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ArcelorMittal Long Carbon
Research & Development
Tensile membrane action in fire of composite
slabs with cellular steel beams
Prof. Olivier Vassart
ArcelorMittal Long Carbon
Research & Development 2
FICEB+ - Partnership
ArcelorMittal Long Carbon
Research & Development 3
Additional fire resistance through 3D
membrane effect - Bailey's methods extended
to Long span Cellular Beams
ArcelorMittal Long Carbon
Research & Development 4
Behaviour of slab and beam during a fire
Composite slab is one-way
spanning onto unprotected beam
ArcelorMittal Long Carbon
Research & Development 5
Behaviour of slab and beam during a fire
Plastic hinge forms in unprotected beam
fan yield line forms in slab
ArcelorMittal Long Carbon
Research & Development 6
Behaviour of slab and beam during a fire
Strength of composite beam
continues to reduce
resulting in the yield pattern shown
ArcelorMittal Long Carbon
Research & Development 7
Behaviour of slab and beam during a fire
With increasing loss of strength for the beam
the slab behaviour tends towards a yield line pattern
given for the slab acting without the beam
ArcelorMittal Long Carbon
Research & Development 8
Load
capacity
(bending &
membrane
action)
Temperature
Strength of slab based on lower
bound assuming no beam strength
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Research & Development 9
X Y
Z
Diamond 2008 for SAFIR
FILE: RealEP
NODES: 658
BEAMS: 174
TRUSSES: 0
SHELLS: 432
SOILS: 0
N1-N2 MEMBRANE FORCE PLOT
TIME: 2540.639 sec
- Membrane Force
+ Membrane Force
Tension
Compression
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Research & Development 10
Horizontal movement
Fracture
Compression failure Compression failure
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Research & Development 11
15 m 9 m
3D fire Test
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Research & Development 12
Bearing structure
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Research & Development 13
Steel sheeting and reinforcement
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Research & Development 14
Design Loads
Description Characteristics
kN/m2 Load Factor
Design Load
kN/m2
Partition 1.0 1.0 1.0
Services &
Finishes 0.5 1.0 0.5
Live Load 3.5 0.5 1.75
Total 3.25
The loads used within the structure are the same as those
which are commonly used in the design of office buildings.
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Research & Development 15
Fire Loads Toome Test
Crib Heat Release Rate
of 1M Wide by 1M Long by 0.5M High Wooden Crib consisting of 44mm2 square section sticks
-200
0
200
400
600
800
1000
1200
1400
1 75 149 223 297 371 445 519 593 667 741 815 889 963 1037 1111 1185 1259 1333 1407 1481 1555 1629 1703 1777 1851 1925 1999 2073 2147 2221 2295
Time
Kilo
watts (
kW
)
Assuming the design for an office, the fire load density would
be 511 MJ/m2 according to Table E.2 of EN 1991-1-2.
For the test, a fire load of 40 kg of wood/m2 was used, which
corresponds finally to a fire load of about 700 MJ/m².
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Research & Development 16
Fire Loads
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Research & Development 17
Fire protection
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Research & Development 18
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Research & Development 19
Shape of the beam after the fire
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Research & Development 20
Shape of the beam and connection
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Research & Development 21
Additional fire resistance through 3D
membrane effect – Final Method
ArcelorMittal Long Carbon
Research & Development 22
Additional fire resistance through 3D
membrane effect – Final Method
Material properties
0
0,2
0,4
0,6
0,8
1
0 200 400 600 800 1 000 1 200
Re
du
cti
on
fa
cto
rs
Temperature ( C)
kEa,θ
kap,θ
kay,θ
0,0
0,2
0,4
0,6
0,8
1,0
0 200 400 600 800 1 000 1 200
Re
du
cti
on
fa
cto
rs (x
1E
-3)
Temperature ( C)
kEa,θ
kap,θ
kay,θ
a) θ < 600 °C b) θ ≥ 600 °C and cooling phase
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Research & Development 23
Ansys Numerical Model
B5
B4
a) 3D view b) 3D zoom view
B5
B4
B1
B3
B2
c) Bottom view
Test - beam
Model 1 – slab
Model1 – beamModel 2 – slab
Model 2 - beam
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Research & Development 24
SAFIR Numerical Model
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Research & Development 25
Numerical simulation
Vertical displacements
Realistic modelling?
Secondary beam: BEAM finite elements
Secondary beam: SHELL finite element
Ansys model comparison
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Research & Development 26
Numerical simulation
Model 4: unprotected beams with shell elements
Temperatures at 90 min (ISO fire)
°C
Ansys model comparison
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Research & Development 27
Numerical simulation
Model 4: unprotected beams with shell elements
Temperatures at 90 min (ISO fire)
°C
Ansys model comparison
ArcelorMittal Long Carbon
Research & Development 28
Numerical simulation
Model 4: unprotected beams with shell elements
Vertical displacements at 90 min
-587 -447 -308 -169 -30 39 (mm) -100 -239 -378 -517
Ansys model comparison
ArcelorMittal Long Carbon
Research & Development 29
Numerical simulation
Model 4: unprotected beams with shell elements
Vertical displacements at 90 min
-562 -430 -298 -165 -33 33 (mm) -99 -231 -364 -496
Ansys model comparison
ArcelorMittal Long Carbon
Research & Development 30
Numerical simulation
Model 4: unprotected beams with shell elements
Inward lateral torsional buckling
End
109 °C ≤ θa ≤ 392 °C
Mid-span
400 °C ≤ θa ≤ 636 °C
t = 15 min
Ansys model comparison
ArcelorMittal Long Carbon
Research & Development 31
Numerical simulation
Model 4: unprotected beams with shell elements
Inward lateral torsional buckling
Mid-span
667 °C ≤ θa ≤ 800 °C
End
157 °C ≤ θa ≤ 540 °C
t = 30 min
Ansys model comparison
ArcelorMittal Long Carbon
Research & Development 32
Numerical simulation
Model 4: unprotected beams with shell elements
Inward lateral torsional buckling
t = 60 min
End
308 °C ≤ θa ≤ 883 °C
Mid-span
963 °C ≤ θa ≤ 1 001 °C
Ansys model comparison
ArcelorMittal Long Carbon
Research & Development 33
Numerical simulation
Model 4: unprotected beams with shell elements
Inward lateral torsional buckling
End
227 °C ≤ θa ≤ 710 °C
Mid-span
876 °C ≤ θa ≤ 937 °C
t = 90 min
Ansys model comparison
ArcelorMittal Long Carbon
Research & Development 34
Numerical simulation
Comparison of the 4 numerical models
Vertical deflections
«Simplified» kept model : model 4
Unprotected secondary beam
Slab
-500
-450
-400
-350
-300
-250
-200
-150
-100
-50
0
0 10 20 30 40 50 60 70 80 90Temps (min)
Flè
ch
e d
e l
a s
oli
ve
in
téri
eu
re (
mm
)
Modèle 1
Modèle 2
Modèle 3
Modèle 4b
Defl
ecti
on
of
the u
np
rote
cte
d b
eam
(m
m)
Time (min)
-700
-600
-500
-400
-300
-200
-100
0
0 10 20 30 40 50 60 70 80 90Temps (min)
Flè
ch
e d
e l
a d
all
e (
mm
)
Modèle 1
Modèle 2
Modèle 3
Modèle 4b
Defl
ecti
on
of
the s
lab
(m
m)
Time (min)
Ansys model comparison
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Research & Development 35
RFCS MACS+ Software
ArcelorMittal Long Carbon
Research & Development 4/17/2012 36
THE NATIONAL SEMINARS OBJECTIVES
• to distribute the produced data to the practitioners in order that
they become aware of what are the advantages of the
membrane effect as of its applicability
SEMINARS
MACS+
RFCS MACS+ Seminars
ArcelorMittal Long Carbon
Research & Development 37
Thank you for
your attention
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