The Certified Fire wall Why the Firestop wall? • Insulate and keep a fire in ONLY ONE cell of a building • Avoid the structure and the front fall towards the outside – Secure intervention of firefighters & emergency services – Optimize rescues • Meet the new insurance companies requirements – 4h certified ! Presentation Plan • Section I: Firewall Firebreak 4h general presentation • Section II: Firewall Firebreak 4h detailed presentation • Section III: Firewall Firebreak 4h CSTB Certification Test • Section IV: Firebreak system promotion & development • Section V: Extra part on Fire regulation Section I Firewall Firebreak General Presentation Firebreak 4h: Description • Standard panels : – Length: 2,50 m – Height: 1,25 m – Thickness: 170 mm • Smaller panels available (for adaptation to the wall dimensions) • ALUZINC coating • Less than 100 kg/m2 • Steel structure on each side Internal Composition • Symmetrically, successive coats of : – Cellular glass (Foamglas) – Plaster (Prégyfeu) – Core in Fibro-silicate – + bonding (special glue) Steel sheet in ALUZINC Foamglas Plaster Fibro-silicate Plaster Foamglas Steel sheet in ALUZINC 17 cm Main Advantages • Light construction with a good stability • Flexible (easy to dismantle, well adapted for the renovation) • No foundations needed (pressure on the ground surface around 1kg/cm2 a height of 15 meters) => construction simplified, removable and reusable • Delivery in standard panels ready for use • Easy erection by a steel fabricator • 4h ISO-fire resistance attested by the approved French laboratory of the CSTB, for a height of 15m with unlimited width Main Advantages • The only one fire wall system in the market (4h, 15m) certified • Collapse towards the side of the fire, therefore no risk for firefighting and rescue teams • Good thermal insulation : Maximum temperature of 120 degrees on the outer face • Good acoustic insulation => Rw (C t r) = 43 (-1, -3) dB • Aluzinc Benefits : aesthetics (naturally silver), excellent resistance to corrosion, officially approved for food storage application (according to the standard NFA 36-712-6 April 2006) : No specific treatment or additional surface is to be added Sustainable Advantages • Free of fibers : Inside the wall, mineral, insulating and non combustible materials (M0) • Guaranteed corrosion protection against perforation • Dry system (doesn’t require water during construction phase) • Doesn’t emit toxic substances (gases and fumes) during normal conditions and in case of fire • Recyclable and environmentally inert materials Sustainable Advantages • Safe working conditions during erection (light elements) • Fast, easy and cheap installation process • Allows less disruptive refurbishment for existing buildings • Possibility of re-use and relocate the wall • Storage on pallets, less space needed, less trucks, less fuel consumption Scope of applications Industry Refurbishment / Rehabilitation Combustible Materials Warehouses Warehousing companies Food storage Refrigerating industry Other possible applications : Theatres / Concert halls Maritime/Naval applications Section II Firewall Firebreak Detailed Presentation Mechanism • The wall is supported by a steel structure on each side • The structure doesn’t bear the wall … but the FRAME ! • Fuse fixations : bimetallic strip joined with tin => when the tin casts, the steel structure comes off and sags on the fire. Steps of fire expansion in a warehouse cell • Start of fire in a cell • Vertical fire expansion Steps of fire expansion in a warehouse cell • Accumulation of warm gas under the roof • Deformation of the frame • Fusible connections ensure that the link between wall and heated structure disappears Steps of fire expansion in a warehouse cell • The fire is spreading in the burn-out cell. • The structure collapses on the fire. • Fully developed fire and failure of the heated structure. The wall supported by the structure on cold side ensures 4 hours of fire resistance. Steps of fire expansion in a warehouse cell • Fire is decreasing / Decay phase of the fire • Protected by Firebreak, the adjacent cell on the cold side is safe. It is not damaged. Structure and fitting: Fastening systems Fuses on 5 m x 5 m grid Traditional endwall structures Designed to resist wind and roof loads: manufacturer does not need to make specific allowance for fire-resistance capability. Layout of fuses on endwal structures on either side 5m 5m 5m 5m 5m 5m 5m 5m Standard design : One fuse every 5 metres : 1 fuse for 25 square metres Firebreak 4h: structure and assembly Wall density 98.75 kg/m2 Structure (beams) Special fasteners Firebreak wall Horizontal & vertical joints Floor fastening Exceptional reliability: 4 hours / 15 metres high / unlimited width Overall view, elevation Standard panel Non-standard panel, type 1 Non-standard panel, type 2 Fast elevation with two team works Structure and assembly Assembly method • • Assembly with small mobile crane Easy fitting (slot-in) Approximate weight of panel 300 kg Unlimited width Firebreak wall up to 15 metres high Structure and assembly: joints Aluzinc strip, 1 mm thick Aluzinc facing, 1 mm thick Steel hat-section rail, 1.2 mm thick Palusol PM A2 stainless steel Lag screw TH 6 x 80 ZN steel self-tapping screw TH 4.7 x 16 Horizontal and vertical assembly Structure and fitting: Floor fastening Floor fastening Concrete - Generally no need to strengthen an existing concrete slab - “U” or flat section performs fastening rail and levelling functions - Fastening on existing concrete Levelling mortar base (thickness as required) Concrete floor slab • Time savings • Clean, dry worksite • Lower assembly costs Floor surface pressure around 1 kg/cm2 for partition 15 metres high Lifting spreader supplied Structure and fitting: Extention through façade and roof 1m 50 cm Façade Roof Section III Firewall Firebreak CSTB Certification test Fitting of hat-section assembly profiles and lag bolts Intumescent strip and screw-down closure sheet Test load corresponding to height of 15 meters Test carried out by CSTB CSTB certification test After 4 hours 15 minutes in standard fire conditions, only half the thickness has been destroyed. CSTB evaluation & test report CSTB evaluation & rating report II – Findings II.1 – Rating criteria: standard II.1.1 – Load-bearing capacity Duration: 240 minutes II.1.2 – Flame and fume seal-off Duration: 240 minutes II.1.3 – Heat insulation Duration: 240 minutes II.2 – Laboratory evaluation basis II.2.1 – Test report n° RS07-050 (self-supporting wall, load 1162 daN / ml) Section IV Firebreak system Promotion & Development Exhibition at Batimat trade show in Paris, November 2007 Exhibition at Expoprotection trade show in Paris, November 2008 In recognition to its innovative characteristics, the Firebreak Wall 4H has received a the Innovation award Development • Firebreak 2 hours : height 15 m • Firebreak 1 hour : height 12,5 m • Acoustic tests of Firebreak 4hours • Getting European Technical Accreditations • Floor and ceiling firestop => High Buildings Section V Extra Part on Fire regulation Regulations …require compliance with structural fire-resistance rating criteria Fire resistance rating criteria • R (SF): mechanical resistance time under standard test conditions of ISO 834 load-bearing structures • RE or E (PF): flame and fume seal-off time partition structures (slabs, walls) • REI or EI (CF): heat insulation (140°C on face opposite to fire) partition structures (slabs, walls) Regulation and decrees General texts Decrees, orders, circulars French Ministry of Ecology & Sustainable Development • Decree of 5 August 2002 on prevention of disasters in covered warehouses requiring authorization under item 1510 (Official Journal of 1 January 2003, page 50) • Decree giving innovative specification of clear objectives Measures on fire resistance of warehouses Article 6 ( specific objectives) “In general terms, construction measures seek to ensure that collapse of a particular item (wall, roof, pillar, beam, etc.) does not lead to a domino-effect collapse of the building structure as a whole (typically the neighbouring storage cells, or the partitions between them), and that if collapse occurs it does so within rather than outside the initial fire zone.” Physical data • Survival is possible up to 80°C (or possibly 150°C for firefighters in special clothing). • Usual materials resist temperatures up to 500°C and beyond. • When materials reach 500°C, the local ambient temperature is much higher. • Conclusion: Conditions have ceased to be life-sustaining long before structural collapse occurs in the fire Consequences • Local collapse of a structure in a fire is not a catastrophe in itself provided that we can be certain there are no people alive in the collapse zone…. BUT • Collapse of one item must not lead to collapse in structures not affected (or less affected) by the fire, which may not yet have been vacated or which may be occupied by firefighters Domino collapse must be avoided. In most cases, the feasibility of rescuing victims in a building on fire depends not so much on the fire resistance of the structure as on the risk of domino collapse. Domino collapse, illustration Metal racks absorbed domino collapse of the structure in prestressed concrete Objective: inward collapse kinematics • Metal structures usually respond well to this criteria. • A design guide is available, based on a parametric study by CTICM (SCMF site). • • CTICM = Centre Technique et Industriel de la Construction Métallique (Steel construction technical and industrial institute) SCMF = Syndicat de la Construction Métallique de France (French Constructional Steelwork Association) « Item 1510 » storage warehouses : compartmentalization and layout Article 9 Storage cells should be limited in surface area to reduce the amount of combustible material burning in the event of fire, and prevent fire propagating from one cell to another. Storage cells should not exceed 3,000 square metres if there is no automatic fire extinguishing system, or 6,000 square metres if there is an automatic fire extinguishing system. « Item 1510 » storage warehouses : compartmentalization and layout Article 8 Storage warehouses should be split up into cells to reduce the amount of combustible material burning in the event of fire. Compartmentalization should be capable of preventing fire propagating from one cell to another. To meet this objective, the cells must meet the following requirements: • The partitions between the storage cells must have a firebreak capability of at least two hours. « Item 1510 » storage warehouses : compartmentalization and layout • The partitions must continue through the roof and extend at least 1 metre above it at this point. Either the roof must be covered with a protective strip extending over a width of least 5 metres on either side of the partitions, or alternatively, if warranted, a dry standpipe may be fitted along the partitions to afford similar protection. • Unless the outer walls have a one-hour firebreak capability, cell partitions must extend through the outer walls and terminate either in a section 1 metre wide along the outer walls, or extend for 0.50 metres beyond the outer walls. Storage compartmentalization and layout Fire partition walls may be arranged in any configuration with respect to the load-bearing structure. APSAD Regulation Regulatory minimum requirements can be tightened by additional requirements specific to insurance companies. APSAD Regulation 2 – Firebreak partitions 2.1 – Purpose A firebreak partition (FBP) separates two buildings or two parts of the same building so that fire breaking out on one side of the partition will not propagate to the other side. 2.2 – Behaviour in fire A firebreak partition must be rated to at least REI 240, whichever side is exposed to the fire risk. The fire resistance of the firebreak partition must be validated by an accredited technical inspector or by a worksite report issued by an accredited laboratory, as appropriate. A work completion report must be submitted to the project owner in two copies, one for the insurance company. Validation concerns the fire resistance of load-bearing items, filling materials and the fittings of openings and passageways through the partition. Ouvrages séparatifs coupe-feu Règle ARSADR15 – Edition xx 2007.0 APSAD Regulation Firebreak partitions must extend at least 1 metre above the highest point of an area extending 7 metres either side of the partition. (See figure 2.4.1.1.a.) 2.4.2 – Extension through outer walls 2.4.2.1 – Title pending Firebreak partitions must extend 0.5 metres clear beyond the outer face of an outer wall. (See figure 2.4.2.1.a.) Top view Partition 1 metre above highest point in this area Figure 2.4.1.1.a – Firebreak extending above roof between two buildings of same height If the partition separates buildings of different heights, this requirement applies to the higher of the two buildings. (See figure 2.4.1.1.b.) FBP Building A Building B Figure 2.4.2.1.a – Firebreak extending beyond outer wall This requirement may be lifted if there is a strip rated to EI 120 at least 2 metres wide along the whole height of the outer wall either side of the partition, in material rated A1 or A2s1d0, with no opening it it. (See figure 2.4.2.2.a.) Top view Facade FBP FBP Figure 2.4.1.1.b – Firebreak extending above roof between two buildings of different heights This measure is to ensure that fire cannot propagate through the firebreak, by direct action of the flames or by radiated heat, and to provide a screen protecting firefighting personnel as they work to extinguish the fire. Building A Building B Facade Figure 2.4.2.2.a – Exception to extension through outer wall: façade with no openings, rated EI 120, in material rated A1 or A2s1d0 APSAD Regulation 2.5.2 – Openings (unobstructed bays) Openings in a firebreak partition must be fitted with automatically closing double doors rated EI 90 and E1 120, meeting the design and fitting requirements specified in APSAD rule R 16. (See figures 2.5.1.a and 2.5.1.b.) Horizontal section FBP Firebreak door, open FBP Firebreak door, closed Figure 2.5.1.a – Double firebreak door Bays must not be more than 3.8 metres wide or 4.4 metres high. Door closure must be operated by means of an automatic detection system or independent type I sensor-triggers. The materials surrounding the openings (lintels and jambs) must be strong enough to support the weight of the firebreak doors and withstand the impacts of repeated open-close action. If the material is not strong enough (cellular concrete, for example), a special frame must be built on which to fit the door mechanisms. (Figure 2.5.1.c.) Metal lintels are not allowed. APSAD Regulation Type of partition Fire resistance Selfsupporting Load bearing Extension through roof Structure materials Openings Ventilation & air conditioning ducts Conveyors Firebreak partition REI 240 or EI 180 on both faces of double-face firebreak partition. Yes Load borne by means of brackets or consoles and sliding supports. Load-bearing capability allowed for double firebreak partition. Extension 1 metre above roof and A1 or A2s1d0 protective strips 5 metres either side. A1 or A2s1d0 Automaticclosure double doors, EI 90 and E 120. Not allowed Compliant with APSAD rule R16 Regulatory firebreak partition REI 120 No requirement Target result: no domino collapse and no outward collapse of fire outbreak cell. Extension 1 metre above roof. Extension 0.5 metres beyond façade or 1 metre along façade on either side. Roof covered with protective strip 5 metres either side No requirement Automaticclosure doors, EI 120 EI 120 EI 120 Ordinary partition REI 120 No requirement Load-bearing by sliding supports or fuse links. As firebreak partition, except for concrete roofs A1 or A2s1d0. ”Fragile” faces not allowed if rack parallel to ordinary wall Automaticclosure single doors, E 120 EI 120 Compliant with APSAD rule R16 Fireproof compartment REI 90 for outer face and EI 90 for other faces Not applicable Not applicable Not applicable A1 or A2s1d0 Single doors EI 90 & A 120 (inner face) Single doors E 90 (outer face) EI 120 Compliant with APSAD rule R16 APSAD Regulation Metal-frame firebreak walls are not allowed unless they have a double face. (See section 2.7.) APSAD R15 rule: self-supporting firebreak walls were required for reasons of symmetry, which appeared logical at the time, but not now. Traditionnal construction by concrete pillars embedded in the floor Fitted in front of concrete pillar Stringer As an initial approximation, the firebreak capability of a wall in solid prefabricated concrete panels can be calculated using the simple rules set out in standard P 92-701 (DTU fire concrete), as shown in the table below. These rules apply two walls with a slenderness ratio no more than 50. The walls may be exposed to fire on one or both sides. Frame Firebreak capability ½ hour 1 hour 1½ hours 2 hour s 3 hours 4 hour s Loadbearing walls Thickness (cm) 10 11 12 15 20 25 Nonloadbearing walls Thickness (cm) 6 7 9 11 15 17.5 Concrete frame Concrete framework Fireproof joints between panels Variant: panels fitted between reinforced concrete pillars BUT… deformation of free-standing (i.e. self-supporting) wall embedded in floor Initial position Deformed position Convex deformation on side exposed to heat Wall Self-supporting firebreak walls: potentially dangerous The wall leans outward from the fire if not free to rotate at the foot. This goes against the aims of item 1510. Former rules (APSAD R15) • There is no straightforward, reliable method for designing a selfsupporting wall compliant with standards. Resort must be made to sophisticated calculation models that are not in current usage. • Former rules do not allow for the effect of temperature gradient when determining stress. (Text in extenso in R15 till 2007.) • But the temperature gradient, and the second-order effects thereof, is the main cause of wall collapse. Conclusion • Current recommendations (APSAD R15) should come under serious critical review. • Embedded pillars and outer façade shear walls should be prohibited if they can be exposed to high temperature gradients. • Interior firebreak walls embedded in the floor should only be allowed if the effects of expansion and the resulting additional stress on neighbouring structures can be properly evaluated. Is full chaining really necessary? Not if we can be sure that collapse will be in the right direction without risk for the wall. Classical deformation and possible solution? Wall embedded at foot and free at top Wall supported horizontally at foot and top Wall curves gradually In the scenario to the right, the wall curves less, so the weight offset is less, and the risk of collapse is toward the fire rather than away from it. As we said previously, thanks to its steel structure the Firebreak wall is not concerned by this problem Thank you for your attention Contacts : Fabrice Sokolowsky, Innovation & Development Manager fabrice.sokolowsky@arcelormittal.com Frédéric Goujon, Project Manager frederic.goujon@arcelormittal.com