Design of Sprinklered Shopping Centre Buildings for Fire Safety

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Design of Sprinklered Shopping Centre Buildings for Fire Safety
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    Design of Sprinklered Shopping Design of Sprinklered Shopping Design of Sprinklered Shopping Design of Sprinklered Shopping Centre Buildings for Fire Centre Buildings for Fire Centre Buildings for Fire Centre Buildings for Fire SafetySafetySafetySafety by    I. D. Bennetts, K. W. Poh   I. R. Thomas   Victoria University Content     page INTRODUCTION..................................................1 BACKGROUND....................................................2 PARTS OF SHOPPING CENTRE BUILDING.............................................................4 BUILDING CHARACTERISTICS..........................6 FIRE SAFETY ASPECTS.....................................8 OCCUPANT AVOIDANCE.................................14 SMOKE DEVELOPMENT AND MANAGEMENT..................................................17 FIRE DETECTION AND SUPPRESSION..........20 FIRE SPREAD AND MANAGEMENT................22 BRIGADE COMMUNICATION AND RESPONSE........................................................23 MANAGEMENT OF FIRE SAFETY....................24 CONCLUSIONS.................................................29 REFERENCES...................................................29  APPENDIX 1 Example........................................31  APPENDIX 2 Exposed Surface Area to Mass Ratio of Steel Sections— k  sm   (m 2 /tonne)..............40 Published by:    OneSteel – Market Mills Ingal Street Newcastle NSW 2300  Australia   First Published, November 2000 Scope   This publication applies to sprinklered shopping centre buildings having a rise in storeys of up to 4. The buildings may contain covered walkways and a combination of the following classes of building (in terms of the BCA): Class 6 —  Retail including specialty shops, major stores, department stores, supermarkets Class 9b —  Cinemas Class 7 —  Carparks including open deck and sprinklered carparks Class 5   — Offices The publication applies to buildings which are of substantially non-combustible construction. However, this should not be taken to exclude the use of timber stud wall construction between specialty shops. Reprint edition, September 2006 Disclaimer    Neither the authors, OneSteel nor Victoria University warrant or make any representation whatsoever that the information contained in this document , or the procedures set out in it, or any advice derived therefrom, will be suitable for all fire engineered building fire safety designs. The information contained herein is intended primarily for the benefit of suitably qualified and competent fire engineering practitioners. Fire engineering design activities require the application of professional knowledge, engineering  judgements and appropriate understanding of the assumptions, limitations and uncertainties involved.  1 INTRODUCTION The construction and extension of large shoppingcentres is an area of commercial developmentwhich is being pursued actively in Australia. Thereis a belief that some aspects of the current deemed-to-satisfy provisions for these buildingsmay be unnecessarily onerous, imposingunnecessary financial burdens on developers andowners and which do not relate to the risk to lifefrom fire in these buildings.A two-year intensive research project, Fire CodeReform Centre (FCRC) Project 6, was conductedto study all significant aspects relating to firesafety in shopping centres. The purpose of thisproject was to review the requirements in theBuilding Code of Australia (BCA) [1] which applyto low-rise sprinklered shopping centres and topropose a more rational set of fire-safetyrequirements to improve the cost effectiveness ofthese buildings (both in terms of constructioncosts and maintenance in operation) whilstmaintaining the current high levels of fire safety.A set of reports [2-8] which describe the variousaspect of the research work have been published.The final report [9], also published as an FCRCdocument, summarises the research andsystematically evaluates fire-safety aspects ofshopping centre buildings makingrecommendations for the design of such buildings.Since that time, further evaluation and testinghave been conducted and the design principlesand procedures given in the above publicationshave been extended in the light of newinformation. The design principles and procedureshave taken into account the methodologies andfire-safety system structure given in the FireEngineering Guidelines [10] prepared by FCRCand endorsed by Australian Building Codes Board.The purpose of this publication is to present thismodified design approach. This approach willenable the designer to satisfy the fire-safety objectives   and relevant performance requirements  of the BCA. The satisfaction of the performancerequirements depends on many factors, includingthe correct choice of materials of construction,appropriate egress requirements, adequate firesuppression, and appropriate structural fireresistance.The design is applicable to buildings which containmultiple classes, when considered with respect tothe BCA, which may contain a covered walkway ormall and the following classes of buildings:Class 6 —Retail including specialty shops,major stores, department stores,supermarketsClass 9b —CinemasClass 7 —Carparks including open deck andsprinklered carparksClass 5 —OfficesIt does not apply to retail warehouse buildingswhere goods are stored in tall racks greater than 4m in height and where the sprinklers are locatedonly at roof height. This is not to say that theinformation presented in this publication can notbe applied to other situations but that it may benecessary to consider additional matters.It is recognised that both life safety and propertyprotection are of importance in shopping centrebuildings. A large fire in these buildings may notonly present a major threat to life and may resultin significant direct property losses, but moreimportantly, an ongoing loss of sales revenuethrough interruptions and delays to the provisionof goods and services. Therefore, life safety andproperty protection are considered in thispublication.It needs to be stated that it is practicallyimpossible to design modern shopping centres tosatisfy all of the deemed-to-satisfy provisions ofthe BCA. Furthermore, the factors which have, byfar, the greatest impact on fire safety, are notaddressed by attempting to design the building tosatisfy the deemed-to-satisfy provisions. It followstherefore, that a fire-engineering evaluation of thetype presented in this publication, is essential forshopping centre buildings.  2 BACKGROUND Research Project FCRC Project 6 was conducted to study allsignificant aspects relating to fire safety inshopping centres. Research participants includedBHP Research, BCC, Victoria University ofTechnology and Scientific Services Laboratories.The project involved various parts, including: ã  review of current BCA requirements ã  survey of shopping centres ã  review of retail fire incidents ã  review of retail fire statistics ã  identification of key issues ã  fire testing ã  study of behaviour of building occupants ã  study of effectiveness of smoke controlsystems ã  systematic evaluation of fire safetySome aspects of the project are outlined below. Case Studies 1010 97 accounts of fires in retail and shopping centrebuildings, as reported in the literature, have beenconsidered. Ref. [5] documents details of thefatalities experienced in retail buildings in the USAover a 10 year period from 1983 to 1993 (except1986). The data was obtained from the NationalFire Incident Reporting System (NFIRS) in theUSA [11].The analysis of the case studies revealed anumber of apparent trends and the followingtentative observations can be made: General Observation from Case Studies    The majority of fires appear to havebeen started by electrical faults orarson.    In the majority of situations firesonly developed to a significantsize if the fire was initiated inunpopulated areas (eg. storageareas or ceiling spaces) or whenthe building was unoccupied.    A major mechanism of firespread to other parts of thebuilding appears to have beenthrough the ceiling space.    Partial sprinklering is adangerous practice which canlead to the centre beingeffectively destroyed. Fire Statistics USAAUS The statistical data on USA retail fires attended bythe fire brigade were analysed. These data,contained in the NFIRS database, includes 10years (1983 to 1993 excluding 1986) of data andrepresents 77,996 retail fires.For comparison, a further study was carried out ondata available from the New South Wales (NSW)Fire Brigades for NSW for the years 1986 to 1992.An analysis of Australian fire statistics forcommercial buildings has also been undertaken.A comparison of the data indicates thatremarkably similar trends are demonstratedbetween the USA and Australian data and thisconfirms that it is reasonable to use the largerUSA database for understanding many aspects offires in retail buildings.It is clear from the data that fire in retail premisesdoes not present a significant risk to life. Therewere 86 deaths in 77,996 retail fires over 10 yearsin the USA and only two fatal fire incidents inNSW. The figure below shows the average fatalityrate for civilians (as opposed to fire fighters)obtained from the USA data. average civilian fatality rate (deaths per 1000 fires) 0.741.127.4 residentialapartmentsretailpremisesshopping complexes In NSW the comparable figure for retail premisesis 0.79 deaths per 1,000 fires, but since this isbased on only two fatal fire incidents, the figuremust be used with caution. The Australia fatalityrate in residential buildings is 7.08 per 1,000 firesThere is a general trend, for the numbers ofcivilian deaths and injuries to increase with size ofthe fire. In fact it is shown in the analysis given in[6] that if by some means all fires could beconfined to the object first ignited, the civilianfatality rate would probably fall by a factor of nine. Survey of Shopping Centre As part of the research project it was consideredimportant to gain an adequate understanding of allaspects of shopping centres that relate to firesafety. This knowledge is essential to permit ameaningful fire-safety analysis.  3 Information on these matters was gained bymeans of a very comprehensive study of a majorshopping centre in Victoria over a continuous twomonth period and through visits to elevenshopping centres in Victoria and NSW. The centresubjected to the comprehensive study had a grossretail area of 58,000 m 2  having a department storewith a rise in storeys   of 4 at one end of a twostorey mall and was considered to berepresentative of a large modern shopping centre.The other centres had rise in storeys   of up to 5,and with one exception, had floor areas whichwere similar or greater than that associated withthe centre used for the detailed study.For each centre visited, interviews wereconducted with operational staff to understandtheir approach to a variety of matters and to obtaina general overview of practices and construction.A summary of the findings from these visits and ofthe data obtained is given in [3]. Fire Tests In designing shopping centres for fire safety, it isessential to have some understanding of thecharacteristics of fires that may occur in thesebuildings, and because of the paucity of relevanttests, it was considered essential to conduct aseries of fire tests that would provide such data. Full-Scale Fire Tests Eleven full-scale fire tests were conducted toinvestigate the effects of fires in specialty shopsand major stores in a shopping centre. Fire Test Program Tests1 & 2 simulate fires in a toy store undersprinklered and non-sprinkleredsituations. Tests3 & 4 simulate fires in the storage area ofa shoe shop under sprinklered andnon-sprinklered situations. Tests5 to 9 simulate fires in clothing storesunder sprinklered situation. Tests10 & 11 simulate fires in book shop/ newsagent under sprinkleredsituation.fire test on toy storeset-upfire test on shoe storage areaset-upfire test on clothing storeset-upFire test on book shop/ newsagent set-up As a result of these tests, 3 types of fire wereidentified according to their size: C1  —fires which are kept small without thepresence of sprinklers. C2   —fires controlled by the presence ofsprinklers. C3   —fires which are significantly more severethan C1 and C2.The results of the tests are reported in detail in [7]and a videotape is available. Model Fire Tests Model Tests can be used to enable a betterunderstanding of aspects of smoke movement inshopping centres. Such testing has been carriedout in the past by others to develop a basis forvarious numerical correlations. A set of modeltests is being conducted at Victoria University ofTechnology using the model four-storey buildingshown below. The model is 1/7 scale and isdesigned such that horizontal openings can beincorporated in the floors and the roof. This modelhas been used to study the flow of smoke throughfloor openings and the effects of roof vents on theamount of smoke in each level. model four-storey buildingSmoke movement in modelbuilding   Behavioural Study A review of emergency incidents in shoppingcentres and a series of interviews with shoppingcentre staff and management was undertaken [9].On the basis of this work the followingobservations are made: ã  alarm is unlikely, by itself, to initiateevacuation ã  the presence of dense smoke in part of thebuilding is a much more effective cue and willbe sufficient for people to move away fromthat area ã  the decision to evacuate or move away fromthe fire-affected area will be positivelyreinforced by the presence of wardens andstaff ã  the presence of a crowd of people moving in aparticular direction (towards an exit) will alsohave a reinforcing effect on those who havenot started to move ã  if the fire is sufficiently large that other levelsof the mall begin to experience dense smoke,then evacuation of these smoke-affectedparts will be initiated ã  the natural tendency of staff is to guide peopletowards the major entrances (exits) that arecommonly used by occupants. There is a fearof using unfamiliar exits and these will only beused if there is no alternative
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