2. What is Fire ?
FIRE is a process of combustion
characterized by the evolution of
Heat, Light, and Smoke.
SMOKE is the cloud of finely
dispersed solid matter like soot.
Gray colour is due to the presence
of water vapours.
10. BBeehhaavviioouurr ooff CCoonnccrreettee iinn FFiirree
• On Heating Concrete losses its strength
• No significant loss up to 2000C
• Significant loss occurs at 6000C
Very little residual strength is left after 6000C
15. FFIIRREE SSAAFFEETTYY
LLIIFFEE SSAAFFEETTYY FIRE
PPRROOTTEECCTTIIOONN
Design
of
Egress Routs
Pressurization
of
Protected Spaces
Active
Measures
Passive
Measures
1. Sprinkler
2. Detectors
3. Hydrants
4. Extinguishers
1. Compartmentation
2. Fire Retardant
3. Fire Resistance
16. FIRE SAFETY
ENGINEERING
LIFE SAFETY
DESIGN OF
EGRESS
ROUTES
PRESSURISATION
OF PROTECTED
SPACES
FIRE SAFETY
FIRE
PREVENTION
FIRE
PROTECTION
PASSIVE
GOOD
HOUSE
KEEPING
MATERIALS ACTIVE
FIRE
RESISTANT
STRUCTURE
MINIMISE
ACCUMULATION
OF
COMBUSTIBLES
COMPART-MENTATION
FIRE
RETARDANT
MATERIALS
FIRE
VENTING
FIRE
EXTINGUISH
-MENT
FIRE
DETECTOR
MANUAL AUTOMATIC MANUAL AUTOMATIC
EXTIN-GUISHERS
HYDRANT
SYSTEM
AUTOMATIC
SPRINKLER
SYSTEM
FLOODING
SYSTEMS
17. STOICHIOMETRIC BBUURRNNIINNGG OOFF MMEETTHHAANNEE
CH4 + 2O2 ® CO2+2H2O
16 64 44 36
Reactants Products of combustion
Fuel 1 Kg CO2 : 2.75 Kg
Air 16 Kg ((Approx) ) H2O : 2.25 Kg
N2 :12.0 Kg (Approx)
SSiinnccee tthhee rreeaaccttiioonn iiss nnoott ccoommpplleettee,, ttrraacceess ooff CCOO,, HHCCLL,, HHCCNN
eettcc aarree aallssoo ffoouunndd iinn tthhee pprroodduuccttss ooff ccoommbbuussttiioonn
19. LLIIFFEE SSAAFFEETTYY --22
CCaarrbboonn MMoonnooxxiiddee::
Toxicity of CO is due to its affinity for hemoglobin to form COHb
resulting in decreased supply of oxygen to body tissues. The critical
limits of exposure is determined as follows:
Concentration x time = 35,000 ppm-min.
10 minutes exposure to 3,500 ppm is hazardous
Safe upto 100 ppm exposure
20. LLIIFFEE SSAAFFEETTYY --33
HHYYDDRROOGGEENN CCYYAANNIIDDEE::
Hydrogen cyanide is 20 times more toxic than carbon
monoxide. It does not react with hemoglobin but
inhibits the use of oxygen by cells. The concentration-time
rule is
Concentration x time = 1500 ppm-min
50 ppm may be tolerated upto 30 min
21. LLIIFFEE SSAAFFEETTYY --44
HHYYDDRROOGGEENN CCHHLLOORRIIDDEE::
• HCL is a sensory as well as pulmonary irritant
• 75 ppm is extremely irritating to eyes and upper respiratory
tract
OOXXYYGGEENN::
17% impairs motor co-ordination
11% causes headache
9% Shortness of breathe, nausea
3.2% death within 45s
23. BBuuiillddiinngg EEvvaaccuuaattiioonn
BASIS:
ASET : Available Safe Egress Time
To be determined through available model
RSET : Required Safe Egress Time
RSET .LE. ASET
T-HELP : Time for Human Escape and Life Potential
RSET .NG. T-HELP
24. T-HELP: Time for Human Escape aanndd LLiiffee PPootteennttiiaall
T-HELP = tinc- tdet
“Inc“ refers to the time of incapacitation, and
“det” Refers to the time of detection
25. TT--HHEELLPP CCRRIITTEERRIIAA
CCRRIITTEERRIIOONN--11
Upper layer reaches to head level or its temperature reaches to
100 deg C.
-- wwhhiicchheevveerr ccoommeess ffiirrsstt
CCRRIITTEERRIIOONN--22
Upper layer reaches to floor level or its temperature reaches to
160 deg C.
-- wwhhiicchheevveerr ccoommeess ffiirrsstt
45. WWhhaatt iiss aa MMooddeell??
Physically of mentally contrived emulation of
‘reality’ suggested by what understanding we
have of the phenomenon
46. MODEL POTENTIAL
A Model must have capacity or ‘potential to
be valuable
A model is valuable depends upon the case and
how the model is employed
A model which has the potential to be valuable
may not be valuable in a given case because it
may be inappropriate for that case.
48. FFOORR EEXXAAMMPPLLEE::
800
600
400
200
200 400 600 800 100
0
120
Time(S) 0
Temperature (C)
FFiirree MMooddeell:: LLiimmiittaattiioonnss--11
Validation: means proven correct, but term validation is misleading in
itself, because validation is carried out with a limited set of experiments only.
Shows that there is a need for repetition of experimental tests.
49. FFiirree MMooddeell:: LLiimmiittaattiioonnss--22
CCoommppaarriissoonn wwiitthh eexxppeerriimmeennttss uunnddeerr iiddeennttiiccaall iinnppuuttss
Ranking of Predicted
Temperature TTEESSTT
Foam Slab HHoouussee DDeepptttt.. SSttoorree
Highest FIRST FAST ASET
Middle - ASET FAST
Lowest FAST FIRST FIRST
Conclusion: We can not assume consistency of prediction of one
model in relation to another model
50. DDEEVVEELLOOPPEEDD MMOODDEELLSS
CALFIRE CALculate Fire in Room and Enclosures
FIREMAP Fire Induced Risk Evaluation and Mapping
SAFE-R Safe and Accessible Fire Escape - Routes
SEEM Stack Emission Engineering Model
53. SSAAFFEE--RR mmeetthhooddoollooggyy
I. Identification of paths for each source node,
II. Calculation of traversal time of each path,
III. Determination of dynamic capacity of each path,
IV. Arranging paths in ascending order in terms of traversal
time,
V. Calculation of number of evacuees per unit time step,
VI. Presentation of result in tabular form,
54. BBUUIILLDDIINNGG EEVVAACCUUAATTIIOONN--33
SAFE-R MODEL
Has been developed to plan the evacuation process
Identification of Paths for each Source Node
Calculate Traversal Time of each Path
Calculate Dynamic Capacity of each Path
Number of evacuees per unit time
Helps to reject the use of longer Paths
Helps to reduce bottlenecking and waiting time
56. BBUUIILLDDIINNGG EEVVAACCUUAATTIIOONN--44
SAFE-R NETWORK
Building plan is represented in the form of a network of
Nodes and Arcs.
Node represents spaces such as Hall, Room, Corridor
Arc represents the connection between two Nodes
Example:
Room Node Exit
Nodes : Source node (Room)
Exit node (Open)
Arc : Door between Room & Open
62. 250
200
150
100
50
0
SAFE-R EVACNET+
0 25 50 75 100 125 150 175 200
Time,s
No. of people inside the building
Number of people left inside the building aatt aannyy iinnssttaanntt ooff ttiimmee
65. Safety Features
Wind load of 320 kmpH hurricane
Worst Seismic load in Aleutian Tectonic Plate
Sprinkler System
Fire alarm system
Escape routes
Two Hours fire resistance
66. Fuel Load : 90,000 lit.
Fuel Density : 0.8 kg/lit.
Fuel Mass : 72,000 kg
Heat of Comb : 44 MJ/kg
Fire Load : 3.168 x 106 MJ
Fire Duration : 1 hr
Heat release rate : 880 MW
Equivalent to 2 NAPS or 2 Super TPPs.
Fire Load
67. Room Temperature – 1
Floor Area : 4,032 m2
Building Volume : 1.66 x 106 m3
Air Density : 1.0 kg/m3
Air Mass : 1.66 x 106 kg
Specific Heat : 1.2 kJ/kg-K
T = 3168 x 106/1.66 x 106 x 1.2
T = 15900 C
Assumption : Building is insulated
68. Room Temperature – 2
Plane Strike : 300 m from base
Height involved : 112 m
Air mass : 4032 x 112
: 0.45 x 106 kg
Energy lost to ambient : 60 – 80%
T = 23460 C with 60% losses.
= 17600 C with 70% losses.
Reported temperature : 17270 C
Melting Point of Steel : 15700 C
69. Fire Resistance - 1
Steel Columns covered with insulating material provided
guarantee to stand for a minimum of 2 hrs during normal fire
conditions, i.e.,
Fire Resistance = 2 hrs.
Fire Resistance is determined in a Standard Furnace, whose
temperature is raised in accordance with
DT = 345 log 10 (8t + 1)
t is time in min.
70. Theoretical Fire Resistance – 1
. 25mm thick, hollow steel column
25mm . Insulation Board
li
Insulation Steel
Tf
di
Ts
Heat balance provides
( )
s s s i
A T T
dT
= l -
s i i f s
V C d
dt
r
T =
1727 C
T ?
s
O
f
=
71. 2000
1800
1600
1400
Theoretical Fire Resistance – 2
Column temperature under real time fire
1570
C
Temperature, 1200
1000
800
600
400
200
0
0
400
800
Time, S Standard time – temperature curve
Column temperature under standard fire
30 min 50 min
1200
1600
2000
2400
2800
3200
3600
4000
4400
4800
5200
5600
6000
6400
6800
7200
72. Equivalence of Fire Severity - 1
1200
1000
800
Standard time – temperature curve
Temperature, C Fire Severity is defined as area under the curve.
600
400
200
0
0
400
800
1200
1600
2000
2400
2800
3200
3600
4000
4400
4800
5200
5600
6000
6400
6800
7200
Time, S
Fire Severity should remain Constant.
Fire Severity in the present area is equal to
97429.250 C-min
73. Equivalence of Fire Severity - 2
Under the influence of elevated temperature,
fire resistance reduces.
1727 x t = 97429.25
t = 57 min
Very close to the time of Collapse
Temperature, oC
Time, min
1727
?
75. VENT/ FAN SIZE
Information on the proper size of VENT or for deciding
suitable specification of an extractor FAN is required
to check the descent of the hot gas layer below a
certain level.
83. Conclusions
Initially, the individual floor perimeter columns collapsed due to
combination of factors such as high temperature and aircraft debris.
The fire continued for about an hour, steel columns melted, fire
resistance reduced to one fourth.
Large amount of heat transferred to lower portion through radiation
and conduction, thus weakening the structure below.
The columns started buckling after loosing strength and over
loading.
Once the floor collapsed, each new falling floor added to the
downward force. Subsequently, the upper portion fell and hit the
intact structure below.
High speed express elevators helped in removing people @ 1.375
persons per second per elevator, i.e. 4,950 persons per hour per
elevator.
Had the impact zone been lower, the structure may have fallen like a
tree.