Evaluation of a Fire Risk Index Method for Multistorey Apartment Buildings Hultquist, Hans; Karlsson, Björn 2000 Link to publication Citation for published version (APA): Hultquist, H., & Karlsson, B. (2000). Evaluation of a Fire Risk Index Method for Multistorey Apartment Buildings. (LUTVDG/TVBB--3088--SE; Vol. 3088). Department of Fire Safety Engineering and Systems Safety, Lund University. 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LUND UNIVERSITY PO Box 117 221 00 Lund +46 46-222 00 00 Evaluation of a Fire Risk Index Method for Multi- storey Apartment Buildings Hans Hultquist Björn Karlsson Department of Fire Safety Engineering Lund University, Sweden Brandteknik Lunds tekniska högskola Lunds universitet Report 3088, Lund 2000 Research funded by Nordic Wood, NUTEK and SBUF Evaluation of a Fire Risk Index Method for Multi-storey Apartment Buildings Hans Hultquist Björn Karlsson Lund 2000 Evaluation of a Fire Risk Index Method for Multi-storey Apartment Buildings Hans Hultquist Björn Karlsson Report 3088 ISSN: 1402-3504 ISRN: LUTVDG/TVBB--3088--SE Number of pages: 67 Illustrations: Hans Hultquist Keywords Standard QRA, quantitative risk analysis, index method, semi-quantitative index method, FRIM-MAB, mean risk, risk profile, fire risk, multi-storey apartment buildings. Abstract A need for methods to assess fire risks in timber frame buildings lead to the development of FRIM- MAB, a Fire Risk Index Method for Multi-storey Apartment Buildings. The main objective of this report is to evaluate this method against a different risk analysis method, in this case a standard QRA (quantitative risk analysis) based on an event tree. Four different multi-storey apartment buildings in the Nordic countries were analysed in this study. The QRA resulted in a certain ranking of the four buildings with respect to fire risk. The Fire Risk Index Method was then used to analyse the same buildings. Three slightly different approaches were used to arrive at a fire risk index for each building. The Index Method results gave exactly the same ranking as the quantitative risk analysis for all three approaches. The conclusion of the analysis is therefore that FRIM-MAB seems to work reasonably well for multi-storey apartment buildings, but further studies are recommended to confirm this. © Copyright: Brandteknik, Lunds tekniska högskola, Lunds universitet, Lund 2000. Brandteknik Department of Fire Safety Engineering Lunds tekniska högskola Lund University Lunds universitet P.O. Box 118 Box 118 SE-221 00 Lund 221 00 Lund Sweden [email protected] [email protected] http://www.brand.lth.se http://www.brand.lth.se/english Telefon: 046 - 222 73 60 Telephone: +46 46 222 73 60 Evaluation of a Fire Risk Index Method for Multi-storey Apartment Buildings Summary Summary The second phase of the Nordic Wood project “Fire-Safe Wooden Houses” has been running since 1997. The project is divided into three main areas: i. Strategic knowledge ii. Technical knowledge and methods iii. Development of products and systems The project “Fire Risk Assessment” was formed as a sub-project to “Strategic knowledge”. The need for new and better fire risk assessment methods resulted in the work to produce a semi-quantitative index method, the Fire Risk Index Method for Multi-storey Apartment Buildings (FRIM-MAB). In this report FRIM-MAB is referred to simply as the Index Method. Earlier reports have described the development of the Index Method. The purpose of this report is to get some idea of the validity of the method. Work was therefore carried out to compare it against other risk analysis methods, that have some bases in accepted fire design methods. However, in many cases there are no accepted fire design methods available. For example, firestops at joints, intersections and concealed spaces are very important in timber-frame buildings, but there is no method available to calculate or numerically compare different design solutions in this respect. The evaluation can therefore only result in some indications on validity and is to a considerable extent based on subjective judgement. The comparative methodology used is a standard quantitative risk analysis (QRA) based on an event tree. The analysis resulted in two rankings of the buildings analysed, one from FRIM-MAB and one from the standard QRA. These rankings were compared and some conclusions drawn on how well FRIM-MAB operates. The events in the QRA event trees for the analysed buildings were flaming fire, fire detected automatically, occupant suppressing, sprinkler failure, door open, location of occupants, flashover and spread, level and asleep. All or some of these events make up the event trees. The standard QRA resulted in a number of risk profiles and a ranking based on the expected number of people exposed to critical conditions given a fire. Four existing timber-frame buildings were analysed, one in Sweden (Wälludden), one in Norway (Einmoen), one in Denmark (Casa Nova) and one in Finland (Viikki). The result from FRIM-MAB and from the QRA resulted in the same fire risk ranking, where the Vikki building had the lowest risk and the Casa Nova building the highest. The main conclusions that can be drawn from this analysis is that the Index Method ranks the buildings analysed in the same order as the very different QRA method. This indicates a certain validity and shows that the Index Method can be a very useful tool, although no proof of validity can be given. More work is recommended, where existing buildings are analysed and the method developed further. Evaluation of a Fire Risk Index Method for Multi-storey Apartment Buildings Summary Evaluation of a Fire Risk Index Method for Multi-storey Apartment Buildings Table of contents Table of contents 1 INTRODUCTION............................................................................................................................4 1.1 BACKGROUND.............................................................................................................................4 1.2 OVERVIEW OF THIS REPORT........................................................................................................4 2 METHODOLOGY...........................................................................................................................6 2.1 GENERAL....................................................................................................................................6 2.2 STANDARD QRA.........................................................................................................................7 2.3 DIFFICULTIES USING SUGGESTED TOOLS ON A MEDIUM-RISE APARTMENT BUILDING..................7 3 APARTMENT BUILDINGS ANALYSED..................................................................................10 3.1 GENERAL QUALITATIVE DESIGN REVIEW (QDR).....................................................................10 3.2 SPECIFIC ON EACH BUILDING.....................................................................................................11 4 EVENTS IN THE EVENT TREE.................................................................................................14 4.1 INITIAL FIRE LOCATION?...........................................................................................................14 4.2 FLAMING FIRE?.........................................................................................................................14 4.3 FIRE DETECTED AUTOMATICALLY?...........................................................................................14 4.4 OCCUPANT SUPPRESSING?........................................................................................................15 4.5 SPRINKLER FAILURE?................................................................................................................15 4.6 DOOR OPEN?.............................................................................................................................15 4.7 LOCATION OF OCCUPANTS?.......................................................................................................15 4.8 LEVEL?.....................................................................................................................................16 4.9 FLASHOVER AND SPREAD?........................................................................................................16 4.10 ASLEEP?....................................................................................................................................17 5 RESULTS FROM THE STANDARD QRA.................................................................................18 5.1 SENSITIVITY ANALYSIS.............................................................................................................19 6 INDEX METHOD VERSION 1.2.................................................................................................20 6.1 GENERAL..................................................................................................................................20 6.2 THREE DIFFERENT RISK INDICES...............................................................................................20 6.3 RESULTS...................................................................................................................................22 7 COMPARISON BETWEEN INDEX METHOD AND STANDARD QRA..............................24 8 CONCLUSIONS.............................................................................................................................26 REFERENCES.....................................................................................................................................28 Appendix A Evacuation calculations...............................................................................................................30 Appendix B HAZARD scenario......................................................................................................................32 Appendix C Event trees for analysed buildings...............................................................................................34 Appendix D Full version of Index Method.......................................................................................................38 Appendix E Detailed parameter definitions.....................................................................................................58 Appendix F Index Method results....................................................................................................................60 Appendix G Comments given on using the Index Method...............................................................................62 Appendix H Comparison with concrete building.............................................................................................64