3
Functions
Dinning
Sight-view
Dinning Hotel lobby
Gym F&B and Swimming pool
Outdoor sight-view
Ourdoor swimming pool
4
Fire Risk Analysis
• Maximum roof height 12m
• Open space within the entire bridge
• Flashover unlikely to happen
• Fire spread may happen as fire loads can be very close to each other.
32m
12m
A fire spread model should be used for the dinning area.
5
Fire Spread Model
a. Realistic fire spread mode b. Simplified fire spread mode 18m 18m
Each table (including 12 chairs) takes an area of 3.5m×3.5m. Average Heat Release Rate : 500kW/m2. Fire Load: 652MJ/m2.
6
Heat Release Rate of One Table
6.125MW
6.2min 21.5min
17.4min
• Peak Heat Release Rate
0.5×3.5×3.5=6.125MW
• Total fire load
652×3.5×3.5=7987 MJ
• Use fast t-square fire, fire development time is 6.2min. Steady burning phase is 15.3min.
• Ignore the fire development phase, a steady burning would last for 17.4min.
7
Fire Travelling
0
17.4min
6.2 12.4 18.6 24.8
17.4min
17.4min
17.4min
17.4min
42.2 Time (min)
Row 1
Row 2
Row 3
Row 4
Row 5
8
Heat Transfer to Steel Members
Convection with the air hc
Radiation to the air hr,a
Radiation from the flame hr,f
arcfr hhhh ,, −−=
• Net heat absorbed by the steel member
• Temperature increase of the steel member
ssss CV
thTρΔ×
=Δ
)( 44, msssar TTAh −×= σε
( )msc TTAh −= αsc
( )44s, sfcfr TTAh −×Φ= σε
9
Calculation of the view factor
• Flame size, including the fire diameter and flame height is calculated according to SFPE Handbook.
• Flame then simplified to a block with all external panels radiating heat.
• View factor for a steel member is calculated as the sum of these panels.
Top panel 14×3.5
Side panel 3.5×3.5
Side panel 3.5×3.5
10
Calculation of the view factor
• In case of a travelling fire, the view factors from several fires may need to be considered at the same time.
0
17.4min
6.2 12.4 18.6 24.8
17.4min 17.4min
17.4min
17.4min
42.2 Time (min)
Row 1
Row 2 Row 3
Row 4
Row 5
11
Steel Temperatures
0 100 200 300 400 500 600 700 800 900
0 20 40 60 80 100
N1 N3 N6 N9
time (min)
Temperature (
°C)
Temperature development during a complete travelling procedure
12
Simplification of the Temperature Distribution
0 100 200 300 400 500 600 700 800 900
0 5 10 15 20 Node ID
Temperature (
°C)
Node Numbering and zone division
Simplify the non-uniform temperature distribution along half of the frame to four groups.
13
Temperature development for the frame
• Each segment of 3.5m width of the frame is subjected to the travelling fire at a 6.2min interval. At time=40min….
Fire travelling direction
1
2 3 4 5 6
Fire zone
14
Structural Response
• All steel members that were in contact with the flame showed residual plastic strain and visible plastic deformation after the fire.
15
Load Bearing Principle • Structure remained stable by load-redistribution
-600
-500
-400
-300
-200
-100
0
100
200
0 10 20 30 40 50 60 70 80 90
time (min) Axial force (kN
)
heated members adjacent members
1 2
3
4 5 6
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