taskforce meeting zurich 6./7.09.2004
DESCRIPTION
Taskforce Meeting Zurich 6./7.09.2004. Summary and Progress Jochen Köhler, ETH Zurich, Switzerland. Contents. Stress Strain Relation Serviceability DOL GLULAM Connections Quantification of model parameters. Stress Strain Relation. According to Glos (1978). Stress Strain Relation. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/1.jpg)
Taskforce Meeting Zurich 6./7.09.2004
Summary and Progress
Jochen Köhler, ETH Zurich, Switzerland
![Page 2: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/2.jpg)
Contents
• Stress Strain Relation
• Serviceability
• DOL
• GLULAM
• Connections
• Quantification of model parameters
![Page 3: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/3.jpg)
Stress Strain Relation• According to Glos (1978)
1
2 3 4
0
0
N
N
t
k
k k k
E
,1
1 ,,
,
2
3, ,
14
,
1 1
1
1
1
c a
N c ac c u
c u
c
c u c c u
c a
fk
fN E
f
kE
Nk
f N E
kk
f
![Page 4: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/4.jpg)
Stress Strain Relation• According to Glos (1978)
1
2 3 4
0
0
N
N
t
k
k k k
E
,1
1 ,,
,
2
3, ,
14
,
1 1
1
1
1
c a
N c ac c u
c u
c
c u c c u
c a
fk
fN E
f
kE
Nk
f N E
kk
f
![Page 5: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/5.jpg)
Stress Strain Relation• According to Glos (1978)
1
2 3 4
0
0
N
N
t
k
k k k
E
,1
1 ,,
,
2
3, ,
14
,
1 1
1
1
1
c a
N c ac c u
c u
c
c u c c u
c a
fk
fN E
f
kE
Nk
f N E
kk
f
, ,
,
1
1
c a c u
c uc
c
f f
fN
N E
Conditions:
![Page 6: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/6.jpg)
Stress Strain Relation• According to Glos (1978)
, ,
,
1
1
c a c u
c uc
c
f f
fN
N E
Conditions:
-0.71 0.65 0.34-0.71 -0.28 00.65 -0.28 0.650.34 0 0.65
cE c ,c uf ,c af
cE
c,c uf
,c af
![Page 7: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/7.jpg)
• According to Glos (1978)Discussion:
MOE in tension = MOE compression ?
Quantification of asymptotic compression strength and strain.
Modelling of N ?
Typical values:
, , 1c a c uf f
8.0/, cyc ff
%2.18.0 c
cu 3
Stress Strain Relation
![Page 8: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/8.jpg)
Stress Strain Relation
Actions:
• Quantify asymptotic stress
• Include into the Model Code
Coordination:
Jochen Köhler
![Page 9: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/9.jpg)
Serviceability
• According to Torratti (1992):
The following conditions apply– The deformations are calculated in the grain direction only– The maximum stress bending stress is 20 Mpa– Natural conditions environment conditions apply (temperature
and humidity)– The model has been successfully compared to tests on
European softwoods, both solid wood and glulam of different sizes
(t, u) = e (t,u) + c (t)+ ms (t, u)+ u(u)
![Page 10: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/10.jpg)
ServiceabilityRelative deformation
0
0.5
1
1.5
2
2.5
3
0 1000 2000 3000 4000 5000 6000 7000 8000 9000
Time [hours]
Model
![Page 11: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/11.jpg)
Serviceability
Actions:
• Producing a matrix for different load and climate situations. Therefore the following is needed:
– quantify moisture loads (Lars-Oluf Nielsson (Lund)/study from DTU 2003)
– quantify load sequences
– acquiring data, quantify model parameters
– doing calculations and sensitivity analysis
Coordination:Tomi Toratti
![Page 12: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/12.jpg)
DOL
Limit state function:
Model (Nielsen):
Applied stress:
0, ( ) ( , ( ), , )ult ultg S t S t f z p
1
1
2 2
12
with
81
b
i i i
t dtii i
i
FL SLd
t dt qSL
0
S tSL
f
combined with climate deviations 0
with 1S t
SL t tf
![Page 13: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/13.jpg)
DOL
Limit state function:
Model (Barrett):
Applied stress:
01 ( , ( ), , )loadg X S t f z p
1
with
0
i i i
Bt dti id A SL C SL
t dt SL
0
S tSL
f
combined with climate deviations 1 load load moisture moistureg X X
![Page 14: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/14.jpg)
DOL
Gaps:
• DOL - Tension perpendicular to the grain
• DOL - Connections
![Page 15: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/15.jpg)
DOL
Actions:
• Acquire North American data
• Review data, quantify model parameters
• Distribute tasks according ‘Tension perpendicular to the grain’ and ‘Connections’
Coordination:John D. Sorensen
![Page 16: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/16.jpg)
GLULAM
• Glued laminated timber in BENDING
• Load carring capacity depending on the outermost lamination
• Lamination = timber boards with length a; jointed by finger joints
• a is assumed to be Poisson distributed
• The tensile strength and stiffness of each board is assumed to be constant and lognormal distributed.
• The strength of the finger joints is assumed to be lognormal distributed
![Page 17: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/17.jpg)
GLULAM
fm,mean = min {9.3 MPa + 1.15 fl,mean ; 2.7 MPa + 1.15 ffj,mean}
Standard deviations?
Property
Bending f m,,mean = 9.3 + 1.15 f l,mean
Tension parallel to grain f t, 0,k = 6.7 + 0.8 f l,mean
perpendicular to grain f t, 90,k = 0.27 + 0.015 f l,mean
Compression parallel to grain f c, 0,k = 8 f l,mean 0,45
perpendicular to grain f c 0,g,k = 0.75 f l,mean 0,5
Shear shear f v,k = 0.23 f l,mean 0,8
MOE mean E mean = 1.05 E l,mean
Shear modulus G mean = 0.065 E l,mean
![Page 18: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/18.jpg)
GLULAM
Actions:
• Proposal of a simple model
• Test data acquisition
Coordination: Hans-J. Larsen
![Page 19: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/19.jpg)
Connections
Probabilistic Framework:• Johansen equations• “Splitting Mode parallel”• “Splitting Mode perpendicular”
0 0 :F F
0F
90F
1
2 0 0
3 90 90
ef
g nF R
g n F R
g F R
![Page 20: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/20.jpg)
Connections
Probabilistic Framework:• Johansen equations
h,1 1
h,2 2
yh,1 10
2h,1 1
cal y h,1
(g)
(h)
(j)
(k)
0,5
5 (2 )min 2 (1 )2
21,15 2
1
f t d
f t d
Mf t dFf d t
k M f d
![Page 21: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/21.jpg)
Connections
Probabilistic Framework:• Johansen equations
,0 ,90
, 2 2,0 ,90sin cos
h hh
h h
f ff
f f
2,60.3y uM f d
![Page 22: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/22.jpg)
Connections
Probabilistic Framework:• “Splitting Mode parallel”
00
2cG E d h dF t
h
cG the fracture energy for mixed mode according to Peterson [1995] loading
parallel to the grain [Nmm/mm2]
d diameter of the dowel type fastener mm
0E modulus of elasticity parallel to the grain MPa
h member width mm
t member thickness mm
![Page 23: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/23.jpg)
Connections
Mixed Mode Fracture Energy
2 1
1 1 2
411 1 1
2cG
31
32
2
,90
3 2
,90 90
0
1
IIc
Ic
t
v
t
v
G
G
f
f
f E
f E
2
2
162 1.07
3.5
Ic
IIc Ic
NmGm
NmG Gm
IcG is the fracture energy required for opening mode I
IIcG is the fracture energy required for opening mode II
is the timber density 3kg
m
,90tf is the tension strength perpendicular to the grain
vf is the shear strength
90E is the MOE perpendicular to the grain
0E is the MOE parallel to the grain
![Page 24: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/24.jpg)
Connections
Probabilistic Framework:• “Splitting Mode perpendicular”
c90
0.6(1 )
ec
e
h GGF k b
h
h
where,
b width of the component
eh maximum distance between the stressed edge and a fastener
h height of the component
G shear modulus
cG the fracture energy for mixed mode according to Peterson [1995] loading
parallel to the grain [Nmm/mm2]
ck factor depending on the failure mode of the fastener
![Page 25: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/25.jpg)
Connections
Probabilistic Framework:• Effective number of fasteners
1n n
n
C DB
ef n
a tn A n
d d
, , ,A B C D regression coefficients as random variables
1a spacing or loaded end distance parallel to the grain
n number of fasteners in a row in the grain direction
t member thickness mm
Parameter A B C D
mean 0.42 0.91 0.28 0.19
c.o.v.
![Page 26: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/26.jpg)
Connections
Actions:
• Acquire test data
• Case study – reliability analysis
Coordination: André Jorissen
![Page 27: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/27.jpg)
Topic Task Data required Sources (as mentioned in our meeting)
Grading Describe the stochastic properties of graded timber material
Bending strength, MOE bending, density. Regression with indicators
Stress-strain curve
Quantify model parameters, proposal for perpendicular to the grain
Tension and compression tests Glos, Gehri
Serviceability Quantify model parameters Specify moisture load model
Long term test - deflection Toratti
DOL Quantify model parameters Duration of load test data Foschi, Rosowsky, Hoffmeyer
Glulam Propose a simple model Lamella properties, finger joint properties, properties of glulam components
Gehri, Jorissen, Solli, ‘Austrians’
Connections Quantify model parameters Material properties, properties of conections
Rouger, Jorissen
Bending strength model (Isaksson)
Quantify model parameters for different species Definition of weak section
Longithudinal distribution of weak sections Strength of weak section
Isaksson
Quantification of Model Parameters
![Page 28: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/28.jpg)
Quantification of Model Parameters
Actions:
• Collecting Data for a Data Base
Coordination:
![Page 29: Taskforce Meeting Zurich 6./7.09.2004](https://reader033.vdocuments.mx/reader033/viewer/2022051417/5681478c550346895db4bc76/html5/thumbnails/29.jpg)
Summary
Topic: Coordination:
Stress Strain Relation, Basic Material Properties- Tension Perpendicular
- Grading
Jochen Köhler??
??
Serviceability Tomi Toratti
GLULAM Hans-J. Larsen
DOL- Connections
John Sorensen??
Connections André Jorissen
Data Base ??
Moisture ??