kerto manual bolted connections
TRANSCRIPT
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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
APRIL 2013
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