Joachim Schmid – gaisrosaugos inžinierius. Nuo 2015 m. Šveicarijos technologijų instituto Ciuriche mokslinis bendradarbis. 2008-2015 m. Švedijos karališkojo technologijų instituto mokslinins bendradarbis. Priklauso kelioms Europos standartizacijos komiteto grupėms, kurios rengia Eurokodo 5 pataisas dėl medinių konstrukcijų projektavimo ir gaisrosaugos reikalavimų. Publikacijų apie CLT konstrukcijų elgesį gaisro sąlygomis autorius. Pranešimas skaitytas praktinėje tvarios statybos konferencijoje "Naujasis betonas - CLT" 2018 m. lapkričio 15 d., Vilniuje (VGTU). Daugiau informacijos - www.naujasisbetonasCLT.lt

1. 2018-11-15
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The new concrete is CLT!
Fire Design of CLT
“The New Concrete is CLT!”
1
Fire Design of CLT structures
Joachim SCHMID
ETH – IBK‐Chair of Timber Structures
IGNIS – Fire • Design • Consulting
Vilnius, 2018‐11‐15
Joachim Schmid, Michael Klippel (ETH Zürich, IGNIS)
with contributions of Norman Werther (TUM, IGNIS)
and Alar Just (TALTECH, IGNIS)

2. 2018-11-15
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The new concrete is CLT!
Fire Design of CLT
Reaction to fire
temperature
time
Coolingphase
Fullydevelopedfire
Ignition
Initialphase
Flash over
Spread
Observe:
• Non-linear Classes A to D (F)
• 3 tests available
• Testing of end product
• Not a material property only
• In general wood is class D
• Wood based products are never non-
combustible
• Today no reliable possibility exists to
simulate R2F
3
Image: J. Schmid
Image:J.Schmid
Image:CbyMaxPixel
Fire Resistance
Fire Resistance
 All elements in contact with the
compartment are exposed to
the same fire exposure.
 Temperature development is
depending of the thermal inertia
of the enclosure and the oxygen
access.
 Temperature are not depending
of the reaction to fire
classification.
 Fire duration is depending of the
available fire load.
Bilder: träguiden.se
Load bearing (R) Insulation (I)Integrity (E)
Compartimentation (EI)
temperature
time
Coolingphase
Fullydevelopedfire
Ignition
Initialphase
Flash over
Spread
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3. 2018-11-15
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The new concrete is CLT!
Fire Design of CLT
Fire Safety Engineering
temperature
time
Coolingphase
Fullydevelopedfire
Ignition
Initialphase
Flash over
Spread
Definition of the particular
fire development
5
Fire Safety Engineering – “Burn out”
[748, 1946]
Challange:
- Actual concept (e.g. R60) is based on the consumption of the typically
available fire loads (residential, office, storage,….)
- Comparison:
 Non-combustible structure  950 MJ/m2 (furniture)
 Additionally 100% wooden surface  950 MJ/m2 + 1700 MJ/m2
(char layer corresponds fire load of a library)
BUT: How much burns outside of the building (at the facade)?
AND: How much longer will it burn?
 Combustibles in a room (fire load in a fire compartment)
Burn out – Definition
 Use of all available fire load (i.e. movable fire load, e.g. furnature)
 Cooling phase without intervention (sprinkler, fire brigade)
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4. 2018-11-15
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The new concrete is CLT!
Fire Design of CLT
2018 – News from Australia
[A.Dunn COST FP1404 presentation 1st Oct. 2018]
Forte Living, Melbourne MacArthur Gardens, Sydney International House, Sydney AVEO Norwest, Sydney
25 King Street Brisbane Project: 10 storey Hotel, Perth
[A.Dunn COST FP1404 presentation 1st Oct. 2018]
• Australia implemented successfully
„high rise buildings“ made from CLT
• Fire Safety was mainly a “catching up”
with Europe
• Solutions for „middle class houses“
(4 to 6 storeys) not developed yet
• No advances for timber framing (yet)
7
2018 – NEWS from Switzerland
2004
Winterthur, Wohnhäuser Areal Giesserei
Fire Safety
&
Timber
construction
Internationale
Cooperation
Maintenance
Building
regulations Research
&
Development
technical
Fire protection
Information
Communication
Help
Education
&
Quality
insurance
8
Winterthur, Wohnhäuser Areal Sue&til
[R. Wiederkehr COST FP1404 presentation 1st Oct. 2018]
[A. Frangi COST FP1404 presentation 1st Oct. 2018]
2018

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The new concrete is CLT!
Fire Design of CLT
2018 – NEWS from Switzerland
2004
Low rise
Up to 11 m height
Ca. 1 – 3 storeys
Medium rise
Up to 30 m height
Ca. 4 – 8 storeys
High rise
Higher than 30 m height
9 and more storeys
2018
9
Images : A. Frangi at COST FP1404 presentation 1st Oct. 2018
Multi storey timber
buildings: 10%
# of plies
[-]
Layup Total thickness # of producers
[mm] [mm] [-]
Floor elements
3 20-20-20 60 2
3 40-40-40 120 4
5 20-20-20-20-20 100 4
5 40-20-20-20-40 140 2
5 40-20-40-20-40 160 5
5 40-30-40-30-40 180 2
5 40-40-40-40-40 200 5
Wall elements
3 30-20-30 80 2
3 30-40-30 100 2
3 40-20-40 100 2
3 40-40-40 120 2
5 20-20-20-20-20 100 5
Eurocode - News #1 : Reducing the product portfolio
Input from industry partners
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The new concrete is CLT!
Fire Design of CLT
EN 1995-1-2:2022
Chapters in Eurocode 5-1-2 (fire part):
4 Tabulated design data
- 4.1 Field of application
- 4.2. x-ply CLT
- …..
5 Simplified design methods
- 5.1 General
- 5.2 Effective cross-section method
- …
6 Advanced design methods
Simply
Complex
Complexity
Limited
Increased
Accuracy
Limitations
Larger field of application
November 2022
EN 1995-1-2
Eurocode - News #2 : Answering different needs
11
Timber in fire – Step 1: considering of the cross section reduction
Bild: träguiden.se
Pyrolyse:
Thermo-chemical decomposition of organic material (from 200°C). Contrary to the gasification and the
combustion this process occurs only under high temperature without oxygen.
Charring rate β
Share between the char (coal) depth dchar in [mm]
and the time of fire exposure t in [min]
t
dchar
minmm.
min
mm
t
dchar
80
63
50

1
12

7. 2018-11-15
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The new concrete is CLT!
Fire Design of CLT
Timber in fire – Step 1: considering of the cross section reduction
 Is depending on the fire exposure
 constant value for standard fire
 Is not significantly dependent on the density
 Is depending on the moisture content
 Is depending on the wood species
  spruce:  ≈ 0.7 mm/min
 Basic design charring rate 
 Double rate after fall‐off of a fire protection
(e.g. gypsum or wood based board)
Grundlagen “Holz-Brand”
Charring rate 
1
13
Timber in fire – Step 1: considering of the cross section reduction
Design charring
rate
Basic design charring
rate
Factor Description
ks Cross section factor
kpr Protection coefficient
k3 Post protection coefficient
kn Edge factor
kg Gap factor
kcr Crack factor
kj Joint factor
kco Connection factor
General model to describe the residual cross section (new):
Delay of
(i) start of charring and
(ii) charring
due to fire protection
system
1
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8. 2018-11-15
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The new concrete is CLT!
Fire Design of CLT
Timber in fire – Step 1: considering of the cross section reduction
Design charring
rate
Basic design charring
rate
General model to describe the residual cross section (new):
Increase of
charring rate
due to not available fire
protection (gypsum, char
coal)
1
15
Factor Description
ks Cross section factor
kpr Protection coefficient
k3 Post protection coefficient
kn Edge factor
kg Gap factor
kcr Crack factor
kj Joint factor
kco Connection factor
Timber in fire – Step 2: considering of the heated cross section
Bild: träguiden.se
«cold»
inner part
20°C
Consideration of the heated zone by an additional
reduction of the residual (virgin) cross-section
with a so-called zero-strength-layer (ZSL) d0
2
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9. 2018-11-15
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The new concrete is CLT!
Fire Design of CLT
Summary: Design of timber members in fire
2) Consideration of the heated zone by an
additional reduction of the
residual (virgin) cross-section
with a so-called zero-strength-layer (ZSL) d0
important coefficients:
d0 = 7…14 mm
1) Calculation of the residual cross section at the
requested time of fire resistance classification
important coefficients:
kpr = 0.7
k3 = 2
β0 = 0.65 mm/min βn = 0.65 mm/min
1
2
The performance of CLT in fire
Char layer fall-off (loss of stickability) possible
Main parameters:
adhesive, layer thickness, orientation of panel,…
Increase of charring ratePossibility of second flash over
A B
Foto: A. Just Foto: ETH Zürich

10. 2018-11-15
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The new concrete is CLT!
Fire Design of CLT
Example: Fire test in Estonia
After 2h and 16 min:
Fire re-starts again
Pictures: Just A. et al (2018)
After 1h and 50 min:
Fire almost stopped
Possibility of second flash overA
Design of CLT members in fire
2) Consideration of the heated zone by an
additional reduction of the
residual (virgin) cross-section
with a so-called zero-strength-layer (ZSL) d0
important coefficients:
d0 = 7mm
1) Calculation of the residual cross section at the
requested time of fire resistance classification
important coefficients:
kpr = 0.7
k3 = 2
βn = 0.65 mm/min
1
2
Foto: ETH Zürich

11. 2018-11-15
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The new concrete is CLT!
Fire Design of CLT
21
STEP 1: Calculation of residual cross-section
(or char depth dchar)
«stepped model»
n= 0.65 mm/min
n= 0.78 mm/min
1
n= 0.65 mm/min
22
STEP 1: Calculation of residual cross-section
(or char depth dchar)
CASE 1
 1st layer: design charring rate
n = 0.65 mm/min
 If falling off of 1st layer:
2x 0 = 1.3 mm/min
until 25mm of char layer has been formed
CASE 2
 If no falling off of charring layers occurs:
n=0.65 mm/min
CASE 1
CASE 2
FLOOR ELEMENTS
1

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The new concrete is CLT!
Fire Design of CLT
23
STEP 2: Calculation of effective cross-section
Use of tabulated data
dchar= 20 mm dchar= 39 mm dchar= 59 mm
Layup specification (R 30 min) (R 60 min) (R 90 min)
20+20+20 2.0 7.0 n.a.
40+40+40 8.0 4.0 n.a
20+20+20+20+20 3.0 9.5 5.0
40+20+20+20+40 6.0 5.0 8.0
40+20+40+20+40 5.0 6.0 9.0
40+30-40-30-40 5.0 5.0 3.0
40+40+40+40+40 5.0 5.0 2.0
Zero strength layer d0 thickness for specific CLT layups
2
24
STEP 2: Calculation of effective cross-section
Simplified model:
«twelve and two»
- Model for any CLT floor element
- Flexible for any layup
- Easy to use
- Higher accuracy
2
2
1

13. 2018-11-15
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The new concrete is CLT!
Fire Design of CLT
STEP 2: Calculation of effective cross-section
Simplified model:
«twelve and two»
40+20+40+20+40
i = 1
i = 2
20
160
char
19.5
dcharhfi
R30
140.5
i = 3
i = 4
2040
7.0
d0
133.5
hef
R30
2
STEP 2: Calculation of effective cross-section
Simplified model:
«twelve and two»
40+20+40+20+4040+20+40+20+40
160
h20
hfi
121.0
40
98.0
hef
char
7.0
2.0
i = 2
i = 3
i = 4
20
dchar
d0
39.0
R60
2

14. 2018-11-15
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The new concrete is CLT!
Fire Design of CLT
STEP 2: Calculation of effective cross-section
Simplified model:
«twelve and two»
40+20+40+20+4040+20+40+20+4040+20+40+20+40
20
160
h20
hfi
104.0
40
92.0
hef
12.0
i = 3
i = 4
i = 2
char
Same value as in
tabulated design
R90
2
More to read & more to do
www.costfp1404.com
Send «home exercise» to schmid@ibk.baug.ethz.ch
 feedback by end of Jan 2019

15. 2018-11-15
15
The new concrete is CLT!
Fire Design of CLT
Joachim Schmid, Michael Klippel (ETH Zürich, IGNIS)
with contributions of Norman Werther (TUM, IGNIS)
and Alar Just (TALTECH, IGNIS)