travelling fires for structural design
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Across Disciplines
Fire Structures
Fire &Structures
The interface between fire and structures is theintersection of the two sets
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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.
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Structures
Fire &Structures
Lame Substitution of the 2nd kind
When fire engineers are entirely replaced by pseudo-science.It is mainstream.
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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.
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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.
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Scale matters
Here beFire Tests
Over there be
Real BuildingsBlind
extrapolation
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Blind extrapolation
from limited experienceFire in Furnace
Fire in Normal
compartment
Fire in Large compartment
Fire in Multi-
storey building
Blind
extrapolation
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Limitations
For example, limitations according Eurocode:
Floor areas < 500 m2
Near rectangular enclosures
Heights < 4 m
No ceilings openings
Moderate thermal-inertia of lining
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WTC Transit Hub
< 500 m2 floor?
< 4 m high?
Excel, London
Rectangular?
N ili i ?I l ti li i ?
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No ceiling opening?
© Arup/Peter Cook/VIEW
©
© Renzo Piano
Insulating lining?
Arup CampusThe Shard
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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.
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“The Titanic complied with all codes.
Lawyers can make any device legal, only
engineers can make them safe"
Prof VM Brannigan
University of Maryland
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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)
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*
IGNITION SPREAD TRAVEL
Fire spread – large floor
area of the fire increasing with time
A
Amax Amax
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TRAVELLING FIRES METHODOLOGY
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Travelling fires (TF)
- 2.5%, 10%, 25%, and 48%
Eurocode (EC) parametriccurves- short-hot (SH) and long-cool (LC)
FIRE SCEARIOS
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Heat Transfer, Tg-> Ts
STEEL
CONCRETE
TFM
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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
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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
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LOCATION OF PEAK TEMPERATURE
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COMPARISON TO TRADITIONAL METHODS(steel + 60 min fire protection)
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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
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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