Transcript Ei dian otsikkoa - Associazione aicap

FIRE SAFETY WITH CONCRETE
- Experiences from real fires and full scale tests
Tauno Hietanen
standardization manager
Finnish Concrete Industry Association
Contents of the presentation
- examples and cases on:
• Comprehensive fire protection with concrete
– Case: Colindale London
• Effects of thermal deformations
– Case: Library fire in Sweden
• Case: Windsor Tower fire in Madrid
• Fire damage costs
Tauno Hietanen
Rakennusteollisuus RT ry
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Essential requirements
- Safety in case of fire
Comprehensive
fire protection
Construction Product Directive:
– the load bearing capacity of the
construction can be assumed for
a specific period of time;
– the generation and spread of
fire and smoke within the works
are limited;
– the spread of the fire to
neighbouring construction
works is limited;
– occupants can leave the works
or be rescued by other means;
– the safety of rescue team is
taken into consideration.
Protection of
people
Protection of
property
Protection of
environment
Inside defined area
Outside defined
area
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Rakennusteollisuus RT ry
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Concrete does not burn
• Best European Reaction to fire class A1
•
•
•
•
does not ignite
does not spread fire or smoke
does not increase fire load
does not generate toxic gases
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Rakennusteollisuus RT ry
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Temperature development in buildings
Univ. Prof. Dr. techn. Dr. h.c. Ulrich Schneider
Vienna University of Technology
Effects of fire load on the fire scenario
Temperature T [°C]
Standard Temperature Curve
Concrete/Brick
Timber Construction
Duration of fire t [min]
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Rakennusteollisuus RT ry
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Case: Timber construction site Colindale London 2006
Several 6 storey timber
framed blocks were
destroyed in fire
•15.39 Fire was discovered in
block A2 of building complex A
and Fire Service was alerted
•15.42 The whole of building
complex A is on fire
•15.44 Fire Brigade arrives
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Rakennusteollisuus RT ry
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•
•
•
•
15.39 Fire was discovered
15.44 Fire Brigade arrives
15.48 Building complex A (blocks A1, A2 and A3) begins to collapse.
16.26 Fire spreads to the upper floors of block B1 of building complex B
Block A under construction where the fire starts
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Rakennusteollisuus RT ry
Block B partly finished
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•17.10 The whole of block B1 is on fire, with flames visible on the roof
of block B2
•17.31 Fire spreads from the roof of block B2 to the lower storeys
•17.58 80% of block B2 is on fire
•17.34 The London Fire Brigade brings the fire under control.
•21.30 The fire is extinguished
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Rakennusteollisuus RT ry
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European resistance to fire classification
REI is based on standard fire
National fire regulations
(required class or fire resistance time)
Parametric fire
Fire resistance
time
Nominal fire
European REI
classification
CE marking based
on harmonized
product standard
REI
Fire parts of Eurocodes
- Tabulated data
- Simplified calculation
- Advanced calculation
EN 13501-2
Classification standard
EN 1363, EN 1365
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Rakennusteollisuus RT ry
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Fire tests
Parametric fire curves
Fire safety Engineering FSE
Standard fire
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Rakennusteollisuus RT ry
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• Gas temperatures as function
of fire load, oxygen supply
(openings), surface materials
etc.
• Active fire protection methods
may also be taken into
account (fire brigade,
sprinklers,…)
• Fire safety level is not the
same as by using standard
fire curve
• Later alterations are limited
(use of the building, openings,
surface materials,…)
Effects of thermal deformations
Tauno Hietanen
Rakennusteollisuus RT ry
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The effects of thermal deformations need normally
not be considered
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Rakennusteollisuus RT ry
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Thermal expansion and deflection of a simply
supported hollow core slab in fire test
Expansion
loaded
unloaded
Deflection
loaded
unloaded
Note: only a small part of the
deflection is caused by external
load, most of it is thermal curvature
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Rakennusteollisuus RT ry
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Thermal expansion and rotation of a simply
supported hollow core slab in fire test
Note: Expansion at mid height and bottom of the slab
-restrained expansion creates additional ”prestressing” force
- no risk that the slab would fall down from the supports due to
curvature
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Rakennusteollisuus RT ry
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Influence of restraint
Welded joint
Friction bearing
•The connections should be
detailed in such a way that restraint
force gives ”prestressing” in the
lower part of the beam increasing
fire resistance
•Restraint in the upper part is
negative for fire resistance
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Rakennusteollisuus RT ry
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Library collapse in Linköping in Sweden 1996
concrete structure designed for 60 minutes collapsed 47 minutes
after fire alarm and 30 minutes after flash-over in heavy fire
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Rakennusteollisuus RT ry
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Ignition and fire spread
Joint 30 mm
Opening between floors, 52 m long
Staircase and stabilizing walls
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Rakennusteollisuus RT ry
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Collapsed part
Slab exposed to fire on both
sides – large thermal expansion
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Rakennusteollisuus RT ry
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Cast in situ flat slab 250 mm with columns Ø 350 mm
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Rakennusteollisuus RT ry
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This collapse was result of several reasons:
•The slab was exposed to fire on both sides – higher temperature
and only small thermal deflection
•Too few expansion joints – 54 m long slab
•Too few stabilizing walls
•High fire load: library, wooden suspended ceiling
•Sensitive structural systems
Reference (in Swedish ):
Yngve Anderberg, K.G. Bernander,
Biblioteksbranden I Linköping den 21
september 1996, Studium av orsaken till
tidig ras
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Rakennusteollisuus RT ry
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Fire in Windsor Tower in Madrid 2005.
Concrete structures performed extraordinary well in
severe fire
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Rakennusteollisuus RT ry
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Madrid Windsor Tower fire in February 2005
• fire started on 21st storey
of 29-storey office building
in Madrid’s financial
district
• the building was being
refurbished, including
fireproofing steel perimeter
columns and new external
escape stairs
• 22 office floors were in use
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Rakennusteollisuus RT ry
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STRUCTURAL SYSTEM
• Technical floors above 3rd
and 16th floors
• normal strength concrete
central core, columns and
waffle slab floors
• steel perimeter columns
• when fire broke out steel
columns above technical
storey 2 had not yet been
fireproofed
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Rakennusteollisuus RT ry
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storeys 4 to 16
storeys 17 to 27
concrete columns instead of walls
steel columns
technical storey
storey high beams through the building
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Rakennusteollisuus RT ry
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•23:05 Fire alarm on 21st storey
(other sources say at 23:16)
•23:25 Fire brigade arrives
•23:35 21st storey was
completely in flames
•0:20 Fire had reached storey 28
•1:00 Large portions of the
façade began to fall off
•1:15 Northeast corner of the
building above technical floor
collapsed
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Rakennusteollisuus RT ry
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Rakennusteollisuus RT ry
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Rakennusteollisuus RT ry
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•The fire spread downwards
and reached 5th storey at
7:00
•The fire was considered to
be under control at 15:00
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Rakennusteollisuus RT ry
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Rakennusteollisuus RT ry
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The spread of the fire to
neighbouring construction
works was avoided because
the concrete frame resisted
the whole fire without
collapse.
It was decided to demolish
the building
Technical investigation was made
and published by INTEMAC, NIT 2
– 05, in Spanish and English
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Rakennusteollisuus RT ry
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Costs of fire damages
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Rakennusteollisuus RT ry
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”Fire in multi family houses”
“Brand i flerbodstadshus”
A Report on the cost of fire
damages in relation to the
building material of which the
houses are constructed.
Author Olle Lundberg
Sweden
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Rakennusteollisuus RT ry
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Regardless of the building material fires will occur, but the building
material is heavily influencing the severity of the fire!
– Statistics from Insurance
Association in Sweden
who's members are
covering/paying 90% of the
fires in Sweden.
– Limited to Big Fires where
the total insurance coverage
is more than € 150 000 excl
house content.
– 90% of fires in the fire
statistics analysed for the
period 1995 to 2004, hence
is representative. (Totals 125
fires).
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Rakennusteollisuus RT ry
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Wooden multi family houses in Sweden
•
Represent 10% of the number
of multi family houses, but
56% of the Big Fires!
•
Average cost per fire and per
apartment in wooden houses
is 5 times that of cement
based houses.
•
Cost
– Wooden houses:
€ 50 000
– Cement based houses:
€ 10 000
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Rakennusteollisuus RT ry
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• The likelihood of developing a
fire to a Big Fire is 11,5 times
as high in wooden houses
than in cement based houses
• Of the burned houses :
– 9% of the cement
constructed houses and
– 50% of the wooden
constructed houses have
to be demolished
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Rakennusteollisuus RT ry
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Does not
burn or
increase
fire load
Prevents
spread of
fire and
smoke
Loadbearing
Separating
CONCRETE
STEEL
TIMBER
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Rakennusteollisuus RT ry
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Concrete offers built-in fire resistance
Thank you for your attention
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Rakennusteollisuus RT ry
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