Travelling Fires for Structural Design

8/16/2019 Travelling Fires for Structural Design

1/25


2/25


3/25

Across Disciplines

Fire Structures

Fire &Structures

The interface between fire and structures is theintersection of the two sets


4/25

Fire

Fire &Structures

Failure of structure

at T = XºC

Lame Substitution of the 1st kind

When structural engineers are entirelyreplaced by pseudo-science.

It still survives in many standards.


5/25

Structures

Fire &Structures

Lame Substitution of the 2nd kind

When fire engineers are entirely replaced by pseudo-science.It is mainstream.


6/25

Fire &Structures

Failure of

structures at

T=XºC

Lame Substitution of the 3rd kind

When both fire and structural engineers are simultaneously

replaced by pseudo-science. Any similarity with reality is a mere coincidence.


7/25

Ancient Traditional Design Fires

Standard Fire, 1880

(on paper since 1912)

Swedish Curves, 1972

Eurocode Parametric

Curves, 1995

Imposed assumption:Uniform burning and uniform

temperature, just like inside a

furnace.


8/25

Scale matters

Here beFire Tests

Over there be

Real BuildingsBlind

extrapolation


9/25

Blind extrapolation

from limited experienceFire in Furnace

Fire in Normal

compartment

Fire in Large compartment

Fire in Multi-

storey building

Blind

extrapolation


10/25

Limitations

For example, limitations according Eurocode:

Floor areas < 500 m2

Near rectangular enclosures

Heights < 4 m

No ceilings openings

Moderate thermal-inertia of lining


11/25

WTC Transit Hub

< 500 m2 floor?

< 4 m high?

Excel, London

Rectangular?

N ili i ?I l ti li i ?


12/25

No ceiling opening?

© Arup/Peter Cook/VIEW

©

© Renzo Piano

Insulating lining?

Arup CampusThe Shard


13/25

Love the Architects: design is out of bounds

Jonsdottir et al, Out of range, Fire Risk Management 2009

• Buildings from 1850-1990: 66% of volume within limitations

• Buildings from 2000: 8% of volume within limitations (figure)

Modern architecture increasingly produces buildingswhose fire behaviour falls outside our field of knowledge

We surveyed 3,000compartments, most of

the campus, in King’s

Buildings at the

University of Edinburgh.


14/25

“The Titanic complied with all codes.

Lawyers can make any device legal, only

engineers can make them safe"

Prof VM Brannigan

University of Maryland


15/25

WHY?

Fires have been

observed to travel acrossa floor plate burning

over a limited area

Non-uniform

temperature

distributions

Long fire durations (up

to 20 h – Meridian Plaza)

World Trade Centre, New York (2001)

Windsor Tower, Madrid (2005)

Faculty of Architecture, TU Delft (2008)

Interstate Bank, Los Angeles (1988)

One Meridian Plaza, Philadelphia (1991)


16/25

*

IGNITION SPREAD TRAVEL

Fire spread – large floor

area of the fire increasing with time

A

Amax Amax


17/25

TRAVELLING FIRES METHODOLOGY


18/25

Travelling fires (TF)

- 2.5%, 10%, 25%, and 48%

Eurocode (EC) parametriccurves- short-hot (SH) and long-cool (LC)

FIRE SCEARIOS


19/25

Heat Transfer, Tg-> Ts

STEEL

CONCRETE

TFM


20/25

Structural Results – Rebar Temperature

0

100

200

300

400

500

0.1 1 10 100

R e b a r T e m p e r a t u r e ( ° C )

Time (h)

2.5%

5%

10%

25%

50%

100%

Law et al, Engineering Structures 2011


21/25

Family of fires – not just one fire cast in stone

range of sizes range of spread rates

R e b a r T e m p e r a t u r e


22/25

LOCATION OF PEAK TEMPERATURE


23/25

COMPARISON TO TRADITIONAL METHODS(steel + 60 min fire protection)


24/25

Conclusions In large compartments, post-flashover

fire cannot occur, but a travelling fire

would develop.

1. TFM is a novel framework

complementing traditional methods

2. TFM can produce more onerous

conditions for the structure.

3. TFM triggers previously unnoticed

structural mechanisms.

4. Among the fastest knowledge-

transfer case from research to industry

in FSE.

ARUP

S


25/25

4 Pancras Square Battersea

One New Ludgate

The ScalpelTwo New Ludgate

S2 King’s CrossNova Victoria

View 58

Kings House

Barlett, UCL

39 iconic

buildings

in UK

Sponsors:

CERIB

Documents

Travelling Fires for Structural Design