EN 1995 Eurocode 5: Design of timber structures

EUROCODESBackground and Applications

“Dissemination of information for training” workshop 18-20 February 2008 Brussels

EN 1995 Eurocode 5: Design of timber structures Organised by European Commission: DG Enterprise and Industry, Joint Research Centre with the support of CEN/TC250, CEN Management Centre and Member States

Tuesday, February 19 – Palais des Académies EN 1995 - Eurocode 5: Design of timber structures Bordet room

9:00-9:45 Introduction by chairman S. Winter Technische Universität München

9:45-10:45 Design of beams and columns – stability – theory of second order

S. Winter Technische Universität München

10:45-11:15 Coffee

11:15-12:00 Tension perpendicular to the grain – holes –curved beams

P. Dietsch Technische Universität München

12:00-12:30 Serviceability – deflection and vibration H. Kreuzinger Technische Universität München

12:30-14:00 Lunch

14:00-15:30 Connections – Lateral load capacity - Withdrawal capacity -dowels

A. Leijten TU-Eindhoven

15:30-16:00 Coffee

16:00-16:45 Components and assemblies and Structural detailing and control

H. Hartl University of Innsbruck

16:45-17:30 Bridges H. Kreuzinger Technische Universität München

17:30-18:00 Final discussion S. Winter Technische Universität München

All workshop material will be available at http://eurocodes.jrc.ec.europa.eu

http://eurocodes.jrc.ec.europa.eu/

INTRODUCTION

S. Winter Technische Universität München

1

EN 1995-1-1Design of timber structures

EN 1995-1-1 Design of Timber Structures Design of Timber StructuresEN 1995-1-1

Storage building in Japan 4 Jh. v. Ch.

Design of Timber StructuresEN 1995-1-1

Stave church in Norway 13th century


Bridge across river Sinne (Switzerland)


Faculty of architecture (Lyon)

EN 1995-1-1 Design of Timber Structures

EN1995-1-1 Scope and structure

• Section 1: General definitions, terminology• Section 2: Basis of design: Timber specific supplement to EN1990• Section 3: Material properties to be used for design• Section 4: Durability concept• Section 5: Basis of structural analysis• Section 6: Ultimate limit state design principles• Section 7: Serviceability limit states• Section 8: Fasteners• Section 9: Design of components and assemblies• Section 10: Workmanship, structural detailing and control

2


EN1995-1-1 - Definition of axes

EN1995


Link of EN 1995-1-1 to EN1990 and EN1991

EN 1990EN 1990

EN 1991EN 1991

EN 1992EN 1992 EN 1993EN 1993 EN 1994EN 1994

EN 1995EN 1995 EN 1996EN 1996 EN 1999EN 1999

Structural Structural safetysafety,,serviceability serviceability andanddurabilitydurability

Actions onActions onstructuresstructures

Design andDesign anddetailingdetailing

EN 1997EN 1997 EN 1998EN 1998 GeotechnicalGeotechnicaland and seismicseismicdesigndesign


National Annex• Contains nationally determined

parameters• These override EN1995-1-1 values• Take account of national conditions,

such as geographical or workmanship differences

• Are yet not published in all countries

How to spot NDPs!


National choices overview


General General conceptconcept

12

Ed

Effect of Actions:Self-LoadWindSnowVariable loadsTemperatureFire....

Rd

Resistance:StructureStructural ElementsMaterials, E-Modulus etc.cross sections, Area, Moment of Inertia

Semi-probalistic safety concept

≤

3

Safety

frequ

ency

frequ

ency

EffectEffect of of actionaction LoadLoad carryingcarryingcapacitycapacity RR

95% 95% quantilequantile 5% 5% quantilequantile

EEkk RRkk

γγFF γγMMEEdd RRdd

SafetySafety


Design Design situationssituations

•• Permanent Permanent situationsituation((afterafter erectionerection of of thethestructurestructure))


•• temporarytemporary situationsituation((duringduring erectionerection))



•• AccidentialAccidential situationsituation((impactimpact, , firefire))



Limit Limit statesstates

•• UltimateUltimate limitlimit statesstates•• ServiceabilityServiceability limitlimit statesstates

For all For all designdesign situationssituations thethe limitlimit statesstates shallshallnotnot bebe exceededexceeded. .


Limit state design

• Limit states are functional levels beyond which the structure no longer satisfies the performance criterias.

• Ultimate limit state:

– Safety level– Concerns safety of people– Integrity of structure

• Serviceability limit state

– Comfort of building user– No excessive deflection, vibration,

cracks– Negotiable from project to project

4


•• CharacteristicCharacteristic ActionsActions accordingaccordingto EN 1991to EN 1991

GGkk e.ge.g. . selfself--weightweightQQkk e.ge.g. wind, . wind, snowsnow, , traffictrafficAAkk e.ge.g. . impactimpact

ActionsActions


UltimateUltimate limitlimit statestate

Design Design valuesvalues of of actionsactionsBasic Basic combinationcombination::

ΣγΣγG,j G,j ⋅⋅ GGkk,j,j + + γγQ,1 Q,1 ⋅⋅ QQkk,1,1 + + ΣγΣγQ,i Q,i ⋅⋅ ψψ0,i 0,i ⋅⋅ QQkk,i,i

e.g. e.g. 1,351,35 ⋅⋅ GGkk + + 1,51,5 ⋅⋅ WWkk + + 1,51,5 ⋅⋅ 0,50,5 ⋅⋅ SSkk

simplified:simplified:Most Most unfavourableunfavourable variable variable actionaction: :

ΣγΣγG,j G,j ⋅⋅ GGk,jk,j + + γγQ1 Q1 ⋅⋅ QQk,1k,1 1,351,35 ⋅⋅ GGkk + + 1,51,5 ⋅⋅ WWkk

All All unfavourableunfavourable variable variable actionsactions::ΣγΣγG,j G,j ⋅⋅ GGk,jk,j + 1,35 + 1,35 ⋅⋅ ΣΣ QQk,ik,i 1,351,35 ⋅⋅ ((GGkk + + WWkk + + SSkk))

EN 1995-1-1 Design of Timber Structures Design and calculation principles

From a statistic point of view it´s unlikely that all actions/loads act at the sametime with their fully values.

ψ0 combination coefficient (in fundamental design situations)ψ1 frequent coefficient (in accidential design situations and servicability

calculations)ψ2 quasi-permanent coefficient (in servicability calculations)

Principle rule:

G K Q,1 K ,1 0,i Q,i K ,ii 2

G Q Qγ γ ψ γ≥∑⋅ + ⋅ + ⋅ ⋅

⇒ Coefficient for represantative values of actions ψ(for exact national data see: National Annexes)

Use of ψ0 from the second variable action/load.

Design values of actions; coefficient for representativevalues of actions:


CombinationCombination factorsfactors


CombinationCombination factorsfactors

0,00,00,20,20,50,5SnowSnow ((≤≤ 1000 m)1000 m)0,00,00,50,50,60,6WindWind0,80,80,90,91,01,0StorageStorage areasareas0,60,60,70,70,70,7CongregationCongregation areasareas0,30,30,50,50,70,7DomesticDomestic residentialresidential areasareasψψ22ψψ11ψψ00ActionAction


Partial Partial safetysafety factorsfactors forfor actionsactions(EN 1990)(EN 1990)

γγQQ = 1,5= 1,5γγGG = 1,35= 1,35unfavourableunfavourableγγQQ = 0= 0γγGG = 1,0= 1,0favourablefavourable

variablevariablepermanentpermanentActionAction

5

25

Partial Safety Factors γ F (γ G ,γQ ) , γ M

Gk × γ G + Qk × γQ ≤ kmod × Rk / γ M (timber: γ M = 1,3)

Safety factors in case of fire or other accidentialsituations: γ = 1,0

Safety Concept - simplified


ServiceabilityServiceability limitlimit statesstates

CalculationCalculation of of •• deformationsdeformations•• vibrationsvibrations


III.1 Eurocode 5 in basic; loads/actions on structures

. the combination of actionsunder consideration

d Q kQ Qγ= ⋅

d G kG Gγ= ⋅

Increase the actions/load by partial safety factors γ (gamma factors)

less safety risks

1,01,0Check at servicabilitylimit state

1,51,35unfavourable effect-1,0favourable effect

Structural design calculation

γQγGDesign situation


Design Design valuesvalues of of actionsactionscharacteristiccharacteristic (rare) (rare) combinationcombination: : ΣΣGGkk,j,j + + QQkk,1,1 + + ΣψΣψ0,i 0,i ⋅⋅ QQkk,i,i

GGkk + + WWkk + + 0,50,5 ⋅⋅ SSkk

quasiquasi--permanent permanent combinationcombination::ΣΣGGkk,j,j + + ΣψΣψ2,i 2,i ⋅⋅ QQkk,i,i

GGkk + + 0,00,0 ⋅⋅ WWkk + + 0,00,0 ⋅⋅ SSkk

ServiceabilityServiceability limitlimit statesstates


ComparisonComparison of of safetysafety conceptsconcepts

SafetySafety factorfactor

LoadLoad durationduration -- and and serviceservice--classclass

timbertimber


CombinationCombination factorfactorψψ

combinationscombinationsActionAction

ConceptConcept of of permissiblepermissible

stressesstresses

SemiSemi--probalisticprobalisticmethodmethodTakingTaking intointo accountaccount





timbertimber


w+s/2 w+s/2 oror s+w/2s+w/2CombinationCombination factorfactorψψ



stressesstresses


6





timbertimber

γγ = 1,35 (G)= 1,35 (G)γγ = 1,50 (Q)= 1,50 (Q)SafetySafety factorfactor




stressesstresses






timbertimber

γγ = ?= ?((permissiblepermissible stress)stress)γγ = 1,35 (G)= 1,35 (G)

γγ = 1,50 (Q)= 1,50 (Q)SafetySafety factorfactor


combinationscombinations

ActionAction


stressesstresses





kkmodmod

0,6 0,6 permanent,SCpermanent,SC 110,9 0,9 shortshort, SC 1, SC 10,5 0,5 permanent, SC 3permanent, SC 30,7 0,7 shortshort, SC 3, SC 3


timbertimber





ActionAction


stressesstresses




??((permissiblepermissible stress) stress)

ReductionReduction of 1/6 of 1/6 (SC 3)(SC 3)

kkmodmod

0,6 0,6 permanent,SCpermanent,SC 110,9 0,9 shortshort, SC 1, SC 10,5 0,5 permanent, SC 30,7 0,7 shortshort, SC 3, SC 3


timbertimber





ActionAction


stressesstresses



γγ = 1,3 (5%= 1,3 (5%--Quantil)Quantil)SafetySafety factorfactor



kkmodmod



timbertimber





ActionAction


stressesstresses



γγ = ?= ?((permissiblepermissible stress)stress)

γγ = 1,3 (5%= 1,3 (5%--Quantil)Quantil)SafetySafety factorfactor



kkmodmod



timbertimber





ActionAction


stressesstresses


7


Materials and service classes


Steps for the designer

• Identify material strength and stiffness properties in supporting standard

• Establish modification factors– Material– Load– Service class

• Determine material resistance for calculation


Design value of material propertiesXd

Xk - characteristic value of a strength propertyγM – partial factor for a material propertykmod – modification factor, taking into account duration of load and moisture content

Xd =kmod • Xk

γM


σd fd≤

loading resistance

freq

uenc

y

÷ γMEk

design values

5%-quantiles

fkx γGγQ

Edx kmod

Structural design calculation

EC 5-1-1 Design of Timber Structures

CharacteristicCharacteristic valuesvalues of material of material propertiesproperties

•• 5%5%--Quantil of Quantil of strengthstrength propertiesproperties, , e.ge.g. . Bending Bending strengthstrengthTension Tension strengthstrengthCapacityCapacity of a of a connectionconnection

•• MeanMean valuevalue of of stiffnessstiffness propertiesproperties, , e.ge.g..ModulusModulus of of ElasticityElasticity((exceptionsexceptions: : TheoryTheory of second order, of second order, bucklingbuckling))


Partial safety factor γM

Recommended material safety factor γM = 1,3

8

EN 1995-1-1 Design of Timber Structures Timber Structures

Mechanical properties in general• Different in growth directions

• Modulus of elasticity

• Mechanical properties are related to the density

0100020003000400050006000700080009000

1000011000

0 10 20 30 40 50 60 70 80 90

α in [°]

Eα

in [N

/mm

²]

3

110011 000

sin370

Eαα

=

⋅ 3 3

11000 37011000 sin s370

Eco

α

α α

⋅=

⋅ +

EN 1995-1-1 Design of Timber Structures Timber Structures

Hygroscopisc isotherms for fir timber by W.K. Loughborough, R. Keylwerth


Effect of moisture content

The mechanical properties of timber aremoisture dependend!

- ExampleChange of moisture content from12% to 20%leads to a significant reduction

68 N/mm²

92 N/mm²= 0,7391


Moisture dependend strength properties are leading to

Service Classes

Higher humidity compared to SC 2u > 20%320°C und 85% rel. humidityu ≤ 20%220°C und 65% rel. humidityu ≤ 12%1

Environmental conditionsAverage moisturecontent um

Service Class


ActionsActions on a on a floorfloor

00 1010 2020 3030 4040 50500,00,0

1,01,0

2,02,0

00 1010 2020 3030 4040 50500,00,0

1,01,0

2,02,0

pp[[ kk

NN //mm

]]22

LoadLoad durationduration[a][a]

QQGG


LoadLoad durationduration classesclasses

9


kmod · fk kmod for the action/load with shortest design situation

Ultimate limit state:

Serviceability limit state:

separate for each action/load

wel · (1+ kdef)

def

E1 k+

Influence of service classes and duration of load


Festigkeitsklasse (Sortierklasse nach DIN 4074-1)

C16 C24 C30 C35 C40

Festigkeitskennwerte in N/mm2

Biegung fm,k 2) 16 24 30 35 40

Zug parallel ft,0,k 2)

rechtwinklig ft,90,k

10 0,4

14 0,4

18 0,4

21 0,4

24 0,4

Druck parallel fc,0,k rechtwinklig fc,90,k

17 2,2

21 2,5

23 2,7

25 2,8

26 2,9

Schub und Torsion fv,k 3) 6) 2,7 2,7 2,7 2,7 2,7

Steifigkeitskennwerte in N/mm2

Elastizitätsmodul parallel E0,mean 4)

rechtwinklig E90,mean 4) 8000 270

11000 370

12000 400

13000 430

14000 470

Schubmodul Gmean 4) 5) 500 690 750 810 880

Rohdichtekennwerte in kg/m3

Rohdichte ρk 310 350 380 400 420 1) Nur maschinen sortiert 2) Nadelrundholz geschält ohne angeschnittene Faser: +20% 3) Beim Nachweis von Querschnitten die mindestens 1,50 m vom Hirnholz entfernt liegen, darf fv,k um 30 %

erhöht werden. 4) Für die charakteristischen Steifigkeitskennwerte E0,05, E90,05 und G05 gelten die Rechenwerte:

E0,05 = 2/3·E0,mean E90,05 = 2/3·E90,mean G05 = 2/3·Gmean 5) Der zur Rollschubbeanspruchung gehörende Schubmodul darf mit GR,mean = 0,10·Gmean angenommen

werden. 6) Als Rechenwert für die charakteristische Rollschubfestigkeit des Holzes darf für alle Festigkeitsklassen mit

fR,k = 1,0 N/mm2 angenommen werden.

Strength properties for timber (Tab. F. 5 DIN 1052)(for exact national data see: National Annexes)


Festigkeitsklasse des Brettschichtholzes GL 24 GL 28 GL 32 GL 36

h = homogen c = kombiniert h c h c h c h c

Festigkeitskennwerte in N/mm2

Biegung fm,y,k 1) 24 24 28 28 32 32 36 36

fm,z,k 2) 28,8 24 33,6 28 38,4 32 43,2 36

Zug parallel ft,0,k

rechtwinklig ft,90,k

16,5 0,5

14 0,5

19,5 0,5

16,5 0,5

22,5 0,5

19,5 0,5

26 0,5

22,5 0,5

Druck parallel fc,0,k rechtwinklig fc,90,k

24 2,7

21 2,4

26,5 3,0

24 2,7

29 3,3

26,5 3,0

31 3,6

29 3,3

Schub und Torsion fv,k 3) 3,5 3,5 3,5 3,5 3,5 3,5 3,5 3,5

Steifigkeitskennwerte in N/mm2

Elastizitätsmodul parallel E0,mean 4)

rechtwinklig E90,mean 4) 11600 390

11600320

12600 420

12600 390

13700 460

13700 420

14700 490

14700460

Schubmodul Gmean 4) 5) 720 590 780 720 850 780 910 850

Rohdichtekennwerte in kg/m3

Rohdichte ρk 380 350 410 380 430 410 450 430 1) Bei Brettschichtholz mit liegenden Lamellen und einer Querschnitthöhe H ≤ 600 mm darf fm,y,k mit folgendem Faktor

multipliziert werden: (600 / H)0,14 ≤ 1,1 2) Brettschichtholz mit mindestens 4 hochkant stehenden Lamellen 3) Als Rechenwert für die charakteristische Rollschubfestigkeit des Holzes darf für alle Festigkeitsklassen fR,k = 1,0

N/mm2 angenommen werden. 4) Für die charakteristischen Steifigkeitskennwerte E0,05, E90,05 und G05 gelten die Rechenwerte:

E0,05 = 5/6·E0,mean E90,05 = 5/6·E90,mean G05 = 5/6·Gmean 5) Der zur Rollschubbeanspruchung gehörende Schubmodul darf mit GR,mean = 0,10·Gmean angenommen werden.

Strength properties for glulam (Tab. F. 9 DIN 1052)(for exact national data see: National Annexes)


kmod- und kdef-values

Modification value kmod und deformation value kdeftaking into account service class and load duration

kmod Modification value for ultimate limit state design

kdefDeformation value for serviceability limit state design


kmod- values


kdef-values

10


Size factors

Size factors taking into account volume effects

kh is a variable factor in correlation with the referencedepth in bending

Solid timber Glulam LVL


Strength Classes – solid timber

Visual grading:

Criteria: Knots, cracks, discoloration, bark etc. Reliability ??

Mechanically grading:

Radiation:Empfänger Sender

Bending principe:

Laufrichtung F

w

EmpfängerMeasurement of naturalfrequency:

Strength Classes – solid timber Grading


Strength Classes – solid timber (EN 338)


Strength Classes – glulam (EN 1194)

11


Strength Classes – glulam (EN 1194)


Strength Classes – glulam (DIN 1052)


Strength Classes – glulam (EN 1995-1-1)

Warning Letter !!

Solid timber: fv.k = 2,0 N/mm²

Glulam: fv.k = 2,5 N/mm²

will be taken into account by a factor kcr


kcrack-value

M

kvcrackdv

kfkf

γmod,

,

⋅⋅=


Wood based panels

Wood based panels covered by EN 1995-1-1

Missing materials: Cement bonded particle board,

gypsum based panels,

X – lam (cross laminated glulam) ….

Design of Timber StructuresEC 5-1-1 Holzbau Grundlagen

Plywood (EN 636)

12


LVL (EN 14374)


OSB (EN 300)


Particleboard (EN 312)


Fibreboard, hard (EN 622-2)


Fibreboard medium (EN 622-3)


Fibreboard MDF (EN 622-5)

13


Beams and columns

yIM

z

z ⋅

( )z,yσ

+

=

yM

zMy

z

zIM

y

y ⋅


z

z

yy

σ+

-

max σm

min σm= Vd 6

5

Design resistance for cross-sections


Ultimate limit state: 05d mod

M

XX kγ

= ⋅

Bending strength:m,k

m,d modM

ff k

γ= ⋅

t ,0 ,kt ,0,d mod

M

ff k

γ= ⋅

Servicability limit state: d mX X=

Modulus of elasticity: d 0,meanE E=

Design value of material properties:

Tensile strength:


Vd = design value of the shear force S = static moment (section modulus)

= b·h2/8 (rectangle cross-section)I = second moment of area (moment of inertia)

= b·h3/12 (rectangle cross-section)b = widthfv,d = design shear strength for the actual condition

dd v,d

V1,5 fA

τ = ⋅ ≤ d

v,d

1,5 V A 1f⋅

≤

dd v,d

V S fI b

τ ⋅= ≤

⋅

d

v,d1

fτ

≤

Shear


[ ][ ][ ]

≥ ⋅

dd

v ,dv ,d

A in cm²V

erf A 15 with V in kNf

f in N/mm²dimensioning

τ = ⋅ ≤dd v ,d

V15 f

A⋅ ≤d

v,d

V A15 1

f

τd in [N/mm²]Vd in [kN]A in [cm²]fv,d in [N/mm²]

[ ][ ]

≥ ⋅

dd

A in cm²erf A 9 V with

V in kN

For sawn timber C 24, service class 2 and medium term action:


uniaxial bending

Roof construction

Pfette

Sparren

static systems

dm,d m,d

n

M fW

σ = ≤ d n

m,d

M / W 1f

≤

σm,d = design value of bending stressMd = design value of bending momentWn = netto moment of resistance considering the cross section weaksfm,d = design value of bending strength

rafter

purlin

14


fm,y,k · 1,1h ≤ 250 mm

250 mm < h <600 mm

fm,y,k600 mm ≤ h

h ⋅

0,1

m,y ,k600f

h

dm,d m,d

n

M1000 fW

σ = ⋅ ≤ d n

m,d

M / W1000 1f

⋅ ≤

σm,d in [N/mm²]Md in [kNm]Wn in [cm³]fm,d in [N/mm²]

Influence of height of of glulam

Ultimate limit state


[ ][ ][ ]

nd

n dm,d

m,d

W in cm³Merf W 1000 mit M in kNmf

f in N/mm²

≥ ⋅

Dimensioning

For sawn timber C 24, service class 2 and medium term action:

[ ][ ]

≥ ⋅

nn d

d

W in cm³erf W 68 M with

M in kNm


4,3

m

w

y y

100 100 mm

yy wz

qz

yy wz

Fc

Fc

Stability of Members

β=1

lef

2


imperfections additional bending moment

c,0,dc,0,d c c,0,d

n

Fk f

Aσ = ≤ ⋅ c,0,d n

c c,0,d

F A1

k f≤

⋅

An: local cross section weakenings might be neglected at the stress verification if they are not situated in the middle third of the buckling length.

kc: local cross section weakenings might be neglected at the calculationof the buckling coefficient.

Compression members endangered by buckling

Structural design calculation using compressive stress values and reducedcompressive strength:


c 2 2rel ,c

1k 1k k λ

= ≤+ −

Buckling coefficient

k = ( ) 2c rel ,c rel ,c0,5 1 0,3β λ λ ⋅ + ⋅ − +

βc = 0,2 for solid timber 0,1 for glued laminated timber and LVL

λrel,c = Relative Slendernessc,0,k c,0,kef

0,05 0,05

f fi E E

λπ π

= ⋅ = ⋅⋅

l

λ = efil

= Slenderness

lef = β · s = effective lenght β = buckling length coefficient i I A=


β=1

lef

2

Buckling length coefficient β

β=0,5

lef

4

β=2

lefs

1

β=0,7

lef

3

15


Compression member with intermediate lateral support:

buckling length = distance of lateral support

different buckling lengths lef,y and lef,z :

2

1y z

Scheibe

hho

hu3

z y

h


Design calculation


Design calculation

1. determination of buckling lengths lef for buckling around the principal axis2. calculation of the slenderness ratio λy and λz

3. determination of instability factors kc,y und kc,z

ef iλ = l with i = 0,289 · h resp. = 0,289 · w at rectangular cross sections

4. verification of buckling resistance

c,0,dc,0,d c c,0,d

n

F10 k f

Aσ = ⋅ ≤ ⋅ c,0,d n

c c,0,d

F A10 1

k f⋅ ≤

⋅

σc,0,d in [N/mm²]Fc,0,d in [kN]An in [cm²]fc,0,d in [N/mm²]


29934039044851558866072377381284167600260

22125229033639145452258663967970957600240

15818120924428633739745951455758748400220

10912614617020124028834339944447640000200

72,783,697,111413616319924329334037532400180

45,952,961,572,586,510512916120224728425600160

27,231,436,643,151,662,97898,712716420219600140

14,817,12023,628,334,643,255,272,597,613014400120

7,28,39,711,513,91721,327,436,450,47210000100

7,006,506,005,505,004,504,003,503,002,502,00mm²mm

Nd, max in kN for a buckling length of lef in m Aa

for axial compression

Design resistance of squared columns C 24 in Service class 2 for medium action load

a

a


ThankThank youyou veryvery muchmuchforfor youryour attentionattention!!

1

Univ.-Prof. Dr.-Ing. Stefan Winter

European Standardisation

Standards for thedesign of timber structures


Personal Statement

What is the inspiration to work, research and teach on the field of

timber engineering and fire safety?


Timber

is worldwide the leading biogene based construction material and

perhaps one of the key materials to find sustainable solutions for

spaceship earth!


Standardisation helps• Trade

• Quality control

• Design and constructionof structures

in the European Union and all over the world!


Target of the European CommissionA unique set of standards for thedesign of building structures until2010

Drafting of the codes: Technical committees of CEN(CEN = Comité Européen de Normalisation)

Implementation of the codes:National legal bodies with support from thenational standardisation bodies, e.g. DIN


The European CommissionDefines the regulations (standards)

But NOT the requirements.

The requirements, especially safetyrequirements (e.g. fire safety) areestablished by the national legal bodies!!

2


National StandardisationBodies (e.g. DIN, BSI)are participating in thestandardisation process, set up „mirror committees“ to comment to European Standards and

implement finalized and translatedstandards as national standards, e.g.

DIN EN 1995-1-1: Eurocode 5 –Design of timber structures Univ.-Prof. Dr.-Ing. Stefan Winter

The following types of standards

are available:

• Test standards

• Product standards

• Design standards

• Value standards

• Umbrella standards


Test standards

define methods to evaluatecharacteristic material properties, e.g.EN 380 Timber Structures – Test methods – General principles for static load testing

EN 789 Timber Structures – Test methods –Determination of mechanical properties of wood basedpanels

EN 14358 Timber Structures – Evaluation of characteristic 5-percentile values


Product standards

define the product, product classesand (in a harmonized standard) theattestation of conformity procedure, e.g.EN 300 Oriented Strand Board – Definitions, classificationand specifications (without Annex ZA)

EN 14081-1 Strucutural timber with rectangular cross sections – Part 1, Grading requirements to strengthgraded timber (with Annex ZA)

EN 14080 Glued laminated timber products –requirements (with Annex ZA)


Note

Product standards give requirementsfor the production control, but containno characteristic values for the design of timber structures. These values aregiven in separate (value) standards, e.g.EN 338 Structural Timber – Strength Classes

EN 12369-1 Wood based panels – Characteristic valuesfor the design of timber structures – Part 1: OSB, chipboard and fibreboards


Note

Because not all product standardsgive requirements for the evaluation of conformity and CE-marking, theseregulations are given in separate umbrella standards, e.g.

EN 13986 Wood based panels for use in construction–Characteristics, evaluation of conformity and marking

3


Note

Cause this umbrella standards couldeffect the national safety level, thememberstates could implementadditional applicaton standards, e.g. toDIN EN 13986 Wood based panels for use in construction– Characteristics, evaluation of conformityand marking

in Germany DIN V 20000-1 Application of construction products in structures – Part 1: Wood based panels


Design standards

Define the procedures of design of timber structures based on thecharacteristic values given in productstandards which are evaluatedaccording to the valid test standards

EN 1995-1-1 Eurocode 5 – Design of timber structures –Part 1-1: General rules and rules for buildings


Design standards

comprise a set of standards regarding

actions and general regulations, e.g.EN 1990 Eurocode – Basis of structural design

EN 1991-1-1 Eurocode 1 – Actions on structures – Part 1-1: General Actions - Densities, self-weight, imposedloads for buildings

EN 1991-1-2 Eurocode 1 – Actions on structures – Part 1-2: General Actions - Actions on structures exposed to fire


Note

The design methods used in theEurocodes are linked to the test standards. If the test method changesa different design method could benecessary!

A complete final set of standards isscheduled for October 2010!


Engineers use the design codes forcalculating a timber structure –

How do they know, that the material taken into account is the material usedon site?

⇒ CE - mark


The CE – mark shows

that the product is in accordance

with the relevant product standard.

The mark contains classes ordeclared characteristic values to beused in the design procedure

4


CE – marking

Example for a CE mark of a wood based panel (OSB)

No. of certification

company

Year of marking

Relevant standard

Type of panel

Class of combustability


CE – marking is based on internal and external factory production controlaccording to the attestation of conformity procedure given by theEuropean Commission.

It is accepted by the national authorities to use the characteristicvalues of the product in accordancewith the legal regulations.


CE – marking is necessary

for free trade but also

for the legal control.

It shows the (end-)user the conformityand usability of the product.


Approvals

In addition to materials and structuresaccording to standards, new constructionmaterials or building kits can be used withan

European Technical Approval (ETA) given by an notified body(e.g. DIBT, VTT, BRE) ⇒ CE-Zeichen


An exampel: Oriented Strand Board

Product standard


Harmonised (umbrella) product standard


5


Value standard




German application standard

E.g. γ-values for the calculation of material properties using a deterministic design

TENSION PERPENDICULAR TO THE GRAIN – HOLES –CURVED BEAMS

P. Dietsch

Technische Universität München

Chair of Timber Structures and Building Construction

EN 1995 - Timber Structures Tension Perpendicular to Grain

Dipl.-Ing. Philipp Dietsch Eurocodes - Background & Applications 18th – 20th of February 2008, Brussels

Eurocodes – Background and Applications EN 1995 – Tension Perpendicular to Grain

Dipl.-Ing. Philipp Dietsch

Technische Universität MünchenChair of Timber Structures and Building Construction





Timber – Strength Classes

ft,90,k≈1/30 ft,0,k

fv,k≈1/10 fm,k

[EN 338]




σm σm

D

Z

D

Z

F⊥

F⊥σt,90

σt,90

Double tapered, curved and pitch cambered Beams

Distribution of Tension Perpendicular to Grain Stresses

rin





l

h= h ap

σmaxσmax

τmax

σm

Distribution of Shear Stresses





Distribution of Shear and Tension Perpendicular to Grain Stresses

Tension perp. to grainShear

(Kirchanschöring, MPA BAU) (Neuburg on the Danube, MPA BAU)[SIA 265]

Interaction




F F F

F F F


Brittle materials – Size Effect

„A member under tension stress is only as strong as the weakest link“

The strength of a brittle material is a function of its volume under uniform stress.

m

i

j

j

i

VV

ff

⎟⎟⎠

⎞⎜⎜⎝

⎛=




Double tapered, curved and pitch cambered Beams in EC 5

.

.

.

[EN 1995-1-1:2004; 6.4.3, p. 48ff]





.

.

.

[EN 1995-1-1:2004; 6.4.3, p. 48ff]





.

.

.





Strengthening Measures

Self-tapping screws with continuous threads or threaded rods

Plywood / Laminated Veneer Lumber

rin

rin




lad

ladτmax

τef

Outer lamella


Strengthening Measures – Screws or threaded Rods

Fritz Leonhardt, Vorlesungen über Massivbau

rin




t t


Strengthening Measures – Plywood / Laminated Veneer Lumber glued to Timber Member

Strengthening measures (screws / plates) should be designed to carry full tension perpendicular to grain stresses and should cover the entire area under tension perp. to grain stresses (curved area)

rin




Moisture Conditions

Ice-rink arena(Ingolstadt, MPA BAU)

20 mm = 25,1 %

55 mm = 18,9 %95 mm = 19,1 %

Gymnasium with skylights(Benediktbeuern, MPA BAU)

10 mm = 7,5 %70 mm = 10,5 %120 mm = 11,7 %




©Stefan Kühn

In Glulam Beams – Crack Distribution enabled

f t,90

σc,90

σt,90

Moisture Conditions – Cracks caused by Shrinking

∆W




©Stefan Kühn

In Glulam Beams – Crack Distribution enabled

f t,90

σc,90

σt,90

(Benediktbeuern, MPA BAU)


∆W




In Combination with Fasteners – Crack Distribution impeded

(Feldkirchen, Prof. Winter)


Residual cross section to transmit shear stresses and/or stresses in tension perp.

￫ reduction of applicable strength values or cross sections by e.g. kcr




Notched Beams

Picture: Prof. H. Blaß, TH Karlsruhe




Notched Beams in Concrete

Fritz Leonhardt, Vorlesungen über Massivbau

→ Constant tensile strength in all directions




10 ≤ ft,0,k ≤ 21 [MN/m2]

ft,90,k ≈ 0.5

Notched Beams in Timber

→ Tensile strength changes with varying angle between load and grain

ft,90,k ≈ 1/30 ft,0,k




σt,90

σc,90

ft,90


σt,90

τ




Notched Beams in Timber – Constructive Measures

σt,90

ft,90

σt,90

ft,90





.

.

.

.

.

[EN 1995-1-1:2004; 6.5.2, p. 52ff]





.

.

.

.

.

[EN 1995-1-1:2004; 6.5.2, p. 52ff]




σt,90

σc,90

ft,90

Notched Beams in Timber – Strengthening Measures

> ℓ a

dℓ a

d

h ef

h

Example of reinforcement in concrete structures

Strengthening measure / reinforcement by self-tapping screws with continuous thread




σt,90

σc,90

ft,90

Notched Beams in Timber – Strengthening Measures

h ef

h

t t

ℓr

Strengthening measure / reinforcement by glueing plywood / LVL to the sides of beam, glueline pressed by nails




Cross Connections

Pictures: Prof. H. Blaß, TH Karlsruhe




→ Pure Compression (Fc)Perpendicular to Grain

Fc = F

→ Pure Tension (Ft) Perpendicular to Grain

Ft = F

→ Tension and CompressionPerpendicular to Grain

Fc = 1-η*F; Ft = η*F

Cross Connections

F

F

F




Cross Connections – Influences on load-carrying Capacity

F

h 1h 2

h 3h n

ar

F/2 F/2

t t

b e

h

Load-carrying capacity depends on stressed volume and stress distribution / stress peaks and is therefore influenced by:• Ratio between distance be and beam depth h• Fastener spacing in grain direction / length ar• Penetration thickness t




Cross Connections

.

.

.

[EN 1995-1-1:2004; 8.1.4, p. 59ff]




Cross Connections

.

.

.

See also STEP C2 „Tension perpendicular to the grain in joints“

[EN 1995-1-1:2004; 8.1.4, p. 59ff]




Cross Connections – Strengthening Measures

F

ℓ ad,

tℓ a

d,c

F

F/2 F/2

F/2 F/2

ℓ ad,

c

Self-tapping screws with continuous thread

Plywood / LVL, glued, pressed by screws

critical area




Openings

Pictures: Prof. H. Blaß, TH Karlsruhe




V/2

V/2

V

Openings

V




Openings




Openings - Constructive Measures

Size – as small as possible (minimize reduction in cross section)

Round openings or chamfered corners (avoid stress peaks)

Place in center line of member, at distance from supports




Openings - Strengthening Measures

h ro

h ro

h d

aℓa

h ro

h ro

h d

aar ar aar ar aℓr ℓr

t t




Tension Perpendicular to Grain - Conclusion

• Tension perpendicular to grain strength very low• Avoid tension perp. to grain stresses whenever possible• Members with tension perp. to grain stresses are:

– Double tapered, curved and pitch cambered beams– Notched members, members with holes or cross connctions

• Tension perp. to grain stresses also develop with changing moisture content

• Possible reinforcements are: Self-tapping screws with continuous thread, drilled or glued-in rods, plywood / LVL…

• Proposal: reinforcements should be designed to carry full tension perp. to grain stresses (cracked tension perp. to grain zone)




Literature

• Timber Engineering – STEP 1, STEP 2; Centrum Hout; The Netherlands

• Erläuterungen zu DIN 1052:2004; DGFH; Germany (in German)• CIB – W18 Proceedings; TH Karlsruhe; Germany• Design of Structural Timber to EC5; Palgrave; GB• Structural Timber Design to Eurocode 5; Blackwell Publishing; GB

SERVICEABILITY – DEFLECTION AND VIBRATION

H. Kreuzinger

Technische Universität München

1Chair of Timber Structures and Building Construction

EN 1995-1 Timber Structures Eurocodes - Background & Applications 18th – 20th of February 2008, Brussels

Section 7 Serviceability limit states

Heinrich Kreuzinger



Serviceability limit statesCalculation of • Deformations, Deflections• Vibrations



Deflections, Deformations

Vibrations

∑∫⋅

+⎟⎟⎠

⎞⎜⎜⎝

⎛ ⋅+

⋅+

⋅=

enVerbindung serSystem * KFFds

GAQQ

EANN

EIMMw

f2 ⋅π==ωMK

7.1 Table 1



Section 2.2.3

)1( def

mean

kE

E+

=







Deflections Vibrations

wf

⋅=

8,05

Frequency



Vibrations:

Servicability limit states

If necessary

Ultimate limit states

FatigueDurability



Serviceability (Ohlsen)



floor, beam

( ) ( ) tsinxwt,xw 0 ωψ ⋅⋅= ( ) tsinwtw 0 ω⋅=

Viechtach, Bertsche

Single degree of freedom System



w (t)

M

KR

F (t)

Lemgo, Mayer/Ludscher, SFS




w (t)

M

KR

F (t)M Mass tK Stiffness kN/mR Damping kN/(m/s)

R=2 M D ωD Damping ratio

( )

!52

2

22

cminww

f

fgg

KgM

KGw

fMK

g

g

g

=

⋅⋅==

⋅==

⋅⋅==

πω

πω




!5 cminww

f g

g

=

Hzf

cmmmw pg

2,76,08,0

5

6,063,0

=⋅

=

==+

Frequency - Deformation

Factor for beam

w




Zeit

Deformation

period T (in Sekunden)




Deflection wVelocity v Acceleration a

Deformationw

w0 t

Velocityv

v0t

Acceleratora

a0t

·ω

·ω



F(t)

tti

sN55m/skg550,059,81255

hg2MvMdtF(t)I

⋅=⋅=⋅⋅⋅

=⋅⋅⋅=⋅=⋅= ∫

Impuls ITi=0F=infinite

Impuls

Heeldrop



Velocity v

IM

sm

kgsN

MIv =

⋅=

t= 0

Impuls



( )( )tωζ1sineζ1ωM

Iw(t) 2tω

2⋅⋅−⋅⋅

−⋅⋅= ⋅⋅−ζ

0,01ζund1ζ1ωM

I2

==⋅−⋅⋅

Impuls



Number of frequencies f1,n ≤ 40 Hz

444

4

0,1 1 nbEJ

EJff bn ⋅+⋅=

l

l

25,0

b4

42

040 EJ

EJb1

f40n

⎥⎥⎦

⎤

⎢⎢⎣

⎡⋅⎟

⎟

⎠

⎞

⎜⎜

⎝

⎛−⎟⎟

⎠

⎞⎜⎜⎝

⎛=

ll

( )Mbmbm

nvSI

1

2

1200

60404 40 =⋅⋅

≈+⋅⋅

⋅+⋅=

ll

,,

Impuls – I = 1Ns, 7.3.3(5) f1,n frequency of a platen number of waves in

direction verticalto the main span



Experimental solution, Found by testing

sm

EIEIm6,0v 25,0

b25,05,0 ⋅⋅

=l

Impuls – Heeldrop I = 55 Ns



7.3.3(2)

KF

w 0=

uniform load

EI384q5w

4

⋅⋅⋅

=l

Fl

3

F bEI48Fw

⋅⋅⋅

=l

4b

F EIEI

1,1b

l

l⋅=

Single load

bF



7.3.3(2)

7.3.3(1)

No resonancef >8 Hz(w < 0,5 cm)

f < 8 Hz(w > 0,5 cm)

frequencywG,instquasi ständig, g+ψ2p

4

7.2Enough rigidity smalldeflection

w < l/Xdeflectionw

1

EN 1995-1-12004 (E)

aim LimitValue

4321

Serviceability limit states



7.3.3(2)SIA 265

Velocityv<b(f1

ζ-1)

50 < b < 150

ζ = 0,01

ImpulsI=1 Ns(up to 40 Hz)

5

7.3.3(2)SIA 265

Small deformationRigidity perpendicular to the main span

u <0,5 bis4 mm

DeflectionSingle loadF=1kN

3



Mohr /bmh/velocityv<6 b(f1

ζ-1)velocityheeldropI=55Ns, ti = 0,05s

6

Information

DIN 1052,2004 9.3

Frequenzkeine Resonanz-untersuchungFrequenzResonanz-untersuchung

w < 6 mm

w > 6 mm

DurchbiegungwG,instquasi ständig, g+ψ2p

2



7.3.3 (1)poorerperformance

a< 0,35 bis 0,7 m/s2

AccelerationResonanceWalking

8

7.3.3.(1)better performance

a<0,1 m/s2AccelerationResonanceWalking

7

7.3.3(1) Special Investigation f < 8 Hz

Kreuzinger, H.; Blaß, H.J.; Ehlbeck, J.; Steck, G.: Erläuterungen zu DIN 1052:2004-08 –Entwurf, Berechnung und Bemessung von Holzbauwerken. Hrsg.: DGfH, Bruderverlag, Albert Bruder GmbH, Karlsruhe

Compare:



Damping ratio

D, ζ R/(2 M ω)δ,Λ logarithmic Damping ratio, 2 π D, 2 π ζ

πΛ

≅

=Λ+

2D

wwln

1i

i

Some values for D:steel 0,005concret 0,008timber 0,010 bis 0,02


EN 1995-1 Timber Structures Eurocodes - Background & Applications 18th – 20th of February 2008, BrusselsSIA

Wenn keine genaueren Informationen vorliegen, ist das Dämpfungsmass ζ (logarithmisches Dekrement geteilt durch 2π) ein Wert von 0,01 anzunehmen. Weitere Richtwerte sind:-Holztragwerte ohne mech. Verbindungen 0,010-Holztragwerte mit mech. Verbindungen 0,015-Holzdecken ohne schwimmenden Estrich 0,010-Decken aus Brettschichtholz mit

schwimmenden Estrich 0,020-Holzbalkendecken aus Brettstapeldecken

mit einem schwimmenden Estrich 0,030



Schweizer NormSwiss codeSIA 265



y

pz, Fz

zxl=4,2 m

b = 6,3 m

Example - System



h = amam-2

a3 a1

Ny

y

Nx

xMx

My

z

Qy

Qx

BSP



Self weight 3,23 kN/m2

Trafic load 2,00 kN/m2

Quasi ständige Kombination nach DIN 1055-100, Gl 24

22 /83,30,23,023,3 mkNpgqs =⋅+=⋅Ψ+=



Decke: BSP 155 mm 5 Lagen je 31 mm

31 93 155

( )( )

23

233

2333

41,3155,012111000

71,0031,0093,012111000

70,2031,0093,0155,012111000

MNmEI

MNmEI

MNmEI

b

b

=⋅⋅=

=−⋅⋅=

=+−⋅⋅=

+l

l

Biegesteifigkeiten:

l b

Bending Stiffness




31 93 155

( ) 444333 246001046,2031,0093,0155,0121 cmmI =⋅=+−⋅= −

l

Biegesteifigkeiten:

l b




31 93 155mma

mma

b 62319312431155

=−==−=l

MNdnGaS

MNdnGaS

i

Rbb

i

R

3,9031,01

175062,01

6,18031,02

175124,01

22

22

=⋅

⋅⋅=

⋅⋅⋅

=

=⋅

⋅⋅=

⋅⋅⋅

= ll

Shear Stiffness

l b




31 93 155

Wirksame Steifigkeiten: 2

21

1

lSEI

EIefEI

⋅⋅

+⋅=

π

2

2

2 50,2

2,46,18704,21

1704,2 MNmefEI =

⋅⋅

+⋅=

πl

2

2

2 70,0

3,63,971,01

171,0 MNmefEIb =

⋅⋅

+⋅=

π

Näherung:

Effective Stiffness



w´= -ψ

Biegung ohne Schub (EI, GA ∞)

Reine Schubverformung (GA, EI ∞)

Im Fachwerkmodell: ○ Elastische Gurte (EA), ○ Dehnstarre Diagonalen (EA ∞)

Im Fachwerkmodell: ○ Dehnstarre Gurte (EA ∞),○ Elastische Diagonalen (EA)

EADiagonalen→ ∞EARiegel→ ∞ w´=γ

Abschnitt 8.6, Anhang D

F F

EI48Fw

3

⋅⋅

=l

GA4Fw⋅

⋅=

l

Beispiel – Biege- Schubverformung



Deflection, single span

mmm

efEIgw

21,61021,6

50,23842,41083,35

3845

3

434

=⋅=

⋅⋅⋅⋅

=⋅

⋅⋅=

−

−

l

l

Frequency

Hzw

f 09,7621,08,0

58,05

=⋅

=⋅

=

Deflection, Frequency



Anisotrope Platte, Trägerrostm*: Masse (tausend t/m2)k: Zahl der Wellen in x-Richtungn: Zahl der Wellen in y-Richtungn40: Zahl der Eigenfrequenzen unter 40 Hz

yb

nxkw nknkππψ sinsin,, ⋅⋅⋅=

l

mEJ

fb

nEJkEJm bl

lll

⋅=+= 204

44

4

442

2; πππω

44

44

0, nbEJ

EJkff b

nm ⋅⋅+=l

l

Frequency plate



Hzm

efEIf 19,710383,0

50,22,422 3220 =

⋅⋅

⋅=⋅

⋅=

−ππ

l

4444

444

4

44 055,0

3,650,22,47,0 nknkn

befEIEI

k b ⋅+=⋅⋅

⋅+=⋅

⋅

⋅+

l

66,5339,432,529,528,82

42,827,916,88,887,39154321

n Wellen senkrecht zur Tragrichtung k Wellen in Tragrichtung

Frequency plate



Frequencies



Eigenform1 f= 5.9 Hertz

Eigenform 2 f= 6.5 Hertz



k=1

n = 1f = 7,39 Hz

n = 2f = 8,88 Hz

n = 3f = 16,8 Hz

n = 4f = 27,9 Hz




k=2

Eigenform 2,1f =28,2 Hz



deflection

kdef = 0,8, EDIN 1052, Tble 3.2

defdef k

efEIkefEI+

=1

)(



0,0112/4,2 =1/37511,2 mm

ψ2⋅(1 + kdef)⋅wQ,inst0,3⋅(1+0,8)⋅3,25=1,8 mm

(1 + kdef)⋅wG,inst

1,8·5,25 =9,4 mm

1Wfin

Quasi ständige Bemessungssituation nach Gleichung (42) DIN 1052

7.2Enough rigidity Smalldeflection

w < l/Xdeflectionw

1



Deflection single load

F = 1kN

mEIEI

b bF 78,2

50,27,0

1,12,4

1,144 =⋅=⋅=

l

l

mmmbEI

FwF

F 22,01022,078,250,248

2,410148

3333

=⋅=⋅⋅

⋅⋅=

⋅⋅⋅

= −−

l

l

0,22< 0,5 bis 4 mm

DIN ENV 1995-1-17.3.3SIA 265

QuerverteilunggeringeVerformung

u <0,5 bis4 mm

DurchbiegungEinzellastF=1kN

3



f1,1 = 7,19 Hz < 8 Hz !!

Frequency

7.3.3(2)

7.3.3(1)

No resonancef >8 Hz(w < 0,5 cm)

f < 8 Hz(w > 0,5 cm)

frequencywG,instquasi ständig, g+ψ2p

4



Impuls I=1 Ns

„better performance“

( ) ( )sm

bmn

v 00132,02003,62,438356,04,04

2006,04,04 40 =

+⋅⋅⋅+⋅

=+⋅⋅

⋅+⋅=

l

( ) ( )smb f 014,0100 101,019,71 == −⋅−⋅ξ

7.3.3(2)SIA 265

Velocityv<b(f1

ζ-1)

50 < b < 150

ζ = 0,01

ImpulsI=1 Ns(up to 40 Hz)

5



sm

EIEImv

b

027,070,050,2383

6,0

6,0

25,025,05,0

25,025,05,0

=⋅⋅

=⋅⋅

=l

Limit 6 . 0,014 = 0,084 m/s > 0,027

heeldrop I=55 Ns

Mohr /bmh/velocityv<6 b(f1

ζ-1)velocityheeldropI=55Ns, ti = 0,05s

6



Decke: f = 7,19 HzGehen: Resonanz

fs = 7,19 / 3 = 2,4 Hz

21,103 925,03.33

25207001,0)/3(

smffV

MF

s =⋅⋅

=⋅⋅α

BeschleunigungWohlbefinden

a<0,1 m/s2BeschleunigungResonanz-untersuchung

7

22 /1,0/37,093,04,0 smsm >=⋅

7.3.3 (1) f < 8 Hz: Special investigation



Gehen: Resonanz fs = 7,19 / 3 = 2,4 Hz

21,103 925,03.33

25207001,0)/3(

smffV

MF

s =⋅⋅

=⋅⋅α

22 /7,0/37,093,04,0 smsm <=⋅

DIN1052, 9.3(3)besondereUnter-suchungen

BeschleunigungSpürbar, nicht störend

a< 0,35 bis 0,7 m/s2

BeschleunigungResonanz-untersuchung

8



Summary

⎟⎟⎠

⎞⎜⎜⎝

⎛Rigidity

w 1

w (t)

M

KR

F (t)

Deformation



Frequency

⎟⎟⎠

⎞⎜⎜⎝

⎛=

massrigidityff

w (t)

M

KR

F (t)



Velocity ⎟⎠⎞

⎜⎝⎛

massv 1

w (t)

M

KR

F (t) I



Acceleration

⎟⎟⎠

⎞⎜⎜⎝

⎛dampingmass

a 11

w (t)

M

KR

F (t)



Wanted:

great stiffness

high mass

high frequency

high damping

Timber floors

most

no

not always

yes

CONNECTIONS – LATERAL LOAD CAPACITY - WITHDRAWAL CAPACITY -DOWELS

A. Leijten

TU-Eindhoven

Brussels, 18-20 February 2008 – Dissemination of information workshop 1

EUROCODESBackground and Applications EN1995-1-1: Section 8 - Connections

TIMBER CONNECTIONS

by

Dr. Ad Leijten

TU-Eindhoven

The Netherlands

Former PT-member



We can not escape connections

THE WEAKEST LINK



Villaggio Commerciale “Le Acciaierie“ inCortenuova Italy

Holzbau S.P.A











What kind of connections do we use?



Carpenter connections (not in Eurocode 5)

National regulations apply



Carpenter connections �� compression forces



Glued connections (not in Eurocode 5)

Structural Finger joints Glued in steel rods

National regulations apply



What do we find in Eurocode 5

Section 8: Connections with metal fasteners

-Mechanical connections with

- Dowel type fasteners- Nails, staples, screws, dowels and bolts

- Punched metal plate fasteners- Shear plates- Split-rings

EN1995-1-1: Section 8 - Connections



Nails < 8 mm (EN14592)definition profiled nails Bolts > 8 mm

Dowels > 6 mmScrews



Punched metal plate fasteners

Split-ring connectors64- 104 mm diameter

Bolts M12 to M20



Steel – to – timber



Steelplate – in – timber



Eurocode 5 allows:

Design by testing:

-EN 1075, EN 1380, EN 1381, EN 26891, EN 28970

Design by calculation

- Model provided in EN1995-1-1



Design by calculation - covers



The design model for laterally loaded dowel-type-fasteners

(based on Johansen (1949)

Background:

-Structural Education Timber Program (STEP 1)(1994)

-Timber Engineering; Thelandersson & Larsen (2003) ISBN 0-470-84469-8

Laterally loaded axially loaded



single shear

fasteners

double shear



Forces in dowel type fastener

Double shear



Spacing requirements determine timber dimensions

a12 2a1 a 2

a 2

0 1( ) ( ) 1 with

0 1

≤ ≤�+ ≥ � ≤ ≤�

kk k

k

ka2a2

ka1a1

ka1a1

k a2a 2

a2

Only for connectors

Split-rings andshear plates



Embedment = femb

Idealised

fstuik= f v

embedment

Splittingforce

ffembemb

displacemendisplacementt

Starting point for strength model - Embedment strength



Determination of embedment strength –EN 383

Eurocode 5 Design clause embedment strength

Nails (not pre-drilled)

Nails pre-drilled

Bolts/dowels

2-0,3h,k k0,082 N/mmf dρ=

2h,k k0,082 (1- 0,01 ) N/mmdf ρ=



Taken from Sawata and Yasumura (2002).

Background: Whale L. and Smith, I. The derivation of design clauses for nailed and bolted joint in Eurocode5, In Proceedings of paper CIB-W18 paper 19-7-6/ Florenze 1986

Yasumura, M. and Sawata, K., Determination of embedment strength of wood for dowel-type-fasteners. In:Journal of Wood Science, nr. 48, 2002, Japan Wood Research Society, Inst. Of Wood Techn, Akita, Japan

Parallel Perpendicular



Dowels Parallel All wood species

0,0

20,0

40,0

60,0

80,0

100,0

120,0

200 400 600 800 1000 1200

Density

Em

bedm

ent

5mm data

7mm data

8mm data

12mm data

16mm data

20mm data

30mm data

Embedment test - parallel to grain

Background: Leijten, A.J.M. & Köhler, J.& A Jorissen, Review of Probability Data for Timber Connectionswith Dowel-Type Fasteners; In Proceedings of CIB-W18, paper 37-7-12, Edinburgh, UK, September 2004



Re-evaluation parallel to grain embedment results

for future consideration in EC5?

Nails (pre-drilled)

Coniferous

Bolts and dowels

Coniferous

Decideous

EN1995-1-1: Section 8 - Connections

1,07 0,25;0

;90

0,097

?h

h

f d

f

ρ −==

1,35 0,27;0

1,48 0,42;90

0,0104

0,046

h

h

f d

f d

ρ

ρ

−

−

=

=

1,09 0,25;0

1,13 0,46;90

0,087

0,106

h

h

f d

f d

ρ

ρ

−

−

=

=



Some failure modes ofsingle shear fasteners

Some failure modes ofdouble shear fasteners

Mode I Mode II Mode III



Equations for every failure mode

Fasteners in single shear

h,1,k 1

h,2,k 2

2 2

h,1,k 1 2 32 2 2 2

1 1 1 1

y,Rkh,1,k 1 ax,Rkv,Rk

2h,1,k 1

h,1,k 2

(a)

(b)

2 1 1 (c)1

4 (2 )min 1, 05 2 (1 ) (d)2 4

1, 051 2

� �� β + β + + + β − β +� � � � � � + β � � �� β + β= β + β + − β +

+ β � �

+

f t d

f t d

f t d t t t t

t t t t

Mf t d FFf d t

f t d y,Rk ax,Rk2

2h,1,k 2

ax,Rky,Rk h,1,k

4 (1 2 )2 (1 ) (e)

4

21,15 2 (f)

1 4

�� β + β� β + β + − β +

β� � �� β +� + β��

M F

f d t

FM f d



Equations for every failure mode

Fasteners in double shear

h,1,k 1

h,2,k 2

y,Rkh,1,k 1 ax,Rkv,Rk 2

h,1,k 1

ax,Rky,Rk h,1,k

(g)

0,5 (h)

4 (2 )min 1,05 2 (1 ) (j)

2 4

21,15 2 (k)

1 4

β ββ β β

β

ββ

�� +�= + + − + � + � � �� +� +�

f t d

f t d

Mf t d FF

f d t

FM f d



Some failure modes ofsingle shear fasteners

steel to woodconnections

thick t > d = fastener diameter

thin steel plate t < 0,5d



Test results still higher than Johansen equations

Cord effect:

Only valid forMode II and III

Requires knowledge about withdrawalTheory for nails 15% extra

Background: Kuipers, J. Van der Put, T.A.C.M., Betrachtungen zum Bruchmechanismus von Nagel verbindungen,In: Ingenieuholzbau in Forschung und Praxis, J. Ehlebeck and G. Steck, editors, Bruderverlag Karlsruhe 1982




% are estimatesMaximumNails 15%Grooved nails 50%Screws 100%Bolts 25%Dowels 0%

Cord effect:Fax/4 = withdrawal capacity/4 = estimated effect




h,1,k 1

h,2,k 2


h,1,k 1

ax,Rky,Rk h,1,k

(g)

0,5 (h)

4 (2 )min 1,05 2 (1 ) (j)

2 4

21,15 2 (k)

1 4

β ββ β β

β

ββ

�� +�= + + − + � + � � �� +� +�

f t d

f t d

Mf t d FF

f d t

FM f d




theory

kkm

kd FFy

kFF ⋅=⋅=⋅= 69,0

3,1

9,0modDesign value

Ms = yield bending moment steel fastenerPartial material factor of timber γγγγmapplied to yield bending moment of steelfastener!!Better seperate:

Mode III

schroef,hs dfMF ⋅⋅⋅⋅δ+δ⋅= 12

1

2



15,169,0

79,0 =⋅⋅=

k

k

F

Ffactor

Taking both γm - seperately

kd

khschroefked

khschroef

ked

hm

khschroef

sm

ked

FF

fdMF

fd

MF

ky

fd

y

MF

⋅=

⋅⋅⋅+

⋅=

⋅⋅⋅⋅+

=

⋅⋅⋅⋅+

=

79,01

479,0

9,03,11,11

4

1

4

,1,,

,1,,

mod,

,1,

,

,

δδ

δδ

δδ

For Mode II factor is 1,05

Mode III




h,1,k 1

h,2,k 2


h,1,k 1

ax,Rky,Rk h,1,k

(g)

0,5 (h)

4 (2 )min 1,05 2 (1 ) (j)

2 4

21,15 2 (k)

1 4

β ββ β β

β

ββ

�� +�= + + − + � + � � �� +� +�

f t d

f t d

Mf t d FF

f d t

FM f d

Eurocode 5 equations



Yield moment of dowel type fasteners

Large diameter bolts and dowels

Small rotation at failure �� No full plastic yielding

0.0

2.04.0

6.0

8.010.0

12.0

14.0

16.018.0

20.0

8 10 12 14 16 18 20 22 24 26 28 30

d

R

diameter

Rotationangle

2,6y,Rk u,k0,3= f dM

Background: Jorissen, A.J.M. Blass, H.J., the fasteneryield strength in bending, In: Proceedings of CIB-W18paper 31-7-6, 1998



Failure of multiple of fasteners in a row

Splitting

Shear

Tensile



Failure of multiple of fasteners in a rowCaused by group effect�� Only for load component in grain direction

13d

Cumulatievestress

Stress ⊥⊥⊥⊥



Failure of multiple of fasteners in one row

Caused by group effect�� effective number

Nails:

Bolts & dowels:

Background:Double shear timber connections with dowel type fasteners, A.J.M. Jorissen, ISBN 90-407-1783-4, DUP Delft,1998

4 090

13d

ann ,

ef =

efef

knn =

a For intermediate spacings, linearinterpolation of kef is permitted

0,5-a1 = 4d

0,70,7a1 = 7d

0,850,85a1 = 10d

1,01,0a1 ≥≥≥≥ 14d

PredrilledNotpredrilled

kefSpacinga



BeBe carefulcareful withwith cheesecheese connecionsconnecions



Failure at fastener perimeter (Prof.Racher, Fr.)

Block shear:Full penetration

Plug shearPartial penetration

Tensile or shear failure, which happens first?Literature: Johnson, H, Stehn, L, A Linear Fracture Mecanics Evaluation of Plug Shear Failure,In Proc of 8th

world conf on Timber Engineering WCTE 2004, Finland



�t,1

�t,2

�v,1 �v,2 �v,3 �v,4

�v,5 �v,6 �v,7 �v,8

1

2

net,t t,o,kbs,Rk

net,v v,k

1,5max

0,7

��= ��

A fF

A f

t ef

Fasteners keepstraight

Not correct inEC5

see previoussheet

Tensile failure

Shear fracture

Correlationparameters



Amendment A1

New design rules for:compressive strength perpendiculer to grainPresent rules unsafe

13

l

lef



Amendment A1

AdditionAxially loaded screws

Traditonal screwsDiameter thread=smooth shankNot very effective

not hardenedlow bending moment>8mm requires predrilled holes



Amendment A1

AdditionAxially loaded screws

Very effectivehardenedself tappinghigh axial stiffness

Background:Blaß, HJ; Bejtka, I: Self-tapping screws as reinforcements in connections with dowel-type fasteners. In:Proceedings. CIB-W18 Meeting, Karlsruhe, Germany 2005. Paper 38-7-4Blass H.J. Joints with dowel-type-fasteners, In: Timber Engineering Thelanderson and Larsen, editors, Wiley &Sons (2003):





Some examples

Leg or coach screw



Some examples

Spax-S

Heco Topix/Fix

Rapid Komprex



Tecfi Woodpecker

BMF Torx

SFS WT



Check:- Withdrawal failure

- Tear-off failure of the head

- Pull through of the head

- Tensile failure of the screw

- Torsional capacity

- Group effect (neff number of effective fasteners)



-Withdrawal: Code proposals in EU countries

( )aa

ldR kefkaax 22

5,138,0

,, cos5,1sin

106,3

⋅+⋅×⋅⋅⋅=

− ρπ

efk

kax ldaa

R ⋅⋅⋅+⋅×=

−

2342

26

; cossin

1060 ρ

( ) ( ) ρ⋅−⋅⋅+= nomhecnomkax dldR 6,05,1,

Eurocode 5 :

( )aa

ldR kefkax 22

38,0

1, cos5,1sin

100,37,1

⋅+⋅×⋅⋅⋅⋅=

− ρπ



Model uncertainty

0

5

10

15

20

25

-1 -0,8 -0,6 -0,4 -0,2 0 0,2 0,4 0,6 0,8 1

ln(model/meetpunt)

Fre

qu

enti

e..

Eurocode 5

Current EC5 design rule unsafe



New proposal in Amendment A1:

Screws as defined in EN 14592

6 mm ≤≤≤≤ d ≤≤≤≤ 12 mm

All others:Parameters determined by tests EN14592 (EN 1382) 80

22 21

,

a

kefaxefk,a,ax

acos,asin

l.d.fnR ��

�

��

�ρρ

⋅+=

acos,asin

l.d,nR

,k

,ef

efk,a,ax 22

8090

21

520

⋅+ρ⋅

=



- Head tear off- Axial screw strength:

Determine by tests:EN 14592

- Torsional capacityEN 14592

axax fAR ⋅=



Head pull throughEN 14592Test standard EN 1383

axax fAR ⋅=

( ) ( )( ) kcskk fddR ,90,2

212

21 0,3- ⋅⋅⋅⋅⋅= π

Eurocode 5:

20,16 kk dN ⋅=

Zulassung Germany 9.1-235:

In the absents of information Clause 8.5.2. bolt washers



•short elastisch behaviour•Large non-elastic traject



Model uncertainty design rule 9.1-235andn Eurocode 5 for screwswith washers

0

1

2

3

4

5

6

7

8

9

-1 -0,5 0 0,5 1 1,5

ln (model/meetwaarde)

Fre

qu

enti

e

Eurocode 5Zulassung



- Group (tear out) effect:Due to a lack of background informationBased on test by Gehri:

0,9ef =n n



Splitting by perpendicular to grain forces

FEd

Fv,Ed,1 Fv,Ed,2

he h

bα

bb/2b/2

a) b)

Background: Leijten A.J.M. & Vander Put T.A.C.M, Evaluation of Perpendicular to Grain Failure of Beamscaused by Concentrated Loads of Joints, In: Proceedings of CIB-W18, paper 33-7-7, Delft, 2000.

Design clause 8.1.4 (3) is formulated as a maximumshear force criterion on either side of the connection



Related failure?Learn from failures

During festivalstairs fully occupiedwith peoplefell downI person didn’t survive





Cause of failure

� Effective cross-section?

� Splitting?

� Shear off wooden pins?




0,35

pl

max for punched metalplate fasteners100

1

1 for all other fasteners

w

w

� �� = � ��

e90,Rk

e

14

1

=� �

−� � �

hF b w

h

h

Fracture mechanics background

14 is calibration parameter

w = (political factor)

Design clause 8.1.4 (3) isformulated as a maximum shearforce criterion on either side ofthe connection




Some empirical models consider

Fastener spacing

�=

��

��

�=

��

��

+=

��

��

�+=

n

i i

r

s

.

h

h

nk

h

a..

maxk

f)ht(h

a.kkF

1

2

1

kt,90,80

ef2

2

rsk90,

4170

1

1856




Fracture mechanicalmodel

Consider energybalance after crackappears




UK-Test results versus design proposals

05000

1000015000

2000025000

3000035000

4000045000

50000

0 0,2 0,4 0,6 0,8 1

he/h

Str

eng

th[N

]

Test Results Eurocode 5 design

Punched metal plate fasteners



Comparison between models

Eurocode 5




Assumed governing failure mechanism is shearNot by tensile stresses perpendicular to grain

For loaded edges0,7 h �� no splitting

Simply supported��max F

Cantilever beam�� max F/2

F

F/2

hh

hh

he

he



Thank you for yourattention

COMPONENTS AND ASSEMBLIES AND STRUCTURAL DETAILING AND CONTROL

H. Hartl

University of Innsbruck

Brussels, 18-20 February 2008 – Dissemination of information workshop


1

EUROCODE 5, part 1-1Components and assemblies

Structural detailing and control

Hans Hartl

University Innsbruck / Austria

[email protected]

Your logo



2

Components

Components

− Glued thin-webbed beams

− Glued thin-flanged beams

− Mechanically jonited beams

− Mechanically jointed and glued columns

Eurocode 5 part 1-1 Section 9



3

Components – Glued thin-webbed beams

Axial stresses in the flanges:

Axial stresses in the webs:

Eurocode 5 part 1-1 Section 9.1.1

− Design stresses of extreme fibres:

− Design stresses of the mean flange:



4

Components – Glued thin-webbed beams

For webs of wood-based panels, should be verified for secction 1-1 that:

Buckling analysis:Design shear force acting on each web:

Design shear stress at section 1-1:

where:




5

Components – Glued thin-flanged beams

Effective flange widths bef:− I-beams:

− U-beams:


Maximum effective flange widths due to the effects of shear lag andplate buckling:



6

Components – Glued thin-flanged beams

The axial stresses in the flanges, based on the relevant effective flange width, should satisfy the following expressions:

For webs of wood-based panels, it should , for sections 1-1 of an I-shaped cross-section be verified that:

For U-shaped cross-section:


Design shear stress at the section 1-1:



7

Components – Mechanically jointed beams

If the spacing of the fasteners varies in the longitudinal direction, an effective spacing may be used:

A method for the calculation of the load-carrying capacity of mechanically jointed beams is given in Annex B:

Eurocode 5 part 1-1 Section 9.1.3 Annex B

Effective bending stiffness

and:



8

Components – Mechanically jointed beams

Annex B, EN 1995-1-1:2004−Normal stresses

−Maximum shear stress

−Fastener load

Eurocode 5 part 1-1 Section 9.1.3 Annex B



9

Components – Mechanically jointed beams andglued columns

Mechanically jointed columns−Effective slenderness ratio

−Load on fasteners

A method for the calculation of the load-carrying capacity of I- and box-columns, spaced columns and lattice columns is given in Annex C:

Eurocode 5 part 1-1 Section 9.1.4 Annex C

where (EI)ef is determined in accordance with Annex B



10

Assemblies

Assemblies

− Trusses

− Trusses with punched metal plate fasteners

− Roof and floor diaphragms

− Wall diaphragms

− Bracing

Eurocode 5 part 1-1 Section 9.2



11

Assemblies – Trusses

All joints should be capable of transferring a force Fr,d acting in any direction within the plane of the truss.

L is the overall length of the truss

Moment diagrams and effective lengths in

compression (a) No significant end moments (b) Significant

end moments




12

Assemblies – Trusses with punched metalplate fasteners

− For fully triangulated trusses where a small concentrated force has a component perpendicular to the member of < 1,5kN, and where σc,d < 0,4fc,d, and σt,d < 0,4 ft,d, then the requirements of EN 1995 6.2.3 and 6.2.4 may be replaced by

− Punched metal plate fasteners used in chord splices should cover at least 2/3 of the required member height.

− Trusses made with punched metal plate fasteners shall conform to the requirements of EN 14250




13

Assemblies – Roof and floor diaphragms

Simplified analysis of roof and floor diaphragms

For diaphragms with a uniformly distributed load the simplified method ofanalysis should be used provided that:

•the span l lies between 2b and 6b, where b is the diaphragm width•the critical ultimate design condition is failure in the fasteners (and not in the panels);




14

Assemblies – Wall diaphrams

Simplified analysis of wall diaphragms – Method ADesign racking load-carrying capacity

is the lateral design capacity of an individual fastener

External forces




15


Simplified analysis of wall diaphragms – Method AThe external forces which arise in wall panels containing door or window openings and inwall panels of smaller width, can similarly be transmitted to the constructionsituated above or below.


Shear buckling of the sheet may be disregarded, provided that



16


Simplified analysis of wall diaphragms – Method BConstruction of walls and panels to meet the requirements of the simplified analysis




17


Simplified analysis of wall diaphragms – Method BDesign ranking strength of the wall assembly:

and:




18

Shear buckling of the sheet may be disregarded, provided that



External forces



19

Assemblies – Bracing

Single members in compression


Spring stiffness:

Mean design compressive force:

Design stabilizing force



20

Assemblies – Bracing

Bracing of beam or truss systems


Load per unit length:

where:



21



− Materials− Glued joints− Connections with machanical fasteners− Assembly− Transportation and erection− Control− Special rules for diaphragms− Special rules for trusses with punched metal plate

fasteners

Eurocode 5 part 1-1 Section 10



22

Preliminary remark:according to the relevant material – standards; grading and

classification.

− Straightness

− Climatic conditions

− Moisture content

Structural detailing and control - Materials




23

Glued joints− Reliability and quality of joint

− Adhesive manufactoring

− Conditioning period

Connections with mechanical fasteners– Nails

– Bolts and washers

– Dowels

– Screws

Structural detailing and control - Glued joints /connections with mechanical fasteners

Eurocode 5 part 1-1 Section 10.3 / 10.4



24

Structural detailing and control -Connections with mechanical fasteners

General −Wane, splits, knots or other defects shall be limited in the region of the connection

Nails −Nails should be driven in at right angles to the grain−Slant nailing should be carried out−The diameter of pre-drilled holes should not exceed 0,8d

Bolts and washersRequirements for diameters of bolts used with timber connectors




25

Dowels The minimum dowel diameter should be 6 mm. The tolerances on the dowel diameter should be - 0/+0,1 mm. Pre-bored holes in the timber members should have a diameter not greater than the dowel.

Screws •Softwoods, smooth shank diameter d ≤ 6 mm, pre-drilling is not required.

•Hardwoods and for screws in softwoods with a diameter d > 6 mm, pre-drilling is required, with the following requirements:

− The lead hole for the shank should have the same diameter as the shank and the same depth as the length of the shank

− The lead hole for the threaded portion should have a diameter of approximately 70 % of the shank diameter.

•For timber densities greater than 500 kg/m3, the pre-drilling diameter should be determined by tests.

Structural detailing and control -Connections with mechanical fasteners




26

AssemblyThe structure should be assembled in such a way that over-stressing of its members or connections is avoided. Members which are warped, split or badly fitting at the joints should be replaced.

Transportation and erectionThe over-stressing of members during storage, transportation or erection should be avoided. If the structure is loaded or supported in a different manner during construction than in the finished building the temporary condition should be considered as a relevant load case including any possible dynamic actions. In the case of structural framework, e.g. framed arches, portal frames, special care should be taken to avoid distortion during hoisting from the horizontal to the vertical position.

Structural detailing and control – Assembly /Transportation and erection

Eurocode 5 part 1-1 Section 10.5 / 10.6



27

It is assumed that a control plan comprises:− production and workmanship control off and on site;− control after completion of the structure

The control of the construction is assumed to include:− preliminary tests− checking of materials and their identification− transport, site storage and handling of materials;− checking of correct dimensions and geometry;− checking of assembly and erection;− checking of structural details− final checking of the result of the production process, e.g. by visual inspection or proof loading.

Structural detailing and control – Control




28

Structural detailing and control - Specialrules for diaphragm structures

Floor and roof diaphragms

Wall diaphragms




29

Fabrication

Erection− Trusses should be checked for straightness and vertical

alignment prior to fixing the permanent bracing

− When trusses are fabricated, the members should be free from distortion within the limits given in EN 14250

− The maximum bow in any truss member after erection should be limited. (10 to 50 mm)

− The maximum deviation of a truss from true vertical alignment after erection should be limited. (10 to 50 mm)

Structural detailing and control - Special rules for trusses with punched metal plate fasteners

Requirements for the fabrication of trusses are given in EN 14250




30

Thank you for your attention

Hans HartlUniversity Innsbruck / Austria

[email protected]

BRIDGES

H. Kreuzinger Technische Universität München

1


EN 1995-2 Timber Structures Bridges Eurocodes - Background & Applications 18th – 20th of February 2008, Brussels



Flisa, Norwegen



Bridge over river Saalach Bavaria - Salzburg, 70m span

2



Rules given in EC5 part 2 are supplements and should be addedto the rules given in EC5 part 1



2

1

3

1 Timber2 Concrete3 Fastener

Example of grooved connection

Section 1 General



1

a) b)

c) d)

2

22 4 33 4

1 Nail or screw2 Pre-stressing bar or tendon3 Glue-line between glued laminated members4 Glue-line between laminations in glued laminated members

Figure 1.2 – Examples of deck plates made of laminations

Section 1 General

3



Rectangular prestressed deck

Section 1 General



Example of cross-laminated deck plate, X-lam

Section 1 General



Ruderting

Section 1 General

4



Section 2 Basis of design

M

kmodd

RkRγ

⋅≤



γM = 1,156.Pre-stressing steel elements

γM = 1,25γM = 1,0

5. Shear connectors between composite members− normal verification− fatigue verification

γM = 1,54. Concrete used in composite membersγM = 1,153. Steel used in composite members

γM = 1,3γM = 1,0

2. Connections- normal verification− fatigue verification

γM = 1,3γM = 1,25γM = 1,2γM = 1,0

−normal verification−solid timber−glued laminated timber−LVL, plywood, OSB−fatigue verification

1. Timber and wood-based materials

Section 2 Basis of design



Section 3 Material properties

5



Section 4 Durability

4.1 Timber

(1)The effect of precipitation, wind and solar should be taken into account

4.2 Resistance to corrosion

4.3 Protection of timber decks from water by sealing




Roof = constructive protection

Chemical treatment

Alternatives?Section 4 Durability



Bridge in Eching

Constructive protection


6



Constructiveprotection




South-west-side, roof to small?




Chemical treatment


7



Theoretical costs for bridges (Ablöserichtlinien):Timber bridges: theoretical time of duration 50 years

cost per yearactual : 2%New proposal:protected bridges 1,0 %unprotected bridges 1,8 %

To compare:

Steel bridges: Theoretical time of duration 100 yearscosts per year 0,8 %




Timber protection:

Essential task

Documentation in drawings and documents

Part of structural calculation!!





8



Anhang A (informativ)

Empfehlungen zur Dauerhaftigkeit von Holz und Holzwerkstoffen

DN 1074 DauerhaftigkeitSection 4 Durability



DIN 1074Sonne, Regen




Dauerhaftigkeit

Architekt: Dietrich, Tragwerksplanung: Sues, Staller, SchmittPrüfung: Albrecht/Kreuzinger


9



Section 5 Basis of structural analysis

5.1 Laminated deck plates

5.1.1 General

(1)The analysis of timber deck plates shouldbe based upon:- the orthotropic plate theory;- modelling the deck plate by a grid- a simplified method according to 5.1.3

C




90

0




Table 5.1 – System properties of laminated deck plates

0,05

0,080,100,15

0,06

0,060,060,06

0

0,0150,0200,030

Nail-laminatedStress-laminated−sawn sawn−planed planedGlued-laminated

G90,mean/G0,meanG0,mean/E0,meanE90,mean/E0, meanType of deck plate


10









5.1.2 Concentrated vertical loads

1900


11



5.1.3 Simplified analysis

bef

bef = bw,middle + a




Brücke Ruderting, Grossmann

Radlast 120 kN




Section 6 Ultimate limit statesEurocode 5.1, EN 1995-1-1 !

6.1 Deck plates6.1.1 System strength

Section 6 Ultimate limit states

12



Eurocode 5-1-1, System factorSection 6 Ultimate limit states



Railings Bridge in Besensandbach




F

Mbeam

Mmax,beam

mmax,platex

y

mplate

F

1

a) b)

c) d)

2

22 4 33 4 lam

ef

bbn =

platemax,

beammax,ef m

Mb =

Section 6 Ultimatelimit states

13



6.1.2 Stress-laminated deck plates

hF min,pdEd,v ⋅σ⋅μ≤

2350mm

N,min,p =σ




⎪⎭

⎪⎬

⎫

⎪⎩

⎪⎨

⎧=

m,t

dmin

21302

1l

d

t

? 1

1

2

3

l1

Joints of lamellas 1 lamella2 joint3 prestress element




14



Bridge across railway, Oslo



Oslo

Rectangularprestressed deck plate



Not for bridges: Nails (withdrawal) staplesNail plates1

2

3

Timber-concrete composites1 concrete2 Additional layer3 timber

ED,vEd F,F ⋅= 10

Section 8 Connections

15



2

1

3

ED,vEd F,F ⋅= 10

Timber – concrete - composite

Section 8 Connections



Annex A (informative) Fatigue verification(3) A fatigue verification is required if the ratio κ given by expression (A.1) is greater than:− For members in compression perpendicular or parallel to grain: 0,6

− For members in bending or tension: 0,2

− For members in shear: 0,15

− For joints with dowels: 0,4

− For joints with nails: 0,1

− Other joints: 0,15

where:

fσ σ

κ

γ

−=

d,max d,min

k

M,fat

(A.1)

σd,max is the numerically largest design stress from the fatigue loading;

σd,min is the numerically smallest design stress from the fatigue loading;

fk is the relevant characteristic strength;

γM,fat is the material partial factor.

fat,M

k

min,dmax,d

fγ

σ−σ=κ



A.2 Fatigue loading

LADTobs tnN ⋅α⋅⋅= 365

(1) A simplified fatigue load model is built up of reduced loads (effects of actions) compared to the staticloading models. The load model should give the maximum and minimum stresses in the actual structuralmembers.

(2) The fatigue loading from traffic should be obtained from the project specification in conjunction withEN 1991-2.

(3) The number of constant amplitude stress cycles per year, Nobs, should either be taken from table 4.5 ofEN 1991-2 or, if more detailed information about the actual traffic is available, be taken as:

N n tα=obs ADT L365 (A.2)

where:

Nobs is the number of constant amplitude stress cycles per year;

nADT is the expected annual average daily traffic over the lifetime of the structure; the value of nADTshould not be taken less than 1000;

α is the expected fraction of observed heavy lorries passing over the bridge, see EN 1991-2 clause4.6 (e.g. α = 0,1);

tL is the design service life of the structure expressed in years according to EN 1990:2002 (e.g. 100years).

Annex A (informative) Fatigue verification

16



fat,M

kfatd,fatmax,d

fkfγ

⋅=≤σ

A.3 Fatigue verification

( )( )OBSfat Nlog

RbaRk ⋅β⋅−⋅

−−=

11

(4) The value of kfat should be taken as:

( )( )fat obs

11 log 0Rk Na b R

β−

= − ≥−

(A.5)

where:

d,min d,maxR σ σ= with –1 = R = 1; (A.6)

σd,min is the numerically smallest design stress from the fatigue loading;

σd,max is the numerically largest design stress from the fatigue loading;

Nobs is the number of constant amplitude stress cycles as defined above;

β is a factor based on the damage consequence for the actual structural component;

a, b are coefficients representing the type of fatigue action according to table A.1.

The factor β should be taken as:− Substantial consequences: β = 3

− Without substantial consequences: β = 1




Table A.1 – Values of coefficients a and b

a bTimber members in- compression, perpendicular or parallel to grain 2,0 9,0- bending and tension 9,5 1,1- shear 6,7 1,3connections with- dowels with d = 12 mm a 6,0 2,0- nails 6,9 1,2aThe values for dowels are mainly based on tests on 12 mm tight-fitting dowels.Significantly larger diameter dowels or non-fitting bolts may have less favourable fatigueproperties.

( )( )OBSfat Nlog

RbaRk ⋅β⋅−⋅

−−=

11




M

kd

fkγ

σ ⋅≤ mod

DauerstandfestigkeitDauerfestigkeit

fatM

kfatd

fk,

max, γσ ⋅≤

M

kd

fkγ

σ ⋅≤ mod


17



M

kd

fkγ

σ ⋅≤ mod

ULS

fatM

kfatd

fk,

max, γσ ⋅≤

Lastmodell Ermüdung, = 1 γ Lastmodell Tragsicherheit, γ

Art der Beanspruchung: Biegung, Schub, VerbindungsmittelSchwellen, Wechsel R

Anzahl Nobs


Fatigue



Schub

00,10,20,30,40,50,60,70,80,9

1

0 1 2 3 4 5 6 7 8

logN

kfat

R=0,5R=0R=-0,5R=-1


Timber members shear



τ = +.. τ = -..

Radlast

kvfatkvLk

fatk fkf

,,1,

, 17,222⋅≤

⋅==

ττ

23,017,22

1=

⋅≥fatk

3,15,1 ,mod

1,kv

Lkfk ⋅

≤⋅τ


18




Deflections

Vibrations



Construction part Action Beams, platesand trusses

Main system Characteristictraffic load

Pedestrian loadandLow traffic load

l/400 to l/500

l/200 to l/400





19



w (t)

M

KR

F (t) Systemwerte:M Masse tK Steifigkeit kN/mR Dämpfung kN/(m/s)

f2MK

⋅π==ω

( )2f2gg

KgM

KGw 2g

⋅π=

ω=

⋅==

gwf 5

=

Deflections / VibrationsSystem valuesM – mass [t]K – stiffness [kN/m]R – attenuation [kN/(m/s)]




ll

1805

805

⋅=⋅

=X/,X/,

f

l

10≈f X = 300

Span

frequency




( ) ( ) tsinxwt,xw 0 ωψ ⋅⋅= ( ) tsinwtw 0 ω⋅=


20



m = 1780 kg/m; l = 67,7 m; wg = 8,8 cm

( )Hz1,9

8,80,85

cminw0,85fg

=⋅

=⋅

=







M

K D

EfMK

=

( ) tf2sinGtF s ⋅⋅π⋅⋅α=

Resonanz

ζ⋅

⋅α=

21

MGa1


21



ζζα

⋅=

⋅⋅

⋅=

B

vert MMGa 200

21

1,

1 Person




Gehen α2 ; fS = fE/2

Gehen α1 ; fS = fE

Laufen αL ; fL = fE

1 2 3 4 5 Brückenfrequenz fE

Schrittfrequenz fS

1

2

3

4

5

2,5

Laufen αL

Gehen α2Gehen α1

0,2

0,4

1,3

α

Frequency of bridge

Frequency of stepsSection 7



Annex B (informative) Vibrations caused by pedestriansB.1 General(1) The rules given in this annex apply to timber bridges withsimply supported beams or trusssystems excited by pedestrians.NOTE: Corresponding rules will be found in future versions of EN 1991-2.


22










23





Schwingung

mkN12530K010D

smkN716R

t60MtFF 0

=

=

=

=

Ω⋅=

,

,

sin

w (t)

M

KR

F (t)



M = 120.000 kg

Damping: D=0,01

2vert,1 sm0,17

0,01120000200a =

⋅=

2vert,13 sm0,511317,00,23a =⋅⋅=

2

vollvert,

sm14,50,63,2467,70,170,23

0,6bl0,170,23a

=⋅⋅⋅⋅=

⋅⋅⋅⋅=

a<0,7 m/s2

24



w

M

K R

F

M

K R

(D) (D)

MD

KD RD

mkN12530K010D

smkN716R

t60MtFF 0

=

=

=

=

Ω⋅=

,

,

sinMD = 3,4 t

R = 12,5

D = 0,13

K = 636




0

10

20

30

40

50

60

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5

Effect of damper

500102

1D2

1=

⋅=

⋅ ,

Frequency of impact

deflection




Dämpferprotokoll, Gerb


25



Connection:

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛+⋅±⋅= 2

DD

DD 2D12D

1ga1GF

The calculation:GD = MD x g = 3,2 t x 9,81 m/s2 = 32 kNa = 0,7 m/s2 limit of acceleration of the bridge movementDD = 0,1 value of damping

( ) ( ) ( ) kN0,341344,810,071340,1210,1 21

9,810,7134F 2

D ±⋅=⋅±⋅=⎟⎠

⎞⎜⎝

⎛⋅+

⋅⋅±⋅=




Bridge: 120 t Damper: 3,2 t




Pedestrian bridge: f < 5 Hz

Design of damper! MD = 0,05 Mbridge, vibrating

Design the place for the damper!Fixing: ≈ 2 x GD

Use Bridge

Measure

Observe

Decide


26



Damper was designedBridge in Karlsfeld near Munich




Horizontal vibrations!

Milleniums bridge - London



Einmassenschwinger

27



Zweimassenschwinger

Documents

EN 1995 Eurocode 5: Design of timber structures