

Std.Dev 355.3 0.04 0.176 1.490 0.0027 COV 5.73% 9.5% 6.2% 5.3% 2.7%

Inordertoobtainthelaboratoryspecimens,flatCFRPpanelsweremanufacturedusingtheVacuumAssistedResinTransferMolding(VARTM)process.Panelswerepreparedbydrawinglengthsofbraidedfabricoverthin,rectangularmolds,creatingverywide,thintubes.Panelsweretheninfusedwithresinandallowedtocureundercontrolledenvironmentalconditions.

Theangleanddiameterofbraidedtextilescanbeadjustedbyapplyingforceinthelongitudinaldirectiontothedryfabric.Materialsusedwere24KtowT‐700carbonfibersbraidedatapproximately[ 45.0°]and24‐inch(300mm)diameterandvinylesterresin.Thefabricwastensionedduringmanufacturingtoachieveauseangleforthecarbonfiberofapproximately20degreesandanouterdiameterofapproximately11.75inches.Fromthesepanels,specimenswerecutusingacomputercontrolledwater‐abrasivecuttingmachine.

Initially,tensiontestingwasperformedinaccordancewithASTMD3039tocharacterizeboththeelasticandthestrengthpropertiesofthebraidedcomposite.ASTMD‐3039,however,yieldedultimatetensilestrengthvaluesanaverageof74%belowpredictedvalues.Thisisduetothefreeedgeeffectsoffibersinthecoupon.Forthisreason,othermethodswereinvestigatedtodeterminethetensilestrengthofthebraidedcompositematerial.Thenotchedspecimentensiontest(Figure1)wasdevelopedtomoreeffectivelytestthestrengthparameters.A“bowtie”shapedcouponwaschosenbecausefibercontinuityismaintainedfromendtoendofthespecimen.Thiseliminatedfreeedgeeffectsandtookadvantageofthetensilestrengthofacompositematerialbeingafiberdominatedproperty(onlythecontinuousfiberscontributetostrengthinmeasuringgagesectionarea).ResultsofthecoupontensilestrengthtestingareshowninTable3.



Figure1.NotchedTensionSpecimen

Table3:ResultsoftheNotchedSpecimenTensionTest

MOE(ksi) 6195.3

Specimen Width(in)

Thickness(in)

Area(in^2)

MaxLoad(lb)

Ult.Strain(in/in)

MeasuredStrength(kip/in)

Strength(ksi)

CLTPredictedStrength(ksi)

PercentDifferenceTensileStrength

1 0.8315 0.0970 0.0807 8027.4 0.016065 9.654119 99.527 121.661 18.19%

2 0.8205 0.0990 0.0812 8658.363 0.017205 10.55254 106.5914 121.661 12.39%

3 0.8110 0.0985 0.0799 9071.571 0.01833 11.18566 113.56 121.661 6.66%

4 0.8520 0.1000 0.0852 8994.823 0.017041 10.5573 105.573 121.661 13.22%

6 0.8145 0.0980 0.0798 9622.614 0.019459 11.81414 120.5524 121.661 0.91%

7 0.8130 0.0985 0.0801 8880.889 0.017901 10.9236 110.8995 121.661 8.85%

8 0.8275 0.0990 0.0819 8190.996 0.016139 9.898485 99.98469 121.661 17.82%

9 0.8230 0.1020 0.0839 8909.703 0.017132 10.82588 106.1361 121.661 12.76%

Mean 0.8241 0.0990 0.0816 8794.5449 0.0174 10.6765 107.8530

STD.DEV. 0.0133 0.0015 0.0020 506.3311 0.0011 0.6884 7.0112

COV 1.62% 1.50% 2.45% 5.76% 6.50% 6.45% 6.50%

2.2.5.1.2 ConcreteTestingThecompressivestrengthofcylindricalconcretespecimenswastestedinaccordancewithASTMC39‐05.Thistestrequiresacompressiveaxialloadtobeappliedtomoldedcylindersorcoresuntilfailureoccurs.Thecompressivestrengthoftheconcretespecimeniscalculatedbydividingthemaximumloadattainedduringthetestbythecross‐sectionalareaofthespecimen.Table4showstheresultsoftestingcylindersmadewith15%Conexand1%measuredair.

Table4:ArchFillConcreteTesting

CylinderLabel

Length(in)

Diameter(in)

Cross‐SectionalArea(in2)

MaxLoad(lbs)

CompressiveStrength(psi)

AverageComp.Strength(psi)

a 8 4 12.57 71190 5665.0

b 8 4 12.57 70620 5620.0c 8 4 12.57 73640 5860.0

5715.0

Continuous

Tows

Discontinuous

Tows

GripSection

GageSection



2.2.5.1.3 BeamTestingConcrete‐filledfiberreinforcedpolymer(FRP)beamspecimensweretestedusingafour‐pointbendingapparatus.Simplesupportswereprovidedateachendofthespecimentoprovidefreerotationandloadwasappliedatthebeamthirdpoints.Loadwasappliedtothespecimensusinga110‐kipservo‐hydraulicactuator.Theactuatorismountedbeneaththefloorandloadisappliedbypullingdownwardontheyokeusingahigh‐strengthDYWIDAGThreadbar®.A110‐kiploadcellwasinstalledin‐linetomonitorappliedload.AsketchofthetestsetupisshowninFigure2.ThebeamsectionwasofthesameconstructionastheNealBridgearchmembers.

Figure2:BeamTestFixtures

Threebeamsweretestedtofailureunderstaticload.Theaveragefailureloadforthesethreebeamswas54.3kips.Followingthis,threebeamswerefatiguedforonemillioncycles.Thefirstofthese,fatiguebeam01,wastestedmonotonicallyovera28kiploadrange.ThesecondtwoweretestedinbothpositiveandnegativebendingtoaloadthatwaspredictedtojustachievethemaximumACIrecommendedfatiguestrainforconcrete(0.0015).Thetestingwasperformedsequentially:100,000cyclesinpositivebendingfollowedby100,00innegativeandthenbacktopositive.AsummaryoftheresultsforthefatiguebeamtestingisgiveninTable4.Theaveragestrengthofthefatiguesspecimenswas54.3kips,indicatingthattherewasnosignificantlossofstrengthduetothefatiguing.Infatiguebeam01,asmallamountofresidualdeformationwasobserved,whichincreasedthroughoutthetestasaccumulationofdamageoccurred.Intheremainingtwobeams,noresidualdamagewasseen.



Table5:BeamTestingResults

Specimen LoadingDirection LoadRange FailureLoad FailureMomentFatigueBeam01 PositiveOnly +3.1kto+31k >55k* ‐‐‐FatigueBeam02 Positive +2.05kto+20.5k 53.0k 1272in‐k

Negative +2.05kto‐20.5k ‐‐‐ ‐‐‐Positive +2.05kto+20.5k ‐‐‐ ‐‐‐FatigueBeam03Negative +2.05kto‐20.5k 54.6k 1966in‐k

*Beamcouldnotbebrokenwithequipmentasset,loadassumedtobe55k(actuatorcapacity).

2.2.5.1.4 ArchTestingAnalysisandtestingwasconductedonarchessimilartotheNealBridgearchesbutwithagrossgeometry(spanandheight)approximately65%asbig,havingatestedspanof21’‐2½”.Staticandfatiguetestingwereconducted.Adescriptionofthetestsetup,model,testingprocedure,andresultsaregivenhere.

Anonlinearfiniteelementmodelwasusedtopredicttheresponseofthearchtestspecimens.Byusingsymmetry,themodelwasreducedtoahalfarch.Twodifferentboundaryconditionsweremodeledatthecrownwherethearchmodelwascut.Thesetwocasesarerepresentativeofthetwodamagestatesofthearchspecimen.Priortopeakloading(Figure3A),thecrownbehavesasa“fixedroller”;thatis,rotationandhorizontaltranslationarefixed,andverticaltranslationisunconstrained.AftertheFRPhasruptured,thearchformsahingeatthecrown.Thisconditionmayconservativelybemodeledasa“pinnedroller”;rotationandtranslationintheverticaldirectionareallowed,whilehorizontaltranslationisfixed(Figure3B).Thisisaconservativelowerboundasthehingeretainssomeamountofrotationalstiffnessaftersustainingdamage.Theactualdamagedconditionishighlyvariableandcannotadequatelybemodeledusingthissimplefiniteelementmodel.

Figure3:StructuralModelofArchTest

ThecrackingmomentinthearchesisgreatlyunderpredictedwhenusingtheequationgivenbyACI[ACI318‐08]formodulusofrupture.Thisisattributedtotheunderpredictionofthe



concrete’stensilestrengthinthisresearch.Theunderpredictionofconcretetensilestrengthhasseveraleffectsonthepredictedarchbehavior,includinganunderpredictedlinear‐elasticregionandanunderpredictedstiffnessthroughouttheflexuralresponse.Thefollowingalternateequationwasusedfortheconcretemodulusofruptureinpredictingthebehaviorofthearchspecimens.Thecoefficientisbasedontheexperimentalresults.

�

fcr = 17.5 fc' Equation1

Inthisequation,f’cisthe28‐dayconcretecompressivestrength;thefactorrelatingtolightweightconcretehasbeentakenas1.0forthepurposesofthiswork.Theproposedequationrepresentsa2.3:1increaseoverthemodulusofrupturepredictedusingtheACI318equation.ThemomentcurvaturemodeldevelopedbyBurgueño[1999]accuratelypredictsboththemoment‐curvatureresponseandthemomentcapacityoftheconcrete‐filledFRPbeamspecimensoncethisadjustmentismade.

Allspecimenstestedwererelativelylightlyreinforced.The11.8indiametertubeshadanaveragewallthicknessof0.10in,resultinginareinforcementratio,ρ=3.4%.Duetothe

minimalreinforcement,allspecimensfailedduetotensileruptureoftheFRPreinforcingshell.Thisfailuremodewasconsistentwithmodelpredictionsinallcases.

Figure4:Load‐DeflectionofStaticArchTesting

Table6,below,showsresultsforthestaticandfatiguearchtesting.Thepeakloadatinitialfiberruptureontheundersideofthecrownisgivenaswellasthecorrespondingmomentforthatloadingregionatthecrown.



Table6:ArchTestingResults

Failure Load (kip) COV

Corresponding Moment at

Crown (kip-in)

Number of Specimens

Percent Difference

from Predicted Static Arch 1 74.7 ----- 1440 1 Static Arch 2 71.0 ----- 1370 1 Static Arch 3 70.9 ----- 1370 1 Static Arch 4 71.2 ----- 1380 1 Static Average 72.0 2.6% 1390 4 4.14% Predicted 69.0 ----- ----- ----- ----- Fatigue 1 75.4 ----- 1460 1 Fatigue 2 62.3 ----- 1210 1

Aftertheinitialfailure,thearchmembersretainedtheirstabilityaswellasasignificantamountoftheirinitialloadcarryingcapacity.Thepost‐peakbehaviorofthearchmemberswasstudiedbysubjectingthespecimenstoasecondarystatictestuntilcompletefailurewasforced.Duringthesecondarytests,thearchmemberscontinuedtoshowductilityandenergyabsorption.

2.2.5.2 FullScaleBridgeLoadTestingDiagnosticloadtestingoftheNealBridgewasconductedtoincreasetheunderstandingofthestructuralperformanceofthearchesandtheloaddistributionthroughthesoilandtocalibratetheanalyticalloadratingofthestructure.Digitaldataacquisitionwasusedtoallowfor26loadcasesandalargenumberofinstruments.Adynamictestwasalsoconductedfollowingthestatictesting.Tworoughly66,500pounddoublerearaxledumptruckswereusedtoloadthebridgeforboththestaticanddynamictests.Adescriptionofthetestsconducted,theirresults,andthecorrespondingloadratingisgiveninthissection.Strain,deflectionusinglinearpotentiometerdeflectiongages,andPONTOS3Dimagecorrelationfordeflectionwereusedtocollectstructuralperformancedata.

2.2.5.2.1 LiveLoadTwodumptrucksprovidedbythebridgemaintenancedivisionoftheMaineDOTwereusedastheliveloadforthistesting.Theyweretandemrearaxledumptrucksloadedwithsoil.AxleweightsweretakenbytheMaineStatePolice.Figure5givestheaverageaxleweightsforthetwotrucks.ThetrucksthemselvesareshowninFigure6.



Figure5:AverageLiveLoadofTwoTestTrucks

Figure6:TrucksUsedinTestingofNealBridge

2.2.5.2.2 TestSetupThefirstsetoftestswasconductedwithtwofullyloadeddumptruckssidebyside,4’‐0”apartmeasuredfromtheoutsidesurfaceoftheoutersetofreartires.Thetruckswerefacingnorth.Strain,deflection,andsoilpressuredatawerecollectedforthisseriesoftests.Deflectiondatawerecollectedusinglinearpotentiometerdeflectiongagesatdiscretepointsalongthelengthofthe10tharchfromthedownstreamfaceofthebridge.DeflectiondatawerealsocollectedusedPONTOS3Ddigitalimagecorrelationforaregionofarches10and11atthecrown.ThepositionofthefrontaxleofthetrucksisgiveninTable7andillustratedinFigure7.

Table7:FrontAxlePositionfor1stSeriesofStaticTests

TruckPositionSidebyside 1 2 3 4 5 6 7 8 9

FrontAxleLocation(inchesfrombridgecenterline) 150 210 270 330 390 ‐31 30 90 150



Figure7:Side‐by‐sidetrucklocationsduringloadtesting(seeTable7)

Thesecondseriesoftestsusedbothdumptrucksinthesamedownstreamlane,bothfacingsouth.Thetruckswerecenteredoverarch10,4’‐0”downstreamofcenterline.ThepositionsofthefrontaxleoftheleadtruckaregiveninTable8.Thefrontaxleofthesecondtruckwas41’‐0”behindthefrontaxleofthefirsttruck.

Table8:FrontAxlePositionforLeadTruckduring2ndSeriesofStaticTests

TruckPositionTandem 1 2 3 4 5 6 7 8

182 122 62 2 ‐58 ‐118 ‐178 ‐2389 10 11 12 13 14 15 16

FrontAxleLocationofLeadTruck(inchesfromcenterline) ‐298 ‐358 ‐418 ‐478 ‐538 ‐598 ‐658 ‐718

Figure8:Tandemtrucklocationsduringloadtesting(seeTable8)



Thethirdtestwasadynamictestwiththetruckstravelingatthespeedlimitof45mphacrossthebridgewithheadwayofapproximately10feet.Thetruckswerecenteredinthedownstreamlaneheadingnorth.PONTOSwasunabletocollectdataforthistest.

2.2.5.2.3 Instrumentation Strain,deflection,andsoilpressuredatawerecollectedcontinuouslyduringthestaticanddynamictests.Thefourth,sixth,eighth,andtentharchesfromthedownstreamsideofthebridgewereinstrumentedwithstraingages.Deflectiongageswereplacedonarch10tomeasureperpendiculardeflectionsofthearches.Soilpressuregageswereembeddedinthesoilabovearch10.PhotosofthedeflectiongagescanbeseeninFigure9.PONTOSwasusedtocollectdeflectiondataforthecenter1meterofspanofarches10and11aswellasthedeckingspanningbetweenthosearches.

Figure9:LocationofDeflectionGages:(A)Postcarryingdeflectiongageatshoulder(B)Sectionofarch10monitoredwithdigitalimagecorrelation(C)Postfordeflectiongageatcrown(D)Postcarryingdeflectiongagenearfoundation(E)Locationofdeflectiongageatfooting

Straingageswereinstalledonarches4,6,8and10.Strainwasrecordedon3sectionsofarches8and10andon1sectionofarches4and6.Threelongitudinalstraingageswereplacedateachlocation.Atthebaseofeacharchoneadditionalstraingagewasplacedinthehoopdirection(oppositeEinFigure6).Thethreelocationsonthearchesthatwereinstrumentedincludethecrown,theshoulder85incheshorizontallyfromthecrownandthetopofthecurb

E

D

C B

A



orfoundationconnectionofthearches.Figure11showsthegloballocationofthestrainandpressuregages.ThestraingagelocationateacharchsectionisshowninFigure12.

2.2.5.2.4 MeasurementofSoilPressure

Tenvibratingwiretotalearthpressurecells(TPCs)wereinstalledalongtheoutsideofarch10withinthebackfilltoassesstheinteractionbetweenthestructuralbackfillandthearchduringloading(Figure11).The9”pressurepaddiameterTPCs(Figure10)weremanufacturedbyRoctesttohaveacapacityof4180psf(200kPa).Ateachlocation,aTPCwasinstalledparalleltothegroundsurface(horizontal)withtheedgebetween3”and6”fromthefaceofthebridgedecking.HorizontalTPCswereusedtodeterminetheverticalstressdistributionbesidethearches.Inalllocationsexceptthecenterlineofthearch,TPCswereinstalledparalleltothebridgearchtangent,withthecenterofthepadnearly6”verticallyabovethecenterofthehorizontalTPCpressurepad.TheseslopedTPCswereinstalledtoassesssoil‐structureinteractionfromarch.Additionally,oneTPCwasinstalledbetweenarches9and10toassessloadingdirectlyabovethelessstiffdeckedarea.

AsrecommendedbyRoctest(2005),theTPCswereinstalledbetweenthearchandbackfillwithafinesandlayeratleast4”thickonthebottomandtopofthecelltopreventpointloadingthatcouldleadtoinaccuracyordamage.ThesandlayersunderandabovetheTPCswerecompactedbyhandusingheavytamperbothbeforeandaftertheinstallationtoreducethepresenceofvoidsandadheretoconstructionspecifications.AvoidanceofvibratorycompactionovertheTPCswasrecommendedtoavoiddamagetotheinstruments(Roctest2005).TPCwiringwasrunthroughsmallportsinthedeckingandconnectedtoaCampbellScientificdataloggingsystempoweredbyabatterychargedbyasolarpanel,allofwhichwassecuredtothenorthnorthboundheadwall.InitialTPCdataacquisitionattemptswereproblematic,soactualpressuresinthecelllocationsafterconstructionwerenotdetermined.Relativepressuresduringtheloadtestweregathered.

Figure10:SchematicofaRoctestTotalPressureCell(Roctest2005).

Roctest(2005).InstructionManual:VibratingWirePressureCells,ModelTPC&EPC.<http://www.roctest.com/modules/AxialRealisation/img_repository/files/documents/E1078E‐050708b.pdf>,July2009.



Figure11:LocationofStrainGagesandTotalPressureCells(TPC)

2.2.5.2.5 ResultsThemaingoaloftheloadtestingwastodeterminetheliveloadeffectsandloaddistributionofthetwoloadedtrucks.Themaximumstrain,deflectionandsoilpressuremeasurementsarereportedhereaswellasgraphsofthestrainateachlocationversuseachtrucklocation.Plotsoftheliveloadstrainforeacharchareshowninthefollowingfourfigures.

#1

#2

#3

#1 #2#3

#4

GageLayoutatAllSections GageLayoutatSupports

45°

Top

Bottom

Figure12:LocationofStrainGagesatEachArchSection



Figure13:LiveLoadStrainDataforSectionCofArch4

Figure14:LiveLoadStrainDataforSectionCofArch6

Unloadedbridge

Unloadedbridge

Unloadedbridge

Dynamictest

Unloadedbridge Unloaded

bridge

Unloadedbridge

Dynamictest



Figure15:LiveLoadStrainDataforSectionsA,B,CofArch

Figure16:LiveLoadDataforSectionsA,B,CofArch10


bridge

Unloadedbridge

Dynamictest


bridge

Unloadedbridge

Dynamictest



The maximum live load strain averaged over the time period for each static loading wasnegative 0.0068%. This is 0.4% of the average failure strain (1.74%) of the laminate fromcoupontesting.

AscanbeseeninFigures10through13,thestraingagedataappearstoindicatebothhighvariabilityanddrift.Therearemanypossiblecausesofthisincludingtemperaturevariation,under‐regulatedvoltagetotheinstrumentationandimperfectsolderjointsatthestraingages.

2.2.5.2.6 ConclusionsThemaximummeasuredvaluesofstrainintheFRPandconcretearecomparedtothestraincapacitiesinTable9.Thevaluesofstrainsrepresent25truckpositionsand21strainmeasurementlocations.ThemaximummeasuredpositivestrainintheFRP,whichwasobservedinlaboratorytestingasthecriticalfailuremode,is621timeslessthanthetensionstraincapacity.Thishighnumberresultsfromtheverylowstrainsmeasuredduringfieldloadtesting,andillustratesthereservecapacitythattheNealBridgeFRPhasintension.

Table9:MeasuredStrainsduringFieldLoadTestSeriesvs.MaterialStrainCapacity

MaximumMeasuredLLStrain(i)

(1)

CalculatedDL(ii)StrainatlocationofmaximumLLstrain(2)

MaterialStrain

Capacity(iii)

(3)

TotalStrain(DL+LL)

(4)=(1)+(2)

Straincapacity/demand(iv)

(5)=(3)/(4)

Positive(tension)

2.8E‐05 ‐8.66E‐05 0.0174 2.8E‐05(v) 621

Negative(compression)

FRP‐6.7E‐05 ‐9.58E‐05 ‐0.0087 ‐1.63E‐04 53

Negative(compression)

Concrete‐6.7E‐05 ‐9.58E‐05 ‐0.003(vi) ‐1.63E‐04 18

(i)25truckpositions,21strainlocations

(ii)Archweight,backfill,wearingsurface,neglectingstrainofwetconcrete

(iii)Basedon2.2.5.1.1

(iv)Demandbasedonfieldtestconditions

(v)Conservativelyneglectdeadloadstrain

(vi)BasedonACI318,conservativeforconfinedconcrete

Similarly,whilethecompressivestrengthoftheconcretedidnotcontrolinthelaboratorytests,themaximumcompressivestrainintheFRPadjacenttotheconcreteinTable9is18timesless



thanthecompressivestraincapacityofunconfinedconcrete.ThisfurtherservestoillustratethereservecapacityoftheNealBridge.

Asdiscussed,actualpressuresinthecelllocationsafterconstructioncouldnotbedetermined.Therefore,thechangeinpressuremeasuredduringtheloadtestingwasdeterminedrelativetopre‐loadtestmeasurements.Pressuresweremeasuredat5‐secondintervals,thefastestratepossible.Duetotheslowsamplingrate,nousefuldatawerecollectedduringthedynamictest.

Figure17:IncreaseinTPCpressuresmeasuredfromtime=0duringstaticloadtest(Note:

legendnumbersindicatethesensornumberandlettersindicatehorizontal(H)andsloped(S)).



Figure17showstheincreaseinpressuresmeasuredforallTPCsduringstaticloadtesting.Thenumbersatthetopofthefigureindicatetheapproximateloadregime,whereP1‐1correspondswithside‐by‐sidepressureloadingregime1andP2‐16correspondswithtandempressureloadingregime16(Table7andTable8).

Resultsshowthereislessthana3‐psiincreaseinpressureinallsensors.Thesevaluesaresmallconsideringthatthetruckloadingis125psi,assumingtwotirepatchareasof10”x20”peraxle.Withincreasingdepth,surfaceloadingisdistributedthroughthesoilmassandgeogridstructurelaterallyawayfromthebridge.Itisofinterestthatthesouthabutment,northmid‐span,andnorthabutmentslopedTPCshavegreatermeasuredpressuresthanthehorizontalTPCs.Thisindicatesthatbridgedeflectionsduringloadingengagethesoilmassparalleltothearchtangent.Itisunknownwhythesouthmid‐spanhorizontalTPCshowsgreaterloadingthantheslopedTPC.

Thepressureincreaseateachlocationisdependentonthesurfacelocationofthetrucks,asexpected.Additionally,thesensorsdirectlyundertheloaddonothavethegreatestpressuredifferencesforaparticularloadscenario.Thegreatestpressureisfromsensorsthatarerespondingtoarchdeflections.Thisisbestshownfortandemloadposition16(P‐2‐16).TherearaxleofthesecondtruckisdirectlyoverthemidspanTPC(68‐H),whilethefrontaxleissouthandoverTPCs69through72.TheslopedTPC(73‐S)atthenorthabutmentshowsaloadofnearly1.6psiduringthisloadscenario,eventhoughthereisnodirectverticalloadingatthatpartofthebridge.HorizontalTPC64‐Honlyshowsapressureincreaseof0.8psi,furtherindicatingarchdeflectionisthelikelycauseofloadingTPC73‐S.Figure18showsthedifferenceinpressuremeasuredadjacenttothearchandadjacenttothedeckingbetweenarchesforthenorthernmid‐spanlocation.Itillustratesthatformostloadingscenarios,theTPCalongthearchregistershigherpressuresthantheTPCoverthedecking.Duringmostofthestaticloadtesting,itisgreaterthan75%different(where%changeis

calculatedasthedifferencebetweenthearchanddeckingpressurenormalizedbythearchpressure‐

Figure19).Itisinterestingtonotethatduringside‐by‐sideloadregime4(P1‐4),whichisnearthecentralmid‐spanofthearches,thepressuresaresimilar.Forthisscenario,thedeckingandarcharelikelydeformingtogetherasthereislittlesoilbetweenthepavementandthearchto



redistributestressesawayfromthestructure.Similarresultsoccurwhenloadingisnearthecenterlineandjusttothesouthernendofthebridge.

Figure18:Differencebetweenpressureincreasesduetoloadingatthearchandbetween

archesadjacenttothedecking.

Figure19:Percentchangeinpressuremeasuredbetweenarchesandoveranarch.

Ithasbeenshownthatallstaticloadingconditionsresultedinlessthan3psiincreasesinpressure,whichissignificantlylessthantheappliedloadatthesurface.However,itwasofinteresttodeterminehowmuchofapressurechangeresultedcomparedtotheinsitudeadloadateachoftheselocations.Aspreviouslymentioned,actualpressuresafterbridgecompletioncouldnotbedeterminedduetodataacquisitionproblems.Therefore,deadloadsforthehorizontalTPCswereestimatedbasedontheassumedsoildensityaftercompaction(usingRC=95%forthedryunitweightandthecorrespondingaveragewatercontentfromtheStandardProctorcompactioncurve)andtheweightofthepavingandbasepavinglayers.Table10showsthepercentchangeinpressuredeterminedduringloading.Asexpected,the



shallowestlocationsexperiencethegreatestincreaseinpressures.Thisinformationshouldbeusedwithcaution,however.Itishighlylikelythatgreaterverticalandhorizontalstresseswere“locked‐in”duringcompactionthanestimatedfromsoilweight.Therefore,thedeadloadscalculatedhererepresentthelowerboundofearthpressurefortheunloadedstructure.Inreality,thepercentchangeinpressureattheselocationswillbelessdependingontheactualpressureattheselocations.

Table10:Increaseinpressureduringloadingrelativetoestimatedinsituverticalstresses

2.2.6 MaintenanceandRepairHistory–Thissectionnotincluded.

2.2.7 CoatingHistory–Thissectionnotincluded.

2.2.8 AccidentRecords–Thissectionnotincluded.

2.2.9 Posting–Thissectionnotincluded.

2.2.10 PermitLoads–Thissectionnotincluded.

2.2.11 FloodData–Thissectionnotincluded.

2.2.12 TrafficData–Thissectionnotincluded.

2.2.13 InspectionHistory–Thissectionnotincluded.

2.2.14 InspectionRequirements

2.2.14.1.1 ScheduleandfocusTheNealBridgeshouldbeinspectedevery24months.Inspectionshouldinclude,ataminimum,thearches(surfaceandshape),theheadwall(shape),andthedeckingabovethearches(surfaceandshape).Inaddition,theconditionofselectedboltsalongtheinsideoftheheadwallshouldbeinspected.Threenon‐adjacentboltsoneachsideofthebridgeshouldbeinspected.Ifdeteriorationisfound,additionalinspectionmayberequired.Thefastenerswhichconnectthedeckingtothearchesareprimarilyforconstruction,anddonotrequireinspection.



2.2.14.1.2 ArchesIngeneral,itisexpectedthatthetubingmaterialwillretainitsglossycoatunlesssubjectedtoabrasion.Itis,however,possiblethatsomeareasmayproduceachalkysurfaceifexposedtoextremeultra‐violetlight(UV).Thisshouldnotbeconfusedwithabrasion.Areasofthearchesthatarenolongerglossyshouldbecategorizedasfollows:

Chalky–theseareasarecausedbyexcessUV,notabrasion.ItislikelythatthischalkysurfacewillprotectthematerialfromadditionalUVbutifsignificantareasarefound,additionalinvestigationiswarranted.

Lossofsheen–theseareasshouldbenotedforfollow‐upinspectionbutarenototherwisecritical.

Dryundamagedfabric–theseareasshouldberecoatedwithanappropriateresinsystembutdonotrepresentstructuraldamage.Ifthesourceofabrasionisevident,itshouldberemovedorprotectedagainst.Theareashouldbemarkedforfollow‐upinspection.

Damagedfabric–tornorcutfibersrepresentstructuraldamage.Theseareasshouldbeanalyzedtodeterminepercentcapacityandasuitablelayerofexternallybondedreinforcementshouldbeapplied.Theareashouldbemarkedforfollow‐upinspection.

Figure20–Approximately1”x2”(25mmx50mm)sectionsofarchinvariousconditions:(A)Nodamage(whitepaintmarks)(B)Lightlossofsheen,nostructuraldamage,reportonly(C)

A B

C D



Heavylossofsheen,lightdryundamagedfabric,nostructuraldamage,shouldberecoatedwithresin(D)Lightdamagedfabric,mayrequirestructuralrepair,shouldberecoated

Archesasinstalledwerenotperfectlyroundeitherincross‐sectionoringrossradius.Nokinksorothersharptransitionswerenoted,however,andinspectionsshouldincludeexaminationofoverallgeometryforconsistencyfromarchtoarchandalongeacharch.Notethatthesurfacesofthetubesthemselveshavesomesharpridgesofclearresin.Thesearepartofthemanufacturingprocessandtheirpresenceisnotofstructuralconcern.

Archesshouldbetappedlightlywithahardobjectatroughly12”(30cm)intervalsalongtheirlength,varyinglocationfromtoptobottomofthearch.Tappingarchesshouldproduceasolidsound.Anyhollowsoundingareasshouldbereportedimmediately,andaneffortshouldbemadetomeasuretheareathatishollowsounding.Notethatsomevoidswerefoundduringconstructionandfilledwithresin.Theseareasmaysoundslightlydifferentfromadjacentareas,butshouldnotsoundhollow.Therepairedarchesare#2,#3,#4,#5,#13&#15countingfromthedownstreamend.Voidswerefoundandfilledwithinafootortwooneachsideofcenteraswellasdirectlyatthecrown.Theywereallwithinthetopfewinchesofthetube.

Theoutermostarchoneachsidesupportstheheadwallskin.Thejointbetweenitandthesupportingarch(justtotheinterior)shouldbecheckedforsignsofdamageincludingcracksorextremediscoloration.

2.2.14.1.3 DeckingThebottomofthedeckingspanningbetweenthearchesshouldbeglossywhite.Areasthatarenolongerglossyshouldbecategorizedandtreatedthesameasthearches.

Deckingshouldrunflatfromarchtoarch.Themidspanofthedeckingshouldnotbemorethan1/8”(3.2mm)belowthestraightlineconnectingthetwopointsofcontactwithadjoiningarches.

Thefollowingdeflectionlimitsarerecommendedbasedonamaximumallowablebendingstressinthedeckingpanel.Thisbendingstressisgivenbythemanufacturer,EnduroComposites,andusesasafetyfactorof2.5.Adeflectionlimitof3/8inchisrecommendedforthepanelperpendiculartothearchesandalimitof1/4inchisgivenforthebottomflangeofthedeckinginthedirectionparalleltothearches.Acombinedtotaldeflectionbetweenarchesatthecenterofthebottomflangeof5/8”couldbeseenandisacceptable.SeeFigures15and16forclarificationofdeflectionrequirements.



Figure21:AllowableDeckingDeflectionPerpendiculartoArches

Figure 16: Allowable Decking Bottom Flange Deflection

2.2.14.1.4 HeadwallTheheadwallshouldberoughlyplumbandplanar.Theeastheadwallshowedsomenoticeablebulging,especiallyatthetop,immediatelyafterbackfillwascomplete.Thetopoftheheadwallgeometryshouldberecordedintheas‐builtdrawings.Changesfromtheas‐builtconditionshouldberecorded.Plumbnessshouldbemeasuredandrecordedatfourtofivelocationsoneachheadwall.AppendixDcontainsimagesoftheinspectionnotebookfromtheresidentengineerwithinitialmeasurements.Thesemeasurementswerebasedonastringline.Futuremeasurementsshouldprovideaccuracyandrepeatabilitywithin1/8”suchthata1/4”movementcanreliablybemeasured.Acceleratingmovementwillrequirecorrectiveactionthatmayincludeexcavationandreplacementofeitherthegeogridortheconnectionsbetweentheheadwallandthegeogrid.Decreasingmovementsofupto1/4”frommeasurementsof4/9/09shouldbeacceptable.



2.2.15 StructureInventoryandAppraisalSheets–Thissectionnotincluded.

2.2.16 InventoriesandInspections–Thissectionnotincluded.

2.2.17 RatingRecords–Thissectionnotincluded

2.3 InventoryData–Thissectionnotincluded

2.4 InspectionData–Thissectionnotincluded

2.5 ConditionandLoadRatingData

2.5.1 GeneralTheloadratingforthisbridgewasbasedonSection6oftheManualforBridgeEvaluation(AASHTO2008).Wefollowed6A.1.7.1–DesignLoadRatingusingtheallowanceforalternateanalysismethods.Theanalysismethodandresultsarepresentedbelow.

2.5.2 RevisedConditionandLoadRatingDataThemoment‐curvatureresponsefortheconcrete‐filledFRParchtubeswaspredictedusingthemodeldevelopedbyBurgueño[1999].Materialinputparametersweredeterminedasdescribedintherespectivesectionsofthisreport.TheultimatetensilestrengthofthelaminatewasreducedusingthereductionfactorCE=0.90,asspecifiedinACI440.1RSection7.2[ACI,2006]forcarboncompositesexposedtoearthandweather.Thenominalmomentcapacity,Mn,predictedbythemodelwasreducedbyφ=0.55,asspecifiedinACI440.1RSection8.2.3fortensioncontrolledsections.TheresultingreducedmomentcapacityisφMn=690in*kip.Thepredictedmoment‐curvatureresponseforthearchmembersisshowninFigure17.



Figure17.PredictedMoment‐CurvatureResponseandReducedCapacityforConcrete‐FilledFRPBeamMembers

TheservicelevelloadeffectsweredeterminedfortheNealBridgestructureusingthefiniteelementmodelforcalculationoftheloadratingfactorsRF.ThemomentenvelopesareshowninFigure15andthevaluesaregiveninTable1.Theload‐ratingfactor,RF,wascalculatedusingEquation3.

Equation3

ThecalculatedloadratingfactorsaregiveninTable8.Ateachsectionalongthearch,maximumpositiveandnegativemomentswerecalculated.Inaddition,deadloadmomentsusingγofboth1.25and0.9werecalculated.Theultimatedeadandliveloadmomentswerecombinedtocreatethemaximumabsolutemoment.Theload‐ratingfactorwastakenastheminimumvalueofRFfromtheanalysis.FromthevaluesinTable1theminimumRF=3.7.



Figure17.DeadandLiveLoadMomentEnvelopes



Table8.MomentEnvelopeandLoadRatingFactor

MLu(in*kip) MDu(in*kip)DistanceFromCrown(in) Maximum

NegativeMaximumPositive

γ =1.25 γ =0.9Minimum

RF

184.4 ‐154.3 174.5 ‐77.2 ‐55.6 4.3176.6 ‐125.8 112.3 ‐52.5 ‐37.8 5.8168.6 ‐98.1 63.0 ‐32.0 ‐23.1 7.2160.4 ‐81.1 32.4 ‐15.4 ‐11.1 8.6152.0 ‐84.3 15.4 ‐2.3 ‐1.7 8.2143.4 ‐95.6 13.3 7.5 5.4 7.1134.7 ‐114.2 33.3 14.4 10.4 5.9125.7 ‐125.9 53.6 18.8 13.6 5.3116.7 ‐132.4 70.8 21.0 15.1 5.0107.4 ‐134.1 85.8 21.4 15.4 5.098.1 ‐130.3 98.3 20.2 14.6 5.188.6 ‐122.5 108.5 17.9 12.9 5.579.0 ‐111.6 117.0 14.9 10.7 5.869.4 ‐102.6 120.3 11.3 8.1 5.659.6 ‐94.5 129.5 7.5 5.4 5.349.8 ‐84.9 138.5 3.8 2.7 4.939.9 ‐74.4 146.5 0.3 0.2 4.730.0 ‐65.4 158.6 ‐2.6 ‐1.8 4.320.0 ‐54.1 171.2 ‐4.8 ‐3.5 4.010.0 ‐42.1 180.9 ‐6.2 ‐4.5 3.80.0 ‐29.5 185.0 ‐6.8 ‐4.9 3.7

RFisincreasedorreducedbasedontheadjustmentfactorK,whichrelatestheloadtestresultstothecalculatedresponse.Kaccountsfortwofactors:(1)theratioofcomputedstraininthemembertomeasuredstrain,and(2)theratioofloadeffectsduetothetesttrucktothoseduetothedesignvehicle.Kwascalculatedforeachsectionofthebridge,andtheminimumwastakenastheoverallloadratingfactorforthebridge.Thecalculationsaregivenbelowforthestraingage,locationandtruckpositionthatproducedthelowestoverallloadratingfactor.Itshouldbenotedthatthecalculationsdonotnecessarilyrepresentthemaximumstrainmeasuredduringtheloadtest,butratherthecombinationofmeasuredstrain,andpredictedstrainunderboththetestvehicleanddesignvehiclethatproducetheworstcaseloadratingfactorforthestructure.

Measuredstrainduringloadtestforworstcaseloadrating

Correspondingcalculatedstrainduetotestvehicle

�

Ka =εcε t

−1= −0.469 Equation2:FactorComparingPredictedandMeasuredStrain(Ref.4.8.8.2.3.1‐2)

�

T = εc = −3.772 ∗10−6 Calculatedstrainduetounfactoredtestvehicle

�

W = −5.32 ∗10−7 Calculatedstrainduetounfactoredgrossratingload

�

K = 0.531 T/W



�

Kb = 1.0 Kb–(Ref.4.Table8.8.2.3.1‐1)

�

K = −1+ KaKb = 0.531 Equation3:AdjustmentFactor(Ref.4.8.8.2.3.1‐1)

�

RFT = RFcK = 1.964 Equation4:LoadRatingFactorforLiveLoadCapacityBaseonLoadTestResults(Ref.4)

Basedontheabovecalculation,theminimumloadratingfactorforliveloadcapacitybasedintheresultsofthefieldloadtestis1.96.Theloadratingforthebridgeis1.96timesthedesignliveload.Thedesigntandemproducestheworstcaseloadeffectsinthisstructure.Theresultingloadratingforthearchmembersis1.96x25kips=49kips.

2.5.2.1 ConclusionsBasedontheresultsoffieldloadtestingandtheanalyticalloadratingarevisedloadratinghasbeendeterminedforthebridge.Aminimumloadratingfactorof1.96wasfound.Theloadratingforthebridgemaybetakenas1.96timesthedesignliveload,or49kippertandemaxle.Thetotalliveloadratingforthebridgebasedonapairoftandemaxlesis98kip.

2.6 LocalRequirements–Thissectionnotincluded



2.7 References

(ACI)AmericanConcreteInstitute.(2005).BuildingCodeRequirementsforStructuralConcrete(318‐05)andCommentary(318R‐05),ACICommittee318,AmericanConcreteInstitute,FarmingtonHills,Mich.2005.

(ACI)AmericanConcreteInstitute.(2006).GuidetotheDesignandConstructionofStructuralConcreteReinforcedwithFRPBars(ACI440.1R‐06).FarmingtonHills,MI:AmericanConcreteInstitute.

AASHTO(2007).LRFDBridgeDesignSpecifications,4thed.AASHTO,WashingtonD.C.2007.

AASHTO(2007).ManualforBridgeEvaluation,1sted.AASHTO,WashingtonD.C.2008.

Bannon,D.(2009).CharacterizationofConcrete‐FilledFiberReinforcedPolymerArchMembers.M.S.Thesis.DepartmentofCivilandEnvironmentalEngineering,UniversityofMaine,Orono,2009.

Burgueño,R.(1999).SystemCharacterizationandDesignofModularFiberReinforcedPolymer(FRP)Short‐andMedium‐SpanBridges.(Doctoraldissertation,UniversityofCalifornia,SanDiego,1999).(UMINo.9928617).



AppendixA.MaterialDataSheets



AppendixB.LessonsLearned

Afour‐hourmeetingwasheldatAEWCtoreviewtheNealBridgeprojectanddocumentthelessonslearnedamongsttheMaineDepartmentofTransportation,AEWCandStetson&Watson.OneofthekeyoutcomesisthatthearchescanbeinstalledinhalfadayforabridgeliketheNealBridge.Themosttimeconsumingprocedureswerethefoundationfabricationandthebackfilling.

Thearchfoundationshouldbesimplifiedbyusingarectangularformencompassingallthearchends.Severalideaswereadvancedtofacilitatetheinstallationofthearches.Verticalandhorizontalalignmentjigscouldexpeditetheplacementofthearches,improvetheaccuracyofpositioning,andreducetheconstructionstageon‐sitesolutiondevelopment.Sheetpilesasheadwallmaterialareagoodsolutionthatperhapsshouldbeextendedtowingwalls.Backfillingwasimpededbythegeogrid.Headwallattachmentandbackfillingpresentsoneofthemostsignificantopportunitiesfortimesaving.

Formoredetailsandalistofthelessonsidentifiedduringthemeetingpleasethetableonthenextpage.



Issue Influencingfactors SolutionEmployed RecommendationforfutureAllsteelmustbedomesticsteel,somesteelhadtobeimported

Materialselection

Designnotcomplete,changesontherun,manychangeorders Tightschedule

Needacompletedesignfromthebeginning

Rock(ledge)wastoodeep Siteselection

HeadwallappearanceandalignmentNeedtemporarysupportheadwallconstruction:contractneedspropertoolsConnectionneedsasolidconnection,shouldnotrelyupongeogridtoholdupheadwallinitially

Oncethesoilwasputdowntemporarytiescouldonlyinfluenceheadwallabovethesoillevel

Whalers 1.Differentheadwalldetails2.Needtemporarybracingdetail3.Couldhaverigidtemporarybracingthatbecomespermanent4.UseConspantypeheadwall

SheetpileGoodsolution 3Dcutforfit

1.Pre‐cutsheetpileforabetterfitintochannel2.Useconcretefillerinchannel

Facingsheetonheadwallisnotnecessaryandwouldprobablylookbetterifleftoff.

Colorwastoowhite.Adifferentcolormaybemoreacceptable

Fascia 1.Letthesheetpilebeseen.2.Usefasciatomaskheadwallalignment

Foundation‐concretepiles 1.Didnothaveheadroomdrillingrigwithoverheadwires2.Ledgevariationwas2to8feet3.Pileswouldhavebeentooclosetogether4.DOTgeotechswantedfoundationtobedrock5.Morecontractorshaveabilitytodigholesandfillratherdrill

Fullfoundationtobedrock Digtwoholesandfillwithconcreteandcap

Rebarwasdifficulttoworkwith,difficulttoholdeverythinginplacewhilefillingwithconcrete

Tightschedule

1.Rebardetailshouldhavebeeninseveralpieceslimitedto90degbends2.Footingshouldhavebeenlongeracrosstheroad,onefootoneachsidetoallowforming3.Jhooksconnectingfootingtoarchesshouldhavebeenshorter,90degbendinsidefootingtoallowconstructabilitytoholdtheminplace



Archalignment Methodisnotabigtimefactor 1.4x4woodbeamsstrappedtothearches2.plywoodtemplatewasusedforhorizontalalignment

1.Usefulllengthtemplatewithcompositeboxbeamswithintegratedstrapsforfullwidthofbridgeforverticalalignmentofarches,couldbeapermanentbracetobeleftinplaceforattachingtheheadwall2.Shouldalsoincluderadiusedcutoutsforhorizontalalignment3.Includeareferencepointforalignment,suchasashort,severalinch,verticalcut,orareferencepointonthearchtoalignthearchesrelativetoeachother4.Needindividualpiecestospacearchesduringplacement,strapsareacceptableanddonottakelongtoemploy

Archhandling:difficulttohandlewithoutsomekindofhandle

1.Integratehandlesthatmaybecouldbeusedasspacers

Archfoundation Irregularcutatendofarchmayhavebeenconducivetothearchnotfloating

1.Setarchesonflatfootingandusearectangularformencompassingallarchendstogether2.Redesignrebardetailtofacilitatearchinstall.Minimizetransverserebar.3.1.5"stepdoesnotrequireabulkhead

Decking‐nocomplaints Selftappingscrewsworkedwell

Slump 1.10inchslumpspecified2.Sunrisedidnotdoatrialbatch

1.Specifyslumpflow,musthavetrialbatch2.Specificationshouldaccommodatethesupplier3.Needatleasta3inchhole,preferably4inchdiameter4.Ifflowisslowincreasethesuper

GeogridattachmentGeogridisverytimeintensive

1.Geogriddoubledthebackfill2.Alotofhandcompactaroundlayersofgeogrid

Eyeboltsandbars 1.Useasetofanglebarstoclampgeogrid2.Eliminategeogrid,especiallyabovethearchelevation

Guardrail Useenoughcoversothataguardraildoesnothavetobeinconcrete,canbedriven

Stagedconstruction

Thedesignisamenabletostagedconstruction,onelaneatatime

Headwall/Wingwall Continueheadwalldesigntowingwalls



AppendixC.ConstructionoftheNealBridge

OnemajorattributetothearchtechnologyusedinthestructureoftheNealBridgeisitslightnessandsubsequenteaseofconstruction.Demonstratingthisattributewasamajorgoalofthisproject.Thissectionwillhighlightthemajorareasofconstructionwithemphasisonthecompositetechnologycomponents.

Foundation

ThefoundationfortheNealBridgewasdesignedasatypicalreinforcedconcretefoundation.Fourconcreteplacementswereusedintheconstructionofthefoundations.Theywerethe“seal”pourfortheconcretebeneaththefootingandunderwater,thefootingpourwherethebaseofthearchessat,the“cap”pourtocaptheoldabutment,andthe“curb”pourwhichencasedthebaseofthearches.ThesealpourwasClassSconcretetoledge.TheotherconcreteinthefootingwasClassAstructuralconcrete.RequirementsforthesetwoclassesofconcretecanbefoundintheMDOTspecificationsforthisproject.Otherthansometroubleplacingtheconcreteinthenorthabutmentsealpourandsomeredesignthatfollowed,therewerenosignificantproblemsforthefoundationconstruction.

Arches

TheerectionofthearcheswasanimportantandexcitingstepintheconstructionoftheNealBridge.InonedaythearcheswereshippedfromtheUniversityofMaineinOronotothebridgesiteanderected.Someshimmingandpreparationsweredoneinthemorningofthefollowingday.

ThearcheswereshippedfromOronoinaboxtractortrailerintwoloads.Onceonsitetheywereunloadedfromthetruck,inspectedandthenlaidoutonthegrassnearthebridgeside.Aboomtruckwaspositionedtopickupthearchesfromthelaydownareaandplacethearchesonthefootings.Handlaborwasnotusedtomovethearchesontothefootingduetosafetyandwalkingconditions.Somearchesweresetinplacebyhandoncetheywereinthehole.Onceonthefootingthearcheswerespacedandbracedusingwoodenjigs.Ratchetstrapsavailableatanyhardwarestore,wereusedtotiethearchestogethertemporarily.Approximately5menwereusedinplacingthearches.Theupstreamarchwasthefirsttobeplacedandwaslaterallybraced.Subsequentarcheswerestrappedtothisfirstarchandthentoeachother,thereforebracingthesystemuntildeckingcouldbeinstalled.

Therewereareasforimprovementfoundwhenplacingthearchesonthefootings.Findingabetterwaytocarrythearchesbyhandwasonesuggestion.Ifhandlaborisrequiredtomovethearchessomesortofhandlesystemisdesirable.Thiswillespeciallybetrueforlargerdiameterarcheswherepersonnelwillbeunabletowraptheirarmsaroundthediameterofthearches.Asecondimprovementthatmustbemadeisthemanufacturingtolerancesofthearches.AsmentionedpreviouslyinAppendixB,thedifferenceintheshapeofthearcheswas



anissue.Thehalf‐dayofshimmingwouldhavebeeneliminatedifthearchesmoresimilarinshape.

Decking

Thedecking(orsheathing)wasattachedtothearchesinoneday.Three‐inchlongself‐drillingstainlesssteelscrewswereusedtoattachthedeckingpanelstothearches.Thepanelswere45feetlongandtrimmedwithlargecircularsawateachendtomatchthe7‐degreeskewofthebridge.3½”to4”offillconcretewasplacedontopofthedeckingpriortobackfill.Theconcretewasplacedtoprotectthedeckingfromlargestonesinthebackfillmaterialaswellasfromvandalismfromunderneaththebridge.Therewereconcernsaboutthedurabilityofthedeckingduetoitsthickness.Thickerdeckingpanelsordeckingpanelsdesignedcompositelywithconcreteabovewillbeonesolutiontothisconcern.

HeadwallandBackfilling

TheconstructionoftheheadwallandbackfillingweresignificanttasksintheconstructionoftheNealBridge.TheFRPsheetpileworkedwellasawallmaterial.Thegeogridandconnectionschemedidnotworkaswellasexpected.TheconnectionoftheFRPsheetpiletothearcheswasalsonotagreatdetail.Thethree‐dimensionalcutstofitthepiletothearcheswerenoteasytomake.Anotherconcernraisedwasthattheamountofgeogridlengthenedthetimeneededtobackfillthebridgewiththiscrew.Thesepointswillbediscussedmoreinthefollowingparagraphs.

Thebackfillingbeganwiththeplacementofflowablefillbehindthefootings.Granularbackfillwasusedabovetheelevationofthetopofthefooting.Compactionwasachievedusinghandcompactors,platecompactorsandvibratoryrollers.MaineDOTinspectedthedensitiesateachliftofgranularbackfill.

Thegeogridwasplacedbyhand,generallybytwolaborers.TheunidirectionalgeogridwascutparalleltothestrongaxisofthegridtofitpastthegalvanizedeyeboltsandwraparoundtheFRPrebar.SeeSheet2andSheet3oftheheadwalldrawingsonpages6and7iffurtherclarificationisneeded.ThegeogridwaswrappedaroundtheFRPrebarandattachedtoitselfwithaBodkinbarfromTensar.Tensionofthegeogridwasachievedusingsteelbarsandtwolaborspryingonthegeogrid.Anexcavatorbuckloadofbackfillmaterialwasthenunloadedonthegeogrid.

Vibratoryrollersandheavyplatecompactorswereused.Infutureprojectstheiruseshouldbelimitedinthespecification.ExcessivevibrationswereseenwhenthevibratoryrollerwasinitiallyusedontheNealBridge.Itsusewasthenlimitedtoareasthatwereroughly6to8feetfromtheexposeddeck.Thisseemedadequateinpreventingexcessivevibrationsinthestructure.Itcannotbesaidthatthiswillbetrueforfutureprojectsthough.



Wingwalls

AprecastconcreteT‐WallretainingwallsystemwasusedaswingwallsfortheNealBridge.FortysectionsofT‐Wallwereused,tenateachcorner.Thewallswere13’‐4”tallwitha6”wideby18”thickby10’‐0”longconcretelevelingpadbeneaththewalls.

Paving

PavingoftheNealBridgewasconductedinNovember2008forthebinderandinMay2009forthefinishedwearingsurface.ThebinderwasplacedNovember21st,2008withtheroadopeningonNovember22nd.

Guardrail

TheguardrailsweredrivenasspecifiedintheMaineDOT’sstandardspecifications.Thedepthofthetopofthearcheswasadequatewhichpreventedtheneedforthepostsatthecrownofthearchestobeshortenedandtheirbasesencasedinconcrete.ThisisadetailthatisfavorableandshouldbeachievedwherepossibleinfutureFRParchbridges.



AppendixD.InspectionNotebook–HeadwallMeasurements

design, construction and testing of the neal bridge in

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