Cable Supported Bridges: Concept and Design

592 Pages·2012·13.109 MB·English

by  Niels J. Gimsing, Christos T. Georgakis

Cable Supported Bridges
Cable Supported Bridges
Concept and Design, Third Edition
NIELS J. GIMSING
CHRISTOS T. GEORGAKIS
Department of Civil Engineering
Technical University ofDenmark
Thiseditionfirstpublished2012
(cid:2)2012,JohnWiley&Sons,Ltd
FirstEditionpublishedin1983
SecondEditionpublishedin1997
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LibraryofCongressCataloguing-in-PublicationData
Gimsing,NielsJ.
Cablesupportedbridges:conceptanddesign/NielsJ.Gimsing,ChristosT.
Georgakis.—3rded.
p.cm.
Includesbibliographicalreferencesandindex.
ISBN978-0-470-66628-9(cloth)
1. Cable-stayedbridges. 2. Suspensionbridges. I. Georgakis,ChristosT.
II. Title.
TG405.G552012
624.2038—dc23
2011024092
AcataloguerecordforthisbookisavailablefromtheBritishLibrary.
Setin9/11pt,TimesRomanbyThomsonDigital,Noida,India
Contents
PrefacetotheThirdEdition ix
Introduction 1
1 EvolutionofCableSupportedBridges 7
2 Cables 85
2.1 BasicTypesofCables 85
2.1.1 Helicalbridgestrands(spiralstrands) 85
2.1.2 Locked-coilstrands 87
2.1.3 Parallel-wirestrandsforsuspensionbridgemaincables 88
2.1.4 NewPWSstaycables 90
2.1.5 Parallel-strandstaycables 91
2.1.6 Barstaycables 93
2.1.7 Multi-strandstaycables 94
2.1.8 Parallel-wiresuspensionbridgemaincables 97
2.1.9 Comparisonbetweendifferentcabletypes 101
2.2 CorrosionProtection 102
2.2.1 Suspensionbridgemaincables 102
2.2.2 Staycables 105
2.3 MechanicalProperties 109
2.3.1 Staticstrength 109
2.3.2 Relaxation 111
2.3.3 Fatiguestrength 111
2.3.4 Hysteresisofhelicalstrands 113
2.4 TheSingleCableasaStructuralElement 115
2.4.1 Transversallyloadedcable 115
2.4.2 Axiallyloadedcable 126
2.5 StaticAnalysisofCables 131
2.5.1 Equationofstateforacablesubjectedtoverticalload 132
2.5.2 Staycableundervaryingchordforce 135
2.5.3 Limitlengthandefficiencyratioofastaycable 143
2.6 BendingofCables 148
2.7 DynamicBehaviouroftheSingleCable 157
vi Contents
3 CableSystem 165
3.1 Introduction 165
3.1.1 Purecablesystems 165
3.1.2 Cablesteelquantitycomparison 170
3.1.3 Stabilityofthecablesystem 173
3.2 SuspensionSystem 179
3.2.1 Deadloadgeometry 179
3.2.2 Preliminarycabledimensions 180
3.2.3 Quantityofcablesteel 182
3.2.4 Quantityinthepylon 184
3.2.5 Totalcostofcablesystemandpylon 185
3.2.6 Optimumpylonheight 185
3.2.7 Sizeeffect 187
3.2.8 Structuralsystems 188
3.3 FanSystem 202
3.3.1 Anchorcable 202
3.3.2 Preliminarycabledimensions 205
3.3.3 Quantityofcablesteel 206
3.3.4 Quantityinthepylon 208
3.3.5 Simplifiedexpressions 208
3.3.6 Totalcostofcablesystemsandpylons 209
3.3.7 Comparisonbetweensuspensionandfansystem 209
3.3.8 Inclinedpylons 210
3.3.9 Deformationalcharacteristics 213
3.3.10 Structuralsystems 217
3.3.11 Reductionofsagvariations 221
3.4 HarpSystem 222
3.4.1 Deadloadgeometry 225
3.4.2 Intermediatesupports 226
3.4.3 Preliminarycabledimensions 227
3.4.4 Quantityofcablesteel 229
3.4.5 Quantityofthepylon 229
3.4.6 Simplifiedexpressions 231
3.4.7 Totalcost 231
3.4.8 Structuralsystems 231
3.5 HybridSuspensionandCableStayedSystem 235
3.6 Multi-SpanCableSystem 239
3.6.1 Truemulti-spancablesupportedbridges 241
3.6.2 Non-traditionalmulti-spansuspensionbridges 246
3.6.3 Fixingofcolumn-typepylonstopiers 249
3.6.4 Triangularpylonstructures 250
3.6.5 Horizontaltiecablebetweenpylontops 258
3.6.6 Comparisonbetweendeflectionsofdifferentmulti-spancablestayedsystems 261
3.7 CableSystemsunderLateralLoading 265
3.8 SpatialCableSystems 272
3.9 OscillationofCableSystems 278
3.9.1 Globaloscillations 278
4 Deck(StiffeningGirder) 287
4.1 ActionoftheDeck 287
4.1.1 Axialstiffness 287
Contents vii
4.1.2 Flexuralstiffnessintheverticaldirection 287
4.1.3 Flexuralstiffnessinthetransversedirection 289
4.1.4 Torsionalstiffness 291
4.2 SupportingConditions 291
4.3 DistributionofDeadLoadMoments 299
4.3.1 Thedeadloadcondition 302
4.4 CrossSection 310
4.4.1 Bridgefloor 310
4.4.2 Crosssectionofthedeck 310
4.4.3 Crosssectionofstiffeningtrusses 328
4.5 PartialEarthAnchoring 339
4.5.1 Limitofspanlengthforself-anchoredcablestayedbridges 343
4.5.2 Axialcompressioninthedeckoftheselfanchoredcablestayedbridge 344
4.5.3 Lateralbendingofthedeck 346
4.5.4 Partialearthanchoringofacablestayedbridge 346
4.5.5 Improvingthelateralstability 348
4.5.6 Constructionprocedureforpartiallyearthanchoredcablestayedbridges 349
5 Pylons 353
5.1 Introduction 353
5.2 StructuralBehaviourofthePylon 353
5.3 PylonsSubjectedPrimarilytoVerticalForcesfromtheCableSystem 367
5.4 PylonsSubjectedtoLongitudinalForcesfromtheCableSystem 399
5.5 CrossSection 405
6 CableAnchorageandConnection 413
6.1 AnchoringoftheSingleStrand 413
6.2 ConnectionbetweenCableandDeck 427
6.3 ConnectionbetweenMainCableandHanger 433
6.4 ConnectionbetweenCableandPylon 442
6.5 ConnectionbetweenCableandAnchorBlock 452
7 Erection 463
7.1 Introduction 463
7.2 ConstructionofPylons 463
7.3 ErectionofSuspensionBridgeMainCables 472
7.4 ErectionofStayCables 486
7.5 DeckErection-EarthAnchoredSuspensionBridges 489
7.6 DeckErection-SelfAnchoredCableStayedBridges 501
8 Aerodynamics 517
8.1 HistoricalOverview 517
8.1.1 Nineteenth-centurybridgefailures 517
8.1.2 TacomaNarrowsBridgecollapse 517
8.1.3 TheCarmodyBoard 520
8.1.4 TheFyksesundBridge 520
8.2 TheBridgeDeckandPylon 520
8.2.1 Torsionaldivergence 520
8.2.2 Coupledflutter 524
8.2.3 Buffeting 526
viii Contents
8.2.4 Vortex-shedding 531
8.2.5 Windtunneltesting 532
8.2.6 Duringconstruction 537
8.2.7 Effectsofvehicles 538
8.2.8 Pylonaerodynamics 538
8.2.9 Vibrationcontrol 541
8.2.10 Futuretrends 543
8.3 Cables 544
8.3.1 Introduction 544
8.3.2 Incidencesofwind-inducedcablevibrations 544
8.3.3 Rain-wind-inducedvibrations 545
8.3.4 Drygalloping 546
8.3.5 Scrutonnumber 549
8.3.6 Wakegalloping 550
8.3.7 Aerodynamiccountermeasures 551
8.3.8 Mechanicaldamping 583
8.3.9 Cableaerodynamicdamping 557
8.3.10 Crossties 557
9 ParticularIssues 559
9.1 Pedestrian-InducedVibrations 559
9.1.1 Lateralvibrations 559
9.1.2 Verticalvibrations 562
9.1.3 Serviceabilitylimitstates 565
9.1.4 Vibrationcontrol 567
9.2 SeismicDesign 568
9.2.1 Earthquakeintensity 569
9.2.2 Pylondesign 569
9.2.3 Deckdesign 571
9.2.4 Foundations 571
9.2.5 Seismicanalysis 572
9.3 StructuralHealthMonitoring 573
9.3.1 Equipment 573
9.4 SnowandIceRemovalandPreventionSystems 575
9.4.1 Mechanicalremoval 575
9.4.2 Thermalsystems 577
9.4.3 Passiveprotection 577
References 579
Index 587
Preface to the Third Edition
ThedecisiontoprepareamanuscriptforabooktitledCABLESUPPORTEDBRIDGESwastakenbyNielsJ.Gimsing
in 1980 following his three year affiliation as an adviser on bridge technology to Statsbroen Store Bœlt—the client
organizationestablishedtodesignandconstructabridgeacrossStorebælt(GreatBelt)inDenmark.Duringthedesign
periodfrom1976to1979,alargenumberofdifferentdesignsforcablestayedbridges(withspansupto850m)and
suspensionbridges(withspansupto1800m)werethoroughlyinvestigatedanditwasduringthatperiodtheideamatured
towriteabookcoveringbothcablestayedbridgesandsuspensionbridges.Thechancetopreparethemanuscriptcamein
1979whentheDanishGovernmentdecidedtopostponetheconstructionoftheStorebæltBridgeandtokeepthedesign
workatrestforaperiodoffiveyears.
ThemanuscriptfortheFirstEditionwascompletedin1982andthebookwaspublishedin1983.
ThedecisiontoprepareamanuscriptforaSecondEditionwastakenin1994whenNielsJ.Gimsingwasinvolvedin
thedesignofboththe1624mmainspanoftheStorebæltEastSuspensionBridgeandthe490mmainspanoftheØresund
cablestayedbridge.Bothbridgeswereunderconstructionduringthewritingofthemanuscript(from1994–1996)andso
usefulinformationonconstructionissuescouldbecollected.
TheSecondEditionwaspublishedin1997;fourteenyearsaftertheFirstEditionappeared.
TheSecondEditionwassoldoutfromthepublisherafteronly5yearsonthemarket,soaThirdEditionbecamedesirable,
andinitiallyitwasanticipatedthatthiswouldbejustasimpleupdatingoftheSecondEdition.However,whendigging
deeperintothematteritbecameevidentthataconsiderableevolutionhadtakenplaceduringthedecenniumfollowing
thepublishingoftheSecondEdition.Verynotablecablesupportedbridgeshadbeenconstructedandanumberofdesign
issuesrelatedprimarilytodynamicactionshadgainedinprominence.
Itwas,therefore,realizedthattheThirdEditionhadtobemorethanjustasimpleupdatingoftheSecondEdition.To
emphasizetheimportanceofissuespertainingtodynamicactionsandhealthmonitoringitwasdecidedthattwonew
chapterswouldbeadded.Withhisyearsofexperiencewithinthefield,ChristosT.Georgakiswasentrustedwiththistask.
TheThirdEditionispublishedin2011;fourteenyearsaftertheSecondEditionappeared.
Besidesrevisionsandadditionsinthetextitwasalsodecidedtoupdatethefiguresbypreparingtheminelectronic
versionsthatcouldbemoreeasilyeditedtoappearinauniformmannerthroughoutthepublication.Thefinancialsupport
tocovertheexpensesforthefigureupdatingcamefromtheCOWIFoundation.ThefigureswereupdatedbyKristian
NikolajGimsing.
IntheprocessofpreparingtheThirdEdition,highlyappreciatedcontributionscamefromProfessorYozoFujinoofthe
University of Tokyo, on matters relating to structural health monitoring and structural control, and from Professor
FrancescoRicciardellioftheUniversityofReggioCalabria,onmatterspertainingtobridgeaerodynamics.PhDstudent
JoanHeeRoldsgaardhelpedgreatlywiththepreparationofelementsofChapters8and9andfortheproofcorrectingofthe
book.Ourgreatappreciationisalsoextendedtoallthosewhoprovidedpictures,figuresandcopyrightpermissions.They
aretoomanytomentionhere.
NielsJ.GimsingandChristosT.Georgakis
TechnicalUniversityofDenmark
June2011
Introduction
Inthefamilyofbridgesystemsthecablesupportedbridgesaredistinguishedbytheirabilitytoovercomelargespans.
Atpresent,cablesupportedbridgesareenabledforspansintherangefrom200mto2000m(andbeyond),thuscovering
approximately90percentofthepresentspanrange.
Forthevastmajorityofcablesupportedbridges,thestructuralsystemcanbedividedintofourmaincomponentsas
indicatedinFigure0.1:
(1) thedeck(orstiffeninggirder);
(2) thecablesystemsupportingthedeck;
(3) thepylons(ortowers)supportingthecablesystem;
(4) theanchorblocks(oranchorpiers)supportingthecablesystemverticallyandhorizontally,oronlyvertically,atthe
extremeends.
Pylon (or Tower)
Cable System
Deck (or Stiffening Girder)
Anchor Pier or Anchor Block
Figure0.1 Maincomponentsofacablesupportedbridge
Thedifferenttypesofcablesupportedbridgesaredistinctivelycharacterizedbytheconfigurationofthecablesystem.
Thesuspensionsystem(Figure0.2)comprisesaparabolicmaincableandverticalhangercablesconnectingthedeckto
themaincable.Themostcommonsuspensionbridgesystemhasthreespans:alargemainspanflankedbyshorterside
spans.Thethree-spanbridgeisinmostcasessymmetricalwithsidespansofequalsize,butwherespecialconditionsapply,
thesidespanscanhavedifferentlengths.
Incaseswhereonlyonelargespanisneeded,thesuspensionbridgemayhaveonlythemainspancablesupported.
However,totransmitthehorizontalcomponentofthemaincablepullactingatthepylontops,themaincablewillhaveto
continueasfreebackstaystotheanchorblocks.
Asingle-spansuspensionbridgewillbeanaturalchoiceifthepylonsareonlandorclosetothecoasts/riverbankssothat
thetrafficlaneswillcontinueonviaductsoutsidethepylons.
CableSupportedBridges:ConceptandDesign,ThirdEdition.NielsJ.GimsingandChristosT.Georgakis.
(cid:2)2012JohnWiley&Sons,Ltd.Published2012byJohnWiley&Sons,Ltd.
2 CableSupportedBridges:ConceptandDesign
0.2-0.5 L L L
Figure0.2 Suspensionbridgesystemswithverticalhangersandcablesupportofthreespans(top)oronlythemainspan(bottom)
Fan System
0.2-0.4 L L 0.2-0.4 L
Semi-Fan System
Harp System
0.3-0.45 L L 0.3-0.45 L
Figure0.3 Cablestayedbridgesystems:(top)purefansystem;(centre)semi-fansystem;(bottom)harpsystem
Thecable-stayedsystem(Figure0.3)containsstraightcablesconnectingthedecktothepylons.Inthefansystem,all
staycablesradiatefromthepylontop,whereasparallelstaycablesareusedintheharpsystem.
Besidesthetwobasiccablestayedsystems(thefansystemandtheharpsystem),intermediatesystemsareoftenfound.In
thesemi-fansystem,thecableanchoragesatthepylontoparespreadsufficientlytoseparateeachcableanchorageand
therebysimplifythedetailing.Withcableanchoragespositionedatminimumdistancesatthepylontop,thebehaviourof
thesemi-fansystemwillbeveryclosetothatofthepurefansystem.
Thestaycableanchoragesatthedeckwillgenerallybespacedequidistantlysoincaseswherethesidespansareshorter
thanhalfofthemainspan,thenumberofstaycablesleadingtothemainspanwillbegreaterthanthenumberofstaycables
leadingtothesidespan.Inthatcasetheanchorcablefromthepylontopstotheanchorpierswilloftenconsistofseveral
closelyspacedindividualcables(asshownforthesemi-fansystem).
Intheharpsystem,thenumberofcablesleadingtothemainspanwillhavetobethesameasinthesidespans.Withthe
anchorpierpositionedattheendofthesidespanharp,thelengthofthesidespanwillbeveryclosetohalfofthemainspan
length.Thatmightproveinconvenientinrelationtotheoverallstiffnessofthesystem.Itcanthenbeadvantageousto
positiontheanchorpierinsidethesidespanharpasindicatedinFigure0.3.
Thepositionoftheanchorpierclosertothepyloncanalsoprovefavourableinafansystem,ifdesignedwithfansofequal
sizeinthemainandsidespans(Figure0.4).