1.
FIRE SAFETY WITH CONCRETE - Experiences from real fires and full scale tests Tauno Hietanen standardization manager Finnish Concrete Industry Association

2. 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

3. 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
Tauno Hietanen

4. Best European Reaction to fire class A1
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
Tauno Hietanen

5. Effects of fire load on the fire scenario
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
Standard Temperature Curve
Temperature T [°C]
Concrete/Brick
Timber Construction
Duration of fire t [min]
Tauno Hietanen

6. 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
Tauno Hietanen

7. 15.48 Building complex A (blocks A1, A2 and A3) begins to collapse.
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
Block B partly finished
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8. 17.31 Fire spreads from the roof of block B2 to the lower storeys
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
% of block B2 is on fire
17.34 The London Fire Brigade brings the fire under control.
21.30 The fire is extinguished
Tauno Hietanen

9.
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 Classification standard
EN 1363, EN 1365
Fire tests
Tauno Hietanen

10. Parametric fire curves Fire safety Engineering FSE
Parametric fire curves Fire safety Engineering FSE
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,…)
Standard fire
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11. Effects of thermal deformations
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12. The effects of thermal deformations need normally not be considered
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13. Thermal expansion and deflection of a simply supported hollow core slab in fire test
loaded
unloaded
Deflection
loaded
unloaded
Note: only a small part of the deflection is caused by external load, most of it is thermal curvature
Tauno Hietanen

14. 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
Tauno Hietanen

15. 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
Tauno Hietanen

16. 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
Tauno Hietanen

17. Ignition and fire spread
Joint 30 mm
Opening between floors, 52 m long
Staircase and stabilizing walls
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18. Slab exposed to fire on both sides – large thermal expansion
Collapsed part
Slab exposed to fire on both sides – large thermal expansion
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19. Cast in situ flat slab 250 mm with columns Ø 350 mm
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20. 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
Tauno Hietanen

21. Fire in Windsor Tower in Madrid 2005.
Concrete structures performed extraordinary well in severe fire
Tauno Hietanen

22. Madrid Windsor Tower fire in February 2005
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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23. Technical floors above 3rd and 16th floors
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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24. storey high beams through the building
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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25. 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
Tauno Hietanen

26. Tauno Hietanen

27.
Kuvassa näkyy kuppiholvi ja betonipilarit, julkisivun teräspilarien jo romahdettua.
Tauno Hietanen

28. The fire spread downwards and reached 5th storey at 7:00
The fire was considered to be under control at 15:00
Tauno Hietanen

29.
Rakennus palon jo sammuttua. Sortuminen olisi vaarantanut ympäristön ja ilmeisesti sytyttänyt muita rakennuksia. Rakennus purettiin.
Tauno Hietanen

30. It was decided to demolish the building
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
Tauno Hietanen

31. Costs of fire damages
Tauno Hietanen

32. ”Fire in multi family houses” “Brand i flerbodstadshus”
”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
Tauno Hietanen

33.
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 € excl house content.
90% of fires in the fire statistics analysed for the period 1995 to 2004, hence is representative. (Totals 125 fires).
Tauno Hietanen

34. 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: €
Cement based houses: €
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35. 9% of the cement constructed houses and
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
Tauno Hietanen

36. CONCRETE STEEL TIMBER Does not burn or increase fire load
Prevents spread of fire and smoke
Loadbearing
Separating
CONCRETE
STEEL
TIMBER
Tauno Hietanen

37. Concrete offers built-in fire resistance Thank you for your attention
Tauno Hietanen