The document discusses structural fire safety design approaches for tunnels, focusing on system-level considerations. It describes key aspects of tunnel geometry and ventilation systems. Numerical modeling is presented as an essential tool for performance-based design, allowing evaluation of different structural solutions against defined safety and performance objectives. Consideration of both structural and thermal behavior, as well as their interaction over time, is important for accurately assessing structural performance under fire conditions.

1. Approccio sistemico per la sicurezza
delle gallerie in caso di incendio
e problemi strutturali specifici
Prof. Ing. Franco Bontempi
Ordinario di Tecnica delle Costruzioni
Facoltà di Ingegneria Civile e Industriale
Università degli Studi di Roma La Sapienza
Progettazione Strutturale Antincendio
Roma, 14 dicembre 2019
1

2. Scopo della presentazione
• Far vedere gli aspetti piu’ generali della
progettazione strutturale antincendio:
❑Complessita’ del problema;
❑Approccio sistemico;
❑Natura accidentale dell’azione incendio;
❑Progettazione prestazionale/prescrittiva;
❑Aspetti specifici delle gallerie stradali.
2

3. OGGETTO
Caratteristiche delle gallerie
Geometrie
Impianti
1
3

4. GEOMETRIE
4

5. Tipo A - autostrade
5

6. 6

7. Tipo B – extraurbane principali
7

8. Tipo C – extraurbane secondarie
8

9. 9

10. 10

11. 11

12. 12

13. 13

14. 14

15. 15

16. 16

17. Sistema vs Struttura
Opera
Morta
Opera
Viva
17

18. IMPIANTI VENTILAZIONE
18

19. 19

20. Piston effect
• Is the result of natural induced draft caused by
free-flowing traffic (> 50 km/h) in uni-directional
tunnel thus providing natural ventilation.
20

21. Mechanical ventilation
• “forced” ventilation is required where piston
effect is not sufficient such as in
– congested traffic situations;
– bi-directional tunnels (piston effect is neutralized by
flow of traffic in two opposite directions);
– long tunnels with high traffic volumes.
21

22. Longitudinal ventilation system
• Employs jet fans suspended under tunnel roof;
in normal operation fresh air is introduced via
tunnel entering portal and polluted air is
discharged from tunnel leaving portal.
22

23. 23

24. 24

25. Semi-transverse ventilation system
• Employs ceiling plenum connected to central fan
room equipped with axial fans; in normal
operation fresh air is introduced along the tunnel
trough openings in the ventilation plenum while
polluted air is discharged via tunnel portals.
25

26. Transverse ventilation system
• Employs double supply and exhaust plenums
connected to central fan rooms equipped with
axial fans; in normal operation fresh air is
introduced and exhausted via openings in
double ventilation plenums.
26

27. 27

28. 28

29. 29

30. Attachments
• Dispersion stack and fan room combined with
longitudinal ventilation: may be required in order
to reduce adverse effect on environment of
discharge of polluted air from tunnel, where
buildings are located in proximity (< 100m) to
tunnel leaving portal.
30

31. 31

32. Ventilation unit
Air extraction
Ventilation unit
Supply of fresh air
32

33. 33

34. COMPLESSITA’
Approccio prestazionale
Modellazione
Sicurezza
2
34

35. LOOSEcouplingsTIGHT
LINEAR interactions NONLINEAR
System Complexity (Perrow)
35

36. APPROCCIO PRESTAZIONALE
36

37. 37

38. Prescrittivo (1)
APPROCCIO
PRESCRITTIVO
1) BASI DEL PROGETTO,
2) LIVELLI DI SCUREZZA,
3) PRESTAZIONI ATTESE
NON ESPLICITATI
1) REGOLE DI
CALCOLO E
2) COMPONENTI
MATERIALI
SPECIFICATI E
DETTAGLIATI
QUALITA' ED AFFIDABILITA'
STRUTTURALI
ASSICURATI IN MODO
INDIRETTO
GARANZIA DIRETTA DELLE PRESTAZIONI
E DELLA SICUREZZA STRUTURALI
INSIEME DI
STRUMENTI
LOGICI E
MATERIALI #3
INSIEME DI
STRUMENTI
LOGICI E
MATERIALI #1
INSIEME DI
STRUMENTI
LOGICI E
MATERIALI #2
OBIETTIVI
PRESTAZIONALI E
LIVELLI DI
SICUREZZA
ESPLICITATI
APPROCCIO
PRESTAZIONALE
NUMERICAL
MODELING
38

39. Prescrittivo (2)
39

40. Prestazionale (1)
APPROCCIO
PRESCRITTIVO
1) BASI DEL PROGETTO,
2) LIVELLI DI SCUREZZA,
3) PRESTAZIONI ATTESE
NON ESPLICITATI
1) REGOLE DI
CALCOLO E
2) COMPONENTI
MATERIALI
SPECIFICATI E
DETTAGLIATI
QUALITA' ED AFFIDABILITA'
STRUTTURALI
ASSICURATI IN MODO
INDIRETTO
GARANZIA DIRETTA DELLE PRESTAZIONI
E DELLA SICUREZZA STRUTURALI
INSIEME DI
STRUMENTI
LOGICI E
MATERIALI #3
INSIEME DI
STRUMENTI
LOGICI E
MATERIALI #1
INSIEME DI
STRUMENTI
LOGICI E
MATERIALI #2
OBIETTIVI
PRESTAZIONALI E
LIVELLI DI
SICUREZZA
ESPLICITATI
APPROCCIO
PRESTAZIONALE
NUMERICAL
MODELING
40

41. Prestazionale (2)
41

42. START
APPLICAZIONE
DI
REGOLE
PRESTABILITE
E
TECNICHE
PREDEFINITE
END
START
END
DEFINIZIONE E DISANIMA
DEGLI OBIETTIVI
INDIVIDUAZIONE DELLE
SOLUZIONI ATTE A
RAGGIUNGERE GLI
OBIETTIVI
ATTIVITA' DI
MODELLAZIONE E MISURA
GIUDIZIO DELLE
PRESTAZIONI
RISULTANTI
No
Yes
42

43. 43

44. 44

45. MODELLI
NUMERICI
MODELLI
FISICI
RISPETTO DI
PRESCRIZIONI
livello
1
OBIETTIVI
livello
3
DEFINIZIONE
DELLA
SOLUZIONE
STRUTTURALE
livello
4
VERIFICA
DELLE
CAPACITA'
PRESTAZIONALI
LIMITI DELLA
PERFORMANCE i-esima
CRITERIO (QUANTITA')
CHE MISURA
LA PERFORMANCE i-esima
DEFINIZIONE DELLA
PERFORMANCE i-esima
livello
2
ESPLICITAZIONE DEGLI
OBIETTIVI ATTRAVERSO
L'INDIVIDUAZIONE DI n
PRESTAZIONI;
ordinatamente, per ciascuna di
esse, i =1,..n:
ESITO
NO
SI'
A
C
B
45

46. MODELLI
NUMERICI
MODELLI
FISICI
RISPETTO DI
PRESCRIZIONI
livello
1
OBIETTIVI
livello
3
DEFINIZIONE
DELLA
SOLUZIONE
STRUTTURALE
livello
4
VERIFICA
DELLE
CAPACITA'
PRESTAZIONALI
LIMITI DELLA
PERFORMANCE i-esima
CRITERIO (QUANTITA')
CHE MISURA
LA PERFORMANCE i-esima
DEFINIZIONE DELLA
PERFORMANCE i-esima
livello
2
ESPLICITAZIONE DEGLI
OBIETTIVI ATTRAVERSO
L'INDIVIDUAZIONE DI n
PRESTAZIONI;
ordinatamente, per ciascuna di
esse, i =1,..n:
ESITO
NO
SI'
A
C
B
46

47. Esempio di struttura
soggetta a incendio:
hangar
Prof. Ing. Franco Bontempi
Ordinario di Tecnica delle Costruzioni
Facolta’ di Ingegneria Civile e Industriale
Universita’ degli Studi di Roma “La Sapienza”
franco.bontempi@uniroma1.it
47

48. MODELLAZIONE
48

49. Analysis Strategy #1:
Sensitivity governance of priorities
49

50. Analysis Strategy #2:
Bounding behavior governance
p
(p)

p
(p)

50

51. Super
Controllore
Problema Risultato
Solutore #1
Solutore #2
Voting System
Analysis Strategy #3:
Redundancy Governance
51

52. NUMERICAL
MODELING
52

53. Factors for Coupling
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
INFORMATION
FLOW DIRECTION
time
tK
53

54. Fully Coupled Scheme
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
54

55. Staggered Coupled Scheme
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
55

56. Temperature Driven Scheme
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
56

57. Scheme With No Memory
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
time
tK
TERMAL
STATE
(Temperature Field
and Termic Related
Properties)
MECHANICAL
STATE
(Strain and Stress
Fields and
Mechanical related
Properties)
57

58. 58

59. 59

60. 60

61. 61

62. 6262

63. SICUREZZA
63

64. ATTRIBUTES
THREATS
MEANS
RELIABILITY
FAILURE
ERROR
FAULT
FAULT TOLERANT
DESIGN
FAULT DETECTION
FAULT DIAGNOSIS
FAULT MANAGING
DEPENDABILITY
of
STRUCTURAL
SYSTEMS
AVAILABILITY
SAFETY
MAINTAINABILITY
permanent interruption of a system ability
to perform a required function
under specified operating conditions
the system is in an incorrect state:
it may or may not cause failure
it is a defect and represents a
potential cause of error, active or dormant
INTEGRITY
ways to increase
the dependability of a system
An understanding of the things
that can affect the dependability
of a system
A way to assess
the dependability of a system
the trustworthiness
of a system which allows
reliance to be justifiably placed
on the service it delivers
SECURITY
High level / active
performance
Low level / passive
performance
Visions, I., Laprie, J.C., Randell, B.,
Dependability and its threats:
a taxonomy,
18th IFIP
World Computer Congress,
Toulouse (France) 2004.
64

65. Nota: minacce
• generica causa negativa che fa degradare l’integrità
strutturale dalla configurazione nominale: queste
cause possono essere viste come minacce e
possono essere suddivise in:
• a) difetto (fault): è una mancanza e rappresenta
una potenziale causa, attiva o dormiente, di danno;
• b) assetto sbagliato (error): il sistema è in uno stato
errato che può o non può causare un fallimento;
• c) rottura (failure): interruzione permanente di
un'abilità di sistema per eseguire una funzione
richiesta in condizioni operative specifiche.
65

66. damage tolerance
• proprietà di un dispositivo o di una macchina in relazione
alla sua capacità di sostenere i difetti in modo sicuro fino
a quando la riparazione può essere eseguita.
• L'approccio alla progettazione per tenere conto della
tolleranza al danno presuppone l’esistenza di difetti in
qualsiasi struttura e che tali difetti si propaghino con
l'uso. Un dispositivo o una macchina sono considerati
resistenti al danno se è possibile attuare un programma
di manutenzione sostenibile che comporti il rilevamento
e la riparazione di danni accidentali, corrosione e
fessurazioni da fatica, prima che tali danni riducano la
resistenza residua della struttura sotto un limite non più
accettabile. 66

67. graceful degradation
• capacità di un computer, di un sistema elettronico o di
una rete di mantenere comunque una certa funzionalità
anche quando gran parte di essi è stata distrutta o resa
inattiva. Lo scopo del degrado aggraziato è prevenire il
fallimento catastrofico. Idealmente, anche la perdita
simultanea di più componenti non causa tempi di
inattività in un sistema con questa proprietà. In un
degrado aggraziato, quindi, l'efficienza operativa
diminuisce gradualmente man mano che un numero
crescente di componenti fallisce.
67

68. ATTRIBUTES
RELIABILITY
AVAILABILITY
SAFETY
MAINTAINABILITY
INTEGRITY
SECURITY
FAILURE
ERROR
FAULT
permanent interruption of a system ability
to perform a required function
under specified operating conditions
the system is in an incorrect state:
it may or may not cause failure
it is a defect and represents a
potential cause of error, active or dormant
THREATS
Structural Robustness (1)
68
68

69. Structural Robustness (2)
• Capacity of a construction to show a
regular decrease of its structural quality
due to negative causes. It implies:
a) some smoothness of the decrease of
structural performance due to
negative events (intensive feature);
b) some limited spatial spread of the
rupture (extensive feature).
69

70. Levels of Structural Crisis
UsualULS&SLS
VerificationFormat
Structural Robustness
Assessment
1st level:
Material
Point
2nd level:
Element
Section
3rd level:
Structural
Element
4th level:
Structural
System 70

71. Bad vs Good Collapses
STRUCTURE
& LOADS
Collapse
Mechanism
NO SWAY
“IMPLOSION”
OF THE
STRUCTURE
“EXPLOSION”
OF THE
STRUCTURE
is a process in which
objects are destroyed by
collapsing on themselves
is a process
NOT CONFINED
SWAY
71

72. Design Strategy #1: Continuity
72

73. Design Strategy #2: Segmentation
73

74. AZIONE
Natura dell’azione incendio
Carattere accidentale
Carattere estensivo
Carattere intensivo
3
74

75. Aspetti caratteristici dell’incendio
• Carattere estensivo
(diffusione nello spazio):
1.wildfire
2.urbanfire
3.all’esterno di una costruzione
4.all’interno di una costruzione
• Carattere intensivo
(andamento nel tempo).
• Natura accidentale.
75

76. Carattere intensivo
76

77. ISO 13387: Example of Design Fire
77

78. 78

79. flashover
STRATEGIE
ATTIVE
(approccio
sistemico)
STRATEGIE
PASSIVE
(approccio
strutturale)
Tempo t
TemperaturaT(t)
andamento di T(t) a
seguito del successo
delle strategie attive
flashover
STRATEGIE
ATTIVE
(approccio
sistemico)
STRATEGIE
PASSIVE
(approccio
strutturale)
Tempo t
TemperaturaT(t)
andamento di T(t) a
seguito del successo
delle strategie attive
Strategie
79

80. F
L
A
S
H
O
V
E
R
passive
▪ Create fire
compartments
▪ Prevent damage
in the elements
▪ Prevent loss of
functionality in
the building
active
▪ Detection measures
(smoke, heat, flame
detectors)
▪ Suppression
measures (sprinklers,
fire extinguisher,
standpipes, firemen)
▪ Smoke and heat
evacuation system
prevention protection robustness
▪ Limit ignition
sources
▪ Limit hazardous
human behavior
▪ Emergency
procedure and
evacuation
▪ Prevent the
propagation of
collapse, once
local damages
occurred (e.g.
redundancy)
Fire Safety Strategies
systemic structural 80

81. active
protection
passive
protection
no
failures
doesn’t
trigger
Y
N
Y
N
spreads
extinguishes
damages
Y
N
robustness
no
collapse
collapse
Y
N
triggers
prevention1 42 3
Fire Safety Strategies
81

82. 82

83. 83

84. SnakeFighter
84

85. Carattere estensivo
85

86. The Great Fire of Chicago, Oct. 7-10, 1871
86

87. 87

88. 88

89. 89

90. 90

91. Windsor Hotel Madrid
91

92. Natura accidentale
92

93. Situazioni HPLC
High Probability Low Consequences
93

94. LPHC events
Low Probability High Consequences
94

95. HPLC
High Probability
Low
Consequences
LPHC
Low Probability
High
Consequences
release of energy SMALL LARGE
numbers of breakdown SMALL LARGE
people involved FEW MANY
nonlinearity WEAK STRONG
interactions WEAK STRONG
uncertainty WEAK STRONG
decomposability HIGH LOW
course predictability HIGH LOW
HPLC vs LPHC events
95

96. Approcci di analisi
HPLC
Eventi Frequenti con
Conseguenze Limitate
LPHC
Eventi Rari con
Conseguenze Elevate
Complessità:
Aspetti non lineari e
Meccanismi di interazioni
Impostazione
del problema:
DETERMINISTICA
STOCASTICA
ANALISI
QUALITATIVA
DETERMINISTICA
ANALISI
QUANTITATIVA
PROBABILISTICA
ANALISI
PRAGMATICA
CON SCENARI
96

97. CAPITOLO 2:
SICUREZZA
E
PRESTAZONI
ATTESE
QUALITA’
CAPITOLO 3:
AZIONI
AMBIENTALI
CAPITOLO 6:
AZIONI
ANTROPICHE
CAPITOLO 4:
AZIONI
ACCIDENTALI
DOMANDA
CAPITOLO 5:
NORME
SULLE
COSTRUZIONI
CAPITOLO 7:
NORME PER LE
OPERE
INTERAGENTI
CON I TERRENI E
CON LE ROCCE,
PER GLI
INTERVENTI NEI
TERRENI E PER
LA SICUREZZA
DEI PENDII
CAPITOLO 9:
NORME
SULLE
COSTRUZIONI
ESISTENTI
PRODOTTO
CAPITOLO 11:
MATERIALI
E
PRODOTTI
PER USO
STRUTTURALE
CAPITOLO 10:
NORME PER LA
REDAZIONI DEI
PROGETTI
ESECUTIVI
CAPITOLO 8:
COLLAUDO
STATICO
CONTROLLO
Italian Code for Constructions
D.M. 14 settembre 2005
97

98. Il Progettista, a seguito della classificazione e della caratterizzazione delle azioni,
deve individuare le possibili situazioni contingenti in cui le azioni possono
cimentare l’opera stessa. A tal fine, è definito:
• lo scenario: un insieme organizzato e realistico di situazioni in cui l’opera
potrà trovarsi durante la vita utile di progetto;
• lo scenario di carico: un insieme organizzato e realistico di azioni che
cimentano la struttura;
• lo scenario di contingenza: l’identificazione di uno stato plausibile e
coerente per l’opera, in cui un insieme di azioni (scenario di carico) è
applicato su una configurazione strutturale.
Per ciascuno stato limite considerato devono essere individuati scenari di carico
(ovvero insiemi organizzati e coerenti nello spazio e nel tempo di azioni) che
rappresentino le combinazioni delle azioni realisticamente possibili e
verosimilmente più restrittive.
Scenari (D.M. 14 settembre 2005)
98

99. Determine geometry,
construction and
use of the building
Establish maximum likely
fuel loads
Estimate maximum likely
number of occupants
and their locations
Assume certain fire protection
features
Carry out fire engineering
analysis
Acceptable
performance
Accept
design
Modify fire
protection
features
Establish
performance
requirements
No Yes
Buchanan,2002
99

100. 100

101. SVILUPPO
Dinamica degli incendi in galleria
Effetti della ventilazione
4
101

102. FIRE DYNAMICS IN TUNNELS
102

103. Tunnel Fires vs Compartment Fires (0)
103

104. Tunnel Fires Progression (1)
104

105. 105

106. 106

107. Tunnel Fires Progression (2)
107

108. Effects of ventilation
108

109. Temperature development
109

110. Smoke development
• A smoke layer may be created in tunnels at the early stages
of a fire with essentially no longitudinal ventilation. However,
the smoke layer will gradually descend further from the fire.
• If the tunnel is very long, the smoke layer may descend to the
tunnel surface at a specific distance from the fire depending
on the fire size, tunnel type, and the perimeter and height of
the tunnel cross section.
• When the longitudinal ventilation is gradually increased, the
stratified layer will gradually dissolve.
• A backlayering of smoke is created on the upstream side of
the fire.
• Downstream from the fire there is a degree of stratification of
the smoke that is governed by the heat losses to the
surrounding walls and by the turbulent mixing between the
buoyant smoke layers and the normally opposite moving cold
layer.
110

111. Backlayering
111

112. 112

113. Maximum gas temperatures in the ceiling area of
the tunnel during tests with road vehicles
113

114. Maximum gas temperatures in the ceiling area of
the tunnel during tests with road vehicles
114

115. Maximum gas temperatures in the cross section
of the tunnel during tests with road vehicles
115

116. EMERGENCY VENTILATION
116

117. Smoke stratification
117

118. Natural smoke venting
• It can be sufficient in short, level tunnels
where smoke stratification allows for
escape in clear/tenable conditions.
118

119. Smoke filling long tunnel
119

120. Emergency ventilation with
longitudinal system
• It can be employed in unidirectional, medium length
tunnels, with free flowing traffic conditions. Smoke is
mechanically exhausted in direction of traffic circulation,
clear tenable conditions for escape are obtained on
upstream side of fire.
120

121. 121

122. 122

123. k size factor for HGV fire
123

124. k size factor for small pool fire
124

125. Emergency ventilation with semi-
transverse “point extraction” system
• Smoke is mechanically exhausted from single ceiling
opening (reverse mode) leaving clear tenable escape
conditions on both sides of fire.
125

126. 126

127. Observation: goal
• The purpose of controlling the spread of smoke
is to keep people as long as possible in a
smoke-free environment.
• This means that the smoke stratification must be
kept intact, leaving a more or less clear and
breathable air underneath the smoke layer.
• The stratified smoke is taken out of the tunnel
through exhaust openings located in the ceiling
or at the top of the sidewalls.
127

128. Observation: longitudinal velocity
• With practically zero longitudinal air velocity, the
smoke layer expands to both sides of the fire.
The smoke spreads in a stratified way for up to
10 min.
• After this initial phase, smoke begins to mix over
the entire cross section, unless by this time the
extraction is in full operation.
• The longitudinal velocity of the tunnel air must
be below 2 m/s in the vicinity of the fire
incidence zone. With higher velocities, the
vertical turbulence in the shear layer between
smoke and fresh air quickly cools the upper
layer and the smoke then mixes over the entire
cross section. 128

129. Observations: turbulence
• With an air velocity of around 2 m/s, most of the
smoke of a medium-size fire spreads to one side
of the fire (limited backlayering) and starts
mixing over the whole cross section at a
distance of 400 to 600 m downstream of the fire
site. This mixing over the cross section can also
be prevented if the smoke extraction is activated
early enough.
• Vehicles standing in the longitudinal air flow
increase strongly the vertical turbulence and
encourage the vertical mixing of the smoke. 129

130. Observation: fresh air
• In a transverse ventilation system, the fresh air
jets entering the tunnel at the floor level induce a
rotation of the longitudinal airflow, which tends to
bring the smoke layer down to the road.
• No fresh air is to be injected from the ceiling in a
zone with smoke because this increases the
amount of smoke and tends to suppress the
stratification.
130

131. Observation: smoke extraction
• In reversible semi-transverse ventilation with the
duct at the ceiling, the fresh air is added through
ceiling openings in normal ventilation operation.
• If a fire occurs, as long as fresh air is supplied
through ceiling openings, the smoke quantity
increases by this amount and strong jets tend to
bring the smoke down to the road surface. The
conversion of the duct from supply to extraction
must be done as quickly as possible.
131

132. Observation: traffic conditions
• For a tunnel with one-way traffic, designed for
queues (an urban area), the ventilation design
must take into consideration that cars can likely
stand to both sides of the fire because of the
traffic. In urban areas it is usual to find stop-and-
go traffic situations.
• For a tunnel with two-way traffic, where the
vehicles run in both directions, it must be taken
into consideration that in the event of a fire
vehicles will generally be trapped on both sides
of the fire.
132

133. Strategies
133

134. Smoke extraction
• Continuous extraction into a return air duct is
needed to remove a stratified smoke layer out of
the tunnel without disturbing the stratification.
• The traditional way to extract smoke is to use
small ceiling openings distributed at short
intervals throughout the tunnel.
• Another efficient way to remove smoke quickly
out of the traffic space is to install large openings
with remotely controlled dampers. They are
normally in an open position where equal
extraction is taking place over the whole tunnel
length.
134

135. Tunnel with a single-point
extraction system
❑The usual way to control the longitudinal velocity is to provide several
independent ventilation sections.
❑When a tunnel has several ventilation sections, a certain longitudinal
velocity in the fire section can be maintained by a suitable operation of the
individual air ducts.
❑By reversing the fan operation in the exhaust air duct, this duct can be
used to supply air and vice versa.
135

136. FIRE MODELING
136

137. 137
Levels

138. 1D
138

139. 1D
139

140. 2D (zone model)
140

141. 2D (zone model)
141

142. 142

143. FDS Simulation
3D (ventilation)
143

144. FDS Simulation
3D (fire)
144

145. 3D (traffic)
145

146. 146

147. Multiscale
147

148. Multiscale (ventilation)
148

149. Multiscale (fire)
149

150. Multiscale (structural)
150

151. Multiscale (structural)
151

152. PROGETTO
Basis
Failure path
Risk
5
152

153. BASIS
www.francobontempi.org
Str
o N
GER
153

154. Design Process - ISO 13387
A. Design constraints and possibilities
(blue),
B. Action definition and development
(red),
C. Passive system and active response
(yellow),
D. Safety and performance
(purple).
3/22/2011
154

155. SS0a
PRESCRIBED
DESIGN
PARAMETERS
SS0b
ESTIMATED
DESIGN
PARAMETERS
SS1
initiation and
development
of fire and
fire efluent
SS2
movement of
fire effluent
SS3
structural response
and fire spread
beyond enclosure
of origin
SS4
detection,
activitation and
suppression
SS5
life safety:
occupant behavior,
location and
condition
SS6
property
loss
SS7
business
interruption
SS8
contamination
of
environment
SS9
destruction
of
heritage
(0)
DESIGN
CONSTRAINTS
AND
POSSIBILITIES
(1+2)
ACTION
DEFINITION
AND
DEVELOPMENT
(3+4)
SYSTEM
PASSIVE
AND ACTIVE
RESPONSE
BUSOFINFORMATION
RESULTS
DESIGN
ACTION
RESPONSE
SAFETY&PERFORMANCE
FSE
155

156. STRUCTURAL
CONCEPTION
STRUCTURAL
TOPOLOGY
&
GEOMETRY
threats
No
Yes
threats
STRUCTURAL
MATERIAL
& PARTS
No
Yespassive
structural
characteristics
threats
FIRE DETECTION
& SUPPRESSION
No
Yes
active
structural
characteristics
threats
ORGANIZATION &
FIREFIGHTERS
No
Yes
threats
MAINTENANCE
& USE
No
Yes
threats
No
alive
structural
characteristics
Yes
STRUCTURAL
SYSTEM
CHARACTERISTICS
STRUCTURAL
SYSTEM
WEAKNESS
156

157. STRUCTURAL
CONCEPTION
STRUCTURAL
TOPOLOGY
&
GEOMETRY
threats
No
Yes
threats
STRUCTURAL
MATERIAL
& PARTS
No
Yespassive
structural
characteristics
threats
No
Yes
STRUCTURAL
CONCEPTION
STRUCTURAL
TOPOLOGY
&
GEOMETRY
threats
No
Yes
threats
STRUCTURAL
MATERIAL
& PARTS
No
Yespassive
structural
characteristics
threats
FIRE DETECTION
& SUPPRESSION
No
Yes
active
structural
characteristics
threats
ORGANIZATION &
FIREFIGHTERS
No
Yes
threats
MAINTENANCE
& USE
No
Yes
threats
No
alive
structural
characteristics
Yes
157

158. FIRE DETECTION
& SUPPRESSION
active
structural
characteristics
threats
ORGANIZATION &
FIREFIGHTERS
No
Yes
threats
MAINTENANCE
& USE
No
Yes
threats
No
alive
structural
characteristics
Yes
STRUCTURAL
CONCEPTION
STRUCTURAL
TOPOLOGY
&
GEOMETRY
threats
No
Yes
threats
STRUCTURAL
MATERIAL
& PARTS
No
Yespassive
structural
characteristics
threats
FIRE DETECTION
& SUPPRESSION
No
Yes
active
structural
characteristics
threats
ORGANIZATION &
FIREFIGHTERS
No
Yes
threats
MAINTENANCE
& USE
No
Yes
threats
No
alive
structural
characteristics
Yes
3/22/2011 158
PROGETTAZIONE STRUTTURALE
ANTINCENDIO
158

159. Fire fighting timeline
159

160. STRUCTURAL
CONCEPTION
STRUCTURAL
TOPOLOGY
&
GEOMETRY
STRUCTURAL
MATERIAL
& PARTS
FIRE DETECTION
& SUPPRESSION
ORGANIZATION &
FIREFIGHTERS
MAINTENANCE
& USE
CRISIS 160

161. HAZARD
IN-DEPTH
DEFENCE
HOLES DUE TO
ACTIVE ERRORS
HOLES DUE TO
FAILURE PATH
161

162. Controlled vs. Uncontrolled Events
162

163. Controlled vs. Uncontrolled Events
163

164. Fire safety concepts tree (NFPA)
1
2
3
4
5
6
7
8
9
Buchanan,2002
Strategie per
la gestione
dell'incendio
1
Prevenzione
2
Gestione
dell'evento
3
Gestione
dell'incendio
4
Gestione delle
persone e
dei beni
15
Difesa sul posto
16
Spostamento
17
Disposibilità
delle vie
di fuga
18
Far avvenire
il deflusso
19
Controllo
della quantità
di
combustibile
5
Soppressione
dell'incendio
10
Controllo
dell'incendio
attraverso il
progetto
13
Automatica
11
Manuale
12
Controllo dei
materiali
presenti
6
Controllo
del movimento
dell'incendio
7
Resistenza e
stabilità
strutturale
14
Contenimento
9
Ventilazione
8
164

165. 1
2
3
4
5
6
7
8
9
Strategie per
la gestione
dell'incendio
1
Prevenzione
2
Gestione
dell'evento
3
Gestione
dell'incendio
4
Gestione delle
persone e
dei beni
15
Difesa sul posto
16
Spostamento
17
Disposibilità
delle vie
di fuga
18
Far avvenire
il deflusso
19
Controllo
della quantità
di
combustibile
5
Soppressione
dell'incendio
10
Controllo
dell'incendio
attraverso il
progetto
13
Automatica
11
Manuale
12
Controllo dei
materiali
presenti
6
Controllo
del movimento
dell'incendio
7
Resistenza e
stabilità
strutturale
14
Contenimento
9
Ventilazione
8
Fire safety concepts tree (NFPA)
Buchanan,2002
165

166. Basis of tunnel fire safety design
• The first priority identified in the literature for fire
design of all tunnels is to ensure:
1. Prevention of critical events that may endanger
human life, the environment, and the tunnel structure
and installations.
2. Self-rescue of people present in the tunnel at time of
the fire.
3. Effective action by the rescue forces.
4. Protection of the environment.
5. Limitation of the material and structural damage.
• Furthermore, part of the objective is to reduce
the consequences and minimize the economic
loss caused by fires. 166

167. 167

168. RISK CONCERN
168

169. Risk treatment
169

170. Option 1 Risk avoidance, which usually means not
proceeding to continue with the system; this is not
always a feasible option, but may be the only
course of action if the hazard or their probability of
occurrence or both are particularly serious;
Option 2 Risk reduction, either through (a) reducing the
probability of occurrence of some events, or (b)
through reduction in the severity of the
consequences, such as downsizing the system, or
(c) putting in place control measures;
Option 3 Risk transfer, where insurance or other financial
mechanisms can be put in place to share or
completely transfer the financial risk to other
parties; this is not a feasible option where the
primary consequences are not financial;
Option 4 Risk acceptance, even when it exceeds the criteria,
but perhaps only for a limited time until other
measures can be taken.
170

171. Quantitative Risk Analysis
Luur,2002
171

172. Risk Analysis, Assessment, Management
(IEC 1995)
172

173. RISK CONCERNS
DEFINE CONTEXT
(social, individual,
political, organizational,
technological)
RSK ANALYSIS
(for the system are defined organization,
scenarios, and consequences of
occurences)
RISK ASSESSMENT
(compare risks
against criteria)
RISK TREATMENT
option 1 - avoidance
option 2 - reduction
option 3 - transfer
option 4 - acceptance
MONITOR
AND
REVIEW
RISK
MANAGEMENT
RISK
ANALYSIS
RISK
ASSESSMENT
173

174. 174

175. SCENARIOS
DEFINE SYSTEM
(the system is usually decomposed into
a number of smaller subsystems and/or
components)
HAZARD SCENARIO ANALYSIS
(what can go wrong?
how can it happen?
waht controls exist?)
ESTIMATE
CONSEQUENCES
(magnitude)
ESTIMATE
PROBABILITIES
(of occurrences)
DEFINE
RISK SCENARIOS
SENSITIVITY
ANALYSIS
RISK
ANALYSIS
FIRE
EVENT 175

176. ISHIKAWA DIAGRAM
176

177. EVENT TREE
Triggering
event
Fire
ignition
1. Fire
extinguished
by personnel
2. Intrusion of
fire fighters
Arson
Explosion
Short
circuit
Cigarette
fire
YES (P1)
NO (1-P1) YES (P2)
NO (1-P2)
Scenario
Other
A1
A2
A3
A4
A5
3. Fire
suppression
YES (P3)
NO (1-P3)
YES (P3)
NO (1-P3)
Fire
location
AREA A
(PA)
YES (P1)
NO (1-P1) YES (P2)
NO (1-P2)
B1
B2
B3
B4
B5
YES (P3)
NO (1-P3)
YES (P3)
NO (1-P3)
AREA B
(PB)
YES (P1)
NO (1-P1) YES (P2)
NO (1-P2)
C1
C2
C3
C4
C5
YES (P3)
NO (1-P3)
YES (P3)
NO (1-P3)
AREA C
(PC)
177
INCUBAZIONE EVOLUZIONE

178. DEFINE SYSTEM
(the system is usually decomposed into
a number of smaller subsystems and/or
components)
HAZARD SCENARIO ANALYSIS
(what can go wrong?
how can it happen?
waht controls exist?)
ESTIMATE
CONSEQUENCES
(magnitude)
ESTIMATE
PROBABILITIES
(of occurrences)
DEFINE
RISK SCENARIOS
SENSITIVITY
ANALYSIS
RISK
ANALYSIS
NUMERICAL
MODELING
SIMULATIONS
178

179. 179

180. 180

181. 181

182. F (frequency) – N (number of fatalities) curve
• An F–N curve is an alternative way of describing
the risk associated with loss of lives.
• An F–N curve shows the frequency (i.e. the
expected number) of accident events with at
least N fatalities, where the axes normally are
logarithmic.
• The F–N curve describes risk related to large-
scale accidents, and is thus especially suited for
characterizing societal risk.
182

183. FN-curves UK Road Rail Aviation Transport, 67-01
183

184. Persson, M. Quantitative Risk Analysis Procedure for
the Fire Evacuation of a Road Tunnel - An Illustrative
Example. Lund, 2002
184

185. Risk acceptance – ALARP (1)
RISK MAGNITUDE
INTOLERABLE
REGION
As
Low
As
Reasonably
Practicable
BROADLY ACCEPTABLE
REGION
Risk cannot be justified
in any circumstances
Tolerable only if risk
reduction is impracticable
or if its cost is greatly
disproportionate to the
improvement gained
Tolerable if cost of
reduction would exceed
the improvements gained
Necessary to maintain
assurance that the risk
remains at this level
As
Low
As
Reasonably
Achievable
RISK MAGNITUDE
INTOLERABLE
REGION
As
Low
As
Reasonably
Practicable
BROADLY ACCEPTABLE
REGION
Risk cannot be justified
in any circumstances
Tolerable only if risk
reduction is impracticable
or if its cost is greatly
disproportionate to the
improvement gained
Tolerable if cost of
reduction would exceed
the improvements gained
Necessary to maintain
assurance that the risk
remains at this level
As
Low
As
Reasonably
Achievable
185

186. Risk acceptance – ALARP (2)
186

187. 187

188. Risk reduction by design
188

189. Monetary values – cost of human life (!)
What is the maximum amount the society (or the
decisionmaker) is willing to pay to reduce
the expected number of fatalities by 1?
Typical numbers for the value of a statistical life used in
cost-benefit analysis are 1–10 million euros.
189

190. RESISTENZA
6
190

191. The burnt out interior
of the Mont Blanc Tunnel
191

192. Curve temperatura - tempo
192

193. Types of fire exposure
for tunnel analysis
193

194. Cellulosic curve
• Defined in various national standards, e.g. ISO 834, BS 476: part 20, DIN
4102, AS 1530 etc.
• This curve is the lowest used in normal practice.
• It is based on the burning rate of the materials found in general building
materials.
194

195. Hydrocarbon (HC) curve
• Although the cellulosic curve has been in use for many years, it soon became
apparent that the burning rates for certain materials e.g. petrol gas, chemicals
etc, were well in excess of the rate at which for instance, timber would burn.
• The hydrocarbon curve is applicable where small petroleum fires might occur,
i.e. car fuel tanks, petrol or oil tankers, certain chemical tankers etc.
195

196. Hydrocarbon mod. (HCM) curve
• Increased version of the hydrocarbon curve, prescribed by the French
regulations.
• The maximum temperature of the HCM curve is 1300ºC instead of the
1100ºC, standard HC curve.
• However, the temperature gradient in the first few minutes of the HCM fire is
as severe as all hydrocarbon based fires possibly causing a temperature
shock to the surrounding concrete structure and concrete spalling as a result
of it.
196

197. RABT ZTV curves
• The RABT curve was developed in Germany as a result of a series of test
programs such as the EUREKA project. In the RABT curve, the temperature
rise is very rapid up to 1200°C within 5 minutes.
• The failure criteria for specimens exposed to the RABT-ZTV time-temperature
curve is that the temperature of the reinforcement should not exceed 300°C.
There is no requirement for a maximum interface temperature.
RABT-ZTV (train)
Time (minutes) T (°C)
0 15
5 1200
60 1200
170 15
RABT-ZTV (car)
Time (minutes) T (°C)
0 15
5 1200
30 1200
140 15
197

198. RWS (Rijkswaterstaat) curve
• The RWS curve was developed by the Ministry of Transport in the
Netherlands. This curve is based on the assumption that in a worst case
scenario, a 50 m³ fuel, oil or petrol, tanker fire with a fire load of 300MW could
occur, lasting up to 120 minutes.
• The failure criteria for specimens is that the temperature of the interface
between the concrete and the fire protective lining should not exceed 380°C
and the temperature on the reinforcement should not exceed 250°C.
RWS, RijksWaterStaat
Time
(minutes)
T
(°C)
0 20
3 890
5 1140
10 1200
30 1300
60 1350
90 1300
120 1200
180 1200
198

199. 199

200. 200

201. Lönnermark, A. and Ingason, H., “Large Scale Fire Tests in the Runehamar
tunnel – gas temperature and Radiation”,
Proceedings of the International Seminar on Catastrophic Tunnel Fires,
Borås, Sweden, 20-21 November 2003.
201

202. 202

203. Fire Scenario Recommendation
203

204. Verifiche
204

205. Mechanical Analysis
• The mechanical analysis shall be performed for the
same duration as used in the temperature analysis.
• Verification of fire resistance should be in:
– in the strength domain: Rfi,d,t ≥ Efi,requ,t
(resistance at time t ≥ load effects at time t);
– in the time domain: tfi,d ≥ tfi,requ
(design value of time fire resistance ≥
time required)
– In the temperature domain: Td ≤ Tcr
(design value of the material temperature ≤
critical material temperature);
205

206. Verification of fire resistance (3D)
R = structural resistance
T = temperature
t = time
T=T(t)
R=R(t,T)=R(t,T(t))=R(t)
206

207. Verification of fire resistance (R-safe)
R = structural resistance
T = temperature
t = time
Rfi,d,t
Efi,requ,t
207

208. Verification of fire resistance (R-fail)
R = structural resistance
T = temperature
t = time
Efi,requ,t
Rfi,d,t
Failure !
208

209. Verification of fire resistance (t)
R = structural resistance
T = temperature
t = time
Efi,requ,t
Rfi,d,t
Failure !
tfi,d ≥ tfi,requ
209

210. Verification of fire resistance (T)
R = structural resistance
T = temperature
t = time
Efi,requ,t
Rfi,d,t
Failure !
Td ≤ Tcr
210

211. Verification of fire resistance (T)
R = structural resistance
T = temperature
t = time
Efi,requ,t
Rfi,d,t
Failure !
Td ≤ Tcr
211

212. 212

213. 213

214. CONCLUSIONI
Conceptual design
Resilience
7
214

215. Conceptual Design
215

216. Conceptual Design
MULTI-HAZARD
BLACK-SWAN
DISASTER CHAIN
216

217. Flow chart
Tabella dotazioni Frejùs
Forensic Engineering
217

218. 218
Resilience

219. Resilience
• Resilience is defined as “the positive
ability of a system or company to adapt
itself to the consequences of a
catastrophic failure caused by power
outage, a fire, a bomb or similar” event or
as "the ability of a system to cope with
change".
219

220. RESILIENCE
220

221. 221

222. 222
222