Download pdf - 4. Morten Valkvist

12-6-2009 1

Morten ValkvistCompetence Director, Niras Safety, Denmark

Safety

I:\inf\pr-toolbox\over heads\Firmapres entation_nov2005.ppt 2

• Basic intention in PB design verification:

• Verify society’s risk acceptance levels

• Danish approach

• Equal design

• Meet deterministic acceptance criteria

− E.g. objects discernible within 10 m etc.

− Sensitivity studies (failure)

• Risk accep. levels are important in PB design

Performance-Based Designs - Verification

Risk

Bldg.classAssembly

Acceptance Risk Level?

Compare

Safety


Performance-Based Designs - Documentation

Mathematical Model

Knowledgeable

User

Methodology of Use

• Fire design triangle [Beard, A., (Heriot Watt Uni.(UK)]:

• Requirements to PBFC system:

• Control over the risk levels induced by the

three factors

Safety


Mathematical Model

• Fire modelling in PB design

• A priori modelling

• Leads to unclear risk levels

• PBFC system must control math. assumptions

45 kg/s

75 kg/s

60 kg/s - 4. diff. math. models

- Identical design fire

Safety


Knowledgeable User

• Round-robin study of fire modelling

• Dalmarnock Fire Tests [Uni. of Edinb. et al.]

• A priori modelling (8xFDS+2xCFAST)

• Common test description and initial HRR

• HRR of initial fire was provided

• Pre-flashover well-ventilated round-robin studies

[Rein et al. (2009), Fire Safety Journal 44, pp. 590-602]

+500%Texp

-30%Texp

Safety


• Design fire uncertainty – e.g. car fire

• DK: Same building owner may be met with different design fires

• Premovement time

• Fixed: ~30 s => ~300 s

• Distribution of :

Methodology of Use

rddetprettt +=

rdt

[Okamoto et al. (2009), Fire Safety Journal 44, pp. 301-310]

Npers/Ntotal

trdOffice

1.0

Shopping

[EN 12101-5]:

=4,000 kW

Q&

fQ&

DK

: G

reat

variation

with

in g

roup

of

FS

Es a

nd

with

in g

rou

p o

f A

HJs

Safety


Methodology of Use

Vena

contracta

No VC

0 0.5 1 1.5 2 2.50

0.5

1

1.5

2

2.5

3

Froude no. [1]

dm

’’/dt [k

g/(

s*m

2)]

Horizontal vent

Full vent, A

g=1.0 d

h=1.0 AR

v=1.0

Full vent, Ag=1.2 d

h=1.1 AR

v=0.8

Full vent, Ag=1.4 d

h=1.2 AR

v=0.7

Full vent, Ag=1.6 d

h=1.2 AR

v=0.6

Full vent, Ag=1.8 d

h=1.3 AR

v=0.6

Full vent, Ag=2.0 d

h=1.3 AR

v=0.5

Full vent, Ag=2.8 d

h=1.5 AR

v=0.4

Full vent, Ag=4.0 d

h=2.0 AR

v=1.0

Full vent, Ag=5.6 d

h=2.3 AR

v=1.4

Full vent, Ag=3.9 d

h=1.9 AR

v=0.5

Passive vent, Ag=1.0 d

h=1.0 AR

v=1.0

Passive vent,Ag=1.2 d

h=1.1 AR

v=0.8


h=1.2 AR

v=0.7


h=1.2 AR

v=0.6


h=1.3 AR

v=0.6


h=1.3 AR

v=0.5


h=1.5 AR

v=0.4


h=2.0 AR

v=1.0


h=2.3 AR

v=1.4


h=1.9 AR

v=0.5

Vena

contracta

No VC

avg

hvv

avv

fdsvfdsg

hvg

fdsg

fdsv

AC

CCA

A

AC

,

,

,

,,

,

,

,

=

=

• Buoyancy-driven vent modelling

Safety


• Fire safety factors

• is adressing uncertainties

– The more freedom => the more

• What should control

− Risk based approach reflecting societal risk

levels within each bldg. class

– : Uncertainties in input parameters

and assumptions

– Reflected in sensitivity study

– Guideline on sensitivity study

– : Mathematical model assumptions and numerical precision

– Can be model dependent

Proposed Control Measures

( )γf

( ) 0; ≥−= FSLRSETfASETFSL γ

( )γf

iγ

inγ

outγ

Safety


• Fire safety factors

• IMPLICATIONS for model uncertainty:

− Risk based approach

− Clear height [EN 12101-5] compared to 2

m height of person:

– Public: 3 m =>

– Non-public: 2.5 m =>

– Not coupled to a certain model

• Intentions behind PBFC should still be met

− Fire protection costs should be reduced

• The good FSE should not be punished

− Verify proposed fire safety design

− Example: Evac. modelling of spiral stairs


%25:γ%50:γ

Safety


• Capacity of spiral stairs

• AROS Museum of Modern Art, Aarhus (DK)

• Hand rail in 1/3 point to improve capacity

Full-Scale Testing and Verification

[Olafur Eliasson]

ImprovedExisting

Handrail

Safety


Full-Scale Testing and Verification

Staircase Flow

[pers/10 s]

No handrail 16

Handrail 24

ImprovedExisting

• Full-scale test

• 3 rep. tests with 200 pers. in each staircase

• Findings

Lane Outer Centre Inner

Speed

[m/s]

1.3 0.8 0.6

Up

50%

Compares to 0.7 m/s

Safety



• Knowledgeable user/Methodology

• Fire strategies and documentation

− Know your audience (AHJ, eng., arch.)

− Assumptions must be clearly stated

− Increased requirements to AHJ training

• Engineering guidelines should be applied

− Ensures conformity in PB design

− DK: Task force on CFD guideline

• Fire safety engineers must be certified

− National standards of minimum competence

− Education alone does not cut it

− Sanctions can be imposed

Safety


Approval and Peer-Review

• The approval process must:

• Enforce societal risk control

− Approved by building AND fire authorities

– Design parameters (e.g. design fire)

− Requires trained and experienced AHJ’s and third party peer-reviewers

– Certified FSE reviewers in knowledge

centres

– DK: Big difference in training

• Prevent the ”Boiling Frog Syndrome” [Senge, P. M., 1993]

− GLOBAL: Bldgs. with unkown risk level

Safety


End of Presentation

THANK YOU!

[NRCC/MTQ: Full-scale fire test, Ville-Marie Tunnel, Montreal (CA)]

Safety


Commissioning, Operation and Management

• Commissioning:

• Complete test of the fire safety design

− Capacity of sprinklers and SHEVS

− Verify fire protection system operation

matrix (FP-SOM)

− Test report should accompany design

documentation

− DK: FSE contract typically terminates at this point

Safety


Commissioning, Operation and Management

• Operation:

• Design compliance should be ensured

throughout the building lifetime

− System mean life time, L:

− Regular verification of FP-SOM by testing

∑=

=n

i

i

L

1

1

λ

[Klote (2002)] - Other: 1E-5/hr

[Klote (2002)] - Fan: 1E-6/hr

L=23 months L=9 months