structures in fire
TRANSCRIPT
Structures in Fire
Standard temperature curves (design fires)
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1400
0 20 40 60 80 100 120
ISO 834
Hydrocarbon (HC)
RWS
Tem
pera
ture
[o C]
Time [min]
Plate Thermometer in a furnace
Plate Thermometers mounted in a
furnace
Tf
qc
mo
mi
qW
qW
qW
∆p
hn
ho
One-zone model
qr
From the 1960-70’s
Parametric fires
0200400600800
100012001400
0 60 120 180 240 300 360 420
Time[min]
Tem
per
atu
re [
deg
C]
STD
Γ=1
Γ=0,25
Γ=4
From 1980-90’s
�� � ���� 1 ��� ��� �
���
�� � �������� �
���� � ����� � ����
Semi-infinite surroundingstructures
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1300
0.00 1.00 2.00 3.00 4.00 5.00 6.00
Fir
e t
em
pe
ratu
re,
Tf
[0C
]
Time, t [h]
Func
ISO
Parametric
Tf T∞
Thin surrounding structures
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100
200
300
400
500
600
0 200 400 600 800 1000
Tf experiment
Tf Wickström
Tf FDS
Comparison of the actual and estimated fire temperaturein insulated and non-insulated enclosure.
Effect of compartment boundaries on �
Type 1:Gypsum
Type 2:Gypsum + Void +
Gypsum
Type 3:Gypsum + Insulation+
Gypsum
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600
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1400
0 0,5 1 1,5 2
Tem
pe
ratu
re [
°C]
Time [h]
Fire temperature in compartment with different
boundaries, duration 2 hours
Type 1: Gypsum 10 cm
Type 2: Gypsum+Void+Gypsum
Type 3: Gypsum+Insulation+Gypsum
KKR station A, pos 1: PT, QT och TW
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0 500 1000 1500 2000 2500 3000
C21,PT1 Plate thermometer
C45,WT1 welded 0.25
C41,QT1 quick tip 0.25
1
KKR station A, pos 4: PT, QT, TW och PS
0
100
200
300
400
500
600
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800
0 500 1000 1500 2000 2500 3000 3500
Time (min)
Tem
per
ature
(C)
C24,PT4
C48,WT4
C50,TC4
C44,QT4
4
[s]
Position 2
Position 1
Position 4
Position 3
Gas phase measuring positions around I-section steel beam
Station A (1-2)Test 2 - HE200B
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0 0,1 0,2 0,3 0,4 0,5 0,6
Time [h]
Tem
per
atu
re [
C]
A1_meas
A1_calc
A2_meas
A2_calc
A1 A2 A3
A4
A5 A6 A7
Tg
qinc
Tg
Tshε
Kind of boundary conditions
qs = q0 = - k ���
2nd kindPrescribed heat flux
qs = h (Tg – Ts) = - k ��� Tg
3rd kindHeat transfer depending surfacetemperature
Ts
1st kindPrescribedtemperature
x
The three kinds of boundary conditionsNo Kind of Boundary condition Formula
1 Prescribed surface temperature: !�"�# � !$
2 Prescribed surface heat flux: � %&%�'�"�# � ()*”
3a)Natural boundary condition(convection)
� %&%�'�"�# � ()*" � - !. !$
3b)
Natural boundary condition (mixed boundary condition, given convection and radiation conditions, equal radiation and gas temperatures)
()*" � /0 !�1 !$1 2 -3 !� !$
3c)
Natural boundary condition (mixed boundary condition, given convection and radiation conditions, different radiation and gas temperatures)
()*" � /0 !41 !$1 2 -3 !. !$or
()*" � / ()563" 0!$1 2 -3 !. !$
The thermal/fire exposure consists of two parameters:
7) 89:” �≡ 0!41� and �<
7) =>=” � 7) ?@A” 7) BC8” 2 7) :>9”
7) =>=” � D7) 89:” DE�AF 2 G:>9 �< �A
7) 89:” ≡ E�HF 7) =>=” � DE��HF�AF� 2 G:>9 �< �A
Thermal/fire exposure
Setup - CFD
Setup – Thermal response
3
4 and 5
1 and 2
Thermal response calculations
H- section Lower flange Web Upper flange
Method 1 869°C 869°C 869°C
Method 2 877°C 877°C 868°C
Method 3 877°C 876°C 764°C
Method 4 857°C 851°C 731°C
Method 5 729°C 658°C 559°C
1. Eurocode 2. Uniform fire exposure but no concrete3. Uniform fire exposure4. Uniform fire exposure and shadow effects5. Uniform fire exposure and shadow effects
Specific heat and enthalpyConcrete Eurocode
�!� � I �� J! + K LMM
!
0
Replace the cρ withthe enthalpy
Gypsum
Comparison test and calculationGypsum
Summary
1. Thermal/fire exposure consists of twoparameters, qinc (or Tr) and Tg
2. They can be combined into the adiabaticsurface temperature, TAST for given ε and h
3. TAST can be measured with plate thermometers4. TAST can be used for temperature calculations5. ’Heat flux’ cannot be measured in fires6. ’Heat flux’ is not a fire boundary condition