Convegno sulla Resistenza al Fuoco, Cosenza 6 Febbraio 2014, Bontempi

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

www.francobontempi.org

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Scopo della presentazione

• Far vedere gli aspetti piu’ generali dellaprogettazione strutturale antincendio:

Complessita’ del problema;

Approccio sistemico;

Natura accidentale dell’azione incendio;

Progettazione prestazionale/prescrittiva;

Aspetti specifici delle gallerie stradali.


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OGGETTOCaratteristiche delle gallerie

Geometrie

Impianti

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GEOMETRIE

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Tipo A - autostradew

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Tipo B – extraurbane principaliw

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Tipo C – extraurbane secondariew

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Sistema vs Strutturaw

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OperaMorta

OperaViva

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IMPIANTI VENTILAZIONE

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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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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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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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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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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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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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Ventilation unitAir extraction

Ventilation unitSupply of fresh air

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COMPLESSITA’Approccio prestazionale

Modellazione

Sicurezza

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LOO

SE

co

up

lings

TIG

HT

LINEAR interactions NONLINEAR

System Complexity (Perrow)w

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APPROCCIO PRESTAZIONALE

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Prescrittivo (1)

APPROCCIOPRESCRITTIVO

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





OBIETTIVI PRESTAZIONALI E

LIVELLI DI SICUREZZA ESPLICITATI

APPROCCIOPRESTAZIONALE

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Req

uis

iti

Req

uis

iti

Elementi CostituentiElementi Costituenti



Req

uis

iti

Req

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prescrittivo

pre

stazi

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Req

uis

iti

Req

uis

iti


Req

uis

iti

Req

uis

iti

Elementi CostituentiElementi CostituentiElementi CostituentiElementi Costituenti



Req

uis

iti

Req

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prescrittivo

pre

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onale

Prescrittivo (2)w

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Prestazionale (1)

APPROCCIOPRESCRITTIVO

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







OBIETTIVI PRESTAZIONALI E

LIVELLI DI SICUREZZA ESPLICITATI

APPROCCIOPRESTAZIONALE

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Prestazionale (2)R

equ

isit

iR

equ

isit

i




Req

uis

iti

Req

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ti



prescrittivo

pre

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onale

Req

uis

iti

Req

uis

iti


Req

uis

iti

Req

uis

iti




Req

uis

iti

Req

uisi

ti



prescrittivo

pre

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START

END

DEFINIZIONE E DISANIMADEGLI OBIETTIVI

INDIVIDUAZIONE DELLE

SOLUZIONI ATTE A

RAGGIUNGERE GLI OBIETTIVI

ATTIVITA' DI

MODELLAZIONE E MISURA

GIUDIZIO DELLE

PRESTAZIONI

RISULTANTI

No

Yes

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MODELLINUMERICI

MODELLIFISICI

RISPETTO DIPRESCRIZIONI

livello 1

OBIETTIVI

livello 3

DEFINIZIONE DELLA

SOLUZIONE STRUTTURALE

livello 4

VERIFICA DELLE

CAPACITA'PRESTAZIONALI

LIMITI DELLAPERFORMANCE i-esima

CRITERIO (QUANTITA') CHE MISURA

LA PERFORMANCE i-esima

DEFINIZIONE DELLAPERFORMANCE 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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MODELLINUMERICI

MODELLIFISICI

RISPETTO DIPRESCRIZIONI

livello 1

OBIETTIVI

livello 3

DEFINIZIONE DELLA

SOLUZIONE STRUTTURALE

livello 4

VERIFICA DELLE

CAPACITA'PRESTAZIONALI

LIMITI DELLAPERFORMANCE i-esima

CRITERIO (QUANTITA') CHE MISURA

LA PERFORMANCE i-esima

DEFINIZIONE DELLAPERFORMANCE 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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5050

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Analysis Strategy #1: Sensitivity governance of priorities

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Analysis Strategy #2: Bounding behavior governance

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Analysis Strategy #3: Redundancy Governance

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NUMERICALMODELING

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Factors for Coupling

MECHANICALSTATE

(Strain and Stress Fields and

Mechanical related Properties)

TERMALSTATE

(Temperature Fieldand Termic Related

Properties)

INFORMATIONFLOW DIRECTION

timetK

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Fully Coupled Scheme

timetK

TERMALSTATE


Properties)

MECHANICALSTATE



timetK

TERMALSTATE


Properties)

MECHANICALSTATE



timetK

TERMALSTATE


Properties)

MECHANICALSTATE



timetK

TERMALSTATE


Properties)

MECHANICALSTATE



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Staggered Coupled Scheme

timetK

TERMALSTATE


Properties)

MECHANICALSTATE



timetK

TERMALSTATE


Properties)

MECHANICALSTATE



timetK

TERMALSTATE


Properties)

MECHANICALSTATE



timetK

TERMALSTATE


Properties)

MECHANICALSTATE



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Temperature Driven Scheme

timetK

TERMALSTATE


Properties)

MECHANICALSTATE



timetK

TERMALSTATE


Properties)

MECHANICALSTATE



timetK

TERMALSTATE


Properties)

MECHANICALSTATE



timetK

TERMALSTATE


Properties)

MECHANICALSTATE



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Scheme With No Memory

timetK

TERMALSTATE


Properties)

MECHANICALSTATE



timetK

TERMALSTATE


Properties)

MECHANICALSTATE



timetK

TERMALSTATE


Properties)

MECHANICALSTATE



timetK

TERMALSTATE


Properties)

MECHANICALSTATE



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6060

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6161

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6262

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6363

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SICUREZZA

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ATTRIBUTES

THREATS

MEANS

RELIABILITY

FAILURE

ERROR

FAULT

FAULT TOLERANT DESIGN

FAULT DETECTION

FAULT DIAGNOSIS

FAULT MANAGING

DEPENDABILITYof

STRUCTURALSYSTEMS

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 / activeperformance

Low level / passiveperformance

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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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)

66

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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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Levels of Structural Crisis

Us

ual

UL

S &

SL

SV

eri

fica

tio

nF

orm

at

Structural RobustnessAssessment

1st level:Material

Point

2nd level:ElementSection

3rd level:StructuralElement

4th level:StructuralSystem

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Bad vs Good Collapses

STRUCTURE& LOADS

CollapseMechanism

NO SWAY

“IMPLOSION”OF THE

STRUCTURE

“EXPLOSION”OF THE

STRUCTURE

is a process in which objects are destroyed by collapsing on themselves

is a processNOT CONFINED

SWAY

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Design Strategy #1: Continuityw

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Design Strategy #2: Segmentationw

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Esempio di valutazionedi roubustezza strutturale

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Esempio: edificio altow

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Analisi di un componente tipico

D0

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75D1 D2

Scenari (1-2)w

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76D3 D4

Scenari (3-4)w

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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 D4è quello più cattivo:

l’elemento strutturalecritico individuato è lacolonna più esterna!

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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)

Scenari di danneggiamentow

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Collasso secondo scenario 1w

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Moltiplicatore Ultimo e sua variazione

4,053,57

3,192,64 2,40

0,480,86

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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AZIONENatura dell’azione incendio

Carattere accidentaleCarattere estensivoCarattere intensivo

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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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91

ISO 13387: Example of Design Firew

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Andamento nel tempo potenza termicaw

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flash

ove

rSTRATEGIE

ATTIVE(approcciosistemico)

STRATEGIEPASSIVE(approcciostrutturale)

Tempo t

Te

mpera

tura

T(t

)

andamento di T(t) aseguito del successodelle strategie attive

flash

ove

rSTRATEGIE

ATTIVE(approcciosistemico)

STRATEGIEPASSIVE(approcciostrutturale)

Tempo t

Te

mpera

tura

T(t

)

andamento di T(t) aseguito del successodelle strategie attive

Strategiew

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94

95

FLASHOVER

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 ignitionsources

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

activeprotection

passiveprotection

no failures

doesn’t trigger

Y

N

Y

N

spreads

extinguishes

damages

Y

Nrobustness

no collapse

collapse

Y

N

triggers

prevention1 42 3

Fire Safety Strategies

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96

97

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97

98

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co

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98

99

SnakeFighterw

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rg

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99

100

Carattere estensivo

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100

101

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

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101

102

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102

103

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co

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rg

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103

104

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rg

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104

105

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Stro N

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105

106

Windsor Hotel Madridw

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Stro N

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106

107

Natura accidentale

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107

108

Situazioni HPLC

High Probability Low Consequences

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108

109

LPHC events

Low Probability High Consequences

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109

110

HPLCHigh Probability

Low Consequences

LPHCLow 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

Approcci di analisi

HPLCEventi Frequenti con

Conseguenze Limitate

LPHCEventi Rari con

Conseguenze Elevate

Complessità:Aspetti non lineari e

Meccanismi di interazioni

Impostazionedel problema:

DETERMINISTICA

STOCASTICA

ANALISIQUALITATIVA

DETERMINISTICA

ANALISIQUANTITATIVAPROBABILISTICA

ANALISIPRAGMATICACON SCENARI

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112

CAPITOLO 2:SICUREZZA

EPRESTAZONI

ATTESE

QUALITA’

CAPITOLO 3:AZIONI

AMBIENTALI

CAPITOLO 6:AZIONI

ANTROPICHE

CAPITOLO 4:AZIONI

ACCIDENTALI

DOMANDA

CAPITOLO 5:NORMESULLE

COSTRUZIONI

CAPITOLO 7:NORME PER LE

OPEREINTERAGENTI

CON I TERRENI ECON LE ROCCE,

PER GLIINTERVENTI NEITERRENI E PERLA SICUREZZA

DEI PENDII

CAPITOLO 9:NORMESULLE

COSTRUZIONIESISTENTI

PRODOTTO

CAPITOLO 11:MATERIALI

EPRODOTTIPER USO

STRUTTURALE

CAPITOLO 10:NORME PER LAREDAZIONI DEI

PROGETTIESECUTIVI

CAPITOLO 8:COLLAUDO

STATICO

CONTROLLO

Italian Code for ConstructionsD.M. 14 settembre 2005

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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)w

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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

Bu

chanan,

200

2

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114

115

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115

116

SVILUPPODinamica degli incendi in galleria

Effetti della ventilazione

4w

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116

117

FIRE DYNAMICS IN TUNNELS

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117

118

Tunnel Fires vs Compartment Fires (0)

118

119

Tunnel Fires Progression (1)w

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119

120

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120

121

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121

122

Tunnel Fires Progression (2)w

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123

Effects of ventilationw

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123

124

Temperature developmentw

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124

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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125

126

Backlayeringw

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126

127

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127

128

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

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128

129

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

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129

130

Maximum gas temperatures in the cross sectionof the tunnel during tests with road vehicles

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130

131

EMERGENCY VENTILATION

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131

132

Smoke stratification w

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132

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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133

134

Smoke filling long tunnel w

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134

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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135

136

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136

137

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137

138

k size factor for HGV firew

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138

139

k size factor for small pool firew

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139

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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140

141

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141

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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142

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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143

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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144

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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145

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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146

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

Strategies

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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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149

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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150

151

FIRE MODELING

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151

152

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152

153

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153

Levels

154

1Dw

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154

155

1Dw

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155

156

2D (zone model)w

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156

157

2D (zone model)w

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157

158

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158

159

FDS Simulation3D (ventilation)

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159

160

FDS Simulation3D (fire)

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160

161

3D (traffic)w

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161

162

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162

163

Multiscalew

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163

164

Multiscale (ventilation)w

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164

165

Multiscale (fire)w

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165

166

Multiscale (structural)w

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166

167

Multiscale (structural)w

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167

168

PROGETTOBasis

Failure path

Risk

5w

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168

169

BASIS

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169

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

SS0a

PRESCRIBEDDESIGN

PARAMETERS

SS0bESTIMATED

DESIGN

PARAMETERS

SS1initiation and

developmentof fire and

fire efluent

SS2movement of

fire effluent

SS3

structural response and fire spread

beyond enclosureof origin

SS4

detection,

activitation andsuppression

SS5

life safety:occupant behavior,

location andcondition

SS6

propertyloss

SS7business

interruption

SS8contamination

of

environment

SS9

destruction

ofheritage

(0)

DESIGNCONSTRAINTS

AND

POSSIBILITIES

(1+2)ACTION

DEFINITION

ANDDEVELOPMENT

(3+4)

SYSTEMPASSIVE

AND ACTIVERESPONSE

BU

S O

F I

NF

OR

MA

TIO

N

RESULTS

DESIGN

ACTION

SA

FE

TY

& P

ER

FO

RM

AN

CE

FSEw

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DESIGN

RESPONSE

172

STRUCTURAL

CONCEPTION

STRUCTURAL TOPOLOGY

&

GEOMETRY

threats

No

Yes

threats

STRUCTURALMATERIAL

& 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

alivestructural

characteristics

Yes

STRUCTURAL SYSTEM

CHARACTERISTICS

STRUCTURALSYSTEM

WEAKNESS

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173

STRUCTURAL

CONCEPTION

STRUCTURAL TOPOLOGY

&

GEOMETRY

threats

No

Yes

threats

STRUCTURALMATERIAL

& PARTS

No

Yespassive structural

characteristics

threats

No

Yes

STRUCTURAL CONCEPTION

STRUCTURAL TOPOLOGY

&

GEOMETRY

threats

No

Yes

threats

STRUCTURALMATERIAL

& 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

alivestructural

characteristics

Yes

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174

FIRE DETECTION

& SUPPRESSION

No

active structural

characteristics

threats

ORGANIZATION &

FIREFIGHTERS

No

Yes

threats

MAINTENANCE& USE

No

Yes

threats

No

alivestructural

characteristics

Yes

STRUCTURAL CONCEPTION

STRUCTURAL TOPOLOGY

&

GEOMETRY

threats

No

Yes

threats

STRUCTURALMATERIAL

& PARTS

No

Yespassive

structural

characteristics

threats

FIRE DETECTION

& SUPPRESSION

No

Yes

active

structural characteristics

threats


No

Yes

threats

MAINTENANCE

& USE

No

Yes

threats

No

alivestructural

characteristics

Yes

3/22/2011 174PROGETTAZIONE STRUTTURALE

ANTINCENDIO

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175

Fire fighting timeline w

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176

STRUCTURAL

CONCEPTION

STRUCTURAL

TOPOLOGY&

GEOMETRY

STRUCTURAL

MATERIAL& PARTS

FIRE DETECTION& SUPPRESSION


MAINTENANCE

& USE

CRISIS

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176

177IN

-DEPTH

DEFE

NCE

FAILURE PATHw

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177

178

Controlled vs. Uncontrolled Eventsw

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178

179

Controlled vs. Uncontrolled Eventsw

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180

Fire safety concepts tree (NFPA)1

2

3

4

5

6

7

8

9

Bu

chanan,

200

2

Strategie perla gestione

dell'incendio

1

Prevenzione

2

Gestionedell'evento

3

Gestionedell'incendio

4Gestione delle

persone edei beni

15

Difesa sul posto16

Spostamento17

Disposibilitàdelle vie di fuga

18

Far avvenireil deflusso

19

Controllo della quantità

di combustibile

5

Soppressione

dell'incendio

10Controllo

dell'incendio

attraverso ilprogetto

13

Automatica11

Manuale12

Controllo deimateriali

presenti

6Controllo

del movimento

dell'incendio

7Resistenza e

stabilità

strutturale

14

Contenimento9

Ventilazione8

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180

181

1

2

3

4

5

6

7

8

9

Strategie perla gestione

dell'incendio

1

Prevenzione

2

Gestionedell'evento

3

Gestionedell'incendio

4Gestione delle

persone edei beni

15

Difesa sul posto16

Spostamento17

Disposibilitàdelle vie di fuga

18

Far avvenireil deflusso

19

Controllo della quantità

di combustibile

5

Soppressione

dell'incendio

10Controllo

dell'incendio

attraverso ilprogetto

13

Automatica11

Manuale12

Controllo deimateriali

presenti

6Controllo

del movimento

dell'incendio

7Resistenza e

stabilità

strutturale

14

Contenimento9

Ventilazione8

Fire safety concepts tree (NFPA)

Bu

chanan,

200

2

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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

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184

RISK CONCERN

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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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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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Quantitative Risk Analysis

Luur,

200

2

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Risk Analysis, Assessment, Management (IEC 1995)

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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

MONITORAND

REVIEW

RISKMANAGEMENT

RISKANALYSIS

RISKASSESSMENT

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190

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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

RISKANALYSIS

FIREEVENT

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ISHIKAWA DIAGRAMw

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EVENT TREE

Triggering event

Fireignition

1. Fireextinguished 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)

Firelocation

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

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

RISKANALYSIS

NUMERICALMODELING

SIMULATIONSw

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196

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197

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198

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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

FN-curves UK Road Rail Aviation Transport, 67-01w

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

Example. Lund, 2002

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Risk acceptance – ALARP (1)

RISK MAGNITUDE

INTOLERABLEREGION

AsLowAsReasonablyPracticable

BROADLY ACCEPTABLEREGION

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

AsLowAsReasonablyAchievable

RISK MAGNITUDE

INTOLERABLEREGION

AsLowAsReasonablyPracticable

BROADLY ACCEPTABLEREGION

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

AsLowAsReasonablyAchievable

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203

Risk acceptance – ALARP (2)w

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Risk reduction by designw

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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

RESISTENZA

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The burnt out interior of the Mont Blanc Tunnel

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Curve temperatura - tempo

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Types of fire exposure for tunnel analysis

0

200

400

600

800

1000

1200

1400

0 30 60 90 120 150 180

Tem

per

atu

re (

°C)

Time (min.)

Cellulosic Hydrocarbon Hydrocarbon modified

RABT-ZTV train RABT-ZTV car RWS

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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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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, chemicalsetc, 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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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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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)

0 155 120060 1200

170 15RABT-ZTV (car)

Time (minutes) T (°C)

0 155 120030 1200

140 15

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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) 0 203 8905 1140

10 120030 130060 135090 1300120 1200180 1200

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Lönnermark, A. and Ingason, H., “Large Scale Fire Tests in the Runehamartunnel – gas temperature and Radiation”,

Proceedings of the International Seminar on Catastrophic Tunnel Fires, Borås, Sweden, 20-21 November 2003.

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Fire Scenario Recommendationw

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Verifiche

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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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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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Verification of fire resistance (R-safe)


T = temperature

t = time

Rfi,d,t

Efi,requ,t

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Verification of fire resistance (R-fail)


T = temperature

t = time

Efi,requ,t

Rfi,d,t

Failure !ww

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Verification of fire resistance (t)


T = temperature

t = time

Efi,requ,t Rfi,d,t

Failure !

tfi,d ≥ tfi,requ

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Verification of fire resistance (T)


T = temperature

t = time

Efi,requ,t

Rfi,d,t

Failure !

Td ≤ Tcr

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Verification of fire resistance (T)


T = temperature

t = time

Efi,requ,t

Rfi,d,t

Failure !

Td ≤ Tcr

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Comportamenti termo-meccanici

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Trasformazione del calcestruzzo alle alte temperature

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Parametri per la relazione tensioni-deformazioni

per il calcestruzzo ad elevate temperature.

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Calcestruzzo ad aggregato siliceo in condizioni di compressione uniassiale ad elevate temperature

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Variazione del coefficiente di riduzione della resistenza a compressione del calcestruzzo ad

aggregato siliceo con la temperatura

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Relazioni tensioni-deformazioni per acciai da calcestruzzo armato ordinario

laminati a caldo ad elevate temperature

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Parametri per la relazione tensioni-deformazioni per acciai da calcestruzzo armato ordinario

laminati a caldo, a temperature elevate

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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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• 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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CONCLUSIONIConceptual design

Resilience

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Conceptual Designw

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Conceptual Design

MULTI-HAZARD

BLACK-SWAN

DISASTER CHAIN

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Flow chart

Tabella dotazioni Frejùs

Forensic Engineeringw

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Resiliencew

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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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RESILIENCE


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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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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) - [email protected]

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Convegno sulla Resistenza al Fuoco, Cosenza 6 Febbraio 2014, Bontempi

Design

Transcript of Convegno sulla Resistenza al Fuoco, Cosenza 6 Febbraio 2014, Bontempi