A conversion from NFPA 502 standard to practical systems and tested solutions
Tunnel Fire Protection
www.promat-tunnel.com
INTRODUCTION
FIRE CURVES / GENERAL
This document is based on the NFPA 502, Standard for Road Tunnels, Bridges, and Other Limited Access Highways, 2004 Edition. The purpose is to have a conversion document from this standard to practical systems that have been tested by international re-research laboratories, thus enabling designers and engineers to select re-safe solutions for their project. The systems as shown in this document are a selection of the wide range of tested Promat constructions. Please consult the Promat technical department for further details or alternatives in order to meet project specic requirements.
CONCRETE PROTECTION DOORS AIRDUCTS CABLES & SERVICES
The authors are grateful to the NFPA organization for allowing them to use sections of the original NFPA 502 standard text.
CHAPTER
Description 1. Administration Scope # 1.1.1 Ofcial NFPA 502 Standard Text This standard provides re protection and re life safety requirements for limited access highways, road tunnels, bridges, elevated highways, depressed highways, and roadways that are located beneath air-right structures. This standard establishes minimum requirements for each of the identied facilities. The purpose of this standard is to establish minimum criteria that provide protection from re and its related hazards. Where specied, the provisions of this standard shall be retroactive. In those cases where the authority having jurisdiction determines that the existing situation presents an unacceptable degree of risk, the authority having jurisdiction shall be permitted to apply retroactively any portions of this standard deemed appropriate. The level of re protection necessary for the entire facility shall be achieved by implementing the requirements of this standard for each subsystem. As a minimum the following factors shall be evaluated in an engineering analysis and where applying the re and life safety requirements for the facilities covered by this standard: ... (1) Protection of life, (6) Exposure of structure to elevated temperatures, (8d) Built-in re protection features, such as ventilation systems, (9) Protection of facility components, ...
Reference to Promat Technical Note on The Fire Protection of Tunnel Structures & Services (07/2004)
4-5 FIRE CURVES / GENERAL
Scope Purpose Retroactivity Retroactivity
1.1.2 1.2 1.4.1 1.4.2
4. General Requirements
Characteristics of Fire Protection Fire Protection and Fire Life Safety Factor
4.1 4.3.1
(1) : 4 - 5 (6) : 9 - 12 (8d): 26 - 29 (9) : 26 - 31
7. Road Tunnels
Protection of Concrete and Steel Structures Explanatory Material
7.3
Regardless of tunnel length, all primary structural concrete and steel elements shall undergo a re engineering analysis to ensure that the tunnel structure can withstand the anticipated re severity based on the type of trafc to be permitted. Concrete and steel structural elements should have a 4-hour re resistance rating in accordance with the time/temperature curve, for example, ANSI/UL 1709. Concrete and steel structural elements with a minimum re resistance rating of 2 hours in accordance with ANSI/UL 1709 should be permitted where the anticipated design re size is 20 MW or less and ammable liquids in bulk (hazardous) cargo are prohibited from the tunnel. Tunnels with cast in-situ concrete structural elements should be protected such that the temperature of the concrete surface does not exceed 380C (716F) after the dened re exposure conditions. The temperature of the steel reinforcement within the concrete [assuming a minimum cover of 25 mm (1 in.)] should not exceed 250C (482F) under the same re exposure conditions. Tunnels with pre-cast (high strength) concrete elements should be protected such that explosive spalling is eliminated under the dened re exposure conditions. Tunnels with steel or cast iron linings should be similarly protected depending on the design re size. The following typical incidents shall be considered during the development of facility emergency response plans: (10) Damage to structures from impact and heat exposure ...
6 - 26 CONCRETE PROTECTION
Annex A
A.7.3
6 - 26, page 7 (RWS curve) in particular
12. Emergency Response Emergencies
12.2
4 - 5 & 9 - 14
DOORS
7. Road Tunnels
Doors
7.17.4.3
Doors shall be listed re doors with a minimum 1-hour rating and shall be installed in accordance with NFPA 80.
31
AIRDUCTS
10. Emergency Ventilation Smoke control Smoke control
10.2.1 10.2.2
The emergency ventilation system shall provide a means for controlling smoke. In all cases, the desired goal shall be to provide an evacuation path for motorists who are exiting from the tunnel and to facilitate re-ghting operations.
26 - 29 26 - 29
11. Electrical Systems
General
11.1.2
The electrical systems shall maintain ventilation, illumination, communications, drainage, and water supply; shall identify areas of refuge, exits, and exit routes; and shall provide remote annunciation and alarm under all operating and emergency modes associated with the facility Materials that are manufactured for use as conduits, raceways, ducts, cabinets, and equipment enclosures and their surface nish materials, as installed, shall be capable of being subjected to temperatures up to 316C (600F) for 1 hour without supporting combustion and without loss of structural integrity. The following systems shall be provided with reliable power for a re emergency: (1) Lighting, (2) Lighting for means of egress and areas of refuge, (3) Exit signs, (4) Communications, (5) Tunnel drainage and re pumps, (6) Ventilation during a re emergency
CABLES & SERVICES
30
Materials
11.3.1
34 - 35
Power Source
11.4
30
FIRE CURVES
In recent years a great deal of research has taken place internationally to ascertain the types of re which could occur in tunnel and underground spaces. This research has taken place in both real, disused tunnels and laboratory conditions. As a consequence of the data obtained from these tests, a series of time/ temperature curves for the various exposures have been developed as detailed.
Cellulosic (ASTM/ISO) curve:
Full scale tests in the Runehamar tunnel in Norway (September 2003) have shown that the RWS re curve was best simulated
Standard re tests to which specimens of constructions are exposed to are based on the use of the Cellulosic time/temperature curve, as dened in various national standards, e.g. ASTM, ISO 834, BS 476 : part 20, DIN 4102, AS 1530 etc. Although there are other types of re test curves e.g. BS 7436, the curve as detailed below for this exposure is the lowest used in normal practice. This curve is based on the burning rate of the materials found in general building materials and contents.
HydroCarbon curve (HC), similar to ANSI/UL 1709:
Although the Cellulosic curve has been in use for many years, it soon became apparent that the burning rates for certain materials e.g. petrol gas, chemicals etc, were well in excess of the rate at which for instance, timber would burn. As such, there was a need for an alternative exposure for the purpose of carrying out tests on structures and materials used within the petrochemical industry, and thus the hydrocarbon curve was developed. The hydrocarbon curve is applicable where small petroleum res might occur, i.e. car fuel tanks, petrol or oil tankers, certain chemical tankers etc. In fact, although the hydrocarbon curve is based on a standardized type re, there are numerous types of re associated with petrochemical fuels.
FIRE CURVES / GENERAL
HydroCarbon Modied curve (HCM, France):
Derived from the above-mentioned Hydrocarbon curve, the French tunnel regulation asks for an increased version of that Hydrocarbon curve, the so called HydroCarbon Modied curve (HCM). The maximum temperature of the HCM curve is 1300 C (2372 F) instead of the 1080 C (1976 F), standard HC curve. However, the temperature gradient in the rst few minutes of the HCM re is as severe as all Hydrocarbon based res (RWS, HCM, HC), possibly causing a temperature shock to the surrounding concrete structure and concrete spalling as a result of it.
RABT-ZTV curve (Germany):
The RABT curve was developed in Germany as a result of a series of test programmes such as the Eureka project. In the RABT curve, the temperature rise is very rapid up to 1200 C (2192 F) within 5 minutes, faster than the Hydrocarbon curve which rises only to 1100 C (2012 F) after 60 minutes. The duration of the 1200 C (2192 F) exposure is shorter than other curves with the temperature drop off starting to occur at 30 minutes. This test curve can be adapted to meet specic requirements, in testing to this exposure, the heat rise is very rapid, but is only held for a period of 30 minutes, similar to the sort of temperature rise you would expect from a simple truck re, but with a cooling down period of 110 minutes. If required, for specic types of exposure, the heating period can be extended to 60 minutes or more, but the 110 minute cooling period would still be applied.
CONCRETE PROTECTION
RWS curve (The Netherlands):
The RWS curve was developed by the Rijkswaterstaat, Ministry of Transport in the Netherlands. This curve is based on the assumption that in a worst case scenario, a fuel, oil or petrol tanker re with a re load of 300MW could occur, lasting up to 120 minutes, reaching a maximum temperature of 1350 C (2462 F) after 1 hour. The RWS curve was based on the results of testing carried out by TNO in the Netherlands in 1979. The difference between the RWS and the Hydrocarbon curve, is that the latter is based on the temperatures that would be expected from a re occurring within a relatively open space, where some dissipation of the heat would occur, whereas the RWS curve is based on the sort of temperature you would nd when a re occurs in an enclosed area, such as a tunnel, where there is little or no chance of heat dissipating into the surrounding atmosphere. The RWS curve simulates the initial rapid growth of a re using a petroleum tanker as the source, and the gradual drop in temperatures to be expected as the fuel load is burnt off. The failure criteria, for specimens exposed to the RWS time/temperature curve is that the temperature of the interface between the concrete slab and the protective covering should not exceed 380 C (716 F) and the temperature on the reinforcement should not exceed 250 C (482 F) (based on a concrete cover of 25 mm / 1 inch).
DOORS AIRDUCTS CABLES & SERVICES
CONCRETE PROTECTION
Concrete damage after a tunnel re can have severe consequences. Even if the tunnel did not collapse as a result of the re, repair costs are enormous but the economic losses due to closure of the tunnel are even more considerable. Fire induced damage to concrete (known as spalling) is caused by a specic combination of the following mechanisms: Pore pressure rises due to evaporating water when the temperature rises Compression of the heated surface due to a thermal gradient in the cross section Internal cracking due to difference in thermal expansion between aggregate and cement paste
Severe concrete damage after the re in the Channel tunnel, United Kingdom.
Cracking due to difference in thermal expansion/deformation between concrete and reinforcement bars Strength loss due to chemical transitions during heating (A.J. Breunese and J.H.H. Fellinger, TNO Centre for Fire Research, The Netherlands, February 2004) High strength concrete elements (C65-70 / 10.150 psi) are more vulnerable to spalling than cast-in-situ elements (C25-30 / 4.350 psi). In fact, among other parameters, the concrete composition (the content of the mixture, aggregates and admixtures) causes the biggest inuence to the spalling behavior of concrete. In practice these details are often unknown which is why the concrete
Spalling of concrete in a pedestrian tunnel. Fire load was cardboard boxes only.
grade (compression strength) is taken as a reference. It is anticipated that more research will be conducted with the objective to ne-tune the inuence of the concrete composition on its spalling behavior. The below table indicates the required re protection layer related to the selected design re curve and re duration:
Principle of concrete spalling
Fire curve HC / UL 1709 HC / UL 1709 RWS RWS RWS RWS
Fire duration 4 hours 4 hours 2 hours 2 hours 3 hours 3 hours
Temperature criteria Interface Rebar < 325C (< 617 F) < 325C (< 617 F) < 380C (< 716 F) No Spalling < 380C (< 716 F) No Spalling < 250C (< 482 F) < 250C (< 482 F)
Concrete grade C35-40 (5800 psi) C30-35 (5075 psi) C30-35 (5075 psi) C50-55 (7977 psi) C25-30 (4350 psi) C60-65 (9425 psi)
Product PROMAT -H PROMAT -H PROMAT -H PROMAT -T PROMAT -T PROMAT -T
Thickness 25 mm (1 inch) 25 mm (1 inch) 27,5 mm (1,1 inch) 30 mm (1,2 inch) 30 mm (1,2 inch) 30 mm (1,2 inch)
Test institute VTEC (USA) TNO (The Netherlands) TNO (The Netherlands) Redco (Belgium) IBS (Austria) Redco (Belgium)
FIRE CURVES / GENERAL
PROMAT -T boards applied in the Toulon tunnel, France.
PROMAT -T boards can be applied as a post-curved panel (curved on site).
CONCRETE PROTECTION
Westerschelde tunnel, The Netherlands. Ceiling and wall application using PROMAT -H boards. Curved application using PROMAT -T boards.
Curved PROMAT boards applied in the German Elb tunnel (4th tube), Hamburg.
DOORS AIRDUCTS CABLES & SERVICES
Lost formwork system. The boards are laid onto the formwork. Partly inserted screws create the anchorage to the concrete.
Post installation system, by means of anchors.
DOORS
The design and construction of re resisting doors is a complex operation involving the skills and specialized knowledge of architects, re experts, door manufacturers and ironmongers. The designer is the rst in the line of those concerned with the provision of re doors. It is he who ascertains the requirements of the users and decides where and in what form doors will be required. He also assembles the specialized information from the other experts into a design for the complete door, and arranges for the doors to be manufactured. The rst principle to be considered in relation to re resisting doors is that in most respects they are merely ordinary doors with certain additional features, and throughout most of their life will be operating as such. Fire resisting doors, therefore, have to be opened, closed, locked, latched, bolted, cleaned and maintained like any other door. The following points are some of the factors, which should be considered when determining the correct specication to ensure a doorset will provide the required re performance. Relevant test standards and re/smoke requirements. Size of door leaf, generally the door-set should be no larger than the tested door-set, but larger door-sets may be considered suitable for assessment depending on the performance of the tested door-set. Number of door leaves, generally testing a double leaf door-set is more onerous than a single leaf door-set. However, for tunnel applications single leaf doors are most common. Action of door leaf, the performance of a door-set can vary considerably depending on which side is exposed to the re. Ironmongery, generally all ironmongery should have a melting point no less than 1350 C (2462 F). The number, size and position of hinges can be critical. Care should be taken when considering alternative ironmongery to that which was tested. Door strips/smoke seals, Intumescent strips, and smoke seals if required, are normally installed down the sides and along the top edge of the door leaf. Alternatively, they can be inserted into the door-frame. Care should be taken that they are tted correctly around ironmongery.
Fire rated doors in the Westerschelde tunnel, The Netherlands.
FIRE CURVES / GENERAL
Among others, following tunnels have been equipped with re doors containing Promat materials: - Westerschelde tunnel, The Netherlands, 2003 - Schiphol Airport Viaduct, The Netherlands, 2002 - Mont Blanc tunnel, France / Italy, 2000 - Hong Kong Airport tunnel, 1997 - Second Cross Harbour tunnel, Hong Kong, 1989
CONCRETE PROTECTION
Hinged door, Hong Kong.
Sliding door in the Schiphol Airport Viaduct, Amsterdam, The Netherlands.
DOORS AIRDUCTS
Following Promat materials have been applied for the production of these re rated tunnel doors: PROMAT -H and PROMAT -T boards for thermal insulation of the door leaf. DURASTEEL boards for impact resistance of tunnel doors. PROMASEAL intumescent (foaming) strips to seal the joint around the door leaf in case of re.
CABLES & SERVICES
AIRDUCTS
Especially circular and horseshoe shaped tunnels very often have a suspended ceiling to create a ventilation duct within the tunnel roof space (transverse ventilation). Such suspended ceilings are often constructed using cast-in-situ concrete. Real res in tunnels have caused such concrete slabs to collapse, as a result of which: The full ventilation system and its functions were lost during the re Eventual escape routes, situated on top of the suspended ceiling were lost People got trapped in the tunnel and emergency response teams could not reach the scene To protect concrete against re induced collapse we refer to chapter CONCRETE PROTECTION In the German Elb tunnel a (stainless) steel sub-frame with re rated boards on both sides was applied to cope with both the ventilation and re requirements. Smoke extraction hatches were installed to extract exhaust gasses from the tunnel in normal use and to extract heat and smoke in the event of a re. For that reason the steel sub-frame had to be protected against re from both sides. The second method is to install a steel duct system, and then clad with a re protective material, such as PROMAT -H board to provide the duct with a degree of re resistance. For specially aggressive environments, where a greater degree of strength and impact resistance is required, the product DURASTEEL should be considered. PROMAT -H boards can be applied to construct a self supporting duct from the boards alone, without any inner steel liner. During the design phase the air pressure and dimensions of the duct have to be taken into account. The re performance of existing steel ducts can be improved by cladding it with PROMAT boards.
Collapsed suspended ceiling in The Gotthard tunnel, Switzerland
Self supporting DURASTEEL smoke extraction duct. Canary Wharf, United Kingdom
Cross section of tunnel showing air plenum construction, for smoke extraction purposes
Detail of steel sub-frame protected against re with PROMAT boards from both sides. 1. PROMAT -H or PROMAT -T boards 2. Framing system 3. Hanger support system where required 4. Connection to tunnel lining
FIRE CURVES / GENERAL
Due to the complexity of the design of re rated ducts a brief overview of tested systems cannot be given. Following factors inuence the design of ducts: The performance required under re conditions e.g. design re curve and re exposure duration. Function of the duct. In the case of the duct being utilized as an airduct (fresh air supply, also in case of re) the duct should be designed to maintain its functions when exposed to re from outside. Thermal insulation and system integrity during re are the main properties to be maintained. If the duct is installed for smoke extraction purposes (exhaust gases in normal use and hot gases and smoke in case of re) the duct must be designed to cope with elevated temperatures inside the duct itself, maintaining system integrity throughout the re exposure duration. The dimensions of the duct. Especially the width of the airduct appears to be the decisive factor for the design of re rated airducts. The positive and/or negative air pressures to which the airduct will be exposed. Please consult the Promat technical department for further details.
DURASTEEL self supporting duct system
CONCRETE PROTECTION
Self supporting airduct constructed out of PROMAT -H boards. PROMAT boards can also be used to clad existing steel ducts
DOORS AIRDUCTS CABLES & SERVICES
CABLES & S E RVICES
By enclosing standard cables in the Promat Cable Duct Systems a re protection of up to four hours can be achieved. This is dependent on the duct construction, and the re exposure curve, whilst avoiding the use of more expensive and bulkier re-rated cables, which generally cannot provide a performance to the more extreme exposure curves. PROMAT -H, PROMAT -T and DURASTEEL boards are non-combustible and have proven their structural integrity performances in hundreds of re tests in international re testing laboratories. The re exposure temperature of a cellulosic (ISO) re curve reaches 925 C (1697 F) after 1 hour, which is well beyond the requirement of par. 11.3.1. which demands for 316 C (600 F). Moreover, Promat boards have been subjected to the most severe re curve (the Dutch RWS re) reaching 1350 C (2462 F) after 1 hour and still maintained its structural integrity. Apart from structural integrity Promat boards also function as a thermal barrier. The below table indicates the required re protection layer related to the design re curve and re duration:
Damage to cables and services in the Channel tunnel, United Kingdom
Cable protection in the Metro tunnel in Copenhagen, Denmark. PROMAT boards are boxed around the cable tray
Fire curve Fire curve HC RWS ISO/ASTM ISO/ASTM E119-83 + hose stream test ISO/ASTM E119-83 + hose stream test ISO/ASTM E119-83 + hose stream test ISO/ASTM E119-83 + hose stream test
Fire duration Fire duration 1 hour 2 hours 30 minutes 1 hour 3 hours 3 hours 3 hours
Product Product PROMAT -H PROMAT -T PROMAT -H PROMAT -H
Thickness Thickness 2x20 mm (2x0,8 inch) 2x25 mm (2x1 inch) 20 mm (0,8 inch) 2x25 mm (2x1 inch) 2x50 mm (2x2 inch) 15 mm (0,6 inch) + 60 mm (2,4 inch) 25 mm (1 inch) + 50 mm (2 inch) + 25 mm (1 inch)
Test institute Test institute IBMB (Germany) PFL (Belgium) IBMB (Germany) SWRI (USA) Omega Point (USA) Omega Point (USA) Omega Point (USA)
PROMAT -L PROMAT -H PROMAT -L PROMAT -H PROMAT -L PROMAT -H
The failure criterion in re tests of cable ducts is malfunction of one of the cables (short circuit). The temperature build-up in the encasement of the cable duct is dependent on the duct construction, the measurements of the duct and the number of re exposed sides of the duct.
FIRE CURVES / GENERAL
Unprotected cables. In case of re key safety systems could fail
Cable duct protection, using PROMAT -H in the Kil tunnel, The Netherlands
CONCRETE PROTECTION
Unprotected cable penetrations. In case of re, the re may spread to the technical rooms, causing key safety systems to fail (lighting, ventilation etc.)
Unprotected cable penetrations. In case of re, the re may spread to the technical rooms, causing key safety systems to fail (lighting, ventilation etc.)
DOORS AIRDUCTS CABLES & SERVICES
Fire stopping bulkhead system. If re occurs, it can only affect a limited section of the services in a tunnel
Fire stopping system installed correctly, preventing that the re can spread to other locations
Exclusive Promat distributor for the US tunnel market:
American Commercial, Inc. 200 Bob Morrison Blvd Bristol, VA 24201-3810 Tel : +1 276 466 2743 Fax : +1 276 669 0940 http://www.americancommercial.com tclemens@americancommercial.com
Promat Headquarters:
Promat International NV Bormstraat 24 Tisselt BE 2830 BELGIUM Tel : +32 15 71 81 00 Fax : +32 15 71 81 09 http://www.promat-tunnel.com info@promat-tunnel.com
