This document discusses tunnel safety and structural issues related to fires. It begins by outlining the objectives of discussing a systematic approach to fire safety design. Key points include the complexity of the problem, a systemic approach, the accidental nature of fires, and performance-based versus prescriptive design approaches. The document then provides details on tunnel geometries, ventilation systems, and modeling approaches. It emphasizes the need for a performance-based design framework that explicitly defines safety objectives and expected performance.

1. 1
Approccio sistemico per la sicurezza
delle gallerie in caso di incendio
e problemi strutturali specifici
Prof. Dr. Ing. Franco Bontempi
Ordinario di Tecnica delle Costruzioni
Facolta’ di Ingegneria Civile e Industriale
Universita’ degli Studi di Roma La Sapienza
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2. 2
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3. 3
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.
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4. 4
OGGETTO
Caratteristiche delle gallerie
Geometrie
Impianti
1
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5. 5
GEOMETRIE
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6. 6
Tipo A - autostrade
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7. 7
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8. 8
Tipo B – extraurbane principali
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Tipo C – extraurbane secondarie
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11. 11
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12. 12
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17. 17
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Sistema vs Struttura
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Opera
Morta
Opera
Viva
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19. 19
IMPIANTI VENTILAZIONE
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21. 21
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.
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22. 22
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.
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23. 23
TUNNEL VENTILATION SYSTEMS
• Road Tunnel Ventilation Systems have two modes of
operation:
• Normal ventilation, for control of air quality inside tunnels
due to vehicle exhaust emissions:
– in any possible traffic situation, tunnel users and staff must not suffer
any damage to their health regardless the duration of their stay in the
tunnel;
– the necessary visual range must be maintained to allow for safe
stopping.
• Emergency ventilation in case of fire, for smoke control:
– the escape routes must be kept free from smoke to allow for self-
rescue;
– the activities of emergency services must be supported by providing
the best possible conditions over a sufficient time period ;
– the extent of damage and injuries (to people, vehicles and the tunnel
structure itself) must be kept to a minimum.
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24. 24
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.
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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.
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28. 28
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.
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32. 32
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.
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33. 33
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34. 34
Ventilation unit
Air extraction
Ventilation unit
Supply of fresh air
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36. 36
COMPLESSITA’
Approccio prestazionale
Modellazione
Sicurezza
2
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37. 37
LOOSEcouplingsTIGHT
LINEAR interactions NONLINEAR
System Complexity (Perrow)
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38. 38
APPROCCIO PRESTAZIONALE
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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
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RequisitiRequisiti
Elementi CostituentiElementi Costituenti
Elementi CostituentiElementi Costituenti
Elementi CostituentiElementi Costituenti
RequisitiRequisiti
Elementi CostituentiElementi Costituenti
Elementi CostituentiElementi Costituenti
prescrittivo
prestazionale
RequisitiRequisiti
Elementi CostituentiElementi Costituenti
RequisitiRequisiti
Elementi CostituentiElementi CostituentiElementi CostituentiElementi Costituenti
Elementi CostituentiElementi CostituentiElementi CostituentiElementi Costituenti
Elementi CostituentiElementi CostituentiElementi CostituentiElementi Costituenti
RequisitiRequisiti
Elementi CostituentiElementi CostituentiElementi CostituentiElementi Costituenti
Elementi CostituentiElementi CostituentiElementi CostituentiElementi Costituenti
prescrittivo
prestazionale
Prescrittivo (2)
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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
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43. 43
Prestazionale (2)RequisitiRequisiti
Elementi CostituentiElementi Costituenti
Elementi CostituentiElementi Costituenti
Elementi CostituentiElementi Costituenti
RequisitiRequisiti
Elementi CostituentiElementi Costituenti
Elementi CostituentiElementi Costituenti
prescrittivo
prestazionale
RequisitiRequisiti
Elementi CostituentiElementi Costituenti
RequisitiRequisiti
Elementi CostituentiElementi CostituentiElementi CostituentiElementi Costituenti
Elementi CostituentiElementi CostituentiElementi CostituentiElementi Costituenti
Elementi CostituentiElementi CostituentiElementi CostituentiElementi Costituenti
RequisitiRequisiti
Elementi CostituentiElementi CostituentiElementi CostituentiElementi Costituenti
Elementi CostituentiElementi CostituentiElementi CostituentiElementi Costituenti
prescrittivo
prestazionale
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44. 44
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
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45. 45
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46. 46
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47. 47
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
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48. 48
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
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MODELLAZIONE
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50. 5050
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51. 51
Analysis Strategy #1:
Sensitivity governance of priorities
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52. 52
Analysis Strategy #2:
Bounding behavior governance
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53. 53
Analysis Strategy #3:
Redundancy Governance
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54. 54
NUMERICAL
MODELING
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55. 55
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
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56. 56
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)
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57. 57
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)
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58. 58
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)
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59. 59
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)
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60. 6060
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61. 6161
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62. 6262
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63. 6363
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SICUREZZA
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65. 65
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.
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66. 66
ATTRIBUTE
S
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)
66
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67. 67
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).
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68. 68
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
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69. 69
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
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Design Strategy #1: Continuity
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71. 71
Design Strategy #2: Segmentation
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72. 72
Esempio di valutazione
di roubustezza strutturale
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73. 73
73
Esempio: edificio alto
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74. 74
Analisi di un componente tipico
D0
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75. 75D1 D2
Scenari (1-2)
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76. 76D3 D4
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Modalità di collasso (1-2)
D1 D2
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Modalità di collasso (3-4)
D3 D4
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Sintesi dei risultati: elemento critico
0
4
Lo scenario D4
è quello più cattivo:
l’elemento strutturale
critico individuato è la
colonna più esterna!
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80. 80
Modellazione edificio alto
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Scenario 1
(1 asta
eliminata)
Scenario 2
(3 aste
eliminate)
Scenario 3
(5 aste
eliminate)
Scenario 4
(7 aste
eliminate)
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Collasso secondo scenario 1www.francobontempi.org
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Collasso secondo scenario 2www.francobontempi.org
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Collasso secondo scenario 3www.francobontempi.org
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Moltiplicatore Ultimo e sua variazione
4,05
3,57
3,19
2,64 2,40
0,48
0,86
1,41 1,65
0,00
0,50
1,00
1,50
2,00
2,50
3,00
3,50
4,00
4,50
D0 D1 D2 D3 D4
Scenario di danneggiamento
u Delta F
F
Sintesi dei risultati
Δ u
u
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AZIONE
Natura dell’azione incendio
Carattere accidentale
Carattere estensivo
Carattere intensivo
3
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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.
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Carattere intensivo
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ISO 13387: Example of Design Fire
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Andamento nel tempo potenza termica
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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
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95. 95
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
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95

96. 96
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
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96

97. 97
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97

98. 98
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98

99. 99
SnakeFighter
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100. 100
Carattere estensivo
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100

101. 101
The Great Fire of Chicago, Oct. 7-10, 1871
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101

102. 102
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102

103. 103
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103

104. 104
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104

105. 105
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105

106. 106
Windsor Hotel Madrid
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106

107. 107
Natura accidentale
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107

108. 108
Situazioni HPLC
High Probability Low Consequences
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109. 109
LPHC events
Low Probability High Consequences
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110. 110
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
110

111. 111
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
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112. 112
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
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113. 113
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)
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114. 114
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
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115. 115
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116. 116
SVILUPPO
Dinamica degli incendi in galleria
Effetti della ventilazione
4
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117. 117
FIRE DYNAMICS IN TUNNELS
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118. 118
Tunnel Fires vs Compartment Fires (0)
118

119. 119
Tunnel Fires Progression (1)
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119

120. 120
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120

121. 121
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121

122. 122
Tunnel Fires Progression (2)
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123. 123
Effects of ventilation
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124. 124
Temperature development
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125. 125
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.
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126. 126
Backlayering
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127. 127
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128. 128
Maximum gas temperatures in the ceiling area of
the tunnel during tests with road vehicles
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128

129. 129
Maximum gas temperatures in the ceiling area of
the tunnel during tests with road vehicles
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129

130. 130
Maximum gas temperatures in the cross section
of the tunnel during tests with road vehicles
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131. 131
EMERGENCY VENTILATION
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132. 132
Smoke stratification
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133. 133
Natural smoke venting
• It can be sufficient in short, level tunnels
where smoke stratification allows for
escape in clear/tenable conditions.
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134. 134
Smoke filling long tunnel
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135. 135
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.
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136. 136
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136

137. 137
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137

138. 138
k size factor for HGV fire
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138

139. 139
k size factor for small pool fire
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140. 140
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.
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141. 141
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142. 142
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.
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143. 143
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.
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144. 144
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.
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145. 145
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.
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146. 146
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.
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147. 147
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.
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148. 148
Strategies
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149. 149
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.
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150. 150
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.
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151. 151
FIRE MODELING
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152. 152
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153. 153
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Levels

154. 154
1D
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155. 155
1D
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156. 156
2D (zone model)
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156

157. 157
2D (zone model)
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158. 158
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159. 159
FDS Simulation
3D (ventilation)
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160. 160
FDS Simulation
3D (fire)
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161. 161
3D (traffic)
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162. 162
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163. 163
Multiscale
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164. 164
Multiscale (ventilation)
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165. 165
Multiscale (fire)
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166. 166
Multiscale (structural)
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167. 167
Multiscale (structural)
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168. 168
PROGETTO
Basis
Failure path
Risk
5
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169. 169
BASIS
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170. 170
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
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171. 171
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
SAFETY&PERFORMANCE
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DESIGN
RESPONSE

172. 172
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
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173. 173
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
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174. 174
FIRE DETECTION
& SUPPRESSION
No
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 174
PROGETTAZIONE STRUTTURALE
ANTINCENDIO
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175. 175
Fire fighting timeline
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176. 176
STRUCTURAL
CONCEPTION
STRUCTURAL
TOPOLOGY
&
GEOMETRY
STRUCTURAL
MATERIAL
& PARTS
FIRE DETECTION
& SUPPRESSION
ORGANIZATION &
FIREFIGHTERS
MAINTENANCE
& USE
CRISIS
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177. 177IN-DEPTH
DEFENCE
FAILURE PATH
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178. 178
Controlled vs. Uncontrolled Events
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179. 179
Controlled vs. Uncontrolled Events
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180. 180
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
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181. 181
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
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182. 182
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.
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183. 183
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184. 184
RISK CONCERN
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185. 185
Risk treatment
Option 1 :
RISK
AVOIDANCE
Option 2 :
RISK
REDUCTION
Option 3 :
RISK
TRANSFER
Option 4 :
RISK
ACCEPTANCE
START
STOP
No
No
No
Yes
Yes
Yes
No
100 %
50 %
50 %
30 %
20 %
25 %
5 %
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186. 186
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.
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187. 187
Quantitative Risk Analysis
Luur,2002
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188. 188
Risk Analysis, Assessment, Management
(IEC 1995)
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189. 189
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
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190. 190
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191. 191
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
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192. 192
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193. 193
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194. 194
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)
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PREPARAZIONE EVOLUZIONE

195. 195
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
SIMULATIONSwww.francobontempi.org
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196. 196
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197. 197
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198. 198
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199. 199
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.
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200. 200
FN-curves UK Road Rail Aviation Transport, 67-01
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201. 201
Persson, M. Quantitative Risk Analysis Procedure for
the Fire Evacuation of a Road Tunnel - An Illustrative
Example. Lund, 2002
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202. 202
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
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203. 203
Risk acceptance – ALARP (2)
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204. 204
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205. 205
Risk reduction by design
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206. 206
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.
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207. 207
RESISTENZA
6
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208. 208
The burnt out interior
of the Mont Blanc Tunnel
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209. 209
Curve temperatura - tempo
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210. 210
Types of fire exposure
for tunnel analysis
0
200
400
600
800
1000
1200
1400
0 30 60 90 120 150 180
Temperature(°C)
Time (min.)
Cellulosic Hydrocarbon Hydrocarbon modified
RABT-ZTV train RABT-ZTV car RWS
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211. 211
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.
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212. 212
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.
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213. 213
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.
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214. 214
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
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215. 215
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,
RijksWaterStaatTime
(minutes)
T
(°C)
0 20
3 890
5 1140
10 1200
30 1300
60 1350
90 1300
120 1200
180 1200
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216. 216
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217. 217
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218. 218
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.
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219. 219
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220. 220
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221. 221
Fire Scenario Recommendation
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222. 222
Verifiche
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223. 223
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);
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224. 224
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)
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225. 225
Verification of fire resistance (R-safe)
R = structural resistance
T = temperature
t = time
Rfi,d,t
Efi,requ,t
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226. 226
Verification of fire resistance (R-fail)
R = structural resistance
T = temperature
t = time
Efi,requ,t
Rfi,d,t
Failure !
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227. 227
Verification of fire resistance (t)
R = structural resistance
T = temperature
t = time
Efi,requ,t
Rfi,d,t
Failure !
tfi,d ≥ tfi,requ
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228. 228
Verification of fire resistance (T)
R = structural resistance
T = temperature
t = time
Efi,requ,t
Rfi,d,t
Failure !
Td ≤ Tcr
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229. 229
Verification of fire resistance (T)
R = structural resistance
T = temperature
t = time
Efi,requ,t
Rfi,d,t
Failure !
Td ≤ Tcr
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230. 230
Comportamenti termo-meccanici
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231. 231
Trasformazione del calcestruzzo
alle alte temperature
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232. 232
Parametri per la relazione tensioni-deformazioni
per il calcestruzzo ad elevate temperature.
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233. 233
Calcestruzzo ad aggregato siliceo in condizioni di
compressione uniassiale ad elevate temperature
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234. 234
Variazione del coefficiente di riduzione della
resistenza a compressione del calcestruzzo ad
aggregato siliceo con la temperatura
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235. 235
Relazioni tensioni-deformazioni per acciai da
calcestruzzo armato ordinario
laminati a caldo ad elevate temperature
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236. 236
Parametri per la relazione tensioni-deformazioni
per acciai da calcestruzzo armato ordinario
laminati a caldo, a temperature elevate
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237. 237
Spalling
Spalling is an umbrella term, covering different damage phenomena
that may occur to a concrete structure during fire. These phenomena
are caused by different mechanisms:
•Pore pressure rises due to evaporating water when the temperature rises;
•Compression of the heated surface due to a thermal gradient in the cross
section;
•Internal cracking due to difference in thermal expansion between
aggregate and cement paste;
•Cracking due to difference in thermal expansion/deformation between
concrete and reinforcement bars;
•Strength loss due to chemical transitions during heating.
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238. 238
• Explosive spalling occurs during the first 20-30 minutes of the
standard cellulosic and hydrocarbon fire curves.
• After the 2nd minute of a typical hydrocarbon exposure, spalling can
occur in high strength concretes with polypropylene fibres and in
concretes with high moisture content independent of the type of
standard curve. Also, concretes with high moisture content can
suffer spalling after the 3rd minute of exposure.
• External temperature increments between 20-30ºC/min are typical
in the occurrence of explosive spalling.
• Temperature increments of more than 3ºC/min are enough for the
occurrence of explosive spalling.
• Concrete external layers can be released from concrete members
when these reach temperatures between 250 - 420ºC; 375 - 425ºC.
Spalling criteria (literature review)
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240. 240
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241. 241
CONCLUSIONI
Conceptual design
Resilience
7
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242. 242
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243. 243
Conceptual Design
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244. 244
Conceptual Design
MULTI-HAZARD
BLACK-SWAN
DISASTER CHAIN
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245. 245
Flow chart
Tabella dotazioni Frejùs
Forensic Engineering
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246. 246246
Resilience
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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".
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248. 248
RESILIENCE
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249. 249
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250. 250
ACKNOWLEDGEMENTS
• Dr. Konstantinos GKOUMAS – Uniroma1
• Dr. Francesco PETRINI – Uniroma1
• Ing. Alessandra LO CANE – MIT
• Dr. Filippo GENTILI – Coimbra (PT)
• Mr. Tiziano BARONCELLI – Uniroma1
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251. 251
251
251
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252. 252
StroNGER S.r.l.
Research Spin-off for Structures of the Next Generation:
Energy Harvesting and Resilience
Roma – Milano – Terni – Atene - Nice Cote Azur
Sede operativa: Via Giacomo Peroni 442-444, Tecnopolo Tiburtino,
00131 Roma (ITALY) - info@stronger2012.com
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