Structural timber design to Eurocode 5

556 Pages·2007·5.026 MB·English

by  Jack Porteous, Abdy Kermani

STRUCTURAL TIMBER
DESIGN
to Eurocode 5
Jack Porteous
BSc,MSc,DIC,PhD,
CEng,MIStructE,FICE
Director
JackPorteousConsultancy
Abdy Kermani
BSc,MSc,PhD,CEng,
MIStructE,FIWSc
ProfessorofTimberEngineering
NapierUniversity,Edinburgh

STRUCTURAL TIMBER
DESIGN
to Eurocode 5
ToMargaretandJohn
DawnandRomi
STRUCTURAL TIMBER
DESIGN
to Eurocode 5
Jack Porteous
BSc,MSc,DIC,PhD,
CEng,MIStructE,FICE
Director
JackPorteousConsultancy
Abdy Kermani
BSc,MSc,PhD,CEng,
MIStructE,FIWSc
ProfessorofTimberEngineering
NapierUniversity,Edinburgh
(cid:2)C 2007byJackPorteousandAbdyKermani
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Firstpublished2007byBlackwellPublishingLtd
ISBN:978-14051-4638-8
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Porteous,Jack.
StructuraltimberdesigntoEurocode5/JackPorteous&AbdyKermani.
p.;cm.
Includesbibliographicalreferencesandindex.
ISBN-13:978-1-4051-4638-8(hardback:alk.paper)
1.Building,Wooden–Standards–Europe. 2.Structuralframes–Designandconstruction–Standards–Europe.
3.Timber–Standards–Europe. I.Kermani,Abdy. II.Title.
TA666.P662007
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2007037062
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Contents
Preface xi
1. TimberasaStructuralMaterial 1
1.1 Introduction 1
1.2 Thestructureoftimber 2
1.3 Typesoftimber 3
1.3.1 Softwoods 3
1.3.2 Hardwoods 3
1.4 Naturalcharacteristicsoftimber 4
1.4.1 Knots 4
1.4.2 Slopeofgrain 5
1.4.3 Reactionwood 5
1.4.4 Juvenilewood 6
1.4.5 Densityandannualringwidths 6
1.4.6 Conversionoftimber 7
1.4.7 Seasoning 11
1.4.8 Seasoningdefects 11
1.4.9 Cracksandfissures 11
1.4.10 Fungaldecay 11
1.5 Strengthgradingoftimber 11
1.5.1 Visualgrading 12
1.5.2 Machinegrading 12
1.5.3 Strengthclasses 13
1.6 Sectionsizes 16
1.7 Engineeredwoodproducts(EWPs) 16
1.7.1 Glued-laminatedtimber(glulam) 18
1.7.2 Plywood 20
1.7.3 Laminatedveneerlumber(LVL) 22
1.7.4 La minatedStrandLumber(LSL),TimberStrand® 22
1.7.5 ParallelStrandLumber(PSL),Parallam® 25
1.7.6 OrientedStrandBoard(OSB) 25
1.7.7 Particleboardsandfibrecomposites 35
1.7.8 Thinwebbedjoists(I-joists) 37
1.7.9 Thinwebbedbeams(Boxbeams) 39
1.7.10 Structuralinsulatedpanels(SIPs) 40
1.8 Suspendedtimberflooring 41
1.9 Adhesivebondingoftimber 43
1.10 Preservativetreatmentfortimber 45
v
vi Contents
1.11 Firesafetyandresistance 46
1.12 References 48
2. IntroductiontoRelevantEurocodes 50
2.1 Eurocodes:Generalstructure 50
2.2 Eurocode0:Basisofstructuraldesign(EC0) 52
2.2.1 Termsanddefinitions(EC0,1.5) 52
2.2.2 Basicrequirements(EC0,2.1) 53
2.2.3 Reliabilitymanagement(EC0,2.2) 53
2.2.4 Designworkinglife(EC0,2.3) 54
2.2.5 Durability(EC0,2.4) 54
2.2.6 Qualitymanagement(EC0,2.5) 55
2.2.7 Principlesoflimitstatedesign:General(EC0,3.1) 55
2.2.8 Designsituations(EC0,3.2) 56
2.2.9 Ultimatelimitstates(EC0,3.3) 56
2.2.10 Serviceabilitylimitstates(EC0,3.4) 56
2.2.11 Limitstatesdesign(EC0,3.5) 57
2.2.12 Classificationofactions(EC0,4.1.1) 58
2.2.13 Characteristicvaluesofactions(EC0,4.1.2) 58
2.2.14 Otherrepresentativevaluesofvariableactions(EC0,4.1.3) 59
2.2.15 Materialandproductproperties(EC0,4.2) 60
2.2.16 Structuralanalysis(EC0,5.1) 60
2.2.17 Verificationbythepartialfactormethod:General(EC0,6.1) 62
2.2.18 Designvaluesofactions(EC0,6.3.1) 63
2.2.19 Designvaluesoftheeffectsofactions(EC0,6.3.2) 63
2.2.20 Designvaluesofmaterialorproductproperties(EC0,6.3.3) 64
2.2.21 FactorsappliedtoadesignstrengthattheULS 68
2.2.22 Designvaluesofgeometricaldata(EC0,6.3.4) 68
2.2.23 Designresistance(EC0,6.3.5) 70
2.2.24 Ultimatelimitstates(EC0,6.4.1–6.4.5) 70
2.2.25 Serviceabilitylimitstates:General(EC0,6.5) 74
2.3 Eurocode5:designoftimberstructures–Part1-1:General–Common
rulesandrulesforbuildings(EC5) 76
2.3.1 Generalmatters 76
2.3.2 Serviceabilitylimitstates(EC5,2.2.3) 77
2.3.3 Loaddurationandmoistureinfluencesonstrength(EC5,2.3.2.1) 79
2.3.4 Loaddurationandmoistureinfluencesondeformations(EC5,2.3.2.2) 80
2.3.5 Stress–strainrelations(EC5,3.1.2) 82
2.3.6 Siz eandstressdistributioneffects(EC5,3.2,3.3,3.4and6.4.3) 83
2.3.7 Systemstrength(EC5,6.6) 85
2.4 Symbols 87
2.5 References 92
3. UsingMathcad®forDesignCalculations 94
3.1 Introduction 94
3.2 WhatisMathcad? 94
3.3 WhatdoesMathcaddo? 95
3.3.1 Asimplecalculation 95
Contents vii
3.3.2 Definitionsandvariables 95
3.3.3 Enteringtext 96
3.3.4 Workingwithunits 96
3.3.5 CommonlyusedMathcadfunctions 98
3.4 Summary 100
3.5 References 100
4. DesignofMembersSubjectedtoFlexure 101
4.1 Introduction 101
4.2 Designconsiderations 101
4.3 Designvalueoftheeffectofactions 103
4.4 MemberSpan 103
4.5 DesignforUltimateLimitStates(ULS) 104
4.5.1 Bending 104
4.5.2 Shear 115
4.5.3 Bearing(Compressionperpendiculartothegrain) 119
4.5.4 Torsion 123
4.5.5 Combinedshearandtorsion 125
4.6 DesignforServiceabilityLimitStates(SLS) 125
4.6.1 Deformation 125
4.6.2 Vibration 129
4.7 References 133
4.8 Examples 133
5. DesignofMembersandWallsSubjectedtoAxialorCombinedAxial
andFlexuralActions 148
5.1 Introduction 148
5.2 Designconsiderations 148
5.3 Designofmemberssubjectedtoaxialactions 150
5.3.1 Memberssubjectedtoaxialcompression 150
5.3.2 Memberssubjectedtocompressionatanangletothegrain 157
5.3.3 Memberssubjectedtoaxialtension 162
5.4 Memberssubjectedtocombinedbendingandaxialloading 163
5.4.1 Wherelateraltorsionalinstabilityduetobendingaboutthemajor
axiswillnotoccur 163
5.4.2 Lateraltorsionalinstabilityundertheeffectofbendingaboutthe
majoraxis 167
5.4.3 Memberssubjectedtocombinedbendingandaxialtension 168
5.5 DesignofStudWalls 169

5.5.1 Designofload-bearingwalls 169
5.5.2 Outofplanedeflectionofload-bearingstudwalls(andcolumns) 174
5.6 References 176
5.7 Examples 177
6. DesignofGluedLaminatedMembers 205
6.1 Introduction 205
6.2 Designconsiderations 205
6.3 General 207
viii Contents
6.3.1 Horizontalandverticalglued-laminatedtimber 207
6.3.2 Designmethodology 207
6.4 Designofglued-laminatedmemberswithtapered,curvedorpitched
curvedprofiles(alsoapplicabletoLVLmembers) 211
6.4.1 Designofsingletaperedbeams 212
6.4.2 Designofdoubletaperedbeams,curvedandpitchedcamberedbeams 216
6.4.3 Designofdoubletaperedbeams,curvedandpitchedcambered
beamssubjectedtocombinedshearandtensionperpendicular
tothegrain 222
6.5 Fingerjoints 222
Annex6.1 Deflectionformulaeforsimplysupportedtaperedanddouble
taperedbeamssubjectedtoapointloadatmid-spanortoauniformly
distributedload. 222
Annex6.2 Graphicalrepresentationoffactorsk andk usedinthederivation
(cid:2) p
ofthebendingandradialstressesintheapexzoneofdoubletapered
curvedandpitchedcamberedbeams. 225
6.6 References 226
6.7 Examples 227
7. DesignofCompositeTimberandWood-BasedSections 248
7.1 Introduction 248
7.2 Designconsiderations 249
7.3 Designofgluedcompositesections 249
7.3.1 Gluedthinwebbedbeams 249
7.3.2 Gluedthinflangedbeams(Stressedskinpanels) 260
7.4 References 268
7.5 Examples 268
8. DesignofBuilt-UpColumns 292
8.1 Introduction 292
8.2 Designconsiderations 292
8.3 General 293
8.4 Bendingstiffnessofbuilt-upcolumns 294
8.4.1 Theeffectivebendingstiffnessofbuilt-upsectionsaboutthe
strong(y–y)axis 295
8.4.2 Theeffectivebendingstiffnessofbuilt-upsectionsaboutthe
z–zaxis 297
8.4.3 Designprocedure 299
8.4.4 Built-upsections–spacedcolumns 303

8.4.5 Built-upsections–latticedcolumns 308
8.5 Combinedaxialloadingandmoment 311
8.6 EffectofcreepattheULS 312
8.7 References 313
8.8 Examples 313
9. DesignofStabilityBracing,FloorandWallDiaphragms 338
9.1 Introduction 338
9.2 Designconsiderations 338