12.4.2017 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

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

Best European Reaction to fire class A1 12.4.2017 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

Effects of fire load on the fire scenario 12.4.2017 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

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

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 Tauno Hietanen

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 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 Tauno Hietanen

12.4.2017 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 Fire tests Tauno Hietanen

Parametric fire curves Fire safety Engineering FSE 12.4.2017 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 Tauno Hietanen

Effects of thermal deformations Tauno Hietanen

The effects of thermal deformations need normally not be considered Tauno Hietanen

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

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

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

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

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

Slab exposed to fire on both sides – large thermal expansion Collapsed part Slab exposed to fire on both sides – large thermal expansion Tauno Hietanen

Cast in situ flat slab 250 mm with columns Ø 350 mm 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 Tauno Hietanen

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

Madrid Windsor Tower fire in February 2005 12.4.2017 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 Tauno Hietanen

Technical floors above 3rd and 16th floors 12.4.2017 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 Tauno Hietanen

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 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 Tauno Hietanen

Tauno Hietanen

12.4.2017 Kuvassa näkyy kuppiholvi ja betonipilarit, julkisivun teräspilarien jo romahdettua. Tauno Hietanen

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

12.4.2017 Rakennus palon jo sammuttua. Sortuminen olisi vaarantanut ympäristön ja ilmeisesti sytyttänyt muita rakennuksia. Rakennus purettiin. Tauno Hietanen

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

Costs of fire damages Tauno Hietanen

”Fire in multi family houses” “Brand i flerbodstadshus” 12.4.2017 ”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

12.4.2017 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). 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: € 50 000 Cement based houses: € 10 000 Tauno Hietanen

9% of the cement constructed houses and 12.4.2017 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

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

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