钢管混凝土拱桥技术规范

Foreword

FollowingtherequirementsofNoticeonPrintingtheDevelopmentandRevisionPlanofNationalEngineeringConstructionStandardsin2011(JianBiao〔2011〕No.17)issuedbytheMinistryofHousingandUrban-RuralDevelopment,thecodecompilationorganizationsdeveloptheCodebasedonintensiveinvestigationandstudy,summaryofpracticeexperiences,reviewofrelevant'prominentinternationalstandards,andextensiveconsultation.

Thecodecomprises14chaptersandsupplementarycommentaryontheprovisions.Themaintechnicalcontentsinclude:GeneralProvisions;TermsandSymbols;Materials;BasicRequirements;CalculationforUltimateLimitStatesinPersistentSituations;CaleulationforServiceabilityLimitStatesinPersistentSituations;StructureandDetailing;FabricationofSteelTubesofArchRibs;Welding;CorrosionProtectionCoating;ErectionofSteelTubeArchRibs;FillingofConcrete;ConstructionofOtherStructures;Maintenance.

Theprovisionsthatareprintedinboldtypearemandatoryprovisionsandmustbeenforcedstrictly.

TheMinistryofHousingandUrban-RuralDevelopmentsisinchargeoftheadministrationoftheCodeandtheexplanationofthemandatoryprovisions.FuzhouUniversityisresponsiblefortheexplanationofspecifictechnicalcontents.Alrelevantorganizationsarekindlyrequestedtofeedbackanyquestions,commentsandsuggestionsassociatedwiththeimplementationoftheCodebythemanagementgroupoftheCodeinCollegeofCivilEngineeringatFuzhouUniversity(Address:No.2XueyuanRoad,UniversityTown,Minhou,Fuzhou,Fujian350108,China).

ChiefDevelopmentOrganizations:

FuzhouUniversity

CSCECStraitConstructionandDevelopmentCo.,Ltd

ParticipatingDevelopmentOrganizations:

ShenzhenMunicipalDesignandResearchInstituteCo.,Ltd

SichuanProvincialTransportDepartmentHighwayPlanning,Survey,DesignandResearchInstitute

GuangxiRoadandBridgeEngineeringCorporation

ResearchInstituteofHighwayMinistryofTransport

ChangshaUniversityofScienceandTechnology

Chang'AnUniversity

WuhanUniversityofTechnology

HarbinInstituteofTechnology

WuchuanHeavyEngineeringCo.,Ltd

ChiefDraftingStaff:

ChenBaochunWuPingchunWeijiangangWuQingxiongMouTingminChenYiyanChenGuanghuiDingQingjunRuanJiashunZhangJianrenZhaXiaoxiongZhangJinquanLiuYongjianJiaoAnliang

ChiefReviewingStaff:

ZhengJielianHuangQiaoFanWenliPengYuanchengMaBiao

XuYongZhaoLinqiangCaoRuiLongYue

·1·

Contents

1GeneralProvisions (1)

2TermsandSymbols (2)

2.1Terms (2)

2.2Symbols (3)

3Materials (7)

3.1Steel (7)

3.2Concrete (7)

3.3Concrete-FilledSteelTube (8)

3.4OtherMaterials (8)

4BasicRequirements (10)

4.1GeneralRequirements (10)

4.2Actions (11)

4.3StructuralCalculation (12)

5CalculationforUltimateLimitStatesinPersistentSituations (13)

5.1GeneralRequirements (13)

5.2StrengthCalculationforArchRibs (13)

5.3StabilityofArchRib (17)

5.4SuspendersandTies (20)

6CalculationforServiceabilityLimitStatesinPersistentSituations (22)

7StructureandDetailing (23)

7.1StructureTypes (23)

7.2MainArch (23)

7.3ArchSeatsandSpandrelColumns (26)

7.4SuspendersandTies (26)

7.5DeckSystem (27)

8FabricationofSteelTubesofArchRibs (28)

8.1FabricationofSteelTubes (28)

8.2AssemblingofSteelTubesofArchRibs (28)

8.3QualityInspectionforSteelTubeArchRibs (29)

9Welding (32)

10CorrosionProtectionCoating (34)

11ErectionofSteelTubeArchRibs (36)

11.1GeneralRequirements (36)

11.2ErectionandQualityInspectionofSteelTubeArchRibs (36)

12FillingofConcrete (38)

12.1GeneralRequirements (38)

12.2FillingofConcreteintoArchTubes (39)

·2·

12.3QualityInspectionafterFillingofConcrete (39)

13ConstructionofOtherStructures (41)

13.1GeneralRequirements (41)

13.2InstallationandQualityInspectionofSuspendersandTies (41)

14Maintenance (43)

14.1GeneralRequirements (43)

14.2InspectionandAssessment (43)

14.3MaintenanceofStructures (47)

ExplanationofWordinginThisCode (50)

ListofQuotedStandards (51)

·1·

1GeneralProvisions

1.0.1TheCodeisdevelopedtosatisfytherequirementsforbridgeengineeringconstructionandtoensurethatthedesign,constructionandmaintenanceofconcrete-filledsteeltubearchbridgesfollowstherequirementsforsafety,reliability,durability,practicability,technicaladvancement,andeconomicfeasibility.

1.0.2TheCodeisapplicabletothedesign,constructionandmaintenanceofconcrete-filledsteeltubearchbridgesinmunicipalandhighwayengineering.

1.0.3Thedesign,constructionandmaintenanceofconcrete-filledsteeltubearchbridgesshallnotonlycomplywiththeprovisionsspecifiedintheCode,butalsothosespecifiedinthecurrentrelevantnationalstandards.

·2·

2TermsandSymbols

2.1Terms

2.1.1Concrete-filledsteeltube(CFST)archbridge

Abridgewhosemainload-carryingcomponent(s)is(are)concrete-filledsteeltube(s)withacircularcross-section,whichserve(s)asrib(s)foranarch.

2.1.2CFSTarchrib

Anarchrib,whosemainload-carryingelement(s)is(are)concrete-filledsteeltube(s).

2.1.3Steeltubearchrib

Anarchribofahollowsteeltubewithoutfillingofconcreteinside.

2.1.4Concreteintube(coreconcrete)Concretethatisfilledinasteeltube.

2.1.5CFSTmember

AmemberthatismadeofCFST,inwhichthesteeltubeandtheconcretecoreactcompositelytoresistloads.

2.1.6Singletubearchrib

AnarchribthatisformedbyasingleCFSTmemberwithacircularsection.

2.1.7Dumbbell-shapedarchrib

AnarchribthatisformedbytwotopandbottomCFSTmemberswithcircularsectionconnectedbytwosteelwebplates.

2.1.8Trussarchrib

AnarchribthatisformedbytopandbottomCFSTchordsconnectedbywebmemberstoformtrusses.

2.1.9LacedCFSTcolumn

AlacedcolumnthatisformedbymultipleCFSTmembersconnectedtransverselybyhollowsteeltubes.

2.1.10Rigid-frametiedarch

Anarchstructurewhoseribisrigidlyconnectedtopiersandthehorizontalthrustispartiallybalancedbypre-stressedties.

2.1.11Rigid-frametiedthrougharch

Abridgestructurewhosedecksystemissuspendedbelowtherigid-frametiedarch.

2.1.12Rigid-frametiedhalf-througharch

Amulti-spanbridgestructurewhosedecksystematthemainspanispartiallysuspendedbelowtherigid-frametiedarch,whileitsdecksystemsattwosidespansaresupportedabovetwocantileverhalfarches.Thetiesareanchoredoneachendofthesidespans.Itisalsoknownasaflying-birdarch.

2.1.13Confinement(hooping)coefficient

Acoefficientaccountsfortheconfinementeffectofthesteeltubeontheconcretecore.

·3·

2.1.14InitialstressorPreloadingofsteeltube

TheinitialaxialstressinasteeltubecausedbyloadsduetosequentialconstructionproceduresbeforecompositeactionisfullyformedintheCFSTmembers,itisalsocalledinitialstressorpreloadingofCFST.

2.1.15Initialstressingratioorpreloadingratio

Theratioofpreloadingstresstotheyieldstressofthesteeltube.

2.1.16Computationalclosuretemperature

TheaveragetemperatureinthecrosssectionatthemomentofzerothermalstresswhichisconvertedfromthestressesintheCFSTarchribwhentheconcretecorereachesitsdesignstrength.

2.1.17Intersectionjoint

IntersectionlineweldingjointconnectingthemainCFSTtube(chord)withthebranchtube(webtruss).

2.1.18Debonding

Thephenomenonofseparationofthesteeltubefromtheconcretecorethatareattributedtofactorsotherthanqualityissuesincludingthermalgradientandshrinkageoftheconcretecore.

2.1.19Debonding(angle)rate

Thecentralangle(ratio)correspondingtothedebondingregioninthecrosssectionofCFSTmembers.

2.2Symbols

2.2.1Actions(loadsandresistances):

N——Designvalueofaxialforce;

N₁,N₂——Factoredaxialforcesonthetwotubesinadumbbell-shapedarchrib;M——Designvalueofsectionalmoment;

M₁,M₂——Factoredsectionalmomentsonthetwotubesinadumbbell-shapedarchrib;N——Designvalueofaxialcompressiveforcecombination;

S——Designvalueofcombinationofactions;

R——Designvalueofresistanceofacomponent;

R(·)——Loadresistancefunctionofacomponent;

V₁——Designvalueofaxialforceofwebtruss.

2.2.2Materialproperties:

(EA)s——DesigncompressivestiffnessofcompositesectionofCFSTarchrib;(EI)s——DesignflexuralstiffnessofcompositesectionofCFSTarchrib;

(EA)sc1———DesigncompressivestiffnessofgrosssectionofCFSTarchrib;

(EI)sc1——DesignflexuralstiffnessofgrosssectionofCFSTarchrib;

(EA)sc2——GrosscompositecompressivestiffnessofsingletubeCFSTmember;

(EI)sc2——GrosscompositeflexuralstiffnessofsingletubeCFSTmember;

E.——Elasticmodulusofconcrete;

E₅——Elasticmodulusofsteel;

fd——Designcompressivestrengthvalueofconcrete;

fck—Characteristiccompressivestrengthvalueofconcrete;

·4·

fa——Designstrengthvalueofmaterials;

fva——Designshearstrengthvalueofsteel;

fs——Designtensile,compressiveandbendingstrengthvaluesofsteel;

fa——Designtensilestrengthvalueofconcrete;

fik——Characteristictensilestrengthvalueofconcrete;

fy——Characteristicstrengthvalueofsteel;

G.——Shearmodulusofconcrete;

G₅——Shearmodulusofsteel;

N₀——DesignaxialcompressivestrengthofsingletubeCFSTsection;

Nó——DesignaxialcompressivestrengthofsingletubeCFSTsectionconsideringdebonding;

N——DesignaxialcompressivestrengthofeachCFSTsectioninthearchrib;

No——Designaxialcompressivestrengthoftheithtrussmemberintrussarchrib;

No₁——DesigncompressivestrengthofeccentricallyloadedsingletubeCFSTmember;

No₂——DesignstabilityresistanceofeccentricallyloadedsingletubeCFSTmember;

ND——Designcompressivestrengthofdumbbell-shapedorlacedCFSTmember;

Np——Designcompressivestrengthofeccentrically-loadeddumbbell-shapedorlacedCFSTmember;

ND₂——Designstabilityresistanceofeccentrically-loadeddumbbell-shapedorlacedCFSTmember;

N——DesigncompressivestrengthofconnectingsteelwebplatesthatshareloadswithmainCFSTchords;

fpk———Characteristictensilestrengthofsuspendersorties;

α——LongitudinalthermalexpansioncoefficientofCFSTarchribsubjecttouniformtemperaturedistributiononitssection;

αs——Thermalexpansioncoefficientofsteel;

αc——Thermalexpansioncoefficientofconcrete;

Ps——Densityofsteel;

μc——Poisson'sratioofconcrete;

μs——Poisson'sratioofsteel;

σ——Stressinsuspendersorties;

0o——Preloadingstressofsteeltube.

2.2.3Geometricparameters:

aa——Designgeometricparameter;

A——ConvertedareaofCFSTchordsection;

A₆——Totalsectionalareaofhorizontalwebtrussesbetweenadjacentjoints;

A.——Cross-sectionalareaofconcretecore;

Aa——Totalsectionalareaofdiagonalwebtrussesbetweenadjacentjoints;

A——Cross-sectionalareaofconnectingsteelplate;

A,——Cross-sectionalareaofsteeltube;

A——SectionalareaofCFSTcompositemember;

As——Cross-sectionalareaofsteeltubeinCFSTarchrib;

·5·

Ac——Cross-sectionalareaofconcretecoreinCFSTarchrib;

a——DistancefromthecenterofindividualCFSTmembertothevirtualaxisy-yinlacedCFSTcolumn;

b——DistancefromthecenterofindividualCFSTmembertothevirtualaxisx-xinlacedCFSTcolumn;

D——Outerdiameterofsteeltube;

d——Diameterofsuspendersorties;

eo——Loadeccentricity;

f——Riseofarch;

f₁——Riseofarchabovedecksystem;

h₁——Centraldistanceoftwochordsinbendingplaneofdumbbell-shapedorlacedCFSTcolumn;

h₂——Depthofwebplateofdumbbell-shapedCFSTsection;

H——Depthofthecrosssectionofarchrib;r——Calculatedradiusofcrosssection;

i——Cross-sectionalradiusofgyration;

I.——Secondmomentofareaofconcretecoresection;

I₈——Secondmomentofareaofsteeltubesection;

Ic——SecondmomentofareaofcompositesectionofCFST;Is₁——Secondmomentofareaofsteelsection;

Ic——Secondmomentofareaofconcretesection;l——Lengthofcomponent;

L——Calculatedspanofarchbridge;

lo——Calculatedlengthofcomponent;Lo——Clearspanofarchrib;

L₀——Equivalentcalculatedlengthofarchrib;La——Lengthofsuspender;

L₂——Straightlengthofarchribsegment;

lax——CalculatedlengthofacomponentrelativetoaxisX;

loy——CalculatedlengthofacomponentrelativetoaxisY;

l₁——DistancebetweenadjacentjointsoflacedCFSTcolumn;

l₂——Longitudinaldistancebetweenstiffenersalongthewebplatesofdumbbell-shapedarchrib;re——Radiusofcrosssectionofconcretecore;

S——Lengthofarchaxis;

t——Thicknessofsteeltubeorinitialsettingtimeofconcrete;T——Calculatedclosuretemperature;

T₀——Additionaltemperatureincrease;

T₂8——Averageairtemperatureduring28daysafterfillingofconcrete;Eb——Boundeccentricityratio;

0——Anglebetweentwoadjacentarchribsegments;△——Gapbetweenbranchtubesinajoint.

·6·

2.2.4Coefficientsincalculationandothers:

β——Preloadingratioofsteeltube;

50,5——DesignandcharacteristicconfinementcoefficientsofCFSTmember,respectively;p——Loadeccentricityratio;

pc——SteelratioofCFSTsection;

x——Calculationcoefficient;

μ——Slendernesscoefficient;

μo——ImpactcoefficientofvehicularloadforCFSTarchrib;

γo——Importancecoefficientofbridgestructure;

η1——SectionalflexuralstiffnessratioofindividualCFSTchordtothewholeCFSTmember;

φ——Stabilityfactor;

φe——Reductionfactorofeccentricityratio;

λ——NominalslendernessratioofCFSTmember;

λn——Relativeslendernessratio;

λ*——ConvertedslendernessratiooflacedCFSTcolumn;

λ₁——NominalslendernessratioofindividualchordoflacedCFSTcolumn;

λ,λ,——NominalslendernessratiooflacedCFSTcolumnrelativetoX-axisandY-axis,respectively;

a——CoefficientconsideringtheeffectsofslendernessratiowhencalculatingtheresistanceofpreloadedCFSTmembersatultimatelimitstate;

fo——FrequencyofthefirstverticalmodeofvibrationofaCFSTarchbridge;

k——ReductionfactorforcreepoftheloadcapacityofCFSTmember;

K,——Influencefactorforpreloadingratio;

k₁——Loadfactor;

k₂——Trafficlanecoefficient;

k₃—Conversioncoefficientofdesignaxialcompressivestrength;

K——ReductionfactorforloadcapacityofCFSTwithdebonding;

K——Coefficientforconvertedslendernessratio;

K′——Correctionfactorforconvertedslendernessratio;

m——CoefficientconsideringtheinfluenceofeccentricityincalculatingtheresistanceofpreloadedCSFTmemberatultimatelimitstate;

n——NumberofchordsinCFSTtrussarchrib;

V——Ratedspeedoftransmissionpump;

Q——Volumeoffillingconcreteintube.

·7·

3Materials

3.1Steel

3.1.1ThesteeltubeusedinCFSTarchribsshouldbecarbonorlowalloyhighstrengthstructuralsteelofGradeBorabove.ThesteelqualityshallcomplywiththeprovisionsincurrentnationalstandardsGB/T700CarbonStructuralSteelsorGB/T1591HighStrengthLowAlloyStructuralSteels.

3.1.2Steeltubesmayuserolledweldedtubesorseamlesssteeltubes.Whenevertherequirementofrollingissatisfied,straightseamweldedtubesshouldbeused.

3.1.3MainmechanicalpropertiesofsteelshallbeinaccordancewiththosespecifiedinTable3.1.3.

Table3.1.3Mechanicalpropertiesofsteel

Grade

Thicknessordiameter(mm)

Designstrength(N/mm²)

Characteristicstrength

f,(N/mm²)

Tensile,compressiveandflexuralstrengthf₃

Shearstrengthfd

Q235

≤16

>16-40>40—100

190

180

170

110

105

100

235

225

215

Q345

≤16>16-40

>40-63

275/270260

160

155

150

345

325

295

Q390

≤16

>16=40

>40-63

310

295

280

180

170

160

390

370

350

3.1.4ThephysicalpropertiesofsteelspecifiedinTable3.1.4maybeused.

Table3.1.4Physicalpropertiesofsteel

Elasticmodulus

E,(N/mm²)

ShearmodulusG;(N/mm²)

Thermalexpansion

coefficienta(1/°C)

Densityps(kg/m³)

Poisson'sratio

μs

2.06×10⁵

7.90×10⁴

1.20×10-5

7.85×10³

0.30

3.2Concrete

3.2.1ThegradeofconcreteusedinCFSTarchribsshallnotbelowerthanC30,andshouldbeGradesC40-C60.

3.2.2Thecharacteristicaxialcompressivestrengthfek,designaxialcompressivestrengthfea,characteristicaxialtensilestrengthfik,designaxialtensilestrengthfaandelasticmodulusEoftheconcreteshallbeinaccordancewiththosespecifiedinTable3.2.2.TheshearmodulusG₆oftheconcretemaybetakenas40%oftheelasticmodulusE。specifiedinTable3.2.2.ThePoisson'sratioμeofconcretemaybeassumedtobe0.2.

·8·

Table3.2.2Strengthsandelasticmodulusofconcrete(N/mm²)

StrengthGrade

Axialcompressivestrength

Axialtensilestrength

Elasticmodulus

E.

Characteristicvaluefek

Designvaluefd

Characteristicvaluefik

Designvaluefua

C30

20.10

14.30

2.01

1.43

3.00×10⁴

C35

23.40

16.70

2.20

1.57

3.15×10⁴

C40

26.80

19.10

2.39

1.71

3.25×10⁴

C45

29.60

21.10

2.51

1.80

3.35×10⁴

C50

32.40

23.10

2.64

1.89

3.45×10⁴

C55

35.30

25.30

2.74

1.96

3.55×10⁴

C60

38.50

27.50

2.85

2.04

3.60×10⁴

3.3Concrete-FilledSteelTube

3.3.1Thefollowingcombinationsofsteeltubeandconcretemaybeused:

1Q235steelmatchedwithconcreteofGradeC30-C40;

2Q345steelmatchedwithconcreteofGradeC40-C60;

3Q390steelmatchedwithconcreteofGradeC60orabove.

3.3.2Thewallthicknessofsteeltubesshallnotbelessthan8mm.TheratiooftheouterdiameterDtothewallthicknesstofsteeltubesshouldbeintherangeof35×(235/月)-100×(235/f,).ThecharacteristicstrengthvalueofsteelfshallcomplywiththeprovisionsinTable3.1.3.

3.3.3ThedesignconfinementcoefficientofCFST5。shouldnotbelessthan0.60.Thesectionalsteelratiopeshouldbeintherangeof0.04-0.20.Theparametersof5oandp.shallbecalculatedbyusingthe

followingformulae:

(3.3.3-1)

(3.3.3-2)

Where,50——DesignconfinementcoefficientofCFST;

pc——SectionalsteelratioofCFST;

A,——Sectionalareaofsteeltube;

A.——Sectionalareaofconcretecore;

fs——Designtensile,compressiveandflexuralstrengthvaluesofsteel;fa——Designcompressivestrengthvalueofconcrete.

3.4OtherMaterials

3.4.1Highstrengthsteelwiresusedforsuspendersandtiesshouldbecomprisedofd5mmorφ7mmhigh-strengthhot-dipgalvanizedsteelwires.Theircharacteristicstrengthshouldnotbelessthan1670N/mm².ThematerialpropertiesshallcomplywiththeprovisionsinthecurrentnationalstandardGB/T17101Hot-DipGalvanizedSteelWiresforBridgeCables.

3.4.2Steelstrandsusedforsuspendersandtiesshouldbehigh-strengthlow-relaxationprestressinggalvanizedorothercorrosion-protectedsteelstrands.Theircharacteristicstrengthshouldnotbelessthan1860N/mm².ThematerialpropertiesshallcomplywiththeprovisionsinthecurrentnationalstandardGB/T5224SteelStrandforPrestressedConcrete.

·9·

3.4.3Anchoragedevicesforsuspenders,tiesandotherconnectionsshallincorporatehigh-qualitycarbonstructuralsteeloralloystructuralsteel.Theirmechanicalperformanceshallcomplywiththeprovisionsintherelevantnationalstandards.Theprotectivematerialsusedforsuspendersandtiesshallnotcontaincorrosiveingredients.

·10·

4BasicRequirements

4.1GeneralRequirements

4.1.1ThelimitstatedesignmethodbasedontheprobabilitytheoryisadoptedintheCode,inwhichdesigncalculationisconductedaccordingtothedesignformulaeofpartialsafetyfactors.

4.1.2CFSTarchbridgesshallbedesignedaccordingtothefollowingtwolimitstates:

1UltimateLimitState(ULS):AstatethataCFSTarchbridgeoranyofitscomponentsachievesthemaximumload-carryingcapacityorthedeformation/displacementthatfailstocarryloading.

2ServiceabilityLimitState(SLS):AstatethataCFSTarchbridgeoranyofitscomponentsachievesacertainspecifiedlimitfornormaluseordurability.

4.1.3CFSTarchbridgesshallbedesignedtofulfiltheultimatelimitstateandserviceabilitylimitstaterequirementsinpersistentsituations.

4.1.4SeismicdesignofCFSTarchbridgesshallcomplywiththeprovisionsinthecurrentprofessionalstandardsCJJ166CodeforSeismic,DesignofUrbanBridgesorJTG/TB02-01GuidelinesforSeismicDesignofHighwayBridges.

4.1.5ForconnectionsbetweensteelstructuresandsteelcomponentsofCFSTarchbridges,includingthesteeltubearchstructurepriortotheconcretecorereachingitsdesignstrengthattheconstructionstage,theirresistance,deformationcapacityandstabilityshallbedesignedandcalculatedaccordingtosteelbridgestructuredesignandinaccordancewithrelevantcurrentnationalstandards.

4.1.6DuringthedesignofCFSTarchbridges,theconstructionscheme,mainconstructionsequences,qualityrequirementsandallowableunbalancedactionsduringconstructionshallbedeterminedbasedonlocalgeology,transportationandotherconstructionconditions.Thesequencesofstructuralsystemtransformationandtheassociatedmeasuresshallbeclearlydecided.

4.1.7DuringthedesignofCFSTarchbridges,thefollowingcalculationsforeachstageofconstructionshallbecarriedout:

1Stress,deformationandstabilityofarchribcomponentsduringtransportationandassembling;

2Structuralbehaviorofsecondarystructuresassociatedwiththefabricationofarchrib,suchasribhinges,buckles,segmentaljoints,etc.;

3Stress,deformationandstabilityofarchribintheprocessofformation;

4Stress,deformationandstabilityofbridgestructureintheprocessofformation.

4.1.8Calculationforconstructionshalltakeintoaccountpotentialactualactions,includingequipmentandmaterialsforerection,constructionstaff,stackedloadsondeck,aswellaswindload,thermalloadandothertemporaryconstructionloads.Theeigenvalueofelasticstructuralstabilityduringconstructionshallnotbelessthan4.0.

4.1.9CFSTarchrib,horizontalbars,spandrelcolumnsanddeckingbeamsshallbedesignedtosatisfytherequirementsofinspection,maintenanceandrepairinservice.

4.1.10CorrosionprotectionsolutionsforsteelstructuresofCFSTarchbridgesshallbedesignedaccordingtolocalatmosphericenvironment.Theirrepair-freeperiodshallbeatleast15years.The

·11·

corrosionprotectionsystemshouldbedesignedbyconsideringtheexposureenvironmentofabridgeanditsdifferentparts.Therequirementsforgradeofsurfacerustcleaning,surfacecleanliness,surfaceroughness,etc.shallfollowwiththecurrentprofessionalstandardJT/T722SpecificationsofProtectiveCoatingforHighwayBridgeSteelStructure.

4.1.11Requirementsforwater-proofing,drainageanddurabilityofotherstructuralcomponentsofCFSTarchbridgesshallcomplywithrelevantcurrentnationalstandards.

4.1.12BeforeconstructionofCFSTarchbridges,specifictechnicalschemesforconstructionandsafetyshallbedeterminedforeachkeyconstructionprocedure.

4.1.13Theconstructionprocessoflong-spanCFSTarchbridgesshallbemonitoredandcontrolledtoensurethatthearchaxis,internalforces,tensileforcesinsuspendersandties,preloadingstresses,andsoonsatisfythedesignrequirements.

4.2Actions

4.2.1Classificationofactions,combinationofactioneffectsandcalculationforactionsinCFSTarchbridgesshallcomplywithnotonlytheprovisionsintheCode,butalsothoseinthecurrentprofessionalstandardsCJJ11CodeforDesignoftheMunicipalBridgeorJTGD60GeneralSpecificationsforDesignofHighwayBridgesandCulvertsaccordingtodifferentengineeringprojects.

4.2.2VehicularloadimpactcoefficientμoforCFSTarchribsmaybecalculatedbyusingthefollowingequation:

μo=0.05736f+0.0748(4.2.2)

Where,f——FrequencyofthefirstverticalmodeofvibrationoftheCFSTarchbridge(Hz).

4.2.3ThedeformationorsecondarystressesinCFSTarchduetothetemperaturevariationshallbedeterminedbasedonlocalairtemperature,bridgestructure,constructionaldesign,etc..Thecharacteristicvaluesofthermalexpansioncoefficientandactionmaybecalculatedinaccordancewiththefollowingprovisions:

1TheaxialthermalexpansioncoefficientaofaCFSTarchribsubjectedtouniformsectionaltemperaturedistributionmaybecalculatedbythefollowingequation:

(4.2.3-1)

Where,αs——Thermalexpansioncoefficientofsteel(1/℃),a₅=1.2×10-5/℃;

αc——Thermalexpansioncoefficientofconcrete(1/℃),αc=1.0×10-5/℃.

2ForcalculationofadditionalorconstraineddeformationofCFSTarchduetothevariationofuniformsectionaltemperature,thecalculatedclosuretemperatureTshallbetakenasthereferencetemperature,andeffectsofthehighestandlowesteffectivetemperatureactionsareconsidered.

3ThecalculatedclosuretemperatureTmaybecalculatedbythefollowingequation:

(4.2.3-2)Where,T₂₈——Averageairtemperatureduring28daysafterfillingofconcrete(℃);

D——Outerdiameterofsteeltube(m);

T₀——Additionaltemperatureincreaseconsideringtheeffectofhydrationheatofconcretecore,whichisintherangeof3.0°C-5.0°C.Thelowervalueistakenforwinterconstructionandthehigheroneforsummerconstruction.Ifthegradeofconcreteis

·12·

lowerthanC40,thecalculatedclosuretemperaturecanbereducedby1.0℃.

4Thehighestandlowesteffectivetemperaturesmayusethehighestandlowestlocalairtemperatures.

4.2.4Whencalculatingthedeformationandsecondarystres