Guideline on Structural Fire Engineering Part I- Fire Scenarios and Calculation of Temperature Under Fire Struct

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Page 1 of 87 Page 1 of 87

SEB GUIDELINES

SEBGL – OTH6

Guideline on Structural Fire Engineering

Part I: Fire Sce

Part I: Fire Scenarios and Calculation of Temperature under Fire

narios and Calculation of Temperature under Fire

Structural Engineering Branch

Architectural Services Department

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Page 2 of 87 Page 2 of 87 CONTENTS CONTENTS Content Page Content Page 1. Introduction 1. Introduction………..……... 1………..……... 1 2.

2. Fire Safety Codes in Hong KongFire Safety Codes in Hong Kong……… 8……… 8

3.

3. Fire Fire Safety Safety Engineering Engineering and and Structural Structural Fire Fire EngineeringEngineering ……….. 10 ……….. 10

4.

4. Prescriptive Prescriptive and and Alternative Alternative ApproachesApproaches……….…....……….….... 1212

5.

5. General General Principles Principles of of Structural Structural Fire Fire Engineering Engineering ApproachApproach……….... 17………....17

6.

6. Applicability Applicability of of Structural Structural Fire Fire Engineering Engineering ApproachApproach………...18………...18

7.

7. Typical Fire ScenariosTypical Fire Scenarios……….……... 23……….……... 23

8.

8. Fire Fire ModellingModelling………..…... 26………..…... 26

9.

9. Design Design FireFire ……….….. 29……….….. 29

10.

10. Temperature Temperature of of Structural Structural ElementsElements ……….…...……….…... 4848

11.

11. Thermal Thermal Actions Actions for for External External MemberMember ………... ………... 4949

12.

12. Engaging Engaging Fire Fire Engineering Engineering ConsultantsConsultants ………... 61………... 61

13.

13. Design Design ExamplesExamples………...………... 6262

14. References

14. References………....……….... 8585

Annex

Annex A A Sample Sample Clauses Clauses in in Engaging Engaging Structural Structural Fire Fire Engineering Engineering ConsultantConsultant

Copyright and Disclaimer of Liability Copyright and Disclaimer of Liability

This Guideline or any part of it shall not be reproduced, copied or transmitted in any This Guideline or any part of it shall not be reproduced, copied or transmitted in any form

form or or by by any any means, means, electronic electronic or or mechanical, mechanical, including including photocopying, photocopying, recording, recording, oror any information storage and retrieval system, without the written permission from any information storage and retrieval system, without the written permission from Architectural Services Department.

Architectural Services Department. Moreover, this Guideline Moreover, this Guideline is intended fis intended for theor the internalinternal use of the staff in Architectural Services Department only, and should not be relied on by use of the staff in Architectural Services Department only, and should not be relied on by any third party.

any third party. No liability is No liability is therefore undertaken therefore undertaken to any third to any third party. party. While everWhile every efforty effort has been made to ensure the accuracy and completeness of the information contained in has been made to ensure the accuracy and completeness of the information contained in this Guideline at the time of publication, no guarantee is given nor responsibility taken by this Guideline at the time of publication, no guarantee is given nor responsibility taken by Architectural

Architectural Services Services Department Department for for errors errors or or omissions omissions in in it. it. The The information information isis provided

provided solely solely on on the the basis basis that that readers readers will will be be responsible responsible for for making making their their ownown assessment or interpretation of the information. Readers are advised to verify all relevant assessment or interpretation of the information. Readers are advised to verify all relevant representation, statements and information with their own professional knowledge. representation, statements and information with their own professional knowledge. Architectural Services Department accepts no

Architectural Services Department accepts no liability for any liability for any use of the use of the said informationsaid information and data or r

and data or reliance placed on eliance placed on it (including the formulae and it (including the formulae and data). data). Compliance withCompliance with this Guideline does not itself confer immunity from legal obligations.

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Page 3 of 87 Page 3 of 87 1.

1. IntroductionIntroduction

1.1

1.1 There has There has been a been a large body large body of worof work written k written on thon the subject e subject of perfoof performancermance based

based structural fire structural fire engineering. Unfortunately, most engineering. Unfortunately, most of this of this information isinformation is scattered throughout technical journals from different countries and scattered throughout technical journals from different countries and organizations, and

organizations, and not easily not easily accessible to accessible to the practicing the practicing engineer. engineer. TheThe purposes

purposes of of this this Guideline Guideline are are therefore therefore to to provide provide project project officers officers in in ourour Department:

Department: a)

a) background information background information on the behaviour oon the behaviour of fire;f fire; b)

b) the structural behaviour of structural steel, reinforced concrete,the structural behaviour of structural steel, reinforced concrete, composite structure and timber at elevated te

composite structure and timber at elevated te mperature;mperature; c)

c) list of design references; andlist of design references; and d)

d) design examples,design examples,

when a structural fire engineering study is required for the design of when a structural fire engineering study is required for the design of structural members under fire.

structural members under fire. 1.2

1.2 This This set set of of Guideline Guideline is is divided divided into into two two parts:parts: a)

a) Part IPart I will describe the fire scenarios development in a fire, the will describe the fire scenarios development in a fire, the techniques in fire modelling and the procedures to calculate the techniques in fire modelling and the procedures to calculate the maximum gas

maximum gas temperature and temperature and duration oduration of a fire. f a fire. Design examplesDesign examples will be given to

will be given to demonstrate the techndemonstrate the techniques. iques. The gas temperThe gas temperature is anature is an important parameter in deciding whether a structural fire engineering important parameter in deciding whether a structural fire engineering study is required

study is required. . For example, iFor example, if the computef the computed gas temperaturd gas temperature ise is high enough such that the temperature of the structural steel exceeds high enough such that the temperature of the structural steel exceeds 550

550ooC, passive fire protection will likely be required, and hence aC, passive fire protection will likely be required, and hence a structural fire engineering study may not be warranted in the detail structural fire engineering study may not be warranted in the detail design stage.

design stage. b)

b) Part IIPart II will first describe the heat transfer mechanisms from the fire to will first describe the heat transfer mechanisms from the fire to the structural members, and the procedures to obtain the temperature the structural members, and the procedures to obtain the temperature of the m

of the members during embers during a fire. a fire. It will then It will then focus on thfocus on the structurale structural design of steel structure, reinforced concrete, composite structure and design of steel structure, reinforced concrete, composite structure and timber exposed to fire, which will again be followed by design timber exposed to fire, which will again be followed by design examples.

examples. 1.3

1.3 Resources Resources on on Fire Fire Safety Safety EngineeringEngineering

Project officers should note that this set of Guideline only provides an Project officers should note that this set of Guideline only provides an overview on analysis and design of

overview on analysis and design of structural elementsstructural elements exposed to fire, and exposed to fire, and are therefore advised to conduct their own research on the details and are therefore advised to conduct their own research on the details and updated information.

updated information. The following list the resourThe following list the resources that may be helpful:ces that may be helpful: Hong Kong SAR

Hong Kong SAR Government PublicationsGovernment Publications

For private buildings, approval of fire safety designs and inspection of the For private buildings, approval of fire safety designs and inspection of the buildings

buildings upon upon completion completion are are held held responsible responsible by by two two GovernmentGovernment departments – Buildings Department and Fire Services Department. The departments – Buildings Department and Fire Services Department. The building

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against all fire aspects for approval. As government buildings are exempted against all fire aspects for approval. As government buildings are exempted from the

from the Buildings Ordinance Buildings Ordinance, the design of these government buildings in, the design of these government buildings in theory are not necessary submitted to Buildings Department; yet, our theory are not necessary submitted to Buildings Department; yet, our Department is always required to submit to Fire Services Department. The Department is always required to submit to Fire Services Department. The requirements and installation of fire protection systems are monitored by the requirements and installation of fire protection systems are monitored by the Fire Services Department. Buildings Department has issued the following Fire Services Department. Buildings Department has issued the following codes governing different aspects for fire safety:

codes governing different aspects for fire safety: 1.

1. Buildings Department (1996),Buildings Department (1996), Code of Practice for the Provision ofCode of Practice for the Provision of Means of Escape 1996

Means of Escape 1996 (Hong Kong: Building Authority). (Hong Kong: Building Authority). 2.

2. Buildings Department (1996),Buildings Department (1996), Code of Practice for Fire ResistingCode of Practice for Fire Resisting Construction 1996

Construction 1996 (Hong Kong: Building Authority). (Hong Kong: Building Authority). 3.

3. Buildings Department Buildings Department (2004),(2004), Code of Practice for Means of Access forCode of Practice for Means of Access for Firefighting and Rescue 2004

Firefighting and Rescue 2004 (Hong Kong: Buildings Department). (Hong Kong: Buildings Department). These three codes have just been replaced by the following unified code: These three codes have just been replaced by the following unified code: Buildings Department (2011),

Buildings Department (2011), Code of Practice for Fire Safety in BuildingsCode of Practice for Fire Safety in Buildings 2011

2011 (Hong Kong: Buildings Department). (Hong Kong: Buildings Department). This unified code consists of the following parts: This unified code consists of the following parts:

Part

Part A A - - IntroductionIntroduction Part

Part B B - - Means Means of of EscapeEscape Part

Part C C - - Fire Fire Resisting Resisting ConstructionConstruction Part

Part D D - - Means Means of of AccessAccess Part

Part E E - Fire - Fire Properties Properties of of Building Building Elements Elements and and ComponentsComponents Part

Part F F - Fire - Fire Safety Safety Maintenance Maintenance and and ManagementManagement Part

Part G G - - Fire Fire Safety Safety GuidelinesGuidelines

There is an annex “Guidelines from Licensing Authorities” to the unified There is an annex “Guidelines from Licensing Authorities” to the unified code.

code.

Fire Services Department issued the following two codes on active fire Fire Services Department issued the following two codes on active fire protection system or fire services installation:

protection system or fire services installation: 1.

1. Fire Services Department (2005),Fire Services Department (2005), Code of Practice for Minimum FireCode of Practice for Minimum Fire Service Installations and Equipment

Service Installations and Equipment (Hong Kong: Fire Services(Hong Kong: Fire Services Department).

Department). 2.

2. Fire Services Department (2005),Fire Services Department (2005), Code of Practice for Inspection and Code of Practice for Inspection and Testing and Maintenance of Installations and Equipment

Testing and Maintenance of Installations and Equipment (Hong Kong: (Hong Kong: Fire Services Department).

Fire Services Department). Professional Associations Professional Associations 1.

1. The Society of Fire Protection Engineers (SFPE) (The Society of Fire Protection Engineers (SFPE) ( www.sfpe.org/www.sfpe.org/) is the) is the professional

professional association association of of the the US US for for fire fire protection protection engineering, engineering, andand published

published the the following following comprehensive comprehensive text text describing describing the the fire fire sciencescience that underpins fire protection engineering, and providing information in that underpins fire protection engineering, and providing information in the areas of the fundamental science and engineering concepts that are the areas of the fundamental science and engineering concepts that are applied in fire protection engineering, fire dynamics, fire hazard applied in fire protection engineering, fire dynamics, fire hazard calculations, design calculations, and fire risk analysis:

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DiNenno, P J et al (eds.) (2002),

DiNenno, P J et al (eds.) (2002), SFPE Handbook of FireSFPE Handbook of Fire Protection

Protection Engineering Engineering (Bethesda, Maryland: Society of Fire (Bethesda, Maryland: Society of Fire Protection Engineers, 3

Protection Engineers, 3rdrd ed). ed). 2.

2. British Standards Institution (British Standards Institution (www.bsi.org.uk www.bsi.org.uk ) published the following) published the following standards on the principles of structural fire engineering and the design standards on the principles of structural fire engineering and the design of structural members for different materials:

of structural members for different materials: BSI (2003),

BSI (2003), BS BS 5950-8: Structural 5950-8: Structural Use Use of of Steelwork Steelwork in in Building Building –– Part 8: Code of Practice for Fire Resistant Design

Part 8: Code of Practice for Fire Resistant Design (London: British (London: British Standards Institution).

Standards Institution). BSI (2002),

BSI (2002), Eurocode 1: Basis of Design and Actions on Structures, Eurocode 1: Basis of Design and Actions on Structures, Part 1.2: Actions on Structures — Actions on Structures Exposed to Part 1.2: Actions on Structures — Actions on Structures Exposed to Fire (BS EN 1991-1-2

Fire (BS EN 1991-1-2)) (London: British Standards Institution).(London: British Standards Institution). BSI (2005),

BSI (2005), Eurocode 2: Eurocode 2: Design Design of of Concrete Concrete Structures, Structures, Part Part 1.2:1.2: General Rules, Structural Fire Design (BS EN 1992-1-2)

General Rules, Structural Fire Design (BS EN 1992-1-2) (London: (London: British Standards Institution).

British Standards Institution). BSI (2003),

BSI (2003), Eurocode Eurocode 3: 3: Design Design of of Steel Steel Structures, Structures, Part Part 1.2:1.2: General Rules, Structural Fire Design (BS EN1993-1-2)

General Rules, Structural Fire Design (BS EN1993-1-2) (London: (London: British Standards Institution)

British Standards Institution) BSI (2005),

BSI (2005), Eurocode 4: Eurocode 4: Design Design of of Composite Composite Steel Steel and and ConcreteConcrete Structures, Part 1.2: Structural Fire Design (BS EN 1994-1-2) Structures, Part 1.2: Structural Fire Design (BS EN 1994-1-2) (London: British Standards Institution).

(London: British Standards Institution). BSI (2004),

BSI (2004), Eurocode Eurocode 5: 5: Design Design of of Timber Timber Structures, Structures, Part Part 1.2:1.2: General Rules, Structural Fire Design (BS EN 1995-1-2)

General Rules, Structural Fire Design (BS EN 1995-1-2) (London: (London: British Standards Institution).

British Standards Institution). BSI (2001),

BSI (2001), BS BS 7974: 7974: Application Application of of Fire Fire Safety Safety EngineeringEngineering Principles to

Principles to the the Design of Design of Buildings – Buildings – Code of Code of PracticePractice (London:(London: British Standards Institution).

British Standards Institution). BS

BS 79747974 only gives a framework for the application of fire safety only gives a framework for the application of fire safety engineering principles to the design of buildings. It is supported by engineering principles to the design of buildings. It is supported by the

the PD PD 7974-07974-0 toto -7-7 series of Published Documents that containseries of Published Documents that contain guidance and information on how to undertake detailed analysis of guidance and information on how to undertake detailed analysis of specific aspects of fire safety engineering in buildings. The specific aspects of fire safety engineering in buildings. The following parts are relevant to s

following parts are relevant to structural fire engineering:tructural fire engineering: a)

a) Part 0: Guide to design framework and fire safety engineeringPart 0: Guide to design framework and fire safety engineering procedures

procedures b)

b) Part 1: Initiation and development of fire within the enclosurePart 1: Initiation and development of fire within the enclosure of origin;

of origin; c)

c) Part 3: Structural response and fire spread beyond theenclosurePart 3: Structural response and fire spread beyond theenclosure of origin.

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3.

3. The Institution of Structural Engineers (The Institution of Structural Engineers (www.istructe.org.uk www.istructe.org.uk ) published) published the following two comprehensive texts providing guidance on the the following two comprehensive texts providing guidance on the behaviour and structural design of structural elements of all the principal behaviour and structural design of structural elements of all the principal

construction materials: construction materials: IStructE (2003),

IStructE (2003), Introduction Introduction to to the the Fire Fire Safety Safety Engineering Engineering ofof Structures

Structures (London: IStructE). (London: IStructE). IStructE (2007),

IStructE (2007), Guide to the Advanced Fire Safety Engineering ofGuide to the Advanced Fire Safety Engineering of Structures

Structures (London: IStructE).(London: IStructE). 4.

4. The Association for Specialist Fire Protection (www.asfp.org.uk) is aThe Association for Specialist Fire Protection (www.asfp.org.uk) is a trade association representing UK’s manufacturers and installers of trade association representing UK’s manufacturers and installers of passive

passive fire fire protection protection products, products, and and published published the the following following bookbook (commonly known as the “

(commonly known as the “Yellow Book Yellow Book ”) on common proprietary”) on common proprietary materials and systems as passive fire protection products:

materials and systems as passive fire protection products: ASFP (2004),

ASFP (2004), Fire Fire Protection Protection for for Structural Structural Steel Steel in in BuildingsBuildings (Aldershot: Association for Specialist Fire Protection, 3

(Aldershot: Association for Specialist Fire Protection, 3rdrd ed). ed). Publications and Reference Books

Publications and Reference Books 1.

1. Lennon, T (2011),Lennon, T (2011), Structural Fire EngineeringStructural Fire Engineering (London : Thomas(London : Thomas Telford) - This updated book provides comprehensive but concise Telford) - This updated book provides comprehensive but concise summary of the principles of

summary of the principles of structural fire engineering and summarizesstructural fire engineering and summarizes EN1991 Part 1.2

EN1991 Part 1.2,, EN1992 Part 1.2 EN1992 Part 1.2,, EN1993 Part 1.2 EN1993 Part 1.2 and and EN1994 Part EN1994 Part 1.2

1.2 on structural d on structural design of concrete, esign of concrete, steel, composite steel, composite structures understructures under fire.

fire. The booThe book also k also provides exprovides examples on amples on the structural the structural design.design. 2.

2. Lennon, T et al (2007),Lennon, T et al (2007), Designers’ Designers’ Guide Guide to to EN EN 1991-1-2, 1991-1-2, 1992-1-2,1992-1-2, 1993-1-2 and EN 1994-1-2

1993-1-2 and EN 1994-1-2 (London : Thomas Telford) - This book(London : Thomas Telford) - This book provides guide to

provides guide to EN1991 Part 1.2 EN1991 Part 1.2,, EN1992 Part 1.2 EN1992 Part 1.2,, EN1993 Part 1.2 EN1993 Part 1.2 and

and EN1994 EN1994 Part Part 1.21.2 on structural design examples of concrete, steel, on structural design examples of concrete, steel, composite

composite structures structures under under fire.fire. 3.

3. Wang, Y C (2002),Wang, Y C (2002), Steel and Composite Structures, Behaviour andSteel and Composite Structures, Behaviour and Design

Design for for Fire Fire SafetySafety (London: Spon Press) – This book explains the (London: Spon Press) – This book explains the fire behaviour, heat transfer in construction elements and structural fire behaviour, heat transfer in construction elements and structural analysis, and describes the behaviour of steel and composite structures analysis, and describes the behaviour of steel and composite structures in fire.

in fire. 4.

4. Franssen, J M and Real, P V (2010),Franssen, J M and Real, P V (2010), Fire Fire Design Design of of Steel Steel StructuresStructures (Berlin: ECCS) - This updated text explains and illustrates the rules that (Berlin: ECCS) - This updated text explains and illustrates the rules that are given in the

are given in the Eurocode Eurocode 11 for designing steel structures subjected to for designing steel structures subjected to fire by describing the

fire by describing the design process together with worked examples.design process together with worked examples. 5.

5. Law, M and O’Brien, T (1989),Law, M and O’Brien, T (1989), Fire Safety Fire Safety of Bare of Bare External StructuralExternal Structural Steel

Steel (Ascot: SCI) – Although this book is old, it is a classic in (Ascot: SCI) – Although this book is old, it is a classic in structural fire engineerin

structural fire engineering. g. This book exThis book examines flame proamines flame projection fromjection from openings in building facades and heat transfer calculation methods of openings in building facades and heat transfer calculation methods of fires to external unprotected steel

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6.

6. Newman, Newman, G G M M (1990),(1990), Fire Fire and and Steel Steel Construction: Construction: the the Behaviour Behaviour ofof Steel Portal Frames in Boundary Conditions

Steel Portal Frames in Boundary Conditions (Ascot: The Steel (Ascot: The Steel Construction Institute, 2

Construction Institute, 2ndnd ed) – This book describes the behaviour of ed) – This book describes the behaviour of

structural steel portal frames in fire.

Design and Analysis Tools Design and Analysis Tools

There are computer softwares available that can be used to simulate fires in There are computer softwares available that can be used to simulate fires in buildings.

buildings. Common available sofwCommon available sofwares (some being free for use) incluares (some being free for use) include:de: SAFIR (

SAFIR (www.argenco.ulg.ac.be/logiciels/SAFIR/www.argenco.ulg.ac.be/logiciels/SAFIR/), ), aa computercomputer

software developed at the University of Liege for the simulation of the

behaviour of building stru

behaviour of building structures subjected to fire.ctures subjected to fire.

Fire Dynamics Simulator (FDS) (

Fire Dynamics Simulator (FDS) (www.fire.nist.gov/fds/index.htmlwww.fire.nist.gov/fds/index.html), a), a

computational fluid dynamics (CFD) model of fire-driven fluid flow

for heat transport from fires developed by National Institute of

Standards and Technology, the US Department of Commerce.

PyroSim (

PyroSim (www.thunderheadeng.com/pyrosim/www.thunderheadeng.com/pyrosim/), a computer software), a computer software that can simulate temperature of a

that can simulate temperature of a building during a fire.building during a fire.

Consolidated Model of Fire and Smoke Transport (CFAST) Consolidated Model of Fire and Smoke Transport (CFAST) ((www.nist.gov/el/fire_research/cfast.cfmwww.nist.gov/el/fire_research/cfast.cfm), a computer developed by), a computer developed by the National Institute of Standards and Technology (NIST) of the US the National Institute of Standards and Technology (NIST) of the US Department of Commerce, and is free software that use a two-zone Department of Commerce, and is free software that use a two-zone fire model used to calculate the evolving distribution of smoke, fire fire model used to calculate the evolving distribution of smoke, fire gases and temperature throughout compartments of a

gases and temperature throughout compartments of a building during abuilding during a fire.

fire.

OZONE (

OZONE (www.ulg.ac.bewww.ulg.ac.be), a free computer software that combines a), a free computer software that combines a two zone model and a one zone model to predict the temperature and two zone model and a one zone model to predict the temperature and time relationship before and after flashover in a compartment. It can time relationship before and after flashover in a compartment. It can also calculate the temperature of a steel section under that also calculate the temperature of a steel section under that compartment fire, and evaluate the fire resistance of simple steel compartment fire, and evaluate the fire resistance of simple steel elements according to

elements according to Eurocode 3 Eurocode 3.. Academic

Academic InstitutInstitutionsions

The University of Manchester holds the following site providing free The University of Manchester holds the following site providing free information on structural fire engineering (including the theories, information on structural fire engineering (including the theories, prescriptive

prescriptive and and alternative alternative measures measures in in fire fire protection, fprotection, fire ire behaviour, behaviour, firefire modeling, and structural design):

modeling, and structural design):

http://www.mace.manchester.ac.uk/project/research/structures/strucfire/

This site was developed under the direction of a Steering Group with This site was developed under the direction of a Steering Group with representatives from the Institution of Structural Engineers, Building representatives from the Institution of Structural Engineers, Building Control of the City of London, Arup Fire, the Concrete Centre, Corus, Control of the City of London, Arup Fire, the Concrete Centre, Corus,

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British Constructional Steelwork Association, Concrete Block Association, British Constructional Steelwork Association, Concrete Block Association, BRE, etc.

BRE, etc.

Department of Civil and Natural Resources Engineering of the University of Department of Civil and Natural Resources Engineering of the University of Canterbury, NZ also develops the following site publishing their research Canterbury, NZ also develops the following site publishing their research findings and containing links to the

findings and containing links to the various sofwares for fire modeling:various sofwares for fire modeling: http://www.civil.canterbury.ac.nz/fire/firehome.shtml

http://www.civil.canterbury.ac.nz/fire/firehome.shtml

2.

2. Fire Safety Codes in Hong KongFire Safety Codes in Hong Kong

2.1

2.1 A properly designed fire safety system of a building greatly reduces the lossA properly designed fire safety system of a building greatly reduces the loss of life and property during a fire, or in the neighborhood of the building. of life and property during a fire, or in the neighborhood of the building. Nearly

Nearly all all building building regulations regulations and/or and/or codes codes specify specify requirements requirements forfor buildings to

buildings to be designed be designed in such in such a a way that way that they exhibit they exhibit an acceptable an acceptable levellevel of perform

of performance in ance in the evthe event of ent of fire. fire. Similar requireSimilar requirements have ments have beenbeen specified as Regulations 41(1), 41A, 41B, 41C and 41D in the

specified as Regulations 41(1), 41A, 41B, 41C and 41D in the Building Building (Planning) Regulations

(Planning) Regulations and Regulation 90 of the and Regulation 90 of the Building Building (Construction)(Construction) Regulations

Regulations. . Over Over the ythe years, Buears, Buildings Depildings Department and artment and Fire SFire Serviceservices Department have issued the following codes on the performance Department have issued the following codes on the performance requirements complying the statutory requirements:

requirements complying the statutory requirements: a)

a) thethe Code of Practice for the Provision of Means of Escape 1996 Code of Practice for the Provision of Means of Escape 1996 (the (the “MOE Code”);

“MOE Code”); b)

b) thethe Code of Practice for Fire Resisting Construction 1996 Code of Practice for Fire Resisting Construction 1996 (the “FRC (the “FRC Code”);

Code”); c)

c) thethe Code of Practice for Means of Access for Firefighting and RescueCode of Practice for Means of Access for Firefighting and Rescue 2004

2004 (the “MOA Code”); (the “MOA Code”); d)

d) thethe Code of Practice for Minimum Fire Service Installations andCode of Practice for Minimum Fire Service Installations and Equipment

Equipment ; and; and e)

e) thethe Code of Practice for Inspection and Testing and Maintenance of Code of Practice for Inspection and Testing and Maintenance of Installations and Equipment

Installations and Equipment .. 2.2

2.2 The MOE CodThe MOE Code sets out the sets out the requirements oe requirements on the provn the provisions for theisions for the protection of

protection of buildings from buildings from the effect the effect of fire of fire by providing by providing adequate meansadequate means of escape in the event of fire and other emergency. This is achieved by of escape in the event of fire and other emergency. This is achieved by recommending the assessment of population density of floor, the type of recommending the assessment of population density of floor, the type of usage, the minimum number of escape routes and their widths, the usage, the minimum number of escape routes and their widths, the maximum travel distance, the construction of escape routes and appropriate maximum travel distance, the construction of escape routes and appropriate signage etc.

signage etc. The MOA Code The MOA Code seeks to achieve thseeks to achieve the objective of assisting ie objective of assisting inn firefighting and in saving life of people in buildings by ensuring adequate firefighting and in saving life of people in buildings by ensuring adequate access for firefighting personnel in case of fire and other emergencies. This access for firefighting personnel in case of fire and other emergencies. This is achieved by recommending adequate emergency vehiclur access, access is achieved by recommending adequate emergency vehiclur access, access staircases, fireman’s lifts as well as fire fighting and rescue stairways staircases, fireman’s lifts as well as fire fighting and rescue stairways according to the area, us

according to the area, use and height of buildings. e and height of buildings. The FRC Code proThe FRC Code providesvides guidance on compliance with the requirements for fire resisting construction guidance on compliance with the requirements for fire resisting construction stipulated in Part XV of the

stipulated in Part XV of the Building (Construction) Regulations Building (Construction) Regulations . It sets out. It sets out the provisions on protection of buildings from effects of fire by inhibiting the provisions on protection of buildings from effects of fire by inhibiting the spread of fire and

the spread of fire and by ensuring the integrity of structural elements by ensuring the integrity of structural elements and theand the overall stability of buildings. This is achieved by specifying a minimum fire overall stability of buildings. This is achieved by specifying a minimum fire resistance period (or “fire resistance rating” in the FS Code) in accordance resistance period (or “fire resistance rating” in the FS Code) in accordance

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with the type of use, the maximum compartmentation area or volume and with the type of use, the maximum compartmentation area or volume and requirements on protection of adjoining buildings and separation between requirements on protection of adjoining buildings and separation between different uses and occupancies (

different uses and occupancies ( Table 1Table 1).). Table 1

Table 1 Fire Resistance RatinFire Resistance Rating for Premises of g for Premises of Different OccupanDifferent Occupanciescies Class

Class Use Use Compartment Compartment VolumeVolume Fire ResistanceFire Resistance Rating Rating 1 Domestic 1 Domestic No limit No limit 60 mins. 60 mins. 2

2 Hotel Hotel bedroombedroom 3

3 InstitInstitutionutional al Not Not exceedexceeding ing 2500 2500 mm 4

4 Commercial Commercial Not Not exceeding exceeding 10500 10500 mm22 60 mins.60 mins.

5 5 Place of public Place of public entertainment entertainment Educational Educational establishments establishments Not exceeding 2500 m

Not exceeding 2500 m22 60 mins.60 mins.

Exceeding 2500 m Exceeding 2500 m22 but not exceeding 1050

but not exceeding 10500 m0 m22 120 mins.120 mins. 6b

6b Bulk storage andBulk storage and warehouse

warehouse

Not exceeding 28000 m Not exceeding 28000 m andand

10500 m

10500 m22 120 mins120 mins

7

7 Car Car parking parking Not Not exceeding exceeding 10,500 10,500 m m 60 60 mins.mins. ((SourceSource: modified from FS Code Part : modified from FS Code Part C)C)

2.2

2.2 FS FS CodeCode

Buildings Department has just issued the

Buildings Department has just issued the Code of Practice for Fire Safety inCode of Practice for Fire Safety in Buildings

Buildings 20112011 (the “FS Code”), which consolidates and replaces the (the “FS Code”), which consolidates and replaces the requirements of the MOE Code (now Part B of the FS Code), the FRC Code requirements of the MOE Code (now Part B of the FS Code), the FRC Code (now Part C of the FS Code) and the MOA Code (now Part D of the FS (now Part C of the FS Code) and the MOA Code (now Part D of the FS Code).

Code). As the FS Code has alrAs the FS Code has already replaced these threeady replaced these three codes, reference ine codes, reference in this set of Guideline will be based on the FS Code

this set of Guideline will be based on the FS Code. . The objectives of the FSThe objectives of the FS Code are:

Code are: 1)

1) to allow occupants to escape to allow occupants to escape during fire;during fire; 2)

2) to ensure that the fire and to ensure that the fire and smoke would not spread beyond the room ofsmoke would not spread beyond the room of origin;

origin; 3)

3) to ensure structural integrity of the structural elements for a specificto ensure structural integrity of the structural elements for a specific period of time;

period of time; 4)

4) to prevent the outbreak of fire, to abate fire hazards, to suppress fire,to prevent the outbreak of fire, to abate fire hazards, to suppress fire, to prevent loss of property; and

to prevent loss of property; and 5)

5) to ensure structural integrity for fire fighters to ensure structural integrity for fire fighters to perform their duties.to perform their duties. 2.3 The

2.3 The Code of Practice for Minimum Fire Service Installations andCode of Practice for Minimum Fire Service Installations and Equipment

Equipment and theand the Code of Practice for Inspection and Testing and Code of Practice for Inspection and Testing and Maintenance

Maintenance of of Installations Installations and and Equipment Equipment are enforced by the Fire are enforced by the Fire Services Department. The first one provides the minimum fire protection Services Department. The first one provides the minimum fire protection systems required for different types of premises and the specifications for systems required for different types of premises and the specifications for various fire service installations and equipment for meeting the statutory various fire service installations and equipment for meeting the statutory requirements. The second one is to indicate the type and nature of requirements. The second one is to indicate the type and nature of

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inspections and tests which installations and equipment must normally pass, inspections and tests which installations and equipment must normally pass, and provides guidance on administrative procedures for application and for and provides guidance on administrative procedures for application and for inspection and testing and how these systems can be appropriately inspection and testing and how these systems can be appropriately maintained and inspected throughout the building life.

maintained and inspected throughout the building life.

3.

3. Fire Safety Fire Safety Engineering Engineering and and Structural Structural Fire Fire EngineeringEngineering 3.1

3.1 The IThe Institution nstitution of of Fire Fire Engineers Engineers of of the the UK UK ((www.ife.org.uk/www.ife.org.uk/) defines “fire) defines “fire engineering” (or sometimes termed as “fi

engineering” (or sometimes termed as “fire safety engineering”) as:re safety engineering”) as: “the application of scientific and engineering principles, rules

“the application of scientific and engineering principles, rules (Codes),(Codes), and expert judgment, based on an understanding of the phenomena and expert judgment, based on an understanding of the phenomena and effects of fire and of the reaction and behaviour of people to fire, and effects of fire and of the reaction and behaviour of people to fire, to protect people, property and the environment from the destructive to protect people, property and the environment from the destructive effects of fire.”

effects of fire.”

Similarly, the Department of Civil and Natural Resources Engineering of the Similarly, the Department of Civil and Natural Resources Engineering of the University of Canterbury, NZ (

University of Canterbury, NZ ( http://www.canterbury.ac.nz/http://www.canterbury.ac.nz/) defines “fire) defines “fire engineering” as:

engineering” as:

“the art and science of designing buildings and facilities for life safety “the art and science of designing buildings and facilities for life safety and property protection in the event of an

and property protection in the event of an unwanted fire.”unwanted fire.”

Fire engineering is, therefore, a broad term embracing a multi-disciplinary Fire engineering is, therefore, a broad term embracing a multi-disciplinary approach (involving architects, building services engineers, structural approach (involving architects, building services engineers, structural engineers, insurance companies, etc) to determine fire safety strategy for engineers, insurance companies, etc) to determine fire safety strategy for buildings

buildings under under fire fire conditions, conditions, including including the the control control of of fire fire spread spread andand addressing structural stability.

addressing structural stability. 3.2

3.2 There are two There are two broad aspects in broad aspects in the fire enthe fire engineering: fire prgineering: fire preventionevention (designed to reduce the chance of a fire occurring) and fire protection (designed to reduce the chance of a fire occurring) and fire protection (designed to mitigate th

(designed to mitigate the effects of a e effects of a fire should it fire should it nevertheless occur). nevertheless occur). FireFire prevention

prevention includes includes eliminating eliminating or or protecting protecting possible possible ignition ignition sources sources inin order to prev

order to prevent a fire fent a fire from occurring. rom occurring. Fire protection mFire protection measures may beeasures may be passive

passive or or active. active. Active Active measures measures include include detection detection and and alarm, alarm, firefire extinction, and

extinction, and smoke smoke control. control. Passive measurPassive measures include es include structural firstructural firee protection, layout of escape routes, fire

protection, layout of escape routes, fire brigade access routes, and control ofbrigade access routes, and control of combustible

combustible materials materials of of construction. construction. The The term term “fire “fire protectionprotection engineering” therefore comprises active and passive ways of providing engineering” therefore comprises active and passive ways of providing satisfactory protection level to buildings and/or its contents from fires. satisfactory protection level to buildings and/or its contents from fires. Figure 1

Figure 1 shows the role of active and passive fire protection measures shows the role of active and passive fire protection measures during a fire.

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Figure 1

Figure 1 Role of active and pRole of active and passive fire protectioassive fire protection in a firen in a fire 3.3

3.3 “Structural fire “Structural fire engineering” engineering” is a is a special branspecial branch within ch within the fthe fire protectionire protection engineering, and addresses the specific aspects of passive fire protection in engineering, and addresses the specific aspects of passive fire protection in terms of analyzing the thermal effects of fires on buildings and designing terms of analyzing the thermal effects of fires on buildings and designing members for adequate load bearing resistance and to control the spread of members for adequate load bearing resistance and to control the spread of fire.

fire. Figure 2Figure 2 shows the shows the interrelationship of fire engineering, fire protectioninterrelationship of fire engineering, fire protection engineering, and structural fire engineering.

engineering, and structural fire engineering.

Figure 2

Figure 2 Relationship aRelationship among various bmong various branches in fire enginranches in fire engineeringeering 3.4

3.4 Project officers Project officers should thshould therefore note erefore note that the that the term term “fire engineering“fire engineering” (or” (or “fire safety engineering”) embraces all aspects of fire prevention and fire “fire safety engineering”) embraces all aspects of fire prevention and fire protection.

protection. Besides predicting the Besides predicting the performance of structural elements performance of structural elements underunder fire, it also involves the study of the means of escape, smoke control, fire fire, it also involves the study of the means of escape, smoke control, fire spread control, design of sprinkler, alarm, fire-fighting systems, etc. spread control, design of sprinkler, alarm, fire-fighting systems, etc. Structural engineering

Structural engineering design mainly design mainly concerns passive fire concerns passive fire protection. protection. ThisThis Guideline will focus on the structural fire engineering, rather than on the Guideline will focus on the structural fire engineering, rather than on the architectural or BS aspects.

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3.5

3.5 IStructE (2IStructE (2007: 1) 007: 1) states that states that “[t]raditionally, “[t]raditionally, structural structural engineers dengineers did notid not venture into fire design, due to their lack of knowledge of fire behavior …. venture into fire design, due to their lack of knowledge of fire behavior …. Structural fire design brings together the disciplines of structural Structural fire design brings together the disciplines of structural engineering and fire engineering, to allow a performance-based design engineering and fire engineering, to allow a performance-based design approaches to be carried out which can allow more economic, robust, approaches to be carried out which can allow more economic, robust, innovative

innovative and compand complex buildinglex buildings to s to be conbe constructed.” structed.” Professor DProfessor D. J.. J. O’Connor of the Fire Engineering Research Centre of the University of O’Connor of the Fire Engineering Research Centre of the University of Ulster in the ordinary meeting of IStructE of 9 March 1995, once said: “in Ulster in the ordinary meeting of IStructE of 9 March 1995, once said: “in this developing field of [fi

this developing field of [fire] engineering, structural engineers have a uniquere] engineering, structural engineers have a unique opportunity to provide leadership to other building professionals….so that opportunity to provide leadership to other building professionals….so that structural engineers do not restrict their expertise simply to the provision of structural engineers do not restrict their expertise simply to the provision of safety based on passive fire protection, but understand the full complexities safety based on passive fire protection, but understand the full complexities of the life safety and the structural safety issues pertaining to total fire of the life safety and the structural safety issues pertaining to total fire engineering design.”

engineering design.” 4.

4. Prescriptive and Prescriptive and Alternative Alternative ApproachesApproaches 4.1

4.1 There arThere are two e two approaches approaches for for complying complying with thwith the statutory e statutory requirements requirements forfor fire safety, namely:

fire safety, namely: Prescriptive ProvisionsPrescriptive Provisions and and Alternative ApproachAlternative Approach.. 4.2

4.2 Prescriptive ProvisionsPrescriptive Provisions

4.2.1 The simplest approach to satisfy the statutory requirements is to follow 4.2.1 The simplest approach to satisfy the statutory requirements is to follow Prescriptive Provisions in the FS Code, which includes the provisions on Prescriptive Provisions in the FS Code, which includes the provisions on means of escape, emergency vehiclur access, fireman’s lifts, passive means of escape, emergency vehiclur access, fireman’s lifts, passive protection,

protection, etc etc based based on on required required fire fire resistance resistance rating. rating. These These provisionsprovisions aim at providing adequate fire resisting construction to the elements of aim at providing adequate fire resisting construction to the elements of construction of the buildings, providing adequate means of escape, construction of the buildings, providing adequate means of escape, maximum travel distances, and specifying compartmentation within the maximum travel distances, and specifying compartmentation within the building

building and and measures measures for for protection protection of of adjoining adjoining buildings. buildings. However, However, asas these provisions have to account for a wide range of buildings, they cannot these provisions have to account for a wide range of buildings, they cannot provide

provide the the optimum optimum solution solution in in terms terms of of life life safety, safety, property property protection,protection, cost-effective fire protection and operational requirements (

cost-effective fire protection and operational requirements ( PD PD 7974-07974-0).). Perhaps, the main deficiency of Prescriptive Provisions is that they do not Perhaps, the main deficiency of Prescriptive Provisions is that they do not meet the fire safety for complex buildings.

meet the fire safety for complex buildings. BS BS PD PD 7974-07974-0 quotes the quotes the following conclusion of the Cullen report into the Pier Alpha offshore following conclusion of the Cullen report into the Pier Alpha offshore disaster (in which 167 of the 229 people onboard on the oil platform in disaster (in which 167 of the 229 people onboard on the oil platform in North Sea were killed) for the P

North Sea were killed) for the Prescriptive Provisions:rescriptive Provisions: “Many regulations are unduly restrictive

“Many regulations are unduly restrictive in that they are of a in that they are of a type thattype that impose ‘solutions’ rather than ‘objectives’ and are out of date in impose ‘solutions’ rather than ‘objectives’ and are out of date in relation to technological advances.

relation to technological advances. There is a danger thatThere is a danger that compliance takes precedence over wider safety

compliance takes precedence over wider safety considerationsconsiderations.”.” The conclusion highlights the main deficiency of Prescriptive Provisions. The conclusion highlights the main deficiency of Prescriptive Provisions. Other disadvantages include: unable to anticipate all eventualities, unable to Other disadvantages include: unable to anticipate all eventualities, unable to provide

provide an an optimum optimum solutions, solutions, and and unable unable to to meet meet with with the the current current designdesign practice

practice (( BS BS PD PD 7974-07974-0). ). However, However, project oproject officers shofficers should nould note thoute thoughgh with such limitations, Prescriptive Provisions provide an acceptable solution with such limitations, Prescriptive Provisions provide an acceptable solution

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for most buildings with straightforward construction, layout and use,

for most buildings with straightforward construction, layout and use, and areand are therefore adopted in the majority of cases.

therefore adopted in the majority of cases.

4.2.2 The FRC Code (or the FS Code Part C), which applies to elements of 4.2.2 The FRC Code (or the FS Code Part C), which applies to elements of

construction (including structural frame, fire barriers, fixed

construction (including structural frame, fire barriers, fixed lights, fire doors,lights, fire doors, fire shutters or other components, etc) specifies that one or more of the fire shutters or other components, etc) specifies that one or more of the following three criteria to be satisfied (details being specified in Table C2 of following three criteria to be satisfied (details being specified in Table C2 of the FS Code) in a fire:

the FS Code) in a fire: 1)

1) stability, i.e. to avoid collapse stability, i.e. to avoid collapse of load-bearing elements (of load-bearing elements ( Figure 3(a)Figure 3(a)),), 2)

2) integrity, i.e. to resist fire penetration and inhibit spreading (integrity, i.e. to resist fire penetration and inhibit spreading ( FigureFigure 3(b)

3(b)); and); and 3)

3) insulation, i.e. to prevent transfer of excessive heat such that theinsulation, i.e. to prevent transfer of excessive heat such that the unexposed surface of a fire resistant construction should not be heated unexposed surface of a fire resistant construction should not be heated excessively and cause further ignition (

excessively and cause further ignition (Figure 3(c)Figure 3(c)).).

Figure 3

Figure 3 Failure modes of conFailure modes of construction elemstruction elements during fireents during fire ((SourceSource: Wang 2002): Wang 2002)

Similar provisions have been specified in the

Similar provisions have been specified in the Code of Practice for StructuralCode of Practice for Structural Use of Concrete 2004

Use of Concrete 2004 (the “HK Concrete Code”) and (the “HK Concrete Code”) and Code of Practice forCode of Practice for Structural Use of Steel 2005

Structural Use of Steel 2005 (the “HK Steel Code”) issued by Buildings (the “HK Steel Code”) issued by Buildings Department.

Department.

4.2.3 To meet the stability criterion, a building element must perform its load 4.2.3 To meet the stability criterion, a building element must perform its load

bearing

bearing function function and and carry carry the the applied applied loads loads for for the the duration duration of of the the firefire without any structur

without any structural collapse. al collapse. The integrity and The integrity and insulation criteria are insulation criteria are thethe ability of the building element to contain a fire in order to prevent fire ability of the building element to contain a fire in order to prevent fire spreads fro

spreads from the m the room room of orof origin. igin. For structurFor structural elements al elements (including(including structural frame, beam and column), stability criterion must be satisfied, and structural frame, beam and column), stability criterion must be satisfied, and the other criteria may be required for specific structural element. For the other criteria may be required for specific structural element. For example, for floor slab, integrity and insulation criteria must also be example, for floor slab, integrity and insulation criteria must also be satisfied in order to prevent fore spreads through floors.

satisfied in order to prevent fore spreads through floors. Table 2 lists theTable 2 lists the criterion or criteria to be satisfied for main types of structural elements. criterion or criteria to be satisfied for main types of structural elements.

Table 2

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Page 14 of 87 Page 14 of 87 Elements of Elements of construction construction

Criteria to the satisfied

Criteria to the satisfied _{Method of}_{Method of} Exposure Exposure Stability Integrity Insulation

Stability Integrity Insulation Structural frame,

Structural frame, beam or column beam or column

Y

Y N N N N Exposed Exposed facesfaces only only Floor including Floor including compartment floor compartment floor Y

Y Y Y Y Y Each Each sideside separately separately Roof forming part of

Roof forming part of an exit route or an exit route or performing the performing the

function of the floor function of the floor 22

Y

Y Y Y Y Y FromFrom

underside underside

Loadbearing wall not Loadbearing wall not forming a separating forming a separating wall or fire wall or fire compartment wall compartment wall Y

Y N N N N Each Each sideside separately separately

External

External wall wall Y Y Y Y Y Y Each Each sideside separately separately

Notes:

Notes: Y = required and N = not requiredY = required and N = not required

2 2

Project officers

Project officers should also should also refer torefer to Section 4.2.7Section 4.2.7 below, below, oror SEBGL-OTH1SEBGL-OTH1 Guidelines on the Fire Resisting Construction for Roof Structures

Guidelines on the Fire Resisting Construction for Roof Structures for roof not for roof not forming part of an exit route and

forming part of an exit route and not performing the function of the floor.not performing the function of the floor.

((SourceSource: FS Code Part C Table C2): FS Code Part C Table C2)

4.2.4 For structural elements, Prescriptive Provisions specify the material, shape 4.2.4 For structural elements, Prescriptive Provisions specify the material, shape and size, thickness of fire protection materials and construction details to be and size, thickness of fire protection materials and construction details to be used in ord

used in order to satisfy er to satisfy the statutory rthe statutory requirements. equirements. Compliance oCompliance of thesef these provisions is

provisions is deemed to deemed to satisfy the satisfy the statutory requirements laid statutory requirements laid down for firedown for fire resisting construction for buildings in Part XV of the

resisting construction for buildings in Part XV of the Building (Construction) Building (Construction) Regulations

Regulations. The following paragraphs provides brief summary of these. The following paragraphs provides brief summary of these provisions.

provisions. 4.2.5

4.2.5 Prescriptive Provisions for structural steelPrescriptive Provisions for structural steel

4.2.5.1 For structural steelwork, Clause 12.2 of the HK Steel Code specifies the 4.2.5.1 For structural steelwork, Clause 12.2 of the HK Steel Code specifies the

quantitative requir

quantitative requirements for ements for the insulation the insulation and stand stability. ability. For insulFor insulationation (e.g. for the floor slabs), it is specified that the mean and maximum (e.g. for the floor slabs), it is specified that the mean and maximum unexposed face temperatures should not be increased by more than 140 unexposed face temperatures should not be increased by more than 140ooCC and 180

and 180ooC respectively aC respectively above the initial vbove the initial value. alue. For stability, it For stability, it is specifiedis specified that it should be able to carry the load without excessive deflection.

that it should be able to carry the load without excessive deflection. 4.2.5.2

4.2.5.2 The The FS Code FS Code contains Prescriptive contains Prescriptive Provisions for Provisions for the the required firerequired fire protection

protection to to structural structural steel steel by by encasing encasing the the members members with with concrete. concrete. TheThe main disadvantage of such method is that encasing increases the dead main disadvantage of such method is that encasing increases the dead weight of the structure resulting in enlarged member sizes a

weight of the structure resulting in enlarged member sizes a nd foundations.nd foundations. Alternate materials in the form of sprayed mineral coating, intumescent Alternate materials in the form of sprayed mineral coating, intumescent paint

paint and and proprietary proprietary fire fire protection protection board board have have therefore therefore been been used.used. These alternate materials are permitted as prescriptive measures, provided These alternate materials are permitted as prescriptive measures, provided that appropriate test reports on

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4.2.5.3

4.2.5.3 The required thickness The required thickness of the of the alternate materials alternate materials for fire for fire protection ofprotection of structural steelwork can be determined from the performance data sheets, structural steelwork can be determined from the performance data sheets, published in

published in Fire Protection for Structural Fire Protection for Structural Steel in BuildingsSteel in Buildings (ASFP 2002), (ASFP 2002), which is commonly referred to as the

which is commonly referred to as the Yellow Book Yellow Book . The. The Yellow Book Yellow Book provides

provides a a comprehensive comprehensive guide guide of of proprietary proprietary materials materials and and systems systems ofof fire protection

fire protection to structural to structural steelwork. steelwork. For each For each type of type of fire protectionfire protection system, the thickness of fire protection is usually based on the “Section system, the thickness of fire protection is usually based on the “Section Factor” (denoted by A/V (surface area divided by cross sectional area) or Factor” (denoted by A/V (surface area divided by cross sectional area) or Hp/A (heated perimeter divided by cross sectional area)) of the structural Hp/A (heated perimeter divided by cross sectional area)) of the structural member, since the rate at which the structural element will heat up is member, since the rate at which the structural element will heat up is proportional

proportional to to the the surface surface area area of of steel steel exposed exposed to to the the fire fire and and inverselyinversely proportional to the mass or volume of the section.

proportional to the mass or volume of the section. In a fire, a member withIn a fire, a member with low section factor will be heated up at a slower rate than one with high low section factor will be heated up at a slower rate than one with high section factor.

section factor. 4.2.5.4

4.2.5.4 Detailed specification on Detailed specification on the submittals, the the submittals, the alternate materials aalternate materials and thend the workmanship has been included in the Clauses 15.66 – 15.72 of the workmanship has been included in the Clauses 15.66 – 15.72 of the General Specification for Building 2007

General Specification for Building 2007 of of our our Department. Department. ProjectProject officer are required to specify the type(s) of material and the fire resistance officer are required to specify the type(s) of material and the fire resistance ratings to suit his project.

ratings to suit his project. 4.2.5.5 I

4.2.5.5 In the choice n the choice of the appropriate type of material, project of the appropriate type of material, project officer should noteofficer should note that sprayed mineral coating is the cheapest option, and can be rapidly that sprayed mineral coating is the cheapest option, and can be rapidly applied.

applied. Sprayed mSprayed mineral coating ineral coating is therefore is therefore a preferred a preferred option. option. HoweverHowever due to its undulating finish and hence aesthetically unpleasant, it is usually due to its undulating finish and hence aesthetically unpleasant, it is usually preferred

preferred in in surfaces surfaces which which are are hidden hidden from from the the view view (e.g. (e.g. concealedconcealed behind

behind false false ceiling). ceiling). The The properties properties of of the the sprayed sprayed material material shall shall alsoalso cope with the use of

cope with the use of the structure. the structure. For example, whFor example, where vibration or largere vibration or largee deflection is expected, more demanding sprayed material with higher dry deflection is expected, more demanding sprayed material with higher dry density and

density and cohesion cohesion properties properties should should be ube used. sed. Moreover Moreover if thif thee environment is moist (e.g. exterior steel stair or above a swimming pool), environment is moist (e.g. exterior steel stair or above a swimming pool), then the sprayed mineral coating option is not advisable, as there is the then the sprayed mineral coating option is not advisable, as there is the possibility of water seeping into it (because of the porous nature of sprayed possibility of water seeping into it (because of the porous nature of sprayed

mineral).

mineral). Proprietary fire proProprietary fire protection board is tection board is an expensive man expensive method, andethod, and may also su

may also susceptible to thsceptible to the effect oe effect of moisture. f moisture. Hence, its Hence, its application isapplication is also restricted

also restricted to indoor to indoor steelwork with steelwork with dry endry environment. vironment. IntumescentIntumescent fireproofing is a layer of paint which is applied along with the coating fireproofing is a layer of paint which is applied along with the coating system on the structur

system on the structural steel members. al steel members. Intumescent coating Intumescent coating is applied asis applied as an intermediate coat in a coating system (primer, intermediate, and an intermediate coat in a coating system (primer, intermediate, and top/finish

top/finish coat). coat). Because Because of of the the relatively relatively low low thickness thickness of of thisthis intumescent coating (350-700 micrometers), nice finish, and anti-corrosive intumescent coating (350-700 micrometers), nice finish, and anti-corrosive nature, intumescent coating is a preferred option when aesthetical nature, intumescent coating is a preferred option when aesthetical appearance is requir

appearance is required. ed. Moreover, intumescent cMoreover, intumescent coating is the opoating is the option thattion that can be applied to s

can be applied to steelwork in moist environment.teelwork in moist environment. 4.2.6

4.2.6 Prescriptive Provisions for reinforced concrete and timberPrescriptive Provisions for reinforced concrete and timber

For reinforced concrete, fire protection is typically achieved by the For reinforced concrete, fire protection is typically achieved by the minimum dimensions and concrete covers to reinforcement for a given minimum dimensions and concrete covers to reinforcement for a given standard fire resistance rating.

standard fire resistance rating. Clause 4.3 of thClause 4.3 of the HK Concrete Code HK Concrete Code statese states that the covers to steel reinforcement for fire protection shall follow the FRC that the covers to steel reinforcement for fire protection shall follow the FRC