Prescriptive Fire Regulations Defining ISO ... ISO-834 Curve (EN1364 -1) ... 7.
DIF SEK. Fire Protection. Standard fire approach requires. Fire protection in most
...
DIF SEK PART 1 THERMAL & MECHANICAL ACTIONS DIF SEK
Part 1: Thermal & Mechanical Actions
0
Resistance to Fire - Chain of Events Loads
Θ Steel columns
time
1: Ignition
2: Thermal action
3: Mechanical actions
R
time
4: Thermal response
DIF SEK
5: Mechanical response Part 1: Thermal & Mechanical Actions
6: Possible collapse 1
Structural Fire Safety Engineering vs. Classification Prescriptive
DIF SEK
Performance based
standard fire
natural fire
classification
fire safety eng.
fire safety eng.
fire safety eng.
Part 1: Thermal & Mechanical Actions
2
Actions on Structures Exposed to Fire EN 1991-1-2 - Prescriptive Rules
Design Procedures
Prescriptive Rules (Thermal Actions given
by Nominal Fire)
DIF SEK
Performance-Based Code (Physically based Thermal Actions)
Part 1: Thermal & Mechanical Actions
3
Nominal Temperature-Time Curve *) Nominal temperature-time curve Standard temperature-, External fire - & Hydrocarbon fire curve
No data needed
*) Simplified Fire Models Localised Fire Fully Engulfed Compartment - HESKESTADT - HASEMI
- Parametric Fire θ (t) uniform in the compartment
θ (x, y, z, t)
Rate of heat release Fire surface Boundary properties Opening area Ceiling height
*) Advanced Fire Models - One-Zone Model - Two-Zone Model - Combined Two-Zones and One-Zone fire
+ Exact geometry
- CFD
DIF SEK
Part 1: Thermal & Mechanical Actions
4
Prescriptive Fire Regulations Defining ISO Curve Requirements ISO-834 Curve (EN1364 -1) T = 20 + 345 log (8 t + 1)
θ [°C]
1200
1110 1006
1000
945
1049 The ISO curve * Has to be considered in the WHOLE compartment, even if the compartment
842 800
is huge
600
ISO ISO
400
ISO * Never goes DOWN
ISO ISO
Time [min]
ISO
* does not consider the PRE-FLASHOVER PHASE
200 0
ISO
ISO
* Does not depend on FIRE LOAD and VENTILATION CONDITIONS 0
DIF SEK
30
60
90
120
180
Part 1: Thermal & Mechanical Actions
5
Stages of a Natural Fire and the Standard Fire Curve Temperature Pre- Flashover
Post- Flashover 1000-1200°C
Flashover
Natural fire curve
ISO834 standard fire curve
Time Ignition - Smouldering
DIF SEK
Heating
Cooling ….
Part 1: Thermal & Mechanical Actions
6
Fire Protection Standard fire approach requires Fire protection in most cases F30 may be achievable without protection
DIF SEK
Part 1: Thermal & Mechanical Actions
7
Actions on Structures Exposed to Fire EN 1991-1-2 - Performance Based Code
Design Procedures
Prescriptive Rules
Performance-Based Code
(Thermal Actions given
(Physically based Thermal Actions)
by Nominal Fire)
DIF SEK
Part 1: Thermal & Mechanical Actions
8
History Natural Fire Safety Concept Validation with real fire tests Statistics oninto realEurocodes Fires Implementation
Development of NFSC Concept Fire Growth
Probability of Occupancy
st
[MJ/m²]
Dwelling Hospital (room) Hotel (room) Library Office School Shopping Centre Theatre (movie/cinema) Transport (public space)
fail
p O&SFB [-]
-6
Industrial Building 10 0,05 to 0,1 • Some National10 Fire Regulations -6 10 10 Office 0,02 to 0,04 include now alternative requirements -6 Dwellings 30 10 0,0125 to 0,025 based on Natural Fire Based on Statistics : - in the Canton of Bern during 10 years (39104 fires); - in Finland during the year 1995 (2109 fires) and - in France during the year 1995 (82179 fires) and on values given in the standards : - DIN 18230 "Structural fire protection in Industrial Buildings"; - BSI document DD240 Part 1 "Fire safety engineering in Buildings".
Fire Load q f,k
[kW/m²]
Fire Occurence Failure of Occupants or Starting Fire & Standard Firemen in stopping the fire p fi [1/(m².year)]
RHR f
Occupancy Rate 80% fractile Calibration of Design Software 250 250 250 500 250 250 250 500 250
948 280 377 1824 511 347 730 365 122
IS O cu rv e
θ [°C]
1200
Medium Medium Medium Fast Medium Medium Fast Fast Slow
1000 800 600 400 200 0
DIF SEK
0
30
60
90
Part 1: Thermal & Mechanical Actions
180 120 Time [min]
9
NFSC Valorisation Project
DIF SEK
Part 1: Thermal & Mechanical Actions
10
Natural Fire Model *) Nominal temperature-time curve Standard temperature-, External fire - & Hydrocarbon fire curve
No data needed
*) Simplified Fire Models Localised Fire Fully Engulfed Compartment - HESKESTADT - HASEMI
- Parametric Fire θ (t) uniform in the compartment
θ (x, y, z, t)
Rate of heat release Fire surface Boundary properties Opening area Ceiling height
*) Advanced Fire Models - One-Zone Model - Two-Zone Model - Combined Two-Zones and One-Zone fire
+ Exact geometry
- CFD
DIF SEK
Part 1: Thermal & Mechanical Actions
11
List of needed Physical Parameters for Natural Fire Model ! Boundary properties ! Ceiling height
Geometry
! Opening Area ! Fire surface ! Rate of heat release
DIF SEK
Fire
Part 1: Thermal & Mechanical Actions
12
Characteristics of the Fire Compartment Fire resistant enclosures defining the fire compartment according to the national regulations
Material properties of enclosures: c, ρ, λ
Definition of Openings
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Part 1: Thermal & Mechanical Actions
13
Characteristic of the Fire for Different Buildings
Occupancy
Fire Growth Rate
RHR f
[kW/m²]
Fire Load q 80% fractile f,k [MJ/m²]
Dwelling (room) Hospital Hotel (room) Library Office School Shopping Centre Theatre (movie/cinema) Transport (public space)
DIF SEK
Medium Medium Medium Fast Medium Medium Fast Fast Slow
250 250 250 500 250 250 250 500 250
Part 1: Thermal & Mechanical Actions
948 280 377 1824 511 347 730 365 122
14
Fire Load Density Danger of Fire Activation
Compartment floor area Af [m²]
δq1
Examples of Occupancies
Danger of Fire Activation
δq2
25
1,10
0,78
Art gallery, museum, swimming pool
250
1,50
1,00
Residence, hotel, office
2500
1,90
1,22
5000
2,00
1,44
10000
2,13
1,66
Manufactory for machinery & engines Chemical laboratory, Painting workshop Manufactory of fireworks or paints
q f , d =δ δ q1 . δ q 2 . ∏ δ ni . m . q f , k ni
Automatic Fire Suppression
Automatic Fire Detection
Automatic Water Extinguishing System
Independent Water Supplies
δ
δ
n1
0,61
DIF SEK
0
1
Function of Active Fire Safety Measures
2
n2
1,0 0,87 0,7
Automatic fire
Automatic Alarm Detection Transmission & Alarm to by by Heat Smoke Fire Brigade δ δ n3 δ n4 n5 0,87 or 0,73
0,87
Manual Fire Suppression
Work Fire Brigade
Off Site Fire Brigade
δ
δ
n6
0,61
or
n7
0,78
Part 1: Thermal & Mechanical Actions
Safe Access Routes
δ
n8
0,9 or 1 1,5
Fire Fighting Devices
δ
n9
1,0
Smoke Exhaust System δ
n10
1,0 1,5
1,5
15
Rate of Heat Release Curve Stationary State and Decay Phase 10 9
75'' 150''
1
70% (qf,d • Afi) 0 0 0
0
DIF SEK
A f x RHR
0
f
Fast (FGR)
COMPARTMENT FIRE
RHR [MW] RHR [MW]
RHR [MW]
10 Ultra8 9 Fast 7 (FGR) 8 6 7 5 6 4 5 3 4 2 3 2 1
Growing Steady state phase
Medium (FGR)
FireA Growth Rate = FGR x RHR
f
f
Ventilation Controlled Fire Slow (FGR) Decay phase
t [min] Decay Phase
300''
5
600''
10 5
15 10
tdecay
Part 1: Thermal & Mechanical Actions
20 15
25t [min]30 20
Time [min]
16
Natural Simplified Fire Model *) Nominal temperature-time curve Standard temperature-, External fire - & Hydrocarbon fire curve
No data needed
*) Simplified Fire Models Localised Fire Fully Engulfed Compartment - HESKESTADT - HASEMI
- Parametric Fire θ (t) uniform in the compartment
θ (x, y, z, t)
Rate of heat release Fire surface Boundary properties Opening area Ceiling height
*) Advanced Fire Models - One-Zone Model - Two-Zone Model - Combined Two-Zones and One-Zone fire
+ Exact geometry
- CFD
DIF SEK
Part 1: Thermal & Mechanical Actions
17
Simplified Fire Models Fire behaviour LOCALISED FIRE θ (x, y, z, t)
DIF SEK
FULLY ENGULFED COMPARTMENT θ (t) uniform in the compartment
Part 1: Thermal & Mechanical Actions
18
Simplified Fire Models Localised Fire LOCALISED FIRE
FIRE TEST
θ (x, y, z, t)
TYPICAL APPLICATION
DIF SEK
Part 1: Thermal & Mechanical Actions
19
Localised Fire: HESKESTAD Method Annex C of EN 1991-1-2: • Flame is not impacting the ceiling of a compartment (Lf < H) • Fires in open air
Θ(z) = 20 + 0,25 (0,8 Qc)2/3 (z-z0)-5/3 ≤ 900°C Flame axis
The flame length Lf of a localised fire is given by :
Lf = -1,02 D + 0,0148 Q2/5
H Lf z
DIF SEK
D
Part 1: Thermal & Mechanical Actions
20
Localised Fire: HASEMI Method Annex C of EN 1991-1-2: • Flame is impacting the ceiling (Lf > H)
concrete slab beam
θg θ
= Air Temperature at Beam Level
Y = Height of the free zone
Calculated by CaPaFi
x
DIF SEK
Part 1: Thermal & Mechanical Actions
21
Simplified Fire Models Fully Engulfed Compartment Fire FULLY ENGULFED COMPARTMENT
FIRE TEST
θ (t) uniform in the compartment
TYPICAL APPLICATION
DIF SEK
Part 1: Thermal & Mechanical Actions
22
Large Compartment Test
Fire load: 40kg of wood / m2
DIF SEK
Part 1: Thermal & Mechanical Actions
23
Fire behaviour Fuel controlled
Ventilation controlled
Most severe conditions 900
RHRf = 250 KW/m² At / Af = 4.5 Unprotected Steel FIRE LOAD:
800 700 600
qf = 50 qf = 100 qf = 200 qf = 300 qf = 400 qf = 500 qf = 600 qf = 700 qf = 800 qf = 900 qf = 1000
Temperature
500 400 300 200 100
0
0.02
0.04
Small opening
DIF SEK
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
Opening-Factor
Part 1: Thermal & Mechanical Actions
0.22
0.24
0.26
0.28
Big opening
24
Fully Engulfed Compartment Parametric Fire Temperature [°C]
Annex A of EN 1991-1-2 Iso-Curve
1100 1000
O = 0.04 m ½
900
O = 0.06 m ½
800
O = 0.10 m ½ O = 0.14 m ½
700
O = 0.20 m ½
600
For a given b, qfd, At & Af
500 400 300 200 100 0
DIF SEK
0
time [min] 10
20
30
40
50
60
70
80
Part 1: Thermal & Mechanical Actions
90
100
110 120
25
Natural Advanced Fire Model *) Nominal temperature-time curve Standard temperature-, External fire - & Hydrocarbon fire curve
No data needed
*) Simplified Fire Models Localised Fire Fully Engulfed Compartment - HESKESTADT - HASEMI
- Parametric Fire θ (t) uniform in the compartment
θ (x, y, z, t)
Rate of heat release Fire surface Boundary properties Opening area Ceiling height
*) Advanced Fire Models - One-Zone Model - Two-Zone Model - Combined Two-Zones and One-Zone fire
+ Exact geometry
- CFD
DIF SEK
Part 1: Thermal & Mechanical Actions
26
Advanced fire Models LOCALISED FIRE
The Fire stays localised
The Fire switch to a fully engulfed fire
LOCALISED FIRE
FULLY ENGULFED COMPARTMENT
DIF SEK
Part 1: Thermal & Mechanical Actions
27
Real Fire Test Simulating an Office Building Fully engulfed fire
DIF SEK
Part 1: Thermal & Mechanical Actions
28
Two Zone Calculation Software “OZone V2.2”
Download at www.arcelor.com/sections DIF SEK Part 1: Thermal & Mechanical Actions
29
OZone - Results θ Hot θ Cold
DIF SEK
Part 1: Thermal & Mechanical Actions
30
Calibration of Software OZone: Gas Temp 1400 MAXIMUM AIR T EMPERATURE OZone 1200
OZone [°C]
1000
800
600
400
200 MAXIMUM AIR T EMPERATURE IN THE COMPARTMENT 0 0
200
400
600
800
1000
1200
1400
TEST [°C]
DIF SEK
Part 1: Thermal & Mechanical Actions
31
Calibration of Software OZone: Steel Temp 1400 UNPROTECTED STEEL TEMPERATURE 1200
OZone [°C]
1000
800
600
400
200
0 0
200
400
600
800
1000
1200
1400
TEST [°C]
DIF SEK
Part 1: Thermal & Mechanical Actions
32
OZone: Case Study Influence of the Actives Fire Safety Measures 1000
Office : A f = 291,2 m² O.F. = 0,04 m½ ; Fire Load q f,k = 511 MJ/m²
900
No Fire Active Measures
800
Gas temperature [°C]
Off Site Fire Brigade
700
Automatic Fire Detection & Alarm by Smoke Automatic Alarm Transmission to Fire Brigade Automatic Water Extinguishing System
600 500 400
Design Fire Load q f,d [ MJ/m² ]
625 356 310 189
300 200
q f ,d = m δ q1 δ q2 ∏ δ ni q f ,k
100 0
i
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140 150
Time [min]
DIF SEK
Part 1: Thermal & Mechanical Actions
33
Computer Fluid Dynamics (CFD) Not yet widely used! • Not yet user-friendly • Long calculation times
Used in case of: • Complicated geometry (atrium) • Localised fires • Calculation of smoke exhaust
DIF SEK
Part 1: Thermal & Mechanical Actions
34
Resistance to Fire - Chain of Events Loads
Θ Steel columns
time
1: Ignition
2: Thermal action
3: Mechanical actions
R
time
4: Thermal response
DIF SEK
5: Mechanical response Part 1: Thermal & Mechanical Actions
6: Possible collapse 35
Basis of Design and Actions on Structures S
W
Actions for temperature analysis G
A C T I O N S
Q
Thermal Action
FIRE Actions for structural analysis Mechanical Action Dead Load Imposed Load Snow Wind
G Q S W
Fire
DIF SEK
Part 1: Thermal & Mechanical Actions
36
Combination Rules for Mechanical Actions EN 1990: Basis of Structural Design Room temperature E d = γG G + γ
Q,1
Q
1
+ ∑ψ
0,i
γ Q,i Q
i
i >1
f.i. : Offices area with the imposed load Q, the leading variable action E
= 1,35 G + 1,5 Q + 0,6 • 1,5 W + 0,5 • 1,5 S
d
DIF SEK
Part 1: Thermal & Mechanical Actions
37
Combination Rules for Mechanical Actions EN 1990: Basis of Structural Design Fire conditions ≡ Accidental situation = G+ψ
E fi,d
Q +∑ ψ 1or2,1
1
i >1
Qi 2,i
f.i. : Offices area with the imposed load Q, the leading variable action E
= G + 0,5 Q fi,d
Offices area with the wind W, the leading variable action E
= G + 0,2 W + 0,3 Q fi,d
" Maximum Load ratio in fire: 1,0 G / 1,35 G = 0,74
DIF SEK
Part 1: Thermal & Mechanical Actions
38
Values of ψ factors for buildings ψ1
ψ2
0,7 0,7 0,7 0,7 1,0
0,5 0,5 0,7 0,7 0,9
0,3 0,3 0,6 0,6 0,8
0,7
0,7
0,6
0,7 0
0,5 0
0,3 0
0,70 0,70
0,50 0,50
0,20 0,20
0,50
0,20
0
Wind loads on buildings (see EN1991-1.4)
0,6
0,2
0
Temperature (non-fire) in buildings (see EN1991-1.5)
0,6
0,5
0
ψ0
Action Imposed loads in buildings, category (see EN 1991-1.1) Category A : domestic, residential areas Category B : office areas Category C : congregation areas Category D : shopping areas Category E : storage areas Category F : traffic area vehicle weight ≤ 30kN Category G : traffic area, 30 kN < vehicle weight ≤ 160kN Category H : roofs Snow loads on buildings (see EN1991-1.3) Finland, Iceland, Norway, Sweden Remainder of CEN Member States, for sites located at altitude H > 1000 m a.s.l. Remainder of CEN Member States, for sites located at altitude H ≤ 1000 m a.s.l.
DIF SEK
( Reference : EN1990 - February 2002) Part 1: Thermal & Mechanical Actions
39
Load Factor γ G Gk + γ Q ,l Qk ,l Load Factor E / Rfi,d,t [-] fi,d
η fi =
Gk + ψ fi Qk ,l Maximal Load level after R30
1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0
50
100
150
200
250
300
350
400
Massivity Am/V [1/m]
DIF SEK
Part 1: Thermal & Mechanical Actions
40
Resistance to fire - Chain of events PREVIEW Loads
Θ Steel columns
time
1: Ignition
2: Thermal action
3: Mechanical actions
R
time
4: Thermal response
DIF SEK
5: Mechanical response Part 1: Thermal & Mechanical Actions
6: Possible collapse 41
Thermal action on structure PREVIEW Composite Slab
DIF SEK
Column
Part 1: Thermal & Mechanical Actions
42
Resistance to fire - Chain of events PREVIEW Loads
Θ Steel columns
time
1: Ignition
2: Thermal action
3: Mechanical actions
R
time
4: Thermal response
DIF SEK
5: Mechanical response Part 1: Thermal & Mechanical Actions
6: Possible collapse 43
How structures react to fire PREVIEW ! Temperature rise # thermal expansion + loss of both
stiffness and resistance # additional deformation ⇒ eventual collapse
DIF SEK
t = 0 Θ = 20°C
16 min Θ = 620°C
22 min Θ = 720°C
31 min Θ = 850°C
Part 1: Thermal & Mechanical Actions
44