Table Of Content

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August2002 SUBSTRUCTURESANDBEARINGS 19(0 TableofContents Section Page 19.1 ABUTMENTS 19.1(1) 19.1.1 General 19.1 19.1.2 Loads 19.1 19.1.3 GeneralDesignandDetailingCriteria 19.1 19.1.4 Semi-IntegralAbutments 19.1 19.1.5 IntegralAbutments 19.1 19.1.5.1 General 19.1 19.1.5.2 DesignCriteria 19.1 19.1.5.3 SuperstructureandInteriorSubstructureDesignCriteria 19.1 19.1.5.4 IntegralAbutmentDetails 19.1 19.1.6 Free-StandingAbutments 19.1 19.1.6.1 Usage 19.1 19.1.6.2 Epoxy-CoatedSteel 19.1 19.1.6.3 SeismicShearBlocks 19.1 19.1.7 PileSpacingsandLoads 19.1 19.1.7.1 GeneralDesignCriteria 19.1 19.1.7.2 PileDesignforIntegral/Semi-IntegralAbutments 19.1 19.1.7.3 PileDesignforFree-StandingAbutments 19.1 19.1.8 Wingwalls 19.1 19.1.9 Drainage 19.1 19.1.10 Joints 19.1 19.1.10.1 ConstructionJoints 19.1 19.1.11 Concrete 19.1 19.2 INTERMEDIATESUPPORTS 19.2 19.2.1 Types. 19.2 19.2.1.1 PipePileBents 19.2 19.2.1.2 Piers 19.2 19.2.1.3 Multi-ColumnBents 19.2 19.2.1.4 Single-ColumnPiers 19.2 19.2.2 GeneralDesignConsiderations 19.2 19.2.3 SpecialDesignCriteria 19.2 19.2.3.1 PipePileBents 19.2 19.2.3.2 HammerheadPiers 19.2 19.2.4 PierandBentinaSlopedEmbankment 19.2 19.2.5 DynamicLoadAllowance(IM)forPiersandBents 19.2 19(ii) SUBSTRUCTURESANDBEARINGS August2002 TableofContents (Continued) Section Page 19.3 BEARINGS 19.3(1) 19.3.1 General 19.3(1) 19.3.2 FixedSteelBearings 19.3(3) 19.3.2.1 General 19.3(3) 19.3.2.2 Design 19.3(3) 19.3.3 SteelReinforcedElastomericBearings 19.3(5) 19.3.3.1 Elastomer 19.3(5) 19.3.3.2 BehaviorofSteel-ReinforcedElastomericBearingPads.. 19.3(6) 19.3.4 DesignofSteel-ReinforcedElastomericBearingPads 19.3(8) 19.3.5 SeismicDesign 19.3(8) 19.3.5.1 Application 19.3(9) 19.3.5.2 SeismicPerformanceZone1Criteria 19.3(9) 19.3.5.3 ConnectionsforFixedSteelShoes 19.3(10) 19.3.5.4 ConnectionsforElastomericBearingsandPTFE/ ElastomericBearings 19.3(10) 19.3.5.5 SeismicIsolationBearings 19.3(11) # • August2002 SUBSTRUCTURESANDBEARINGS 19.1(1) ChapterNineteen SUBSTRUCTURESANDBEARINGS Section 11 of the LRFD Bridge Design 2. Integral Abutment. Flexible abutment Specifications discusses the design withoutajointbetweenthebackwall and requirements of abutments, piers and walls. pilecap(incrosssection,thebackwalland ChapterNineteenpresentsMDTsupplementary pilecapmay,infact,appearasamonolithic information on the design ofthese structural rectanglewithnoapparentcap). components. Section 13.4 of the MDT Structures Manual presents Department 3. Free-standing Abutment. Rigid abutment criteria for the selection of substructure withajointbetweenthebridgedeckandthe componentswithinthecontextofstructuretype backwall. selection. Figure 19.1Apresentsschematicsforthethree basic types ofabutments. Each ofthese is 19.1 ABUTMENTS discussedinthisSection. 19.1.1 General Abutments shall generally be ofthe cast-in- place,reinforcedconcretetype. Theyshallbe Anabutmentcanincludeabackwall,acapand founded on spread footings, drilled shafts or wingwalls. Theterm"endbent"isoftenused drivenpilefootings. interchangeablywith"abutment."Abackwallis theportionoftheabutmentwhichfunctionsasa Ajointlessflexibleabutment,eitherintegralor wallprovidinglateralsupportforfillmaterialon semi-integral, ispreferred. Free-standing rigid whichtheroadwayrestsimmediatelyadjacentto abutments shallbeusedwheretheanticipated thebridge. translational movements ofthe piles are too great, or settlement of the backwall is Abutmentscanbeclassifiedasrigidorflexible anticipated. The force effects of these abutments. Flexibleabutmentseliminatejoints displacementsmustbeincludedinthedesign. attheendofthesuperstructurebyintegrating the bridge deck with the backwall. Rigid abutments incorporate expansionjoints atthe 19.1.2 Loads end ofthe bridge between the deck and the backwalltoaccommodatethermalmovements. Reference: LRFD Articles 11.6.1.1 and Flexible abutments must be able to 11.6.1.3 accommodate the movements through elastic behaviorofthebridgeandthesurroundingsoil Thestaticearthpressureshallbedeterminedin becausethedeckisintegralwiththeabutment. accordance with Article 3.11 of the LRFD Specifications. Generally, no passive earth An abutmentmaybe designedas one ofthe pressureshallbeassumedtobegeneratedbythe following three types in descending order of prismofearthatthenearfaceofthewall. preference: 1. Semi-integralAbutment. Flexibleabutment 19.1.3 GeneralDesignandDetailingCriteria withapinjointbetweenthebackwalland captofacilitateconstructionandsubsequent Thefollowingappliestothedesignanddetailing maintenance. ofbackwallsandwingwalls: 19.1(2) SUBSTRUCTURESANDBEARINGS August2002 # Semi-IntegralAbutment Cwaotnetrinusotuospneoprene IntegralAbutment '.'V # ;.1i-.-1:••)t• +-M FreeStandingAbutment '••'••;':i*; T...'i-x.^^1 TYPICALABUTMENTTYPES (il) Figure19.1A August2002 SUBSTRUCTURESANDBEARINGS 19.1(3) 1. BridgeApproach.TypicalMDTpracticeis 6. Backwall/Wingwall. Thejunction ofthe to design for the future possibility ofa abutmentandwingwallisacriticaldesign bridge approach slabbutto notbuildthe element,requiringspecialconsiderations. If slab in the initial construction. When thewingwallistiedtothebackwall (i.e., reinforced concrete bridge approach slabs thereisnojoint),designforat-restpressure. are used, live load surcharge will notbe All reinforcementmustbe developedinto considered on the endbent; however, the both elements such that full moment vehicularloadsontheappropriateslabsshall resistancecanbeobtained. beconsidered. Anchortheappropriateslab tAotrhiegiadbuatpmpernotaschifisnlaabhhieglhpsseitsomipcrezvoenen.t 7. pBraecfkewrarledl(Bia.et.t,ern.o bVaetrtetri)c.al Fboarckwtaalll,lsfraere-e compaction of the backfill behind the standing walls, batter maybe considered. abutment. Whereused,thebattershouldbebetween 1:10and1:15(H:V). Provide apaving notch on all on-system structures and off-system structures that 8. Backfill.Abutmentsandwingwallsshallbe haveapproachroadwaysthatarepavedor backfilledwithSelectBackfillspecifiedby likelytobepaved. Ifanapproachslabwill the Geotechnical Section. The neat line be constructed, show it on the General limitsoftheSelectBackfillshallbeshown Layout. on the plans or described in the special provisions. Show the Select Backfill 2. BridgeApproachJoints. Provideaterminal quantityontheroadplans. jointorpavementreliefjointattheendof tthheerrooaaddwwaayypoafvtehmeenbrtidisgecoanpcprertoea.chAsljaobinitf 9. RloeciantfeodrcdiinrgecSttleyelo.verIftahneeaxbpuatnmseinotncjaopi,ntalils is not required if the entire adjacent reinforcementintheabutmentwallshallbe pavementisasphalt. epoxycoated. 3. WwiinnggwwaallllsCsohnonuelcdtinootn.exItnegnednemroarl,eUt-hsahna3pemd 19.1.4 Semi-IntegralAbutments behindthe rearface ofthe abutment. If wingwallslongerthan3mareneeded,then Thesemi-integralabutment,orstubabutment,is anauxiliaryfootingmustbeprovided. Also, MDT's typical end-bent configuration. if longer extensions are necessary, force Transverse and longitudinal superstructure effects in the connection between the forces are transmitted to the substructure wingwallandabutment,andinthewingwall through radius plate steel shoes with anchor itself, shall be investigated, and adequate bolts that allow rotation. Typically, the reinforcingsteelshallbeprovided. backwall and wingwalls are cast around the girderends, attachedtothe slab andisolated 4. Tahnicakbnuetsmse.ntThise3m5i0nimmmu.mwWaallllsthimcakynesbsefoorf farreomusetdh,etphielewicnagp.scaWnheeintheUr-bsehamponeodliwtihnigcwawliltsh constantthicknessorwithabatteredfillface thebackwallandisolatedfromthepilecapor asrequired. Typically,thenearfaceshallbe attachedtothepilecapwiththebackwallleft verticalbut,ifconditionswarrant(e.g.,high freetorotate. Thejointbetweenthebackwall walls,anticipatedtilting),itmaybeslightly and the pile cap facilitates raising the battered. superstructureifsettlementoccurs. 5. ExpansionJoints. Verticalexpansionjoints should be considered for wall lengths exceeding30m. 1 19.1(4) SUBSTRUCTURESANDBEARINGS August2002 • 19.1.5IntegralAbutments therotationpermittedbythepilesissufficiently high,andtheattendantendmomentsufficiently Reference: LRFDArticle11.6.2. low,tojustifytheassumptionofapinned-end conditionforgirderdesign. The ends ofthe structuresarealsoassumedtobefreetotranslate 19.1.5.1 General longitudinally. Traditionally,bridgeshavebeendesignedwith expansionjoints and other structural releases 19.1.5.4 IntegralAbutmentDetails that allow the superstructure to expand and contract relatively freely with changing Integral abutments are typically constructed temperatures and other geometric effects. using the following preferred method. The Integralabutmentseliminateexpansionjointsin superstructure girders are set in place and thebridgedecks,whichreduceboththeinitial anchored to the previously cast-in-place constructioncostsandsubsequentmaintenance abutmentcap. Typically,theconcreteabovethe costs. previously cast-in-place cap is poured at the same time as the superstructure deck. To Using integral abutments is effective in addresssteelgirderstability,refertoComment accommodating the horizontal seismic forces. #2inSection19.1.5.2. Minimumbeamseatlengthrequirementsneed not be investigated for integral abutment Optional constructionjointsmaybeplacedin bridges. thecaptofacilitateconstruction. Theoptional jointbelowthebottomofbeammaybeusedon • all integral abutment bridges regardless of 19.1.5.2 DesignCriteria bridgelength. Thefollowingrequirementsmustbesatisfiedin Theabutmentdetails shallmeetthefollowing allcaseswhereintegralabutmentsareused: requirements: 1. tBaycpkefislulpe.rsAtlrluctiunrteegsraslhalalbubtembeantcskffiolrledgiwridtehr 1. tWhiadnth75.0Tmhme.backwallwidthshallnotbeless SelectBackfill. 2. CapEmbedment. Thepilingshallextenda 2. SteelGirderStability. Wheresteelgirders minimumof500mmintothecap. areused,ananalysisofthenon-composite girderstabilityshouldbemadetolocatethe 3. ConcreteCover. Concretecoverbeyondthe first intermediate diaphragm to provide farthestmostedgeofthegirderattherear stabilitypriortoandduringthedeckpour. faceoftheabutmentshallbeatleast 100 Idniapliheruagomfshtohueldanbaelypsilsa,cedanwitihnitnerm3edmiatoef mthme.paTvhiengminnoticmhumarceao.verTshhealltoalpsoflaapnpgleyotof the end support. An analysis will most steelgirdersandprestressedI-girdersmay likely yield a more economical, larger becopedtomeetthisrequirement. diaphragmspacing. 4. Girder Anchorage. A minimum ofthree holesshallbeprovidedthroughthewebsof 19.1.5.3 SuperstructureandInteriorSub- steel girders and through prestressed I- StructureDesignCriteria girderstoallow#19barstobeinsertedto furtheranchorthegirdertothecap. Position Although the ends ofthe superstructure are theholessothat,whenthebarsareinserted, monolithically attached to integral abutments, theywillbewithinthebackwallcage. . August2002 SUBSTRUCTURESANDBEARINGS 19.1(5) 5. Rsteiirnrfuposrcsehmalelntb.e#1T3hespamciedniamtuammasxiziemuomf 1 PainleinStpeagrcailngo.rsUesmei-ainstienggrlaelraobwutmoefnpti.lesPifloer roefinf3o0rc0ingmms.teel Lboengi#t2u2dina@l b3a0ck0w-amlml hsopawceivnegr,sihfotuhledcnaoptisnoprrompaelrllyyeaxncaelyezded3amn;d maximumspacingalongbothfacesofthe designed as a continuous beam, this abutment. restrictionneednotapply. Ifpractical,one pilemaybeplacedbeneatheachgirder. To 6. CornerBars. UseL-barsextendingfromthe reduce force effects for a large beam rearfaceofthebackwallintothetopofthe spacing,considerationmaybegiventotwin slabat300-mmspacingorless. pilesunderthebeam, spacedatnotlessthan 750mm. SeeChapter20forminimumpile spacings. Thepilesareconsideredtobefree 19.1.6Free-StandingAbutments ended and capable of resisting only horizontalandverticalforces. 19.1.6.1 Usage Usefree-standingabutmentswhereintegraland 2. Nleusmsbteharn.foTuhr,eunnulemsbserotohefrpwiilseesasphaplrlovneodtbbye semi-integral abutments cannot accommodate theBridgeAreaEngineer. themagnitudeofthe longitudinalmovements. pFirleees-,sdtrainldliedngshaafbtustomrenstpsreacdafnootbiengsf.ounded on 3. Oshvaellrhbaen4g5.0mTmh.e minimum cap overhang 19.1.6.2 Epoxy-CoatedSteel 19.1.7.2 Pile Design for Integral/Semi- IntegralAbutments Forabutmentsthathaveabridgedeckexpansion jointlocatedbetweentheendofthedeckandthe Thefollowingcriteriaapplyspecificallytopiles faceofthebackwall,allreinforcingsteelinthe and loads at integral and semi-integral abutmentshallbeepoxycoated. Thisincludes abutments: all cap, backwall and, if present, wingwall reinforcing. 1. Loads/Forces. Forstructuressatisfyingthe requirements provided in Section 13.4.4, force effectsintheabutmentpiles dueto 19.1.6.3 SeismicShearBlocks temperature,shrinkage,creepandhorizontal earthpressuresmaybeneglected. Inseismicareas,shearblocksmaybeformed into the top ofthe abutment cap to provide Analternativeanalysismustbeusedifthe lateralrestraintforbeamsthatdonothaveside criteriainSection13.4.4arenotmet. The restraint provided by the bearings or other followingstepsshouldbeconsideredinthis means. analysis: a. The point of zero superstructure 19.1.7PileSpacingsandLoads movement should be established by consideringtheelasticresistanceofall 19.1.7.1 GeneralDesignCriteria substructuresandbearingdevices. Thefollowingcriteriaappliestopilingforboth b. The effects of creep, shrinkage and integralandsemi-integralabutments: temperatureshouldbeconsidered. 19.1(6) SUBSTRUCTURESANDBEARINGS August2002 • c. Any movement at any point on the Ifpilescannotbedrivenaminimumof3m superstructureshouldbetakenasbeing intonaturalgroundduetoarockstratum, proportionaltoitsdistancetothepoint socketthepilesintoundersizedholesdrilled ofzerodeflection. into the rock. The diameter of the undersized holes shall equal the inside d. Lateral curvature ofthe superstructure diameterofthepipepile,ifpipepilesare may be neglected if it satisfies the used,or25mmlessthanthemaximumpile provisions of Article 4.6.1.2 of the dimensionforsteelH-piles. Socketthe LRFDSpecifications. pile a minimum of 1 m into the rock formation;thepileshouldextendatleast3 e. Vertical force effects in the abutment mbelowthecap. pilesshouldbedistributedlinearlywith load eccentricities properly accounted for. 19.1.7.3 PileDesignforFree-Standing Abutments f. Lateral soil resistance should be consideredinestablishingforceeffects The following criteria apply to piles at free- andbucklingresistanceofpiles. standingabutments: g. Force effects should be combined in 1. PileSpacing. Atleasttworowsofpilesor accordance with the provisions of batteredpilesmustbeprovidedtoprovide Article 3.4.1 ofthe LRFD Specifica- the necessary longitudinal stiffness. The tions. minimumpilespacingis750mmparallelto # thecenterlineoftheabutment. 2. PileType. OnlysteelH-pilesorsteelpipe piles are permitted at integral abutments. 2. Batter. Uptoone-halfofthepilesmaybe Forsemi-integralabutments, steelH-piles, batteredtoincreasetheoverturningstability steel pipe piles or fluted steel piles are ofthestructure. permitted. TheorientationofsteelH-piles (strong versus weak axis) is a design 3. Movement. Theeffectsofthemovements consideration, anditispreferablethatall due to overturning pressures or lateral pilesbe orientedthe same. Allabutment pressuresshallbeinvestigated(e.g.,ensure pilingshallbedrivenverticallyandonlyone thattheclosingofjointsdoesnotoccur). rowofpilingispermitted. 3. PmiilneimDruimvionfg.3 mPiilnestosnhaatlulralbegrodurnidv.en Iaf 19.1.8Wingwalls pilescannotbedriventothisdepthduetoan Reference: LRFDArticle11.6.1.4 existing cohesive earth stratum, with a standard penetration resistance (N) Wingwalls shall be of sufficient length and exceeding 35 blows per 305 mm located depthtopreventtheroadwayembankmentfrom withthe3mintervalbelowthebottomof encroaching onto the stream channel or the the cap, the piles shall be placed in defined clear opening. Design the wingwall oversized, predrilled holes before driving. lengthstokeeptheembankmentatleast300mm bTehe10d0iammemtegrreoaftetrhethoavnertshiezmedaxhoilmeusmshcoruolsds bGeenleorwalltyh,etbheeaslmopeseoatftohreftilhlewitlolpnootfbethseteceappe.r sectionaldimensionofthepile. Theholes than2:1 (H:V), andwingwalllengthswillbe shall be backfilled with uncrushed base establishedonthisbasis. courseaggregatesize 17mm(peagravel) followingthepiledrivingoperation. August2002 SUBSTRUCTURESANDBEARINGS 19.1(7) Withrespecttoabutments,thefollowingapplies furnishingandinstallingmostsystems canbe towingwalls: absorbedinthecostofselectbackfill. 1. PileSupported. Ifturnbackwingwallson Static ground water levels should always be rigidabutmentshaveatotallengthofmore considered while evaluating an appropriate than 3 m, auxiliary pile footings for drainagesystem. Drainagesystemsshouldnot wingwall support should be investigated. beinstalledtoallowpressurizedbackwaterto Pile-supportedwings shallbe avoided for saturatetheabutmentbackfillduringhighwater integralbackwalls. events. 2. wCionngnweactlilosnssh.ouldnIontexgteennedramlo,reUt-hsahna3pemd Gseunpeproarltleyd,onfionrtegrraellaotrivseelmyi-instheaglrlalowabugtimrednetrss behindtherearface ofthe abutment. If withstraightwingsorturnbackwingslessthan3 wingwallslongerthan3mareneeded,force mlong,selectbackfillwillbeallthatisneeded effects in the connection between the topromotegooddrainage. wingwallandabutment,andinthewingwall itself, shall be investigated and adequate Forbridgeswithtallerabutmentwalls,girders reinforcingsteelbeprovided. Forrigidfree- deeperthan 1.5 m or abutments with atotal standingabutments, the forces aremerely heightofmorethan2.5mfromthebottomof due to permanent loads and live-load pilecaporfootingstothetopofthebackwall surcharge. For flexible abutments, other should be given consideration for additional transient loads must be considered in drainage features. If a drainage system is additiontothepermanentloads. determinednecessary,aperforateddrainagepipe placed at the base ofthe abutment wall or 3. Thickness. Theminimumthicknessofany footingispreferred. Thepipeshouldbeplaced wingwall with an abutment shall be 350 insideafreedraininggravelmedia,wrappedin mm. drainagefabricandslopedtodraintoapoint outsidetheabutmentwalls. 4. Design. Unattached wingwalls shall be designedasretainingwalls. The other systems identifiedmaybeusedto addresssite-specificneedswithapprovalbythe 5. Concrete. For wingwalls, use Class DD BridgeAreaEngineer. concrete. 19.1.10Joints 19.1.9Drainage 19.1.10.1 ConstructionJoints Provide positive drainage as needed in the embankmentbehindtheabutmentandwingwalls Toaccommodatenormalconstructionpractices, byusingselectbackfill,weepholes,perforated the designer should indicate the following drainpipe, amanufacturedbackwall drainage horizontal construction joints on the plans. system or a combination of these options. MDT does notuse shearkeys forhorizontal Include provisions for select backfill in all constructionjoints: abutment designs in accordance with the geotechnical recommendations in the 1. In semi-integral abutments, a horizontal GeotechnicalReport. constructionjointshallbeindicatedbetween • thebottomofslabfilletandthetopofthe Providedetailsoftheselecteddrainagesystem backwall. on the bridge plans. Generally, the cost of 19.1(8) SUBSTRUCTURESANDBEARINGS August2002 2. In integral abutments, in addition to the construction joint indicated between the bottom ofslab fillet and the top ofthe backwall, a horizontal construction joint shallalsobeindicatedatbeamseat. 3. In free-standing abutments, a horizontal constructionjointshallbeindicatedonthe drawings between the top ofthe cap or footing and the bottom ofthe backwall. Some expansion joint types may require anotherconstructionjointatthebottomof thepavingnotch. 4. Inturnbackwings,ahorizontalconstruction jointshallbeindicatedatanelevationthe sameasthetopofthecap. Plannedverticalconstructionjointsarenormally associated with phase construction issues or perhapscloseproximitytoanexistingstructure. Provision needs to be made for splicing or mechanical rebar couplers on horizontal rsehionuflodrcbiengatslteeaesl.t75Vmermticfarlomretihnefocrocnisntgrucsttieoenl fVjVll joint. 19.1.11Concrete Use Class DD concrete for all substructure components.