Fire Behaviour of Steel and Composite Floor Systems Numerical parametric investigation of simple design method
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Fire Behaviour of Steel and Composite Floor SystemsNumerical 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 tests• Excellent fire performance of the composite floor
systems (presence of tensile membrane action)• Max of steel 1000 °C, fire duration 120 min• French construction details• Deflection 450 mm
– FICEB (Test 3) full scale natural fire test with CellularBeams
• Objective– Verification of the Simple Design Method to its full
application domain (using advanced calculationmodels)
• 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 beamsProtected 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
ColumnColumn
With mechanical link between slab and columns
Without mechanical link between slab and columns
BeamShear 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
Tempe
rature [°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 101mm 107 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
Stre
ss [M
Pa]
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
Strain
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 primary beams Composite slab
ABC
ABC
ABC
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
FB
ACD
E
13Numerical parametric investigation of simple design method
Validation of the ANSYS numerical model vs Test 1 (2/2)
• Comparison with fire test (deflection)
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
0
100
200
300
400
500
0 15 30 45 60 75 90 105 120Time (min)
Dis
plac
emen
t (m
m)
Mid-span of unprotected
central
Mid-span of protected edge
secondary beamsMid-span of protected
primary beams
Central part of the floor
Test Simulation
Mid-span of unprotected
beams
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
ABC
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
FB
ACD
E
15Numerical parametric investigation of simple design method
Validation of the SAFIR 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
ABC
Objectives
Parametric study
properties
Finite Element
Analysis
Validation of the
numerical model
Effect of boundary
conditions
Parametric study
results
Conclusion
FB
ACD
E
17Numerical parametric investigation of simple design method
Validation of the SAFIR 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 elementObjectives
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
Red
uctio
n fa
ctor
s
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 200R
educ
tion
fact
ors
(x 1
E-3)
Temperature ( C)
kEa,θ
kap,θ
kay,θ
20Numerical parametric investigation of simple design method
Validation of the SAFIR 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
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)
Uns
afe
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 [m
m]
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 [m
m]
Advanced numerical model [mm]
R 30 R 60 R 90 R 120
Uns
afe
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 Spa
n/30
/ tFi
re R
esis
tanc
e
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
. mec
hani
cal s
train
of r
einf
orci
ng s
teel
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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