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    BOLTEDCONNECTIONS

    TABLE OF CONTENTS

    1 General ...................................................................................................................... 22 Material properties ................................................................................................. 23 Loading ..................................................................................................................... 34 Laterally loaded bolts ............................................................................................. 3 4.1 Timber-to-timber connections ..................................................................... 4 4.2 Panel-to-timber connections ....................................................................... 4 4.3 Steel-to-timber connections ........................................................................ 4 4.4 Effective number of fasteners ...................................................................... 45 Multiple shear plane connections........................................................................ 56 Block shear failure .................................................................................................. 6 6.1 Timber failure capacity of joint area ........................................................... 6 6.1.1 Capacity of inner part lamellas ......................................................... 6 6.1.2 Capacity of the edge part of lamellas ................................................7 6.2 Connection forces at an angle to the grain ................................................8 6.3 Alternative dimensioning method ............................................................... 97 Steel plates ............................................................................................................. 10 7.1 Tension strength ........................................................................................... 10 7.2 Embedment strength .................................................................................. 10 7.3 Block tearing .................................................................................................. 108 Axially loaded bolts ............................................................................................... 109 Fastener spacings and edge and end distances .............................................. 1110 Allowed tolerances of bolted connections ........................................................1411 Bibliography ............................................................................................................14

    Calculation example: Laterally loaded timber-to-timber bolt connection ...............15Endnotes ...........................................................................................................................17

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    BOLTED CONNECTIONS

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    This instruction is property of Mets Wood.The instruction has been prepared incooperation with VTT Expert Services Ltd.

    1. GENERAL

    Washers with a side length or an external diameter of at least 3d(where dis the diameter of the bolt) and a thickness of at least 0.3dshould be used under the head of bolts and nuts. Washers should havea full bearing area.

    Bolts should be tightened so that the members fit closely, and theyshould be re-tightened if necessary when the timber has reachedequilibrium moisture content. If re-tightening cannot be done, andthere is a possibility that the timber can dry by over 5 % of its weightafter installation of the bolts, only 80 % of the calculated capacity ofthe bolt connection can be utilised.

    Bolt holes in timber should have a diameter no more than 1 mmlarger than the bolt. Bolt holes in steel plates should have a diameter

    no more than 2 mm or 1.1d(whichever is greater). If the connectionis designed using thick steel plate (tt d) equations and bolt diameterd< 20 mm, the maximum allowed hole in the steel plate should notbe more than 1.1d.

    BOLTED CONNECTIONS

    2. MATERIAL PROPERTIES

    Te calculation method for steel bolts presented in this guide isvalid only for bolts with a diameter d 24 mm and ultimate tensilestrengthfu,k 800 N/mm (class 8.8)1. In addition, the timber thick-ness of side members t1and t2should be at least 4dand in dual ormulti shear plane connections the timber thickness of inner memberstsshould be at least 5d.

    In this guide timber means solid timber, glued laminated timber,Kerto-S and Kerto-. Due to its cross-veneers, Kerto-Q has bettersplitting resistance when compared to other timber when used inflatwise connections.

    Wood-based panels should be CE-marked in accordance with EN13986 (plywood, particleboard, OSB-board, medium fibreboard

    and hard fibreboard) or they should have a local type approval orstatement/certificate from an institution approved by local buildingauthorities that covers their use as load-bearing structures.

    SERVICE CLASS

    FASTENER 1 2 3

    Bolts None None Fe/Zn 25c, Z350

    Steel plates up to 3 mm thickness Fe/Zn 12c, Z275 Fe/Zn 12c, Z275 Stainless steel

    Steel plates from 3 mm up to 5 mm in thickness None Fe/Zn 12c, Z275 Fe/Zn 25c, Z350

    Steel plates over 5 mm thickness None None Fe/Zn 25c, Z350

    Table 1:Strength modification factors for service classes and load-duration classes kmod. and partial factors M for material

    properties and resistances.2

    STRENGTH MODIFICATION FACTORS FOR SERVICE CLASSES AND LOAD-DURATION CLASSES kmod

    LOAD-DURATION CLASS

    MATERIAL SERVICE CLASS PERMANENT ACTION LONG TERM ACTION MEDIUM TERMACTION

    SHORT TERM ACTION INSTANTANEOUSACTION

    Solid timber, round timber,glued laminated timber,

    Kerto LVL, plywood

    12

    3

    0.600.60

    0.50

    0.700.70

    0.55

    0.800.80

    0.65

    0.900.90

    0.70

    1.101.10

    0.90

    Particleboard EN 312-4*and -5, OSB/2*, Hardfibreboard

    12

    0.300.20

    0.450.30

    0.650.45

    0,850.60

    1.100.80

    Particleboard EN 312-6*and -7, OSB/3, OSB/4

    12

    0.400.30

    0.500.40

    0.700.22

    0.900.70

    1.100.90

    Medium fibreboard: MBH.LA*, MBH.HLS, MDF.LA*and MDF.HLS

    12

    0.20-

    0.40-

    0.60-

    0.800.45

    1.100.80

    Partial factors M (EN 1995 recommended values and the Finnish NA values)

    Fundamental combinations:Solid and Round timber in generalSoftwood structural timber, strength class C35

    Kerto LVLGlued laminated timberPlywood, OSBParticle- and fibreboardsConnections

    Accidental combination

    1.301.30

    1.201.251.201.301.301.00

    1.401.25

    1.201.201.251.25according to timber material1.00

    * Can only be used in service class 1

    Bolts and steel plates should, where necessary, either be inherently corrosion-resistant or be protected against corrosion.

    Table 2:The minimum specification for material protection against corrosion for fasteners. Electroplated zinc coating Fe/Zn classes are according

    to ISO 2081 and hot-dip coating Z classes according to EN 10346.3Stainless steel according to EN 10088-1 (grades 1.4401, 1.4301 and 1.4310).4

    Parts that are according to the Finnish national annex are marked with

    green textor they are given in the endnote. These rules may not apply

    outside Finland. The equations by RIL 205-1-2009 are generalized from

    the Eurocode and are on the safe side. Additional general information

    about connections is also collected from several sources.

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    +

    =

    dfM

    tdf

    Mdtf

    R

    khy

    ukh

    y

    ukh

    k

    ,

    2

    ,

    ,

    2

    314.0

    min

    Table 3:In EN 1993-1-1, EN 1993-1-2 and EN 1993-1-8 the following par-

    tial factors are used according to EN 1993 recommended values and FI

    NA for structural members, cross sections and connections.

    MARKING VALUE (EN 1993) VALUE FI: NA

    M0 1.00 1.00

    M1 1.00 1.00

    M2 1.25 1.25

    M3 1.25 1.25

    M3,ser 1.10 1.10

    M4 1.00 1.00

    M5 1.00 1.00

    M6,ser 1.00 1.00

    M7 1.10 1.10

    M,f 1.00 1.00

    3. LOADING

    Bolts can be loaded laterally or axially. Te loading can also becombined lateral and axial load.

    Reductions in cross section should be taken into account whenanalysing the capacity of timber members.

    In compressed Kerto-to-Kerto joints, 2/3 of the perpendicularcompression force can be transferred directly through contactfrom member to member. If the contact surfaces have been CNC-machined, 3/4 of the perpendicular compression force can be trans-ferred directly through contact from member to member. Splitting ofthe compressed side in sloped connections, such as ridge connections,should be prevented by shaping the end of the member or installing

    a hard fibreboard or steel plate with a height of about 3/4 of the totalheight of the connection.

    When a force in a connection acts at an angle to the grain, the bolts oflaterally loaded joints should ideally be positioned at the compressedside of the member. In these cases there is generally no need to checkthe tension capacity perpendicular to the grain. See Figure 5.

    Figure 1:Laterally loaded connection

    4. LATERALLY LOADED BOLTS

    When calculating the lateral load-capacity of the connection, thecapacity of the fastener and block shear in the timber member shouldbe checked. See Figure 1.

    Design capacity of the connection:

    M

    k

    d

    RkR

    =mod

    (1)5

    where kmodis the modification factor for duration of load andmoisture content

    Mis the partial factor for connection resistance

    When connecting two different materials the smallest valueof kmod / M should be used.

    (2)6

    where

    =

    kh

    kh

    kh

    kh

    u

    f

    ft

    f

    ft

    t

    ,

    ,2,2

    ,

    ,1,1

    min

    (3)7

    t1and t2are the thicknesses of the outer timber members

    fh,1,kandfh,2,kare the characteristic embedment strengthsof outer timber members

    fh,s,k is the characteristic embedment strength of innertimber member in two shear plane connection

    d is the fastener diameter

    Te characteristic value for the yield moment:

    );;min( ,,,2,,1,, kshkhkhkh ffff = (4)8

    [Nmm] (5)9

    where fu,k is the characteristic tensile strength of the bolt,

    in N/mm

    d is the fastener diameter, in mm

    4.1 TIMBER-TO-TIMBER CONNECTIONS

    Te characteristic load-carrying capacity for a fastener per shear plane:

    My= 0.3 f

    u,k d 2.6

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    +

    =

    dfM

    tdf

    Mdtf

    dtf

    R

    khy

    kh

    y

    kh

    kh

    k

    ,

    2

    ,

    ,

    ,

    3

    14

    23.1min

    =

    dfM

    dtfR

    khy

    kh

    k

    ,

    ,

    2

    4.0min

    +

    +

    +

    +

    =

    015.090.0

    015.035.1

    015.015.1

    015.030.1

    90

    d

    d

    d

    d

    k

    =

    87.02

    1

    1

    d

    kQ

    =

    )01,01(37

    )01,01(082.0

    ,0, dk

    df

    Q

    k

    kh

    (6)10

    Te characteristic embedment strength, at an angle to the grain:

    where

    [N/mm]

    In general

    for Kerto-Q(7)11

    for Kerto-Q fh,,k=fh,45,kwhen 45 90 14

    k is the characteristic timber density, in kg/m

    dis the fastener diameter, in mm

    is the angle of the load to the grain

    (9)13

    (8)12

    for Kerto-S and Kerto-

    for Kerto-Q

    for softwood

    for hardwoods

    for flatwise connections

    for edgewise connections

    4.2 PANEL-TO-TIMBER CONNECTIONS

    When the thickness of a wood based panel is larger than the limitset out in equation (10), then the characteristic loading capacity ofpanel-to-timber connections should be calculated with the equationsfor timber-to-timber connections.

    [mm] (10)15

    where: fh,panel,kis the characteristic embedment strength of panel,in N/mm

    d is the fastener diameter, in mm

    For plywood the following embedment strength, should be used forall angles to face grain:

    fh,k= 0.11 (1 0.01d) k [N/mm]

    where: k is the characteristic density of plywood, in kg/m

    d is the fastener diameter, in mm

    (11)16

    For particleboard and OSB the following embedment strength shouldbe used for all loading directions:

    fh,k= 50 d0,6 t0,2 [N/mm]

    where: d is the fastener diameter, in mm t is the panel thickness, in mm

    (12)17

    4.3 STEEL-TO-TIMBER CONNECTIONS

    Te capacity of a steel plate should be checked according EN 1993.

    In compressed steel plate connections the buckling length of 0,8Lacan generally be used for outside plates, where Lais the distancebetween the first fasteners at opposite sides of the connection. Tebuckling does not need to be taken into account for steel platesinstalled inside a timber member if the expansion of timber membersis prevented, for example, by using tie bolts and limiting the size ofthe slot for the steel plate to maximum of 1.25tt.

    Te drying shrinkage perpendicular to the grain direction should be

    taken into account with steel-to-timber connections.

    It should also be taken into account that the load-carrying capacityof steel-to-timber connections with a loaded end may be reduced byfailure along the perimeter of the fastener group. Tere are two typesof loaded end failures: block shear and plug shear failure.

    Te characteristic load-carrying capacity for a thin steel plate, withtt 0.5d, in single shear:

    Te characteristic load-carrying capacity for a thick steel plate, withtt d, in single shear:

    where: fh,k is the characteristic embedment strength of the timbermember, equation (4)

    t is the thickness of the timber member

    dis the fastener diameter

    My is the characteristic fastener yield moment, equation (5)

    Te characteristic load-carrying capacity of connections with a steelplate thickness between a thin and thick plate, where 0.5d< tt< d,should be calculated by linear interpolation between equations (13)

    and (14).

    (13)18

    (14)19

    2290

    ,0,

    ,,cossin +

    =

    k

    ff

    khkh

    [N/mm]

    tpanel 80 d

    fh,panel ,k

    []

    []

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    connectionshearmultipleandother two

    membersouterinonlyerwith timbconnection

    );2;2min(

    );min(

    21

    21

    =

    sttt

    tt

    t

    =4

    2

    9.0

    50

    min

    d

    tan

    n

    ni

    i

    ef

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    =

    lamellasmiddlefor63.1

    lamellassidefor68.0

    ,0,

    ,0,

    ,

    i

    kh

    y

    i

    kh

    y

    ief

    tf

    fd

    tf

    fd

    t

    =

    timberlaminatedgluefor7.0

    T-Kertoflatwisefor7.0

    Q-Kertoflatwisefor0.1

    Q-Kertoedgewisefor7.0

    S-Kertofor7.0

    vk

    kvipvvkv fAnkF ,,1.0

    1, =

    0.2

    7.1

    ,0,,

    1.0

    1

    ,0,,

    1.0

    1

    ,

    =

    ktipt

    ktipt

    ktfAn

    fAnF

    >

    =

    kvkt

    kt

    kv

    kv

    kvkt

    kv

    kt

    kt

    ktv

    FFF

    FF

    FFF

    FF

    F

    ,,

    ,

    ,

    ,

    ,,

    ,

    ,

    ,

    ,

    when,3.01

    when,3.01

    6. BLOCK SHEAR FAILURE

    6.1 TIMBER FAILURE CAPACITY OF THE JOINT AREA

    Te effective number of fasteners is taken into account in thefollowing equations. Tis method can be used for Kerto-S, Kerto-Q,Kerto- used flatwise and glued laminated timber.

    o take into account the possibility of splitting or shear or tensionfailure of the joint caused by the force component parallel to grain

    F0,Ed, the following expression should be satisfied:

    Rk

    M

    RdEd F

    kFF ,0

    mod,0,0

    = (19)25

    Where Fi,0,Rk is the timber failure capacity for lamella iof the timbermember calculated according to equation (21) and mis the number of

    joint lamellas in the timber member.

    where: =

    =

    m

    i

    RkiRk FF

    1

    ,0,,0 (20)26

    imber failure capacity for the lamella ishould be taken as:

    Te capacity of inner part lamellas:

    where: fh,0,k is the embedment strength of timber parallel to grain

    Ah,ip= (n n1) d t1

    Fcv,k= Fv,k+ (n2 1) d tef,ifh,0,k

    RkepRkipRki FFF ,,,0, += (21)27

    ( )

    =

    ,;min

    ,;min

    ,,0,,

    ,,0,,

    ,kcvkhiph

    ktvkhiph

    RkipFfA

    FfAF

    in tension joints

    in compression joints(22)28

    (23)29

    (24)30

    (25)31

    (26)32for Kerto-LVL

    for gluedlaminated timber

    (27)33

    n is the number of fasteners

    n1 is the mean number of fasteners in the rows parallel to

    grain (n1=n/n2)d is the fastener diameter

    ti is the lamella thickness penetration of the fastener

    n2 is the maximum number of fasteners in the fastenerrows perpendicular to grain

    ft,0,k is the tension strength of the timber member

    f v,k is the shear strength of the timber member

    (28)34

    ( )( ) iipt tdanA = 22, 1

    ( ) ( )( ) iefipv taannA ,3112, 112 +=

    (29)35

    (30)36

    (31)37

    fy is the yield strength of the fastener

    a1is the fastener spacing parallel to the grain

    a2 is the fastener spacing perpendicular to the grain

    a3 is the fastener end distance

    Te characteristic timber failure capacity of the joint area:

    6.1.1 CAPACITY OF INNER PART LAMELLAS

    35 N/mm2 for Kerto-S

    19 N/mm2 for Kerto-Q (thickness 21-24 mm)

    26 N/mm2 for Kerto-Q (thickness 27-69 mm)

    24 N/mm2 for Kerto-T

    fv,0,edge,k 4.1 N/mm2 for flatwise Kerto-S connections

    fv,0,flat,k 2.3 N/mm2 for edgewise Kerto-S connections

    fv,0,edge,k 4.5 N/mm2 for flatwise Kerto-Q connections

    fv,0,flat,k 1.3 N/mm2 for edgewise Kerto-Q connections

    fv,0,edge,k 2.4 N/mm2 for flatwise Kerto-T connections

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    =

    4,1cosh

    7.2

    4

    3

    a

    as

    end

    =

    4

    365.0

    1

    max

    a

    ashole

    ( ) ktiefend

    kse fdats

    nF

    ,90,3,

    9.0

    1,

    5.014

    =

    ( ) ktief

    hole

    ks fdats

    nF

    ,90,3,

    9.0

    1

    , 5.0

    14=

    =

    kskv

    ks

    kv

    kv

    kvks

    kv

    ks

    ks

    ksv

    FFF

    FF

    FFF

    FF

    F

    ,,

    ,

    ,

    ,

    ,,

    ,

    ,

    ,

    ,

    when3.01

    when3.01

    Figure 3:Definition of symbols for the inner parts of lamellas. 38

    6.1.2 CAPACITY OF THE EDGE PART OF LAMELLAS

    where:

    (32)39( )

    =

    ,;min

    ,;;;min

    ,,0,,

    ,,,,0,,

    ,kcvkheph

    kseksvktvkheph

    RkepFfA

    FFFfAF

    in tensionjoints

    in compression joints

    ieph tdnA = 1,

    khiefkvkcv ftdFF ,0,,,, +=

    and Ftv,k is calculated according to equations (25) - (27) withsubstitutions from equation (36):

    epteptipt AkA ,,, = epvipv AA ,, =

    ( ) iept tdaA = 4, 2

    ( )( ) iefepv taanA ,311, 12 +=

    (33)40

    (34)41

    (35)42

    (36)43

    (37)44

    (38)45

    and

    epv

    eptept

    A

    Ak

    ,

    ,,

    1

    1

    +

    =

    a4 is the fastener edge distance

    (39)46

    Te splitting capacities:

    (40)47

    where: ft,90,k is the tension strength of timber member

    (41)48

    (42)49

    (43)50

    Te capacity of the edge part of lamellas:

    where:

    0.8 N/mm2 for flatwise Kerto-S connections

    0.4 N/mm2 for edgewise Kerto-S connections

    6.0 N/mm2 for flatwise Kerto-Q connections

    0.4 N/mm2 for edgewise Kerto-Q connections

    0.5 N/mm2 for flatwise Kerto-T connections

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    Figure 4:Definition of symbols for the edge parts of lamellas. 51

    6.2 CONNECTION FORCES AT AN ANGLE TO THE GRAIN

    When a force in a connection acts at an angle to the grain, see Figure

    5, the possibility of splitting caused by the tension force component,(FEd sin ), perpendicular to grain, shall be taken into account.

    For solid timber, glued laminated timber, Kerto-S, Kerto- andKerto-Q edgewise, the following expressions shall be satisfied:

    dEdv FF ,90,

    dF

    ,90

    2,1,, ;max

    EdvEdvEdv FFF =

    1,EdvF

    2,EdvF

    where:

    and are the design shear forces on

    Figure 5:Connection forces at the angle of grain. 54

    (44)52

    (45)53

    either side of the connection caused by the connectionforce component (FEd sin ) perpendicular to the grain

    For softwood, the characteristic splitting capacity:

    where: he is the loaded edge distance to the centre of themost distant fastener, in mm, see Figure 5

    his the timber member height, in mm

    bis the member thickness, but not more than thepenetration depth, in mm

    Te equation (46) does not need to be checked for flatwise

    Kerto-Q connections since Kerto-Q when used flatwise is notsensitive to splitting caused by connection forces at an angle tothe grain due to the cross-veneers.

    =

    h

    h

    hbF

    e

    e

    k

    1

    14,90 (46)55[N]

    is the design splitting capacity

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    +=

    ktbttnet

    kvvnetkttnet

    kbtfktL

    ftLftLF

    ,0,1,

    ,1,,0,1,

    ,

    7.0max

    where: fv,k is the edgewise shear strength (fv,0, edge, k = 4.5 N/mm)

    a3is the fasteners end distance

    a1is the fastener spacing parallel to the grain

    n1is the amount of rows parallel to the grain

    Te characteristic plug shear capacity of a Kerto member:

    ( ) ( )( )DanaLvnet

    +=113,

    12

    6.3 ALTERNATIVE DIMENSIONING METHOD

    imber failure capacity of the joint area can be calculated by the met-hod shown in RIL 205-1-2009 in section 8.2.4S Lohkeamismurto.

    When using this method, the connection area for splitting and rowshear is taken into account by using the effective number of fastenernef , see equation (16). Tis method cannot be used for edgewise Kertoconnections.

    When connection force components are parallel to the grain, the tim-ber failure should be checked at tension loaded member ends. Tere

    are two types of timber failure modes: block shear and plug shear.Te block and plug shear capacities do not require checking forconnections where all the fasteners are in a single row parallel to thegrain (n2= 1).

    For Steel-to-timber connections with Kerto-Q, both block shear andplug shear capacity should be checked.

    For bolted connections, where the amount of fasteners in a row paral-lel to grain is not more than four and the bolt spacing perpendicularto the grain a2 5d, the block shear capacity does not need to bechecked.

    For bolted timber-to-timber connection the plug shear capacity doesnot require checking.

    Kuva 6:a) Block shear b) Plug shear 56

    Te characteristic block shear capacity of a timber member:

    ktbttnetkbt fktLF ,0,1,, =

    where: is the tension strength of timber memberwithout the size effect

    ktf ,0,

    (47)57

    (48)58

    =

    bt

    k

    ( ) ( )DanLtnet

    = 22, 1

    n2is the number of rows perpendicular to the grain

    a2is the fastener spacing perpendicular to the grain

    Dis the hole diameter

    t1is the thickness of the timber member (t1 2tef)

    Te characteristic block shear capacity of Kerto-Q member:

    (49)59

    (50)60

    (51)61

    ( )( ) kvkteftnetkps fanaftLF ,0,113,0,,, 1 ++=

    where:

    (52)62

    ( ) ( )DanLtnet

    = 22, 1

    kh

    kef

    fd

    Rt

    ,0,

    =

    (53)63

    (54)64

    1.50, for solid wood and glued laminated timber1.25, for Kerto-LVL

    f v,0, k is the shear strength of the timber member

    Rk is the characteristic load-carrying capacity per shear

    plane per fastenerfh,0,k is the characteristic embedment strength

    fv,0,flat,k 2.3 N/mm2 for flatwise Kerto-S connections

    fv,0,flat,k 1.3 N/mm2 for flatwise Kerto-Q connections

    fv,0,flat,k 1.3 N/mm2 for flatwise Kerto-T connections

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    0.1

    ,

    Rdt

    Ed

    N

    N

    2,

    9.0

    M

    unet

    Rdu

    fAN

    =

    = 5.2;7.14.1min

    0

    21

    dpk

    = 5.2;7.18.2min

    0

    21

    d

    ek

    7. STEEL PLATES

    7.1 TENSION STRENGTH

    where: NEd is the tension force design value

    the design tension capacity for gross area:

    the design tension capacity for net area

    A is the gross area of cross-section

    Anet is the net area of cross-section

    fuis the ultimate tensile strength

    fyis the yield tensile strength

    M0and M2are the partial factors

    (55)

    =

    Rdu

    Rdpl

    RdtN

    NN

    ,

    ,

    , min (56)

    0

    ,

    M

    y

    Rdpl

    fAN

    = (57)

    (58)

    7.2 EMBEDMENT STRENGTH

    Te design embedment strength for a single fastener:

    2

    1,

    M

    ubRdb

    tdfakF

    =

    where:

    parallel to force:

    - for plates end fasteners

    - others

    perpendicular to force:

    - for plates end fasteners

    - others

    ;3 0

    1

    d

    ed =

    4

    1

    30

    1=

    d

    pd

    (59)

    (60)

    7.3 BLOCK TEARING

    Te block tearing design capacity of a steel plate when a symmetricalfastener group has a centric force:

    where: Antis the tension stressed net area of cross-section

    Anvis the shear stressed net area of cross-section

    fuis the ultimate tensile strength

    fyis the yield tensile strength

    M0and M2are the partial factors

    (61)

    8. AXIALLY LOADED BOLTS

    Te axial load-bearing capacity and withdrawal capacity of a boltshould be taken as the lower value of: the bolt tensile capacity; theload-bearing capacity of either the washer or (for steel-to-timber con-nections) the steel plate.

    Te bearing capacity of a washer should be calculated assuming a

    characteristic compressive strength on the contact area of 3fc,90,k.

    Te bearing capacity per bolt of a steel plate should not exceed thatof a circular washer with a diame-ter which is the minimum of:12tt, where ttis the plate thickness; 4d, where dis the bolt diameter.

    Washer with a side length (in the case of square washers) or a diameterof at least 3dand a thickness of at least 0.3dshould be used under thehead and nut. Washers should have a full bearing area.

    fu is the ultimate tensile strength of the steel plate

    fubis the ultimate tensile strength of the fastener

    d is the fastener diameter

    d0is the hole diameter in steel plate

    e1 is the end distance of the fastener

    e2 is the edge distance of the fastener

    p1 is the fastener spacing parallel to load

    p2 is the fastener spacing perpendicular to load

    tt is the thickness of the steel plate

    M2 is the partial factor of the steel plate (see able 3)

    = 0.1;;min

    u

    ubdb

    f

    fa

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    64 RIL 205-1-2009, sivu 11565 EN 1995-1-1:2004, taulukko 8.5 ja VTT 184/03 Rev. 24 March 2009, sivut 20-21

    9. FASTENER SPACINGS AND EDGE AND END DISTANCES

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    Figure 7:Minimum spacings and end and edge distances

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    Figure 8:Fastener spacings and edge and end distances. 65

    SPACING AND EDGE/

    END DISTANCE, SEE FIGURE 8

    ANGLE SOLID TIMBER AND GLUED

    LAMINATED TIMBER

    KERTO-S, KERTO-T AND

    EDGEWISE KERTO-Q

    FLATWISE KERTO-Q

    a1 0 360 (4+|cos|)d (4+3|cos|)dd) 4 d

    a2 0 360 4 da) 4 d a) 4 d a)

    a3t -90 90 max(7d; 80 mm) max(7 d; 105 mm)b) max(4d; 60 mm) c)

    a3c 90 150 (1+6 sin)d (1+6 sin )d 4 d

    150 210 4 d 4 d 4 d

    210 270 (1+6 |sin|)d (1+6 |sin |)d 4 d

    a4t 0 180 max((2+2 sin)d; 3d) max((2+2 sin)d; 3d) max((2+2 sin)d; 3d)

    a4c 180 360 3 d 3 d 3 d

    a) Block shear should also be checked in timber connections ifa2

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    Table 5:For bolted moment resisting multi shear Kerto-to-Kerto flatwise connections with circular patterns of

    fasteners, the following minimum values of distances and spacings may be used. 67

    SPACING AND EDGE/END DISTANCES KERTO-S TO KERTO-Q a) KERTO-S TO KERTO-S KERTO-Q TO KERTO-Q

    End distance6 d in Kerto-S4 d in Kerto-Q

    7 d 4d

    Edge distance4 d in Kerto-S3d in Kerto-Q

    4 d 3d

    Spacing on a circular 5 d 6 d 4 d

    Spacing between circulars b) 5 d 5 d 4 d

    a) When Kerto-Q is used as outer member

    b) Between radius of the circulars

    Figure 9:For bolted moment resisting multi shear Kerto-to-Kerto flatwise

    connections with circular patterns of fasteners.

    10. ALLOWED TOLERANCES OF BOLTED

    CONNECTIONS

    Table 6:Allowed tolerances of bolt connections - allowed deviations

    from designed position, unless structural design otherwise states. 68

    Boltconnection

    bolt locationhole locationtightening

    simultaneous drilling a)

    separate drillingparts to contact

    5 mm b)

    1.5 mm c)

    tilted gap max. 3 mm

    a) Drilling through all the parts without stopping or using a predrilled part as a

    template.

    b)On rows parallel to the grain, the fasteners can have a maximum tolerance of

    5 mm to each other in the parallel direction.

    c)Prerequisite that the timber members have 1 mm bigger holes than the bolt

    diameter and metal plates have 1.5...2.0 mm bigger holes than the bolt diameter.

    11. BIBLIOGRAPHY

    1 EN 1995-1-1:2004. Eurocode 5: Design of timber structures- Part 1-1: General - Common rules and rules for buildings. 2004.2 EN 1995-1-1:2004/A1:2008. Eurocode 5: Design of timber structures- Part 1-1: General - Common rules and rules for buildings. 2008.3 V CERIFICAE NO 184/03. Revised 24 March, 2009. 2009.4 RIL 205-1-2009. Puurakenteiden suunnitteluohja, eurokoodi EN1995-1-1. Suomen Rakennusinsinrien Liitto RIL, 2009.5 EN 1993-1-8:2005. Eurocode 3: Design of steel structures.Part 1-8: Design of joints. 2005.6 EN 1993-1-1:2005. Eurocode 3: Design of steel structures.Part 1-1: General rules and rules for buildings. 2005.

    7 V-S-07046-09. Design method for timber failure capacity ofdowelled and bolted glulam connections. 2009.8 EN 14592:2008+A1:2012. imber structures - Dowel-type fasteners -Requirements. 2012.

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    =

    =

    = mm51

    mm/N63.34

    mm/N63.34mm51

    mm/N63.34

    mm/N63.34mm51

    min

    2

    2

    2

    2

    ,

    ,2,2

    ,

    ,1,1

    kh

    kh

    kh

    kh

    u

    f

    ft

    f

    ft

    t

    CALCULATION EXAMPLE

    LATERALLY LOADED TIMBER-TO-TIMBER BOLT CONNECTION

    Location: Roof truss, lower chord tension joint.

    Capacity of laterally loaded bolt group

    Figure 10:Connection detail drawing

    Checking the possibility of using M12 bolts, d= 12 mm

    Bolt grade is 8.8,fuk= 800 N/mm

    imber beams: Kerto-S flatwise connection.

    Service class: 2, load-duration class: medium term action.

    Te thicknesses of connection timbers, double shear plane connection. t1 = 51 mm > 4d= 48 mm t2 = 51 mm > 4d= 48 mm

    ts = 63 mm > 5d= 60 mm and ts> min(t1,t2) = 51 mm

    Te thicknesses of the connecting timber members are OK.

    Te characteristic embedment strength:

    fh,0,k= 0.082 (1-0.01d) k= 0.082 (1-0.0112) 480 = 34.63 N/mm2

    fh,1,k=fh,2,k=fh,s,k=fh,0,k= 34.63 N/mm

    fh,k= min(fh,1,k;fh,2,k;fh,s,k) = 34.63 N/mm

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    ( )73.1

    73.1

    2min

    mm1250

    mm63mm852

    2

    min

    50

    min4

    2

    9.0

    42

    9.0 =

    =

    =

    =

    d

    tan

    n

    n

    i

    i

    ef

    shear/kN76.62.1

    shear/kN12.108.0mod

    1, =

    =

    =

    M

    k

    d

    RkR

    shear/kN12.10N15973

    N10123min =

    =k

    R

    ( )

    +

    =

    mm12mm/N63.34Nmm1534902

    mm51mm12mm/N63.34

    Nmm15349031mm12mm51mm/N63.344.0

    min

    2

    22

    2

    kR

    +

    =

    dfM

    tdf

    Mdtf

    R

    khy

    ukh

    y

    ukh

    k

    ,

    2

    ,

    ,

    2

    314.0

    min

    Te design capacity per bolt per shear plane:

    kmod= 0.8 and M= 1.2

    For one row of n bolts parallel to the grain direction, the load-carrying capacity parallel tothe grain should be calculated using the effective number of bolts nef :

    Te characteristic value for the yield moment:

    Te characteristic load-carrying capacity per shear plane per fastener for single shear:

    Te design capacity of timber-to-timber connection:

    Rd= amount of bolts per shear capacity shears = (2 1.73) 6.76 kN/shear 2 shears = 46.77 kN

    Utilization rate against timber-to-timber capacity is 86 %. > OK

    a= min( a1; a3) = 85 mm

    t= min( 2t1; 2t2; ts) = min( 102mm; 102 mm; 63 mm ) = 63 mm

    ni= 2

    %8640 ,

    , ===

    d

    dv

    dvR

    FkNF

    My = 0.3 fu,k d2.6= 0.3 800 122.6= 153490 Nmm

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    kN98.67,

    mod,

    ==kbt

    M

    dbt Fk

    F

    When the lateral timber-to-timber load-carrying capacity is calculated according tothe effective number of bolts in a row parallel to grain, the block shear capacity can becalculated according to section 6.3 using equation (47).

    Te characteristic load-bearing capacity of block shear:

    Te design load-bearing capacity of block shear:

    ( ) ( ) mmmmmmDanLtnet

    37)1350()12(1 22, ===

    %5940

    ,

    ,

    , ===

    dbt

    dv

    dvF

    FkNF

    Utilization rate against block shear capacity is59 %. > OK

    1 EN 14592:2008+A1:2012 6.5.22 EN 1995-1-1:2004/A1:2008 table 3.1 and EN 1995-1-1:2004/NA table 2.3(FI)3 EN1995-1-1:2004 table 4.1

    4 EN 14592: 2008+A1:2012 table A.15 EN 1995-1-1:2004 (2.17)6 RIL 205-1-2009 (8.28.1S)7 RIL 205-1-2009 (8.28.2S)8 RIL 205-1-2009 (8.28.3S)9 EN 1995-1-1:2004 (8.30)10EN 1995-1-1:2004 (8.31)11EN 1995-1-1:2004 (8.32) and VTT 184/03 Rev. 24 March 2009 page 2012VTT 184/03 Rev. 24 March 2009 page 2013EN 1995-1-1:2004 (8.33) and VTT 184/03 Rev. 24 March 2009 page 2014VTT 184/03 Rev. 24 March 2009 page 2015RIL 205-1-2009 (8.35.1S)16EN 1995-1-1:2004 (8.36)17EN 1995-1-1:2004 (8.37)18RIL 205-1-2009 (8. 37.1S)19RIL 205-1-2009 (8. 37.2S)20RIL 205-1-2009 (8.37.3S) - (8.37.5S)21RIL 205-1-2009 (8.33.3S)22RIL 205-1-2009 (8.33.4S)23RIL 205-1-2009 page 11624RIL 205-1-2009 page 9625VTT 184/03 Rev. 24 March 2009 ( B.1) and VTT-S-07046-09 (1)26VTT 184/03 Rev. 24 March 2009 (B.2) and VTT-S-07046-09 (2)27VTT 184/03 Rev. 24 March 2009 (B.3) and VTT-S-07046-09 (3)28VTT 184/03 Rev. 24 March 2009 ( B.4) and VTT-S-07046-09 (4)29VTT 184/03 Rev. 24 March 2009 (B.5) and VTT-S-07046-09 (5)30VTT 184/03 Rev. 24 March 2009 (B.6) an d VTT-S-07046-09 (6)31VTT 184 /03 Rev. 24 March 2009 (B.7) and VTT-S-07046-09 (7)32VTT 184/03 Rev. 24 March 2009 ( B.8) and VTT-S-07046-09 (8)33VTT 184/03 Rev. 24 March 2009 ( B.9) and VTT-S-07046-09 (9)34VTT 184/03 Rev. 24 March 2009 page 24

    35VTT 184/03 Rev. 24 March 2009 ( B.10) and VTT-S-07046-09 (10)36VTT 184/03 Rev. 24 March 2009 (B.1 1) and VTT-S-07046-09 (11)37VTT 184/03 Rev. 24 March 2009 (B.12) and VTT-S-07046-09 (12)

    38VTT 184/03 Rev. 24 March 2009 page 2 539VTT 184/03 Rev. 24 March 2009 (B.1 3) and VTT-S-07046-09 (13)40VTT 184/03 Rev. 24 March 2009 (B.14) and V TT-S-07046-09 (14)41VTT 184/03 Rev. 24 March 2009 (B.15) and VTT-S-07046-09 (15)42VTT 184/03 Rev. 24 March 2009 (B.16) and VTT-S-07046-09 (16)43VTT 184/03 Rev. 24 March 2009 page 2644VTT 184/03 Rev. 24 March 2009 (B.17) and VTT-S-07046-09 (17)45VTT 184/03 Rev. 24 March 2009 (B.18) and VTT-S-07046-09 (18)46VTT 184/03 Rev. 24 March 2009 (B.19) an d VTT-S-07046-09 (19)47VTT 184/03 Rev. 24 March 2009 (B.20) and VTT-S-07046-09 (20)48VTT 184/03 Rev. 24 March 2009 (B.21) a nd VTT-S-07046-09 (21)49VTT 184/03 Rev. 24 March 2009 (B.22) and VTT-S-07046-09 (22)50VTT 184/03 Rev. 24 March 2009 (B.23) and VTT-S-07046-09 (23)51VTT 184 /03 Rev. 24 March 2009 page 2752EN 1995-1-1:2004 (8.2)53EN 1995-1-1:2004 (8.3)54EN 1995-1-1:2004 figure 8.155EN 1995-1-1:2004 (8.4)56RIL 205-1-2009 page 9957RIL 205-1-2009 (8.4.1S)58RIL 205-1-2009 (8.4.2S)59RIL 205-1-2009 (8.4.3S)60RIL 205-1-2009 (8.4.1S) and (8 .4.34)61RIL 205-1-2009 (8.4.5S)62RIL 205-1-2009 (8.4.6S)63RIL 205-1-2009 (8.4.3S)64RIL 205-1-2009 (8.4.7S)65EN 1995-1-1:2004 figure 8.766EN 1995-1-1:2004 table 8.5 and V TT 184/03 Rev. 24 March 2009 pages 20 -2167VTT 184/03 Rev. 24 March 2009 page 2168RIL 205-1-2009 table 10.2S

    ENDNOTES

    Fbt,k=Lnet,tt1 kbtft,0,k= 37 mm 63 mm 1.25 35 N/mm = 101.98 kN

    kmod= 0.8 and M= 1.2