Tim imber ber De Desi sign gn accord acco rdin ing g to EC5
Tim imber ber De Desi sign gn accord acco rdin ing g to EC5 EN 1995-1-1: 1995-1-1: 2004 Summary of the AxisVM Axi sVM impl imple ementa mentation tion
• stur sturctu ctural ral timbe timb er materials, materials, parti partia al factors factor s • load duration du ration classe classes, s, servi service ce classes classes • mate material rial properties pro perties for global g lobal analysi analysis s • cros cross-se s-sectio ctions, ns, design eleme lements nts • design strength of ti mber materia materials ls (mod (modifi ification cation factors) • checks of tim timber ber eleme elements nts • design in seismic envirom ent
Timber Design according to EC5 Sturctural timber materials EN 338, EN 1194
• Solid timber /softwood(C), hardwood(D)/ • Glued-laminated timber (Glulam) • Laminated veneer lumber (LVL) Characteristic strength
Notation
Modulus of elasticity
Notation
Mean value parallel to grain
E0,mean
f m,k
Mean value perpendicular to grain
E90,mean
Tensile strength parallel to grain
f t,0,k
E0,05
Tensile strength perpendicular to grain
f t,90,k
5% value of modulus parallel to grain Mean value of shear modulus
Compression strength parallel to grain
f c,0,k
Gmean
Compression strength perependicular to grain
f c,90,k
Density
Shear strength perpendicular to the grain in y direction
f v,k,y
Characteristic value of density
Shear strength perpendicular to the grain in z direction
f v,k,z
Bending strength
Mean value of density
Notation
ρk ρmean
Timber Design according to EC5 Partial factor (
M)
Timber type
Fundamental combination
Ac ci den tal combination
Solid timber
1,30
1,0
Glued laminated timber (Glulam)
1,25
1,0
Laminated veneer lumber (LVL)
1,20
1,0
Timber Design according to EC5 Load duration classes and service classes Load duration class
Order of accumulated duration of characteristi c load
Examples of l oading
Permanent
more than 10 years
self-weight
Long-term
6 months – 10 years
storage
Medium-term
1 week – 6 months
imposed floor load, snow
Short-term
less than one week
snow, wind
Instantaneous
wind, accidental load
Service class
Environmental condition
1
the relative humidity in the surrounding air only exceeding 65% for a few weeks per year*
2
the relative humidity in the surrounding air only exceeding 85% for a few weeks per year*
3
The climatic condition leading to higher moisture contents than Service Class 2
(*) the moisture content in the materials corresponding to a temperature of 20 C o
Timber Design according to EC5 Material properties for global analysis An alysis t ype
Mod ul us SLS
First-order linear elastic analysis
Second-order linear elastic analysis
Vibration analysis
E mean, fin
=
Gmean , fin
=
E d
=
Gd
=
E mean
E mean
(1 + k def ) Gmean
(1 + k def )
E mean γ M
Gmean γ M
Gmean
Modulus ULS E mean
E mean, fin
=
Gmean , fin
=
(1 + ψ 2 ⋅ k def ) Gmean
(*)
(1 + ψ 2 ⋅ k def )
E d
=
Gd
=
E mean
(*)
E mean γ M
Gmean γ M
Gmean
(*) conservative way ψ2 = 1,0 is used Material type
k def Service class 1
Service class 2
Service class 3
Solid timber
0,60
0,80
2,0
Glued laminated timber (Glulam)
0,60
0,80
2,0
Laminated veneer lumber (LVL)
0,60
0,80
2,0
Timber Design according to EC5 Cross-sections, design elements Design assumptions:
• the grain parallel wi th th e member x axis • there is no hole or ot her weaking i n the members • the domi nant bending plane is the x-z plane of the member (moment about y axis) • Iy >= Iz • in case of Glued-laminated tim ber (Glul am) the laminates are parallel wi th th e y axis
• in c ase of Laminated veneer lumber (LVL) the laminates are parallel wi th the z axis
x
z
y
y
Timber Design according to EC5 Cross-sections, design elements Solid timber (softwood, hardwood)
Glued-laminated timber (Glulam)
Laminated veneer lumber (LVL)
Timber Design according to EC5 Design strength of timber materials
Strength modification factors
• k mo d factor depending on the duration of load and the moisture content •k h factor depending on the cross-section size and the reference depth size • k l factor depending on the member length and the reference length •k vo l factor depending on the apex zone volume and the reference volume
Timber Design according to EC5 Design strength of timber materials
• k mo d modification factor Material type
Service class
k mo d Permanent
Long term
Medium term
Short term
Instant.
Solid timber
1 2 3
0,60 0,60 0,50
0,70 0,70 0,55
0,80 0,80 0,65
0,90 0,90 0,70
1,10 1,10 0,90
Glued laminated timber (Glulam)
1 2 3
0,60 0,60 0,50
0,70 0,70 0,55
0,80 0,80 0,65
0,90 0,90 0,70
1,10 1,10 0,90
Laminated veneer lumber (LVL)
1 2 3
0,60 0,60 0,50
0,70 0,70 0,55
0,80 0,80 0,65
0,90 0,90 0,70
1,10 1,10 0,90
Timber Design according to EC5 Design strength of timber materials
• k h modification factor Material type
Solid timber (if h < 150 mm)
Glued laminated timber (Glulam) (if h < 600 mm) Laminated veneer lumber (LVL)
kh
k h
⎧⎪⎛ 150 ⎞ 0 , 2 = min ⎨⎜ ⎟ or 1,3 ⎪⎩⎝ h ⎠
k h
⎧⎪⎛ 600 ⎞ 0 ,1 = min ⎨⎜ ⎟ or 1,1 ⎪⎩⎝ h ⎠
k h
⎧⎪⎛ 300 ⎞ S = min ⎨⎜ ⎟ or 1,2 ⎪⎩⎝ h ⎠
Timber Design according to EC5 Design strength of timber materials
• k l modification factor Material type
Laminated veneer lumber (LVL)
kl
k l
⎧⎪⎛ 3000 ⎞ S / 2 = min ⎨⎜ ⎟ or 1,1 ⎪⎩⎝ l ⎠
Timber Design according to EC5 Design strength of timber materials
• k vo l modification factor Material type
Solid timber
k vo l 1,0 where,
Glued laminated timber (Glulam) Laminated veneer lumber (LVL)
k vol
V ⎞ = ⎛ ⎜ 0⎟ ⎝ V ⎠
0,2
V0 is the reference volume (0,01 m3) V is the stressed vol ume of th e apex zone, and V < 0,67Vb (total vol ume of the beam)
Timber Design according to EC5 Design strength of timber materials
• Design strength calculation Material type
f m,k
f t,0,k
f t,90,k , f c,0,k f c,90,k , f v,k
Solid timber
f t , 0 , d Glued laminated timber (Glulam)
Laminated veneer lumber (LVL)
f m , d
=
=
k mod ⋅ k h ⋅ f t , 0 , k γ M
k mod ⋅ k h ⋅ f m , k
f d
γ M
f t , 0 , d
=
k mod ⋅ k l ⋅ f t , 0 , k γ M
=
k mod ⋅ f k γ M
Timber Design according to EC5 Checks of timber elements (interaction formulas for different design situation)
• Normal force, Moments (stress check parallel to the grain) • Compr ession force, Moments (in plane bucklin g check) • Moment (y), Normal force (lateral torsional buckling check) • Shear (y), Torsion (shear check) • Shear (z), Torsion (shear check) • Moment (y), (tension stress perpendicular to the grain check)
Timber Design according to EC5 Checks of timber elements (interaction formulas for different design situation) Normal force, Moments (stress check) Tension and moment
σ t ,0,d σ m, y,d
+
f t ,0,d f m, y,d
+k m
σ m, z,d
f m, z,d
Compression and moment 2
≤1
⎛ σ c,0,d ⎞ σ m, y,d σ m, z,d ⎜ ⎟+ ⎜ f c,0,d ⎟ f m, y,d +k m f m, z,d ≤1 ⎝ ⎠ 2
σ t ,0,d
f t ,0,d
+k m
σ m, y,d σ m, z,d
+
f m, y,d f m, z,d
≤1
⎛ σ c,0,d ⎞ σ m, y,d σ m, z,d ⎜ ⎟ +k m ⎜ f c,0,d ⎟ f m, y,d + f m, z,d ≤1 ⎝ ⎠
where, k m = 0,7 for rectangular sections k m = 1,0 for other cro ss-section s
Timber Design according to EC5 Checks of timber elements (interaction formulas for different design situation) Compr ession force, Moments (in plane buckling check) Compression and moment
σ c,0, d
k c, y ⋅ f c,0,d σ c,0,d
k c, z ⋅ f c,0,d
+
σ m, y, d
f m, y,d
+ k m
+ k m
σ m, y, d
f m, y,d
+
σ m, z,d
≤1
f m, z,d σ m, z,d
f m, z,d
≤1
where, k m = 0,7 for rectangular sections k m = 1,0 for other c ross-sections k c,y = buckling reduction factor k c,z = buckling reduction factor
Timber Design according to EC5 Checks of timber elements (interaction formulas for different design situation) Moment (y), Normal force (lateral torsional buckling check) Moment and compression
Moment and small tension
2
⎛ σ m,d ⎞ ⎜ ⎟ + σ c,d ≤1 ⎜ k crit ⋅ f m,d ⎟ k c, z ⋅ f c,0,d ⎝ ⎠ where, kc,z is the buckling reduction factor kcrit is the lateral torsional buckling reduction factor:
λrel,m ≤ 0,75 0,75 < λrel,m ≤ 1,4
λrel,m ≤ 0,75
k crit = 1,0 k crit = 1,56-0,75 λrel,m
kcrit = 1/ l2rel,m
σ mc,d
k crit ⋅ f m,d
≤1
where,
σ mc,d
=
M d N d W y
+
A
<0
Timber Design according to EC5 Checks of timber elements (interaction formulas for different design situation) Shear (y), Torsion (shear check) SIA 265:2003 Shear(y) and Torsion 2
⎛ τ ⎞ + ⎜⎜ v , y , d ⎟⎟ ≤ 1 k shape ⋅ f v , d ⎝ f v , d ⎠ τ tor , d
where, k shape is th e cross-section shape factor: k shape = 1,2 for circul ar cross-section
k shape = min{1 + 0,15h / b; 2,0} for rectangular cross-section s
Timber Design according to EC5 Checks of timber elements (interaction formulas for different design situation) Shear (z), Torsion (shear check) SIA 265:2003 Shear(y) and Torsion 2
⎛ τ ⎞ + ⎜⎜ v , z ,d ⎟⎟ ≤ 1 k shape ⋅ f v , d ⎝ f v ,d ⎠ τ tor , d
where, k shape is th e cross-section shape factor: k shape = 1,2 for circul ar cross-section
k shape = min{1 + 0,15h / b; 2,0} for rectangular cross-section s
Timber Design according to EC5 Checks of timber elements (interaction formulas for different design situation) Moment (y), (tension stress perpendicular to the grain check) Moment(y) σ t , 90, d
k dis ⋅ k vol ⋅ f t ,90, d
≤1
where, k di s is the stress distri buti on factor in apex zone factor (k di s =1,4) k vo l is the volum e modifict ion factor i n the apex zone
Timber Design according to EC5 Timber structure design in seismic enviroment (Response-spectrum analysis) Ductility class
Criteria
M
Solid timber: γM = 1,30 Low (DCL)
q =<1,5
Glulam:
γM = 1,25
LVL:
γM = 1,20
Medium (DCM)
1,5
γM =1,0
High (DCH)
2,5
γM =1,0
- The dissapitiv e zones have to be con centrated in to th e joint s - The timber elements work s in elastic assupti on
