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Model Code for
Service Life Design
Model code prepared by
Task Group 5.6
February 2006
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Subject to priorities defined by the Steering Committee and the Presidium, the results of fibs work inCommissions and Task Groups are published in a continuously numbered series of technical publications
called 'Bulletins'. The following categories are used:
category minimum approval procedure required prior to publication
Technical Report approved by a Task Group and the Chairpersons of the Commission
State-of-Art Report approved by a Commission
Manual or
Guide (to good practice)
approved by the Steering Committee of fibor its Publication Board
Recommendation approved by the Council of fibModel Code approved by the General Assembly of fib
Any publication not having met the above requirements will be clearly identified as preliminary draft.
This Bulletin N 34 will be submitted to the General Assembly for approval as anfibModel Code in June 2006.
This report was prepared within Task Group 5.6,Model code for service life design of concrete structures:
Peter Schiessl (Convener, Technische Universitt, Mnchen, Germany)
Phil Bamforth (Principal Construction Consultancy, UK), Vronique Baroghel-Bouny (LCPC, France),
Gene Corley (Construction Technology Laboratories, Inc., USA), Michael Faber (ETH-Zrich,
Switzerland), Jim Forbes (Hyder Consulting, Australia), Christoph Gehlen (Ingenieurbro Schiessl,Germany), Paulo Helene (Univ. de Sao Paulo PCC/USP, Brazil), Steinar Helland (Skanska Norge AS,
Norway), Tetsuya Ishida (Univ. of Tokyo, Japan), Gro Markeset (Norwegian Building Research Institute,
Norway), Lars-Olof Nilsson (Lund Institute of Technology, Sweden), Steen Rostam (Cowi A/S,
Denmark), A.J.M. Siemes (TNO, The Netherlands), Joost Walraven (Delft Univ. of Technology, The
Netherlands)
Full address details of Task Group members may be found in the fibDirectory or through the online services onfib'swebsite, www.fib-international.org.
Cover images: The photos show the carbonation depth of a vertical concrete surface of an existing building after
8 years of exposure without shelter from rain. A phenolphthalein indicator distinguishes areas
with pH < 9.5 (not coloured) and areas with a higher pH (coloured). The graph shows the
development of the carbonation depth over time, xc(t), compared to the cover depth, a. Scatter of
both variables is also given.
fdration internationale du bton (fib), 2006
Although the International Federation for Structural Concrete fib- fderation internationale du bton - createdfrom CEB and FIP, does its best to ensure that any information given is accurate, no liability or responsibility ofany kind (including liability for negligence) is accepted in this respect by the organisation, its members, servantsor agents.
All rights reserved. No part of this publication may be reproduced, modified, translated, stored in a retrievalsystem, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, orotherwise, without prior written permission.
First published in 2006 by the International Federation for Structural Concrete (fib)Post address: Case Postale 88, CH-1015 Lausanne, SwitzerlandStreet address: Federal Institute of Technology Lausanne - EPFL, Section Gnie CivilTel +41 21 693 2747, Fax +41 21 693 6245, E-mail [email protected], web www.fib-international.org
ISSN 1562-3610
ISBN 2-88394-074-6
Printed by Sprint-Digital-Druck, Stuttgart
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fibBulletin 34: Model code for Service Life Design iii
Contents
Preface iv
0 Introduction 1
1 General 5
1.1 Scope 51.2 Associated codes 5
1.3 Assumptions 5
1.4 Definitions 6
1.5 Symbols 10
2 Basis of design 12
2.1 Requirements 12
2.2 Principles of limit state design 14
2.3 Basic variables 14
2.4 Verification 16
3 Verification of Service Life Design 20
3.1 Carbonation induced corrosion uncracked concrete 20
3.2 Chloride induced corrosion uncracked concrete 23
3.3 Influence of cracks upon reinforcement corrosion 24
3.4 Risk of depassivation with respect to pre-stressed steel 25
3.5 Freeze/thaw attack without de-icing agents 25
3.6 Freeze/thaw attack with de-icing agents 27
4 Execution and its quality management 29
4.1 General 29
4.2 Project specification 29
4.3 Quality management 304.4 Materials 31
4.5 Geometry 32
5 Maintenance and condition control 33
5.1 General 33
5.2 Maintenance 33
5.3 Condition control during service life 33
5.4 Action in the event of non-conformity 34
Annex A (informative)
Management of reliability for Service Life Design of concrete structures 36Annex B (informative)
Full probabilistic design methods 44
Annex C (informative)
Partial factor methods 83
Annex R (informative)Reliability management: from SLS to ULS 90
References 109
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fibBulletin 34: Model code for Service Life Design v
Preface
fiband its preceding organizations, CEB and FIP, have a long tradition in treating durability aspects and
to design for them. In 1978 CEB created a first working group, the Task Group Durability. Milestones in
the CEB and FIP work on durability are CEB Bulletins 148 Durability of concrete structures, 182
Durable concrete structures and 238 New approach to durability design. In the latter document the
framework for a probabilistic design approach was set. In 2002 fibestablished Task Group 5.6 Model codefor service life design of concrete structures with the objective to develop a model code document on
probabilistic service life design. The approach developed in this document is intended to be the basis for the
service life design approach of the newfibModel Code, currently under development. Furthermore it might
serve as a basis for further work in ISO (TC 71) and CEN (TC 104 and TC 250/SC2).
The following members of Task Group 5.6 actively contributed to the work (in alphabetic order):
Veronique BAROGHEL BOUNY
Phil BAMFORTH
Gene CORLEY
Michael Havbro FABER Christoph GEHLEN* (secretary)
Paulo HELENE
Steinar HELLAND*
Tetsuya ISHIDA
Gro MARKESET
Lars Olof NILSSON*
Steen ROSTAM
Peter SCHIESSL* (Convener)
*Members of the Drafting Board
The format of this Model Code follows the CEB-FIP tradition: the main provisions are given on the right-
hand side of the page, and on the left-hand side, the comments.
Peter SCHIESSL
Convener offibTask Group 5.6
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0
Introduction
Thebasicideaofservicelifedesignaspresentedinthisdocumentisto
establishadesignapproachtoavoiddeteriorationcausedbyenvironmental
actioncomparabletoloaddesigna
sweareusedtohaveitinourdesign
codes(e.g.EC2).Thatmeansquantifiablemodelsontheloadside(theseare
theenvironmentalactions)andonth
eresistanceside(thisistheresistanceof
theconcreteagainsttheconsideredenvironmentalactions).Thedesign
approachwillbeexamplifiedfor
designagainstreinforcementcorrosion
causedbycarbonationofconcretewithoutloadorrestraintinducedcracks.
Thefirststepinthedesignap
proachistoquantifythedeterioration
mechanismwithrealisticmodelsd
escribingtheprocessphysicallyand/or
chemicallywithsufficientaccuracy(e.g.ingressofcarbonationintothe
concretedependingontheenviron
mentandtherelevantconcretequality
parameters).Suchamodelforingressofcarbonationisgiveninthe
document.Sufficientaccuracymean
sthatthemodelshouldbevalidatedby
realisticlaboratoryexperimentsand
bypracticeobservations,sothatmean
valuesandscatterofthematerialresistanceparametersareknownandcanbe
consideredinthemodel.Inthesa
mewaymodelsfortheenvironmental
actionswith
statistically
quantified
environmentalparameters(e.g.
temperature,relativehumidity,splashraineventsetc.)needtoexist.
Thesecondstepisthedefinitionoflimitstatesagainstthestructureshould
bedesignedfor.Appropriatelimitstateswouldbe
-
depassivationofreinforcementcausedbycarbonation
-
crackingduetoreinforcementcorrosion
-
spallingofconcretecoverduetoreinforcementcorrosion
-
collapseduetolossofcrosssectionofthereinforcement.
Theobjectiveofthisdocumentistoidentifyagreeddurabilityrelated
modelsandtopreparetheframeworkfor
standardizationofperformance
baseddesignapproaches.
ThisModelCodetreatsdesignforen
vironmentalactionsleadingto
degradationofconcreteandembeddedsteel.
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2
0Introduction
Thethirdstepisthecalculation
oftheprobabilitythatthelimitstates
definedaboveoccur(determination
oftheprobabilityofoccurance).This
willbedonebyapplyingthemodelsdescribedinstep1above.Nowadaysit
iscommonlyacceptedthatthesafe
tyofstructuresshouldbeexpressedin
termsofreliability(reliabilityindex
!).Dependingonthetypeoflimitstate
(SLS,ULS)andtheconsequencesof
afailure,valuesfor!aregiveninEC0.
Thefourthstepisthedefinition
ofthetypeoflimitstate(SLS,ULS)of
thelimitstatesdescribedinstep2.Normallydepassivationwillbeclassified
asaSLSasthereisnoimmediate
consequenceonstructuralsafetyifthe
reinforcementisdepassivated.Therefore!-valuesintherangeof!
=1.0to
1.5maybeappropriatefordepassiv
ation.However,theownermayrequire
higher!-valuesforexampletosafelyensuretheaestheticqualityofthe
structure.Forthelimitstatecrackingandspallingthedesignerhastodecide
whichtypeoflimitstateisneeded
orshouldbechosen.If,forexample,
crackingandspallingoccursin
anchoragezoneswithoutsufficient
transversalreinforcement,spallingm
ayleadtocollapse.Inthiscasecracking
andspallingneedtobedefinedasULS.Inothercasesifcrackingand
spallingdoesnotinfluencetheloadbearingcapacityofthestructural
element,crackingandspallingmayb
edefinedasSLS.
TheModelCodeisdividedintofivechapters:
1.General
2.Basisofdesign
3.VerificationofServiceLifeDesign
4.Executionanditsqualitycontrol
5.Maintenanceandconditioncontrol
Theservicelifedesignapproachinthisdocumentiselaboratedforthree
differentlevels.Thefullprobabilisticapproach(level1)willbeusedonlyfor
exceptionalstructures.Basedonthefullprobabilisticapproachapartial
safetyfactorapproachcomparabletoloaddesignisgiven.Thepartialsafety
factorapproach(level2)isadeterm
inisticapproachwheretheprobabilistic
natureoftheproblem(scatterofmaterialresistanceandenvironmentalload)
istakenintoaccountbypartialsafe
tyfactors.Finallythedeemedtosatisfy
approach(level3),againderivedfromthefullprobabilisticapproachis
TheflowchartinFigure1.1-1illustrate
stheflowofdecisionsandthe
designactivitiesneededinarationalservicelifedesignprocesswithachosen
levelofreliability.Twostrategieshavebeenadopted,whereofthefirstis
introducedofthreelevelsofsophistication.Insum4optionsareavailable.
Strategy1:
Level1.
Fullprobabilisticdesignapproach,(option1)
Level2.
Partialfactordesignapproach,(option2)
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elaborated.Thistypeofapproachiscomparabletotheapproachwhichcanbe
foundinthestandardsnowadays.
Howeverdescriptiverulesoftodays
standardsarenotbasedonphysicallyandchemicallycorrectmodelsbut
moreonpractical(sometimesbad)experience.Inthefuturecurrentlyapplied
rulesurgentlyhavetobecalibrateda
gainstthefullprobabilisticapproach.
Anotheroptiongiveninthisdocu
mentistheuseofnonreactivematerials
(e.g.stainlesssteel,strategy2/option
4).
Othermethodsorlevelsbetween
thelevelschosenforthisdocumentmay
beappropriateforServiceLifeDesign(e.g.thedurabilityfactormethod
approach,[1]).
Level3.
Deemedtosatisfydesignapp
roach,(option3)
Strategy2:Avoidanceofdeteriorationdesignapproach,(option4)
Figure1.1-1:Flowchartservicelifedesign
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4
0Introduction
WithinChapter3variousdeteriorationmechanismsaretreated:
carbonation-inducedcorrosion;:
chloride-inducedcorrosion;
freeze/thawattackwithoutde-icing
agents;
freeze/thawattackwithde-icingagents.
Forthesemechanismsbroadacceptedmodelsexist.Otherdeterioration
mechanismsarenottreated,forexamplealkalisilicareaction,andsulfate
attack,mainlyduetothesituationthatbroad
acceptedmodelsdonotexistso
far.
Simultaneousdynamicloadingandcorrosionofsteele.g.intheregionof
loadorrestraintinducedcracks,willleadtoareductioninthefatigue
resistance.TheS-N-curvesasthebasisforfatiguedesignmaybeupto50%
lowerrelatedtothestressrangeco
mparedtoS-N-curvesofreinforcement
withoutcorrosionattack.
Besideabovementionedmechanismsa
lsofatiguecausedbydynamic
loadingandleadingtotimedependentmaterialdegradationandcorrosion
fatiguecausedbydynamicloadingandsimultaneouscorrosioncausedby
environmentalactionisnottreated.
Tomakethisdocumentcomplete,missingmodelshavetobedeveloped
whichhavetorespectthegeneralprinciplesofChapter2.
Theservicelifedesignapproachdescribedinthisdocumentmaybe
appliedforthedesignofnewstruc
tures,fortheupdateoftheservicelife
designifthestructureexistsandrealmaterialpropertiesand/orthe
interactionofenvironmentandstructurecanbemeasured(realconcrete
covers,carbonationdepths)andforthecalculationoftheresidualservicelife.
AttachedtotheMC-SLDare4informativeannexes.Thesearegiving
backgroundinformationaswellasexamplesofproceduresanddeterioration
modelsfortheapplicationinSLD.Othersufficientlyvalidatedproceduresfor
reliabilitymanagementandmodelsfordeteriorationmightbeused.
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1
General
1.1Scope
Traditionally,nationalandinternationalconcretestandardsgive
requirementstoachievethedesireddesignservicelifebasedonthedeemed-
to-satisfyandtheavoidanceofdeteriorationapproach.
Suchoperativerequirementshavetobecalibratedbytheresponsible
standardizationbody.Thisdocumentgivesguidanceforsuchcalibration.
(1)ThepresentModelCodeisapplicableforServiceLifeDesign(SLD)
ofplainconcrete,reinforcedconcreteand
pre-stressedconcretestructures
withaspecialfocusondesignprovisionsformanagingtheadverseeffectsof
degradation.TheModelCodeprovidesthe
basisforservicelifedesignof
concretestructures.Fourdifferentoptionsareoffered:
afullprobabilisticapproach
asemiprobabilisticapproach(partialfactordesign)
deemedtosatisfyrules
avoidanceofdeterioration
Themethodologydescribedinthisdocu
mentmightalsobeappliedfor
assessmentofremainingservicelifeofexistingstructures.
1.2Associatedcodes
CENEN1990Basisfordesign
isbasedonthegeneralprinciplesforthe
verificationofthereliabilityofstructuresgiveninISO2394:1998General
principlesonreliabilityforstructures
(1)Thepresentcodeisapplicableasdescribedunder1.1togetherwith
CENEurocode0(EN1990:2002)
Basisfordesign
ProbabilisticModelCode,Joint
CommitteeonStructuralSafety
(JCSSPMC:2000),www.jcss.eth.ch
CENENV13670-1:2000Executionofconcretestructures
ISO2394:1998(E),Generalprinciplesonreliabilityforstructures
1.3Assumptions
CENENV13670-1ispresentlythemainreferencedocumentforISOTC-
71/SC3whendraftinganinternation
alstandardfortheexecutionofconcrete
structures.
ThisCENstandardmightbereplacedbythecomingEN13670,orbythe
ISOdocumentwhenavailable,orw
iththeexecutionprovisionsinthenext
versionofthefibModelCode.
(1)InadditiontothegeneralassumptionsofEN1990thefollowing
assumptionsapply:
Structuresaredesignedbyappropriatelyqualifiedandexperienced
personnel.
Adequatesupervisionandqualityc
ontrolisprovidedinfactories,in
plantsandonsite.
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6
1General
Theexecutionstandardassumesthattheconstructionmaterialsbroughtto
thebuildingsitecomplywithrelevantproductstandardsdefiningtheir
minimumperformances.
Constructioniscarriedoutbypersonnelhavingtheappropriateskill
andexperience.
Theconstructionmaterialsandproductsareusedasspecifiedinthe
relevantmaterialorproductspecifications.
Thestructurewillbeadequatelymaintainedaccordingtothe
optionsgiveninthisdocument.
Thestructurewillbeusedinaccord
ancewiththedesignbrief.
Theminimumrequirementsforex
ecutionandworkmanshipgiven
inENV13670arecompliedwith.
1.4Definitions
(1)ThetermsanddefinitionsgiveninEN1990applywiththefollowing
amendments:
1.4.1Basicvariable1)8)
partofaspecifiedsetofvariablesrepresentingphysicalquantities,which
characteriseactionsandenvironmentalinfluences,geometricalquantities,
andmaterialproperties.
1.4.2Characteristicvalue(Xkor
Rk)2)
Inthisrespectanominalvaluemeansavaluefixedonnon-statistical
bases,forinstanceonacquiredexper
ienceoronphysicalconditions.
valueofamaterialorproductpropertyhavingaprescribedprobabilityof
notbeingattainedinahypotheticalunlimitedtestseries.Thisvaluegenerally
correspondstoaspecifiedfractileoftheassu
medstatisticaldistributionofthe
particularpropertyofthematerialorproduct.Anominalvalueisusedasthe
characteristicvalueinsomecircumstance.
1.4.3Characteristicvalueofageometricalproperty
(ak)2)8)
valueusuallycorrespondingtothedimensionsspecifiedinthedesign.
Whererelevant,valuesofgeometricalquantitiesmaycorrespondtosome
prescribedfractilesofthestatisticaldistribution.
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1.4.4Characteristicvalueofana
ction(Fk)2)8)
principalrepresentativevalueofanaction
.
1.4.5Designcriteria2)
quantitativeformulationsthatdescribefo
reachlimitstatetheconditions
tobefulfilled.
1.4.6Designservicelife3)8)
Thisdocumentappliestheterm
DesignServiceLife.Themeaningof
thistermisequivalenttothetermD
esignworkinglifeasusedbyCEN.
assumedperiodforwhichastructureor
apartofitistobeusedforits
intendedpurpose.
1.4.7Designsituations1)8)
setsofphysicalconditionsrepresentingtheexpectedconditionsoccurring
duringacertaintimeintervalforwhichthe
designwilldemonstratethatthe
relevantlimitstatesarenotexceeded.
1.4.8Designvalueofageometric
alproperty(ad)1)8)
generallyanominalvalue.Whererelevant,valuesofgeometrical
quantitiesmaycorrespondtosomepresc
ribedfractileofthestatistical
distribution.
Note:Thedesignvalueofageometricalpropertyisgenerallyequaltothe
characteristicvalue.However,itmaybetreateddifferentlyincaseswherethe
limitstateunderconsiderationisvery
sensitivetothevalueofthe
geometricalproperty.Alternatively,itcanbeestablishedfromastatistical
basis,withavaluecorrespondingtoamoreappropriatefractile(e.g.rarer
value)thanappliestothecharacteristicvalue
.
1.4.9Designvalueofanaction(F
d)2)9)
valueobtainedbymultiplyingtherepresentativevaluebythepartialfactor"f.
Note:Theproductoftherepresentative
valuemultipliedbythepartial
factor"F="Sd#"f
mayalsobedesignated
asthedesignvalueoftheaction
(SeeEN19906.3.2)
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8
1General
1.4.10
Designvalueofmaterialorproductproperty
(XdorRd)2)9)
valueobtainedbydividingthecharacteristicvaluebyapartialfactor"mor
"M,or,inspecialcircumstances,bydirectdetermination.
1.4.11
Inspection4)
conformityevaluationbyobservationandjudgementaccompaniedas
appropriatebymeasurement,testingorgauging.
1.4.12
Irreversibleserviceabilitylimitstates2)8)
serviceabilitylimitstateswheresomeconsequencesofactionsexceeding
thespecifiedservicerequirementswillremainwhentheactionsareremoved.
1.4.13
Limitstates2)8)
statesbeyondwhichthestructurenolo
ngerfulfilstherelevantdesign
criteria.
1.4.14
Maintenance5)
setofactivitiesthatareplannedtotakeplaceduringtheservicelifeofthe
structureinordertofulfiltherequirementsfo
rreliability.
1.4.15
Projectspecification7)
documentscoveringtechnicaldataandrequirementsformaterials,
execution,maintenanceandconditioncontrolforaparticularprojectprepared
tosupplementandqualifytherequirementso
fgeneralstandards.
1.4.16
Referenceperiod2)8)
chosenperiodoftimethatisusedasa
basisforassessingstatistically
variableactions,andpossiblyforaccidentalactions.
1.4.17
Reliability1)8)
abilityofastructureorastructuralmembertofulfilthespecified
requirements,includingthedesignservicelife,forwhichithasbeen
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designed.Reliabilityisusuallyexpressedinprobabilisticterms.
Note:Reliabilitycoverssafety,serviceabilityanddurabilityofastructure.
1.4.18
Reliabilitydifferentiation
2)
measuresintendedforsocio-economicop
timisationoftheresourcestobe
usedtobuildconstructionworks,takingintoaccountallexpected
consequencesoffailuresandthecostofthec
onstructionworks.
1.4.19
Repair2)
activitiesperformedtopreserveortorestorethefunctionofastructure
thatfalloutsidethedefinitionofmaintenance.
1.4.20
Representativevalueofa
naction(Frep)2)8)
valueusedfortheverificationofalimitstate.Arepresentativevaluemay
bethecharacteristicvalue(Fk)oranaccompanyingvalue($Fk).
Note:Theaccompanyingvalueofa
variableactionmaybethe
combinationvalue,thefrequentvalueorthequasipermanentvalue.
1.4.21
Resistance1)
capacityofamemberorcomponent,or
across-sectionofamemberor
componentofastructure,towithstandaction
sduetodeterioration.
1.4.22
Serviceabilitylimitstates(SLS)2)9)
SLSisthisdocumentonlytrea
tedinitsnarrowsense,i.e.durability
relatedlimitstates,andnotinitsgeneralwidersense,e.g.tocoverdeflection.
SLSmightbeassociatedwithanydurabilityrelatedconditionbeyond
whichtheownerfeelsuncomfortableandwhichareincludedinthedesign
criteria.
statesthatcorrespondtoconditionsb
eyondwhichspecifiedservice
requirementsforastructureorstructuralmem
berarenolongermet.
1.4.23
Serviceabilitycriterion2)
designcriterionforaserviceabilitylimits
tate.
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10
1General
1.4.24
Ultimatelimitstate(ULS
)2)9)
statesassociatedwithcollapseorwithothersimilarformsofstructural
failure
Note:Theygenerallycorrespondtothem
aximumload-carryingresistance
ofastructureorstructuralmember
1) ThedefinitionisbasedonthatinEN19
90
2)T
hedefinitionisidenticaltothatinEN1990
3)C
ENdocumentsareusingthetermDesignworkinglifewherethis
documentisapplyingDesignservicelife
4)T
hedefinitionisidenticaltothatinISO
9000
5)BasedonISO15686-1:2000BuildingandconstructionassetsService
lifeplanning,Part1:Generalprinciplesclause6.7
6)ThedefinitionisinaccordancewithJC
SSProbabilisticModelCode
Part1
7)BasedonCENENV13670-1
8)T
hedefinitionisbasedonthatinISO2394
9)T
hedefinitionisidenticaltothatinISO
2394
1.5Symbols
(1)Forthepurposeofthisdocument,thefollowingsymbolsapply:
F
Action
Fd
Designvalueofaction
R
Resistance
SLS
Serviceabilitylimitstate
ULS
Ultimatelimitstate
a
Distance,ageexponent
t
Thickness,timebeingconsid
ered
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"
Partialfactor
"c
Partialfactorforconcrete
"f
Partialfactorforactionswithouttakingaccountofmodel
uncertainties
"F
Partialfactorforaction,
alsoaccountingformodel
uncertaintiesanddimensiona
lvariations
"m
Partialfactorsformaterialproperty,takingaccountonlyof
uncertaintiesinthematerialproperty
"M
Partialfactorsformateria
lproperty,takingaccountof
uncertaintiesinthematerial
propertyitselfandinthedesign
modelused
"Sd
Partialfactorassociatedwiththeuncertaintyoftheaction
and/oractioneffectmodel
"Rd
Partialfactorassociatedwith
theuncertaintyoftheresistance
model,plusgeometricdeviationsifthesearenotmodelled
explicitly
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12
2Basisofdesign
2
Basisofdesign
2.1Requirements
2.1.1Basicrequirements
(1)TheSLDofconcretestructuresshallbeinaccordancewiththegeneral
rulesgiveninEN1990.
(2)Thesupplementaryprovisionsforc
oncretestructuresgiveninthis
documentshallalsobeapplied.
(3)ThebasicrequirementsofEN199
0Section2aredeemedtobe
satisfiedforconcretestructureswhenSLD
iscarriedoutaccordingtothe
requirementsgiveninsection2.1.2(2).
2.1.2Reliabilitymanagement
(1)ReliabilitymanagementshallfollowtherulesgiveninEN1990
Section2.
(2)Theservicelifedesignshalleither:
followthegeneralprinciplesforprobabilisticservicelifedesignof
concretestructuresoutlinedinthe
JCSSPMC,ISO2394:1998(E),
respectively.
usethepartialfactormethodgiveninthisdocument
usethedeemed-to-satisfymethodg
iveninthisdocument
bebasedontheavoidance-of-deteriorationmethodgiveninthis
document
2.1.3Design
service
life,durability
and
quality
management
(1)Therulesfordesignofservicelife,du
rabilityandqualitymanagement
aregiveninEN1990Section2.
(2)Thedesignservicelifeistheassumedperiodforwhichastructureor
partofitistobeusedforitsintendedpurposewithanticipatedmaintenance
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butwithoutmajorrepairbeingnecessary.
Thedesignservicelifeisdefinedby:
Adefinitionoftherelevantlimitstate
Anumberofyears
Alevelofreliabilityfornotpas
singthelimitstateduringthis
period
(3)Durabilityofthestructureinitsen
vironmentshallbesuchthatit
remainsfitforuseduringitsdesignservic
elife.Thisrequirementcanbe
consideredinone,oracombination,ofthefo
llowingways:
Bydesigningprotectiveandomitigatingsystems
Byusingmaterialsthat,ifwellmaintained,willnotdegenerate
duringthedesignservicelife
Bygivingsuchdimensionsthat
deteriorationduringthedesign
servicelifeiscompensated
Bychoosingashorterlifetimefor
structuralelements,whichmay
bereplacedoneormoretimesduringthedesignlife
incombinationwithappropriateinspectionatfixedorcondition
dependantintervalsandappropriatemaintenanceactivities.
Inallcasesthereliabilityrequirements
forlongandshort-termperiods
shouldbemet.
(4)Theserviceabilitycriteriashallbe
specifiedforeachprojectand
agreedwiththeclient.
Guidanceforthechoiceofserviceabilitycriteriacombinedwith
appropriatetargetvaluesofreliabilityaregiv
eninAnnexA.
TheConsequenceclasses,ReliabilityclassesandDesignsupervision
levelsareidenticaltothosedefinedinAnnexBofEN1990,whilethe
Inspectionlevelsduringexecution
ofEN1990areonlyoneelementinthe
Executionclassesdefinedinthepresentdocument.
(5)Asaguidancetoreliabilitydifferentiation,AnnexAtothisdocument
definesthefollowinggeneralclassifications:
ConsequenceclassCC3,CC2andCC1
ReliabilityclassRC3,RC2andRC1
DesignsupervisionlevelDSL3,DS
L2andDSL1
ExecutionclassEXC1,EXC2andEXC3
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2Basisofdesign
RobustnessClassROC1,ROC2andROC3
Forservicelifedesign,AnnexA,inaddition,classify4levelsofcondition
controlduringtheservicelife:
CCL3,CCL2,CCL1andCCL0
2.2Principlesoflimitstated
esign
Theperformanceofawholestructureorpartofitshouldbedescribed
withreferencetoaspecifiedsetoflimitstatesandassociatedlevelsof
reliabilitywhichseparatedesiredstatesofthestructurefromundesiredstates.
Itshallbeverifiedthatnoneoftheselimitstatesareexceededwithaless
degreeofreliabilitythangiveninthe
designcriteria.
ThedefinitionsofSLSandULSaregivenin1.4.22and1.4.24.
SLSrepresentsalllimitstatesexc
eptthatassociatedwithcollapseorother
similarformsofstructuralfailure.
ExamplesoflimitstatesassociatedwithSLSanddealtwithinthis
documentmightbe:depassivation
ofreinforcement,cracking,spallingof
cover,erosionofsurfaceduetofreez
e-thaw,etc.
(1)TherulesforlimitstatedesignaregiveninEN1990Section3.
2.3Basicvariables
2.3.1Actionsandenvironmental
influences
Rulesforactionsandenvironmen
talinfluencesarealsogiveninEN1990,
Section4.
(1)ActionsspecifictoSLDaregiveninrelevantsections.
Characteristicvaluesofactionsforusein
SLDshalleitherbe
basedondataderivedfortheparticularprojector
fromgeneralfield-experience
fromrelevantliterature
Otheractions,whenrelevant,shallbede
finedinthedesignspecification
foraparticularproject.
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2.3.2Materialandproductproperties
(1)Therulesformaterialandproductp
ropertiesaregiveninEN1990
Section4.
(2)Characteristicvaluesofmaterialsan
dproductpropertiesforusein
SLDshalleitherbe
basedondataderivedfortheparticularprojector
fromgeneralfield-experience
fromrelevantliterature
Materialsandproductpropertiestobe
determinedwilldependonthe
deteriorationmodelused.Ifdifferentmodels
withdifferentbasicassumptions
areoffered,acheckingprocessshouldbee
stablished,toavoidanincorrect
mixtureofdata.
(3)Materialpropertyvaluesshallbed
eterminedfromtestprocedures
performedunderspecifiedconditions.Aconversionfactorshallbeapplied,
whennecessary,toconvertthetestresultso
flaboratorycastspecimensinto
values,whichcanbeassumedtorepresent
thebehaviourofthematerialor
productinthestructure.
2.3.3Geometricdata
(1)TherulesforgeometricaldataaregiveninEN1990Section4.
Ofparticularrelevanceforservicelifedesign(SLD)areENV13670-1
clause10.6,figure3band3d
concerninglocationofordinaryand
prestressedreinforcement.
Forpracticalreasons,asimplifiedstatisticalapproachbasedon
maximumpermitteddeviationisoftenusedinprojectspecifications.This
isoftenthecasefortheconcretecovertoreinforcement.Thisisnormally
givenasanominalvalue(targetvalue)andmaximumpermittedminusand
plusdeviations.
WhenperformingafullprobabilisticSLD,thismaximumpermitted
deviationhastobetransformedtoagivenfractileofanassumedstatistical
distribution(seeclause4.5(2)).
(2)Designvaluesofgeometricaldatafor
SLDshallbeinaccordancewith
EN1990clause6.3.4oraccordingtom
easurementsonthecompleted
structureorelement.
(3)ENV13670-1Executionofconcretestructuresspecifiespermitted
geometricaldeviations.Ifthedesignassumesstrictertolerances,thedesign
assumptionsshallbeverifiedbymeasurementsonthecompletedstructureor
element.
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2Basisofdesign
2.4Verification
2.4.1Verificationbyfullprobabilisticmethod
Materialparametersderivedfrom
acceleratedshort-timetestsmighthave
aninherentuncertaintyconcerningth
eirapplicationforlong-termmodelling.
Therelevanceofsuchmaterialcharacteristicsshouldthereforebe
calibratedtolong-terminfieldperformance.
Theuncertaintyofmodelsand
parameterswillnormallyinfluencethe
resultoftheSLDtoagreaterdegreewhenusedfordesignofnewstructures
thanwhenassessingremainingservicelifeofexistingstructures.
(1)Thegeneralprinciplesforprobabilisticservicelifedesignofconcrete
structuresoutlinedintheJCSSPMCshallbe
followed.
Inparticularthefollowingfourprinciples
shallbeconsidered:
Probabilisticmodelsshallbeappliedthataresufficientlyvalidated
togiverealisticandrepresentativeresults.
Theparametersofthemodels
appliedandtheirassociated
uncertaintyshallbequantifiablebymeansoftests,observations
and/orexperience.
Reproducibleandrelevanttestmethodsshallbeavailabletoassess
theaction-andmaterial-parameters
.
Uncertaintiesassociatedwithmodelsandtestmethodsshallbeconsidered.
2.4.2Verificationbythepartialfactormethod
(1)Therulesforthepartialfactormethod
aregiveninEN1990Section6
andcanbeusedforSLDwithoutthelimitationsgiveninEN1990clause
6.2.
(2)Thesamemodelsasforthefullprobabilisticmethod,basedondesign
values,shallbeusedforthepartialfactormethod.Simplificationsonthesafe
sidearepossible.
(3)Thepartialfactorformatseparatesth
etreatmentofuncertaintiesand
variabilitiesoriginatingfromvariouscause
s.Intheverificationprocedure
definedinthisdocumentthedesignvaluesofthefundamentalbasicvariables
areexpressedasfollows:
Designvaluesofactionsaregenerally
expressedas
Fd="fFrep
(2.4-1)
whereFreparerepresentativevaluesof
action
"farepartialsafetyfactors
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Designvaluesofmaterialorproductpropertyaregenerallyexpressed
as
Rd=Rk/"m
(2.4-2)
Or,incaseuncertaintyinthedesignmodelistakenintoaccountby:
Rd=Rk/"M=Rk/("m#"Rd)
(2.4-3)
whereRkarecharacteristicvaluesofresistance
"misthepartialfactorformaterialproperty
"Rdisthepartialfactorassociatedwith
theuncertaintyoftheresistance
modelplusgeometricdeviationsifthesearenotmodelledexplicitly.
"M="m#"Rdisthepartialfactorform
aterialpropertyalsoaccounting
forthemodeluncertaintiesanddimensionalvariations.
Designvaluesofgeometricalquantitiestobeconsideredas
fundamentalbasicvariablesaregenerallydirectlyexpressedbytheir
designvaluesad.
Thetargetreliabilitylevelusedforthecalibrationshallbeinaccordance
withChapter2.1.3.(4)
(4)Whenusingthepartialfactormethod,
itshallbeverifiedthatthetarget
reliabilityfornotpassingtherelevantlimitstateduringthedesignservicelife
isnotexceededwhendesignvaluesforactionsoreffectsofactionsand
resistanceareusedinthedesignmodels.
Thepartialfactorsshalltakeintoaccount:
Thepossibilityofunfavourabledeviationsofactionvaluesfromthe
representativevalues
Thepossibilityofunfavourabledeviationsofmaterialsandproduct
propertiesfromtherepresentativevalu
es
Modeluncertaintiesanddimensionalv
ariations
Thenumericalvaluesforthepartialfactorsshallbedeterminedineither
oftwoways:
Onthebasisofstatisticalevaluation
ofexperimentaldataandfield
observationsaccordingtorequirementsofclauseVerificationbyfull
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2Basisofdesign
probabilisticmethod
Onthebasisofcalibrationtoalongtermexperienceofbuilding
tradition
2.4.3Verificationbythedeemed
-to-satisfymethod
Exposureconditionsinthedesignsituationsmightbeclassifiedin
exposureclasses.
Traditionally,deemed-to-satisfy
provisionsincluderequirementstothe
workmanship,concretecomposition,possibleairentrainment,cover
thicknesstothereinforcement,crackwidthlimitationsandcuringofthe
concrete.
However,otherprovisionsmight
alsoberelevant.
Examplesofthecalibrationof
deemed-to-satisfycriteriabasedona
close-tofullprobabilisticmethod
anddataderivedfrom1015yearsold
structuresaregivenin[2].
(1)Thedeemed-to-satisfymethodisaset
ofrulesfor
dimensioning,
materialandproductselectionand
executionprocedures
thatensuresthatthetargetreliabilityfo
rnotpassingtherelevantlimit
stateduringthedesignservicelifeisno
texceededwhentheconcrete
structureorcomponentisexposedtothedesignsituations.
(2)Thespecificrequirementsfordesign,materialsselectionandexecution
forthedeemed-to-satisfymethodshallbedeterminedineitheroftwoways:
Onthebasisofstatisticalevaluation
ofexperimentaldataandfield
observationsaccordingtorequirementsofclauseVerificationbyfull
probabilisticmethod
Onthebasisofcalibrationtoalongtermexperienceofbuilding
tradition
Thelimitationstothevalidityoftheprovisions,e.g.therangeofcement
typescoveredbythecalibration,shallbeclearlystated.
2.4.4Verificationbytheavoidan
ce-of-deterioration
method
(1)Theavoidance-of-deteriorationmethodimpliesthatdeterioration
processwillnottakeplaceduetoforinstance:
Separationoftheenvironmentalactionfrom
thestructureor
componentbye.g.claddingormembranes
Usingnon-reactingmaterials,e.g.certainstainlesssteelsoralkali-non-
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reactiveaggregates
Separationofreactants,e.g.keepingthestructureorcomponentbelow
acriticaldegreeofmoisture.
Suppressingtheharmfulreactione.g.byelectrochemicalmethods
Theassumedeffectivenessofthe
actualconceptshallbedocumented,for
instanceforproductsbycomplying
withrelevantminimumrequirementsin
productstandards.
(2)Thespecificrequirementsfordesign,materialsselectionandexecution
fortheavoidance-of-deteriorationmethodcaninprinciplebedeterminedin
thesamewayasforthedeemed-to-satisfymethod.
Thelimitationstothevalidityoftheprovisionsshallbeclearlystated.
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3VerificationofServiceLifeDesign
3
VerificationofService
LifeDesign
3.1Carbonationinducedcor
rosionuncracked
concrete
3.1.1Fullprobabilisticmethod
3.1.1.1
Limitstate:depassivation
Togetcorrosionanenvironme
ntthatiswetenoughisneeded.For
structuralelementssolelyexposedto
relativedryindoorenvironment,alimit
statedepassivationmaynotberelevantasnosignificantcorrosionwill
develop.
(1)Thefollowingrequirementneedstobefulfilled:
p{}=pdep.=p{a-xc(tSL)