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

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Presentation on theme: "FIRE SAFETY WITH CONCRETE - Experiences from real fires and full scale tests Tauno Hietanen standardization manager Finnish Concrete Industry Association."— Presentation transcript:

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

2 Rakennusteollisuus RT ry 2 Tauno Hietanen 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

3 Rakennusteollisuus RT ry 3 Tauno Hietanen Essential requirements - Safety in case of fire 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. Comprehensive fire protection Protection of people Protection of property Protection of environment Inside defined area Outside defined area

4 Rakennusteollisuus RT ry 4 Tauno Hietanen 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

5 Rakennusteollisuus RT ry 5 Tauno Hietanen 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 Concrete/Brick Timber Construction Standard Temperature Curve Duration of fire t [min] Temperature T [°C]

6 Rakennusteollisuus RT ry 6 Tauno Hietanen Case: Timber construction site Colindale London 2006 Several 6 storey timber framed blocks were destroyed in fire Fire was discovered in block A2 of building complex A and Fire Service was alerted The whole of building complex A is on fire Fire Brigade arrives

7 Rakennusteollisuus RT ry 7 Tauno Hietanen Fire was discovered Fire Brigade arrives Building complex A (blocks A1, A2 and A3) begins to collapse 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

8 Rakennusteollisuus RT ry 8 Tauno Hietanen The whole of block B1 is on fire, with flames visible on the roof of block B Fire spreads from the roof of block B2 to the lower storeys % of block B2 is on fire The London Fire Brigade brings the fire under control The fire is extinguished

9 Rakennusteollisuus RT ry 9 Tauno Hietanen 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 Fire parts of Eurocodes - Tabulated data - Simplified calculation - Advanced calculation EN Classification standard EN 1363, EN 1365 Fire tests CE marking based on harmonized product standard REI

10 Rakennusteollisuus RT ry 10 Tauno Hietanen 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

11 Rakennusteollisuus RT ry 11 Tauno Hietanen Effects of thermal deformations

12 Rakennusteollisuus RT ry 12 Tauno Hietanen The effects of thermal deformations need normally not be considered

13 Rakennusteollisuus RT ry 13 Tauno Hietanen 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

14 Rakennusteollisuus RT ry 14 Tauno Hietanen 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

15 Rakennusteollisuus RT ry 15 Tauno Hietanen Influence of restraint 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 Welded joint Friction bearing

16 Rakennusteollisuus RT ry 16 Tauno Hietanen 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

17 Rakennusteollisuus RT ry 17 Tauno Hietanen Opening between floors, 52 m long Staircase and stabilizing walls Ignition and fire spread Joint 30 mm

18 Rakennusteollisuus RT ry 18 Tauno Hietanen Collapsed part Slab exposed to fire on both sides – large thermal expansion

19 Rakennusteollisuus RT ry 19 Tauno Hietanen Cast in situ flat slab 250 mm with columns Ø 350 mm

20 Rakennusteollisuus RT ry 20 Tauno Hietanen 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

21 Rakennusteollisuus RT ry 21 Tauno Hietanen Fire in Windsor Tower in Madrid Concrete structures performed extraordinary well in severe fire

22 Rakennusteollisuus RT ry 22 Tauno Hietanen 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

23 Rakennusteollisuus RT ry 23 Tauno Hietanen 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

24 Rakennusteollisuus RT ry 24 Tauno Hietanen storeys 4 to 16 storeys 17 to 27 concrete columns instead of walls steel columns technical storey storey high beams through the building

25 Rakennusteollisuus RT ry 25 Tauno Hietanen 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

26 Rakennusteollisuus RT ry 26 Tauno Hietanen

27 Rakennusteollisuus RT ry 27 Tauno Hietanen

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

29 Rakennusteollisuus RT ry 29 Tauno Hietanen

30 Rakennusteollisuus RT ry 30 Tauno Hietanen 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

31 Rakennusteollisuus RT ry 31 Tauno Hietanen Costs of fire damages

32 Rakennusteollisuus RT ry 32 Tauno Hietanen ”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

33 Rakennusteollisuus RT ry 33 Tauno Hietanen 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).

34 Rakennusteollisuus RT ry 34 Tauno Hietanen 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: €

35 Rakennusteollisuus RT ry 35 Tauno Hietanen 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

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

37 Rakennusteollisuus RT ry 37 Tauno Hietanen Concrete offers built-in fire resistance Thank you for your attention

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