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Connections Design for Fire Safety
Cardington Structural Integrity Fire Test
This project has been carried out with the support of the European Community project
Continuing Education in Structural Connections under Leonardo da Vinci Programme.
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Contents
 Structural Connections at Fire
 Distribution of temperature
 Thermal properties
 Component method
 Structural Integrity Test in Cardington Laboratory
 Preparation
 Experiment
 Major results
 Conclusion
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Three Stages of Fire Design
Fire scenario
in compartment
Heat transfer
into structure
Response
of the structure
Connection design at high temperature
 Resistance to collapse R (t) in min.
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Structural Connections at Fire
Temperature Influence on Structure
 Degradation of material properties
 Elongation/shortening of elements
Connections at Fire
 Exposed to diferent forces compare to room temperature
 In colder areas
 Colder compare to elements due to the concentration of mass
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Distribution of Temperature in Connection
425°C
460°C
664°C
hk
300
h
IPE 360
720°C
Example based on prediction according to prEN 1993-2
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Thermal Properties of Connectors
Reduction factor k i. 
1,0
for yield strength of steel ky,
0,9
0,8
for m odulus of elasticity of steel kE, 
0,7
0,6
for strength of welds k w,
0,5
0,4
for strength of bolt k b,
0,3
0,2
Temperature, °C
0,1
0,0
0
100
200
300
400
500
600
Accordig to Annex to prEN 1993-1-2
700
800
900
1000
1100
1200
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Component Method for Connections at High Temperature
Discretisation into components


 



M
z
 
 
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Component Behaviour at High Temperature
Resistance at high temperature
Fi,  = k y ,
Fi,20°C
Stiffness at high temperature
K i,  = k E ,
K i,20°C
Prediction based on room temperature calculacions.
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Connection Behaviour at High Temperature
Resistance at high temperature
Stiffness at high temperature
M i,  = k y, M i,20°C
S ini, = k E, Si,20°C
Prediction based on room temperature calculacions.
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Example of Prediction at High Temperature
M, kNm
100ºC
500ºC
50
20 ºC

M
600ºC
0
0
20
40
800ºC
60
700ºC
80
 , mrad
100
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Cardington Hangar on Postcard, 1925
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Experimental area 48 m x 65 m x 250 m
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Timber Structure - 6 Floors
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Concrete Structure - 7 Floors
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Steel Composite Structure – 8 Floors
Structure finished 1994, plan area 945 m2
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Typical composite structure
Beam-column connections - header plates
Beam-beam connections - fin plates
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Large Scale Fire Experiments on Steel Frame
C
B
A
9000
9000
D
9000
F
E
9000
9000
4
6000
- level 2
136 m2 BS
++22222



 - level 3
9000
3
54 m2 SCI
2
6000
 - level 7
24 m2 ECSC
1
 -3
324
BS
m2
- level 4
area 52,5 m2
ECSC
 - level 4
77 m2
ČVUT
 - level 2
70 m2 SCI
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Major Observations, Compartment, and Loading
Test
Observed
1
2
3
4
5
6
7
One beam heated by gas
One frame heated by gas
Corner compartments
Corner compartment
Large compartment
Office – Demonstration
Structural integrity
Fire compartment
area,
size, m
m2
8x3
24
21 x 2,5
53
10 x 7
70
9x6
54
21 x 18
342
18 x 9
136
11 x 7
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Loading
Mech. G + %
Fire
Q
Gas
30%
Gas
30%
45 kgm-2
30%
45 kgm-2
30%
40 kgm-2
30%
46 kgm-2
30%
40 kgm-2
56%
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Duration, Temperatures, and Deformations
Test
Org.
Level
Time, min
Temp., °C
Deformation, mm
to max. temp.
gas
steel
maximal
residual
1
BS
7
170
913
875
232
113
2
BS
4
125
820
800
445
265
3
BS
2
75
1020
950
325
425
4
BRE
3
114
1000
903
269
160
5
BRE
3
70
-
691
557
481
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BS
ČVUT
2
40
1150
1060
610
-
4
55
1108
1088
~1200
925
7
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Column shortening, Test 2 – BS, 1996
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Cardington Fire Test January 16. 2003
European Fifth Framework Project HPRI – CV 5535
TENSILE MEMBRANE ACTION AND
ROBUSTNESS OF STRUCTURAL STEEL JOINTS
UNDER NATURAL FIRE
Objectives
 Temperatures in elements and joints
 Internal forces in the connections
 Behaviour of the composite slab
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Fire Compartment
Wall three layers of gypsum plasterboard (15 mm + 12,5 mm + 15 mm), with K = 0,19 – 0,24 W/m°K
Window
9 m x 1,27 m
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Protected Members
Columns
External joints
1 m of the primary beam
by 15 mm of Cafco300 vermiculite-cement spray
(K = 0,078 W/m°K)
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Instrumentation
 148 thermocouples
 57 low temperature strain gauges
 10 high temperature strain gauges
E
D
489 – 492
R: 493 – 496
2
505 – 508
R: 509 – 512
497 – 500
R: 501 – 504
C2
C1
C3
513 – 516
R: 517 – 520
C4
West view
537 r
538 r
539 r
C5
C6
C7
East view
Ea
447
441
1
Thermocouples location
through the slab’s depth
in and next to the rib
448
35
442
R
md
70
3
130
md
r
30 30
r
1
444
443
Thermocouples
HT Strain Gauges
445
5
N
446
449
120
D1.5
50
24
E
D
8000
Deformation
1000
2250
2250
2250
2250
1000
1000
224
219
220
221
214
215
216
217
218
209
210
211
212
213
204
205
206
207
208
1500
2
1500
C
225
223
1500
222
201
202
1500
N
203
1
E
D
4500
2
246
242
249
245
3000
251
4500
247
3000
254
N
252
1
243
256
4
253
248
 37 deformations
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Cameras
 10 video cameras
 2 thermo cameras
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Mechanical Load
 Permanent 100%
 Variable permanent 100%
 Live 56%
by sand bags
4th floor
C-D
D
E
E-F
2-3
2
1
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Fire Load
Timber cribs 50 x 50 mm - fire load 40 kg/m2
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Experiment January 16, 2003
Experiment January 16, 2003
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Deformation of Composite Slab
Residual deformation 925 mm (during fire from video cameras reading about 1200 mm ) 30
Cracking of Concrete
Slab
E
D
10
9
8
7
2
~1700
90
60
55
~1500
2030
6
10
5
4
20
3
2
N
1
1
a
b
c
d
e
f
g
h
i
j
k
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Heating and Cooling of Structure
980,0°C
800
600
400
400,0°C
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Gas Temperatures
Gas temperature, °C
Prediction, prEN 1991-1-2
Nominal curve, ISO 834
1200
1100
1000
900
Back of compartnent
800
Front of compartment
700
600
300
500
500
500
400
300
200
100
Time, min
0
0
15
30
45
60
75
90
105
120
135
150
Teplota plynu, °C
Gas 1108 °C in 55 min.
(predicted 1078 °C in 53 min.)
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Beam Temperatures
Beam temperature, °C
Prediction, prEN 1991-1-2, 1993-1-2
1200
1100
D2
Upper flange
1000
E2
Secondary
beam
900
800
Lower flange
700
Fire compartment
600
N
500
Measured values
400
D1
E1
300
200
100
Time, min
0
0
15
30
45
60
75
Beam 1088 °C in 57min.
90
105
120
135
150
(predicted 1067 °C in 54 min.)
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Fin Plate Temperature Profile
Temperature, °C
Beam, bottom flange
1000
D2
E2
D1
E1
800
Fin plate, prediction
600
400
Fin plate, experiment
200
0
Time, min
0
15
30
45
60
75
90
105
120
135
150
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Header Plate Temperature Profile
Temperature, °C
Beam, bottom flange
1000
D2
E2
D1
E1
800
Header plate, prediction
600
400
200
0
Header plate, experiment
Time, min
0
15
30
45
60
75
90
105
120
135
150
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Compartment after Fire
Residual deformation 925 mm.
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Local Buckling of Beam Lower Flanges
D2
E2
N
D1
E1
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Deformation Capacity
of Fin Plate Connection
by Bearing of Plate
D2
E2
N
D1
E1
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Fracture of One Side
of Leader Plate
Connection
D2
E2
Con. D2 - C2
Con. E2 - E1
Con. D2 - D1
N
40
Header Plate Strain Gagues
Stress, MPa
E2
D2
0
0
15
Time, min
30
45
60
75
90
-100
-200
Bottom flange of beam by connection D2
N
D1
Web of beam by connection E2
E1
-300
Web of beam by connection D2
460
-400
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454
457
15
455
461 11
17
100
458
50
456
459
462
9
19
Thermocouples (TC)
TC + HSG in Bolt
HT Strain Gauges (HSG)
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Column Flange Buckling
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Conclusions of Test
 Collapse of structure not reached
 Fire load 40 kg/m2
 Mechanical load 56%
 Good structural integrity of composite slab aproved
 Concept of unprotected beams and protected columns aproved
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Connection Behaviour
 Local buckling of lower flanges during heating
 Fracture of end plates without lost of bearing capacity
 Elongation of holes in fin plates
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Structural Connections at Fire
 Exposed to diferent forces compare to room temperature
Important its robustnost
 In colder areas and due to the concentration of mass colder compare
to elements
No need of special check or of special thermal isulation
 For connections exposed to fire
Component method gives a good prediction of behaviour
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The End
This lesson has been produced with the support of the European Community project
Continuing Education in Structural Connections - CESTRUCO under Leonardo da Vinci Programme.
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Experiment
of project CV 5535 of European Fifth Framework Programme
Tensile membrane action and robustness of structural steel joints under natural fire
Test January 16. 2003
Participating Institutions
Building Research Establishment
Czech Technical University in Prague
Coimbra University
Technical University, Bratislava
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Project Team
Mr. Martin Beneš
Mr. Luis Borges
Prof. Ian Burges
Mr. Dalibor Gregor
Mrs. Petra Hřebíková
Mrs. Magdaléna Chladná
Mr. Derek Jennings
Mr. Tom Lennon
Mr. Ewan Macdonald
Dr. David B. Moore
Mrs. Aldina Santiago
Prof. Luis S. da Silva
Mr. Paul Sims
Dr. Zdeněk Sokol
Dr. Jan Pašek
Mr. Nick Petty
Mr. Jiří Svoboda
Prof. František Wald
Mr. David White
Research Student, CTU Prague
Research Student, University of Coimbra
Research Group Member, University of Sheffield
Research Student, CTU Prague
Research Student, CTU Prague
Research Student, Slovak Technical University, Bratislava
Engineering Technician, BRE Watford
Supervising Engineer, BRE Watford
Technician, BRE Watford
Project Director, BRE Watford
Research Student, University of Coimbra
Research Group Member, University of Coimbra
Project Manager, BRE Watford
Research Group Member, CTU Prague
Research Group Member, CTU Prague
Contracted Technicians, BRE Watford
Res. Group Member, TMV SS, Prague
European Research Group Leader, CTU Prague
Project Leader , BRE Watford
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Lesson
Script
Camera
Photos
Production
Prof. František Wald
Prof. Ian Burges
Dr. David Moore
Prof. Luis S. da Silva
Mr. Luis Borges
Mr. Dalibor Gregor
Dr. Jan Pašek
Dr. Zdeněk Sokol
Mr. Jiří Svoboda
Mrs. Petra Hřebíková
Mrs. Magdaléna Chladná
Mr. Richard Sýkora
Mrs. Zdeňka Zochová
Czech Technical University in Prague
University of Sheffield
Building Research Establisment, Watford
University of Coimbra
University Coimbra
Czech Technical University in Prague
Czech Technical University in Prague
Czech Technical University in Prague
TMV SS, Prague
Czech Technical University in Prague
Technical University, Bratislava
Czech Technical University in Prague
Czech Technical University in Prague
The content of this project does not necessarily reflect the position of the European Community
or the National Agency, nor does it involve any responsibility on their part.
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