Strengthening of Concrete Structures with Adhesive Bonded Reinforcement: Design and Dimensioning of CFRP Laminates and Steel Plates

160 Pages·2014·2.41 MB·English

by  Konrad Zilch

Design and construction in existing contexts is becoming increasingly important,
and often the structures – sometimes of historical interest – can be preserved
easily and at minimum cost by employing strengthening measures. Existing
concrete members can be strengthened by using adhesives to bond additional
reinforcing elements onto or into those members. This book explains the design
rules, together with their background, and uses examples to illustrate their use,
specifically for slabs, beams and columns. Concrete member strengthening
measures can take the form of, for example, flexural strengthening with exter-
nally bonded (surface-mounted) CFRP strips, CF sheets and steel plates, flex-
ural strengthening with CFRP strips bonded in slots (near-surface-mounted re-
inforcement), shear strengthening with externally bonded CF sheets and steel
plates, and column strengthening with CF sheets as confining reinforcement.
The explanations and background information provided are mainly based on the
new German guideline “Strengthening of Concrete Members with Adhesively
Bonded Reinforcement” by the German Committee for Structural Concrete
(DAfStb). This is the first European guideline to regulate this topic in the form
of a supplement to the Eurocode. As it is planned to produce a document in a
future Eurocode 2, the DAfStb guideline serves as a starting point.
The authors are extensively involved in the planning, design, operation and in-
wS Strengthening of
spection of buildings for preservation and reconstruction, and in the updating ithtre
of European Technical Approval Guidelines (ETAGs) and design rules. Ang
dhth
ee Concrete Structures
sn
ivin
Patr oTfU. e Dma.r mDrs.-taIndgt .i nh a1b9i7l. 6D. rF.-oInllgow. Ein. hg . rKeosenararcdh Z pilocsht ss tautd tiheed Ucinviivl eernsgitiny eoef rCinagl iafonrdn igaa, iBneedrk heilse yd,o acntdor tahtee ely Bog of C with Adhesively Bonded
University of Western Ontario, Canada, he worked in the construction industry for many years. From no
dn
1988 to 1993 he was professor for structural analysis at RWTH Aachen University, and from 1993 ec
dr
to 2009 professor for concrete structures at TU Munich. He was a design certifying engineer for more Rete Reinforcement
than twenty years and is senior partner at Zilch + Müller Ingenieure, Munich. ein S
fotru
rcc
PD Dr.-Ing. habil. Roland Niedermeier studied civil engineering and gained his doctorate at TU etu
Munich in 2001. Since 1993 he has been involved in research at TU Munich and MPA BAU, the ac- meres Design and Dimensioning of CFRP Laminates and Steel Plates
credited authority for testing construction materials and products, where he has been the technical nt
director of the Structural Engineering Laboratory since 2001.
Konrad Zilch, Roland Niedermeier, Wolfgang Finckh
Dr.-Ing. Wolfgang Finckh studied civil engineering and gained his doctorate at TU Munich in 2012.
He has been a senior design engineer at Wayss & Freytag Ingenieurbau AG (w&f) since 2012.
ISBN 978-3-433-03086-8
www.ernst-und-sohn.de
BK_Paperback_Strengthening.indd 1 23.05.14 18:00

KonradZilch
RolandNiedermeier
WolfgangFinckh
Strengtheningof
ConcreteStructureswith
AdhesivelyBonded
Reinforcement

Konrad Zilch
Roland Niedermeier
Wolfgang Finckh
Strengthening of Concrete Structures
with Adhesively Bonded Reinforcement
DesignandDimensioning
ofCFRPLaminatesandSteelPlates
TheAuthors AllbookspublishedbyErnst&Sohnarecarefullyproduced.
Nevertheless,authors,editors,andpublisherdonotwarrant
Prof.Dr.-Ing.habil.Dr.-Ing.E.h. theinformationcontainedinthesebooks,includingthisbook,
KonradZilch tobefreeoferrors.Readersareadvisedtokeepinmindthat
TechnischeUniversitätMünchen statements,data,illustrations,proceduraldetailsorotheritems
Theresienstr.90 mayinadvertentlybeinaccurate.
80333Munich
Germany LibraryofCongressCardNo.:appliedfor
PDDr.-Ing.habil.RolandNiedermeier
BritishLibraryCataloguing-in-PublicationData
TechnischeUniversitätMünchen
AcataloguerecordforthisbookisavailablefromtheBritish
MPABAU
Library.
Theresienstr.90
80333Munich
BibliographicinformationpublishedbytheDeutsche
Germany
Nationalbibliothek
Dr.-Ing.WolfgangFinckh TheDeutscheNationalbibliothekliststhispublicationinthe
Wayss&FreytagIngenieurbauAG DeutscheNationalbibliografie;detailedbibliographicdataare
EschbornerLandstraße130-132 available on the Internet at < http://dnb.d-nb. de>.
60489Frankfurt/Main
Germany 2014WilhelmErnst&Sohn,VerlagfürArchitekturund
technischeWissenschaftenGmbH&Co.KG,Rotherstraße
21,10245Berlin,Germany
TheEditors
Prof.Dipl.-Ing.Dr.-Ing.KonradBergmeister Allrightsreserved(includingthoseoftranslationintoother
IngenieurbüroBergmeister languages).Nopartofthisbookmaybereproducedinany
Peter-Jordan-Straße113 form–byphotoprinting,microfilm,oranyothermeans–nor
1190Vienna transmittedortranslatedintoamachinelanguagewithout
Austria writtenpermissionfromthepublishers.Registerednames,
trademarks,etc.usedinthisbook,evenwhennotspecifically
Dr.-Ing.FrankFingerloos
markedassuch,arenottobeconsideredunprotectedbylaw.
GermanSocietyforConcreteandConstruction
Technology
PrintISBN: 978-3-433-03086-8
Kurfürstenstr.129
ePDFISBN: 978-3-433-60403-8
10785Berlin
ePubISBN: 978-3-433-60405-2
Germany
mobiISBN: 978-3-433-60402-1
Prof.Dr.-Ing.Dr.h.c.mult. oBookISBN: 978-3-433-60401-4
Johann-DietrichWörner
GermanAerospaceCenter Typesetting: ThomsonDigital,Noida,India
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TheoriginalGermantextispublishedinBeton-
Kalender2013,ISBN978-3-433-03000-4and
titled“GeklebteVerstärkungmitCFK-Lamellen
undStahllaschen”.
V
Contents
Editorial...................................................................................... IX
1 Introduction.................................................................................... 1
1.1 Thereasonbehindthisbook............................................................... 1
1.2 Strengtheningwithadhesivelybondedreinforcement........................ 1
2 DAfStbguideline............................................................................ 3
2.1 Thereasonsfordrawingupaguideline.............................................. 3
2.2 Preparatorywork................................................................................. 3
2.3 Workontheguideline......................................................................... 4
2.4 Thestructureandcontentoftheguideline.......................................... 4
2.4.1 General................................................................................................ 4
2.4.2 Designanddetailing........................................................................... 4
2.4.3 Productsandsystems.......................................................................... 4
2.4.4 Execution............................................................................................ 5
2.4.5 Planning.............................................................................................. 5
2.5 Safetyconcept..................................................................................... 5
2.6 Applications........................................................................................ 6
2.6.1 Membertobestrengthened................................................................. 6
2.6.2 Strengtheningsystems........................................................................ 7
2.6.3 Ambientconditions............................................................................. 7
2.6.4 Fireprotection..................................................................................... 8
2.7 Relationshipwithotherregulations..................................................... 9
2.8 Documentsandassistanceforpracticalapplications........................... 10
3 Designofstrengtheningmeasureswithexternally
bondedCFRPstrips...................................................................... 11
3.1 Principles............................................................................................ 11
3.2 Verificationofflexuralstrength.......................................................... 13
3.3 Bondanalysis...................................................................................... 15
3.3.1 Principles............................................................................................ 15
3.3.2 Simplifiedmethod............................................................................... 16
3.3.3 Moreaccuratemethod......................................................................... 17
3.3.3.1 General................................................................................................ 17
3.3.3.2 Determiningthecrackspacing............................................................ 19
3.3.3.3 Accurateanalysisofconcreteelementbetweencracks....................... 20
3.3.3.4 Simplifiedanalysisofelementbetweencracks................................... 23
3.3.4 Endanchorageanalysis....................................................................... 24
3.3.4.1 General................................................................................................ 24
3.3.4.2 Endanchorageanalysisatflexuralcracknearest
topointofcontraflexure...................................................................... 24
3.3.4.3 Anchorageanalysisatanarbitraryconcreteelement
betweencracks.................................................................................... 26
VI Contents
3.3.4.4 Endanchorageanalysiswithshearwrapping...................................... 27
3.4 Shearforceanalyses............................................................................ 29
3.4.1 Shearstrength...................................................................................... 29
3.4.2 Shearstrengthening............................................................................. 30
3.4.2.1 Fullwrappinginsteel.......................................................................... 31
3.4.2.2 Fullwrappinginfibre-reinforcedmaterial.......................................... 32
3.4.2.3 U-wrapping......................................................................................... 32
3.4.3 Endstraptopreventconcretecoverseparationfailure........................ 33
3.5 Fatigueanalysis................................................................................... 35
3.6 Analysesfortheserviceabilitylimitstate............................................ 36
3.7 Detailing.............................................................................................. 36
3.7.1 Stripspacing....................................................................................... 36
3.7.2 Provisionofshearstraps..................................................................... 37
3.7.3 Steelshearstraps................................................................................. 37
4 Example1:Strengtheningaslabwithexternally
bondedCFRPstrips...................................................................... 39
4.1 System................................................................................................. 39
4.1.1 General................................................................................................ 39
4.1.2 Loading............................................................................................... 39
4.1.3 Constructionmaterials........................................................................ 40
4.1.3.1 Near-surfacetensilestrength............................................................... 40
4.1.3.2 Concretecompressivestrength........................................................... 41
4.1.3.3 Typeandquantityofexistingreinforcement....................................... 41
4.1.3.4 Positionofexistingreinforcement...................................................... 41
4.1.3.5 Strengtheningsystem.......................................................................... 41
4.2 Internalforces..................................................................................... 42
4.3 Determiningtheprestrain.................................................................... 42
4.4 Simplifiedanalysis.............................................................................. 44
4.5 Accurateanalysis................................................................................ 46
4.5.1 General................................................................................................ 46
4.5.2 Verificationofflexuralstrength.......................................................... 46
4.5.3 Determiningthecrackspacing............................................................ 48
4.5.4 Accurateanalysisofconcreteelementbetweencracks....................... 48
4.5.4.1 Determiningthestripforces................................................................ 49
4.5.4.2 Determiningthebondstrength............................................................ 52
4.5.5 Endanchorageanalysis....................................................................... 55
4.6 Analysisofshearcapacity................................................................... 58
4.7 Serviceabilitylimitstate...................................................................... 59
5 Designofstrengtheningwithnear-surface-mounted
CFRPstrips.................................................................................... 61
5.1 Principles............................................................................................ 61
5.2 Verificationofflexuralstrength.......................................................... 61
5.3 Bondanalysis...................................................................................... 63
5.4 ShearForceAnalyses.......................................................................... 65
Contents VII
5.5 Fatigueanalysis................................................................................... 66
5.6 Analysesfortheserviceabilitylimitstate............................................ 67
5.7 Detailing.............................................................................................. 67
6 Example2:Strengtheningabeamwith
near-surface-mountedCFRPstrips............................................. 69
6.1 System................................................................................................. 69
6.1.1 General................................................................................................ 69
6.1.2 Loading............................................................................................... 69
6.1.3 Constructionmaterials........................................................................ 71
6.1.3.1 Concretecompressivestrength........................................................... 71
6.1.3.2 Typeandquantityofexistingreinforcement....................................... 71
6.1.3.3 Positionofexistingreinforcement...................................................... 71
6.1.3.4 Strengtheningsystem.......................................................................... 71
6.2 Internalforces..................................................................................... 72
6.3 Determiningtheprestrain.................................................................... 72
6.4 Verificationofflexuralstrength.......................................................... 74
6.5 Bondanalysis...................................................................................... 76
6.5.1 Analysispoint..................................................................................... 76
6.5.2 Actingstripforce................................................................................ 78
6.5.3 Bondresistance................................................................................... 79
6.5.4 Bondanalysis...................................................................................... 80
6.6 Shearanalyses..................................................................................... 80
6.6.1 Shearcapacity..................................................................................... 80
6.6.2 Shearstrengthening............................................................................. 81
6.6.3 Checkforconcretecoverseparationfailure........................................ 82
6.7 Analysesfortheserviceabilitylimitstate............................................ 84
7 DesignofcolumnstrengtheningwithCFsheets....................... 87
7.1 Principles............................................................................................ 87
7.2 PropertiesofCFsheetsrelevanttodesign.......................................... 91
7.3 Load-carryingcapacityofcross-section.............................................. 93
7.4 Load-carryingcapacityofmember..................................................... 98
7.5 Creep................................................................................................... 102
7.6 Analysisatultimatelimitstate............................................................ 105
7.7 Analysisatserviceabilitylimitstate.................................................... 111
8 Example3:Columnstrengthening.............................................. 115
8.1 System................................................................................................. 115
8.1.1 General................................................................................................ 115
8.1.2 Loading............................................................................................... 115
8.1.3 Constructionmaterials........................................................................ 116
8.1.3.1 Concrete.............................................................................................. 116
8.1.3.2 Typeandquantityofexistingreinforcement....................................... 116
8.1.3.3 Strengtheningsystem.......................................................................... 117
8.2 Internalforces..................................................................................... 118
VIII Contents
8.3 Determiningthecross-sectionalvalues............................................... 118
8.4 Boundaryconditions........................................................................... 119
8.5 Verificationofcolumnload-carryingcapacity.................................... 120
8.5.1 Creepofconfinedconcrete.................................................................. 120
8.5.2 PropertiesoftheCFsheet................................................................... 121
8.5.3 Distributionoftransversecompression............................................... 122
8.5.4 Multi-axialstressstateinconcrete...................................................... 122
8.5.5 Calculationofcolumnload-carryingcapacity.................................... 123
8.6 Serviceabilitylimitstate...................................................................... 127
9 Summaryandoutlook................................................................... 129
References................................................................................. 131
Index........................................................................................... 145