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Numerical parametric investigation of simple design method
2Numerical parametric investigation of simple design method
• Objectives of parametric study
• Parametric study properties
• Finite Element Analysis
• Validation of the numerical model
• Effect of continuity at the panel boundary
• Parametric study results
• Conclusion
Content of presentation
3Numerical parametric investigation of simple design method
Objectives of parametric study
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
• Background
– FRACOF (Test 1)- COSSFIRE (Test 2) full scale
standard fire test
• Excellent fire performance of the composite floor
systems (presence of tensile membrane action)
• Max θθθθ of steel ≈≈≈≈ 1000 °C, fire duration >>>> 120 min
• French construction details
• Deflection ≈≈≈≈ 450 mm
– FICEB (Test 3) full scale natural fire test with Cellular
Beam
• Objective
– Verification of the Simple Design Method to its full
application domain (using advanced calculation
models)
• Deflection limit of the floor
• Elongation of reinforcing steel
4Numerical parametric investigation of simple design method
6 m x 6 m 6 m x 9 m 9 m x 9 m 6 m x 12 m 9 m x 12 m
Primary beams
Protected secondary beams
Unprotected intermediate beams
7.5 m x 15 m 9 m x 15 m
• Grid size of the floor
Parametric study properties (1/3)
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
According to EC0 load combination in fire situation for
office buildings:
G (Dead Load) + 0.5 Q (Imposed Load)
G= Self weight + 1.25 kN/m²
Q= 2.5 & 5 kN/m²
• Load levels
5Numerical parametric investigation of simple design method
• Link condition between floor and steel columns
Parametric study properties (2/3)
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
Slab-panel
Slab-panel
Column
Column
With mechanical link between
slab and columnsWithout mechanical link
between slab and columns
Beam
Shear stud Beam
Shear stud
Concrete slab
Concrete slab
6Numerical parametric investigation of simple design method
• Fire rating: R30, R60, R90 and R120
Parametric study properties (3/3)
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
0
200
400
600
800
1000
1200
0 10 20 30 40 50 60 70 80 90 100 110 120
Tem
pe
ratu
re [
°C]
Time [min]
R30
R120R90
R60
Heating of boundary
beams (Max. 550 °C)
7Numerical parametric investigation of simple design method
Finite Element Model
• Hybrid model based on several types of Finite Element
with computer code ANSYS
Beam24 : steel beam,
steel deck, and
concrete ribPIPE16 (6 DOF uniaxial element):
connection between steel beam and
concrete slab
BEAM24 :
steel column
SHELL91 (6 DOF multi-layer):
solid part of concrete slab
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
8Numerical parametric investigation of simple design method
Finite Element Model
• Hybrid model based on several types of Finite Element
with computer code SAFIR
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
BEAM Element
SHELL Element
9Numerical parametric investigation of simple design method
Slab panel properties
• S235 beams
• COFRAPLUS60 trapezoidal steel decking (0.75 mm thick)
• Normal weight concrete C30/37
• S500 reinforcement mesh
• Average mesh position (from top surface) = 45 mm
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
58 m
m 101
mm107 mm
62 mm
120 mm (R30)
130 mm (R60)
140 mm (R90)
150 mm (R120)
10Numerical parametric investigation of simple design method
Thermo-mechanical properties (1/2)
• Steel thermo-mechanical properties:
– Thermal properties from EC4-1.2
– Unit mass independent of the temperature (ρa = 7850 kg/m3)
– Stress-strain relationships:
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
0
20
40
60
80
100
120
140
160
180
200
220
240
260
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Stress [MPa]
Strain [%]
20 °C
100 °C
200 °C
300 °C
400 °C
500 °C
600 °C
700 °C
800 °C
900 °C
1000 °C
1100 °C
1200 °C
11Numerical parametric investigation of simple design method
Thermo-mechanical properties (2/2)
• Concrete thermo-mechanical properties:
– Thermal properties from EC4-1.2
– Unit mass as a function of temperature according to EC4-1.2
– Drucker-Prager yield criterion
– Compressive reduction factors from EC4-1.2:
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
0 200 400 600 800 1000 1200
Temperature [ C]
1.2
1
0.8
0.6
0.4
0.2
12Numerical parametric investigation of simple design method
Validation of the ANSYS numerical
model vs Test 1 (1/2)
• Comparison with fire test (heat transfer analysis)
Unprotected steel beams Protected secondary
beams
Protected main beams Composite slab
A
B
C
A
B
C
A
B
C
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
F
B
A
C
D
E
13Numerical parametric investigation of simple design method
Validation of the ANSYS numerical
model vs Test 1 (2/2)
• Comparison with fire test (deflection)
0
100
200
300
400
500
0 15 30 45 60 75 90 105 120
Time (min)
Displacement (m
m)
Mid-span of
unprotected
central
secondary beamsMid-span of
protected edge
secondary beamsMid-span of protected
primary beams
Central part
of the floor
Test Simulation
Simulated deformed
shape of the floor
after test
Comparison of the deflection (slab and beams)
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
14Numerical parametric investigation of simple design method
Validation of the SAFIR numerical
model vs Test 1 (1/2)
• Comparison with fire test (heat transfer analysis)
Unprotected steel beams
Composite slab
A
B
C
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
F
B
A
C
D
E
15Numerical parametric investigation of simple design method
Validation of the ANSYS numerical
model vs Test 1 (2/2)
• Comparison with fire test (deflection)
Simulated stresses in the slab end of the test
Comparison of the deflection (slab and beams)
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
16Numerical parametric investigation of simple design method
Validation of the SAFIR numerical
model vs Test 2 (1/2)
• Comparison with fire test (heat transfer analysis)
Unprotected steel beams
Composite slab
A
B
C
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
F
B
A
C
D
E
17Numerical parametric investigation of simple design method
Validation of the ANSYS numerical
model vs Test 2 (2/2)
• Comparison with fire test (deflection)
Simulated stresses in the slab end of the test
Comparison of the deflection (slab and beams)
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
18Numerical parametric investigation of simple design method
Validation of the SAFIR numerical
model vs Test 3 (1/3)
• Comparison with fire test (heat transfer analysis)
Unprotected steel beams
Composite slab
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
19Numerical parametric investigation of simple design method
Validation of the SAFIR numerical
model vs Test 3 (2/3)
• Hybrid Model to take into account the WPB with BEAM element
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
0
0,2
0,4
0,6
0,8
1
0 200 400 600 800 1 000 1 200
Reduction factors
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
Reduction factors (x 1E-3)
Temperature ( C)
kEa,θ
kap,θ
kay,θ
20Numerical parametric investigation of simple design method
Validation of the ANSYS numerical
model vs Test 3 (3/3)
• Comparison with fire test (deflection)
Simulated stresses in the slab end of the test
Comparison of the deflection (slab and beams)
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
F0
F0
F0 F0
F0
F0
F0
F0 F0
F0
F0
F0
F0 F0
F0
F0
F0
F0
F0
F0
F0
F0
F0
F0 F0
F0
F0F0
F0
F0 F0
F0
F0F0
F0
F0
F0F0
F0
F0 F0
F0
F0F0
F0
F0 F0
F0
F0F0
F0
F0
F0F0
F0
F0 F0
F0
F0
F0 F0
F0
F0
F0
F0
F0 F0
F0
F0
F0 F0
F0
F0
F0
F0
F0 F0
F0
F0
F0 F0
F0
F0
F0
F0
F0 F0
F0
F0
F0 F0
F0
F0
F0
F0
F0 F0
F0
F0
F0 F0
F0
F0
F0
F0
F0 F0
F0
F0
F0 F0
F0
F0
F0
F0
F0 F0
F0
F0
F0
F0 F0
F0
F0
F0
F0
F0
F0
F0
F0
F0
F0 F0
F0
F0
F0
F0 F0
F0
F0
F0
F0 F0
F0
21Numerical parametric investigation of simple design method
Effect of boundary conditions
CORNER
CORNER
9 m
9 m
9 m 9 m
S2S1
S3 S4
Restraint conditions
S2S1
S3 S4
• Conclusion
– More important predicted deflection in the corner grid with 2
continuous edges than in other 3 grids with 3 or 4
continuous edges.
Structure grid of a real building ANSYS model
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
22Numerical parametric investigation of simple design method
Parametric study results (1/4)
Unsafe
Safe
0
100
200
300
400
500
600
700
800
900
1000
0 100 200 300 400 500 600 700 800 900 1000
SDM lim
it [mm]
Advanced numerical model [mm]
R 30 R 60 R 90 R 120
With mechanical link between slab and
columns in advanced calculations
• Comparison of the FEA deflection with the maximum allowable
deflection according to SDM (Simple Design Method)
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
23Numerical parametric investigation of simple design method
Parametric study results (2/4)
Without mechanical link between slab
and columns in advanced calculations
• Comparison of the FEA deflection with the maximum allowable
deflection according to SDM (Simple Design Method)
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
0
100
200
300
400
500
600
700
800
900
1000
0 100 200 300 400 500 600 700 800 900 1000
SDM lim
it [mm]
Advanced numerical model [mm]
R 30 R 60 R 90 R 120
Unsafe
Safe
10%
24Numerical parametric investigation of simple design method
Parametric study results (3/4)
• Comparison of the time when the FEA deflection reaches
span/30 with the fire resistance according to SDM (Simple
Design Method)
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
1
2
3
0,5 2,5 4,5 6,5 8,5 10,5 12,5 14,5
R 30
R 60
R 90
R 120
9m x 9m6m x 6m 6m x 9m 6m x 12m 9m x 12m
t Span/30 / t F
ire Resistance
9m x 15m7.5m x 15m
• Conclusion
– Span/30 criterion is not reached in FEA all through the fire
resistance duration predicted by SDM
25Numerical parametric investigation of simple design method
0%
1%
2%
3%
4%
5%
0,5 1,5 2,5 3,5 4,5 5,5 6,5 7,5
R 30 R 60 R 90 R 120
9m x 12m6m x 12m9m x 9m6m x 9m6m x 6m 7.5m x 15m 9m x 15m
Max. mechanical strain of reinforcing steel
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
Parametric study results (4/4)
• Elongation capacity of reinforcing bars
• Conclusion
– Elongation of reinforcing steel <<<< 5 % = Min. allowable
elongation capacity according to EC4-1.2.
26Numerical parametric investigation of simple design method
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
Conclusion
• SDM (Simple Design Method) is on the safe side in
comparison with advanced calculation results.
• Concerning the elongation of reinforcing steel mesh, it
remains generally below 5 %.
• Mechanical links between slab and columns can reduce the
deflection of a composite flooring system under a fire
situation but they are not necessary as a constructional detail.
• SDM is capable of predicting in a safe way the structural
behaviour of composite steel and concrete floor subjected to
standard fire.
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