ISO/TR 24679-5:2023

Fire safety engineering — Performance of structures in fire — Part 5: Example of a timber building in Canada

This document provides a fire engineering application relative to the fire resistance assessment of a multi-storey timber building according to the methodology given in ISO 24679-1. In an attempt to facilitate the understanding of the design process presented herein, this document follows the same step-by-step procedure as that given in ISO 24679-1. The fire safety engineering approach is applied to a multi-storey timber building with respect to fire resistance and considers specific design fire scenarios, which impact the fire resistance of structural members. A component-level (member analysis) approach to fire performance analysis is adopted in this worked example. Such an approach generally provides a more conservative design than a system-level (global structural) analysis or an analysis of parts of the structure where interaction between components can be assessed. An advantage of the component-level approach is that calculations can be done with the use of simple analytical models or spreadsheets. Advanced modelling using computational fluid dynamics is presented to replicate an actual office cubicle fire scenario and for assessing timber contribution to fire growth, intensity and duration, if any. The thermo-structural behaviour of the timber elements is assessed through advanced modelling using the finite element method. The fire design scenarios chosen in this document are only used for the evaluation of the structural fire resistance. They are not applicable for assessing, for example, smoke production, tenability conditions or other life safety conditions.

Ingénierie de la sécurité incendie — Performances des structures en situation d’incendie — Partie 5: Exemple d’un immeuble en bois au Canada

Le présent document développe une application de l’ingénierie de la sécurité incendie relative à l’évaluation de la résistance au feu d’un immeuble en bois de plusieurs étages conformément à la méthodologie donnée dans l’ISO 24679-1. Dans la volonté de faciliter la compréhension du processus de dimensionnement présenté ci-après, le présent document suit la même procédure par étapes que celle donnée dans l’ISO 24679-1. L’approche d’ingénierie de la sécurité incendie repose sur la résistance au feu d’un immeuble en bois de plusieurs étages et considère des scénarios d’incendie de dimensionnement spécifiques, lesquels impactent la résistance au feu des éléments structuraux. Dans l’exemple développé ci-après, il a été adopté, pour l’analyse de la tenue au feu, une approche au niveau du composant (analyse de l’élément). Une telle approche fournit généralement une conception plus prudente qu’une analyse (structurale globale) au niveau du système ou qu’une analyse des parties de la structure notamment lorsqu’une interaction entre les éléments peut être évaluée. L’approche au niveau du composant présente un avantage qui est que les calculs peuvent être effectués avec l’utilisation de modèles analytiques simples ou de tableurs. Une modélisation avancée utilisant la dynamique des fluides à l’aide d’un modèle de champs est présentée pour reproduire un scénario d’incendie réel d’une cabine de bureau et pour évaluer la contribution du bois dans la croissance, l’intensité et la durée du feu, le cas échéant. Le comportement thermo-structural des éléments en bois est évalué au moyen d’une modélisation avancée utilisant la méthode des éléments finis. Les scénarios d’incendie de dimensionnement choisis dans le présent document sont uniquement utilisés pour l’évaluation de la résistance au feu des éléments de la structure de l’immeuble. Ils ne s’appliquent pas à l’évaluation, par exemple, de la production de fumée, des conditions de tenabilité ou d’autres conditions relatives à la sécurité des personnes.

General Information

• Status: Published
• Publication Date: 18-Jul-2023
• ICS: 13.220.01 - Protection against fire in general
• Technical Committee: ISO/TC 92/SC 4 - Fire safety engineering
• Drafting Committee: ISO/TC 92/SC 4/WG 12 - Structures in fires
• Current Stage: 6060 - International Standard published
• Start Date: 18-Jul-2023
• Completion Date: 19-Jul-2023

Standards Content (Sample)

TECHNICAL ISO/TR
REPORT 24679-5
First edition
2023-07
Fire safety engineering —
Performance of structures in fire —
Part 5:
Example of a timber building in
Canada
Reference number
ISO/TR 24679-5:2023(E)
© ISO 2023

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ISO/TR 24679-5:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
  © ISO 2023 – All rights reserved

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ISO/TR 24679-5:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Design strategy for fire safety of structures . 2
4.1 General design process for fire safety of structures . 2
4.2 Practical design process for fire safety of structures . 2
5 Quantification of the performance of structures in fire . 2
5.1 Step 1: Scope of the project for fire safety of structures. 2
5.1.1 Built-environment characteristics . 2
5.1.2 Fuel loads . 6
5.1.3 Mechanical actions . 8
5.2 Step 2: Identifying objectives, functional requirements and performance criteria
for fire safety of structures . 8
5.2.1 Objectives and functional requirements for fire safety of structures . 8
5.2.2 Performance criteria for fire safety of structures . 9
5.3 Step 3: Trial design plan for fire safety of structures . 10
5.4 Step 4: Design fire scenarios and design fires (thermal actions) . 10
5.4.1 General . 10
5.4.2 Design fire scenarios . 11
5.4.3 Design fires (thermal actions) .12
5.5 Step 5: Thermal response of the structure .
...

TECHNICAL ISO/TR
REPORT 24679-5
First edition
Fire safety engineering —
Performance of structures in fire —
Part 5:
Example of a timber building in
Canada
PROOF/ÉPREUVE
Reference number
ISO/TR 24679-5:2023(E)
© ISO 2023

---------------------- Page: 1 ----------------------
ISO/TR 24679-5:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
PROOF/ÉPREUVE © ISO 2023 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/TR 24679-5:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Design strategy for fire safety of structures . 2
4.1 General design process for fire safety of structures . 2
4.2 Practical design process for fire safety of structures . 2
5 Quantification of the performance of structures in fire . 2
5.1 Step 1: Scope of the project for fire safety of structures. 2
5.1.1 Built-environment characteristics . 2
5.1.2 Fuel loads . 6
5.1.3 Mechanical actions . 8
5.2 Step 2: Identifying objectives, functional requirements and performance criteria
for fire safety of structures . 8
5.2.1 Objectives and functional requirements for fire safety of structures . 8
5.2.2 Performance criteria for fire safety of structures . 9
5.3 Step 3: Trial design plan for fire safety of structures . 10
5.4 Step 4: Design fire scenarios and design fires (thermal actions) . 10
5.4.1 General . 10
5.4.2 Design fire scenarios . 11
5.4.3 Design fires (thermal actions) .12
5.5 Step 5: Thermal response of the structure .
...

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ISO/TRDTR 24679-5:2023(E) .
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ISO TC 92/SC 4/WG 12
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Secretariat: AFNOR
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Date: 2023-05
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Fire safety engineering — Performance of structures in fire — Part 5: Example of a multi-
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storey timber building in Canada
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ISO TR/DTR 24679-5:2023(E)
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© ISO 20222023, Published in Switzerland
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All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or
utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
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requested from either ISO at the address below or ISO’s member body in the country of the
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requester.
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ISO copyright office
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Ch. de Blandonnet 8 • CP 401
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CH-1214 Vernier, Geneva, Switzerland
Tel.  + 41 22 749 01 11
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Fax  + 41 22 749 09 47
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[e-mail]
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ii © ISO 2023 – All rights reserved

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ISO TR/DTR 24679-5:2023(E)
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Contents
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Foreword . iv
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Introduction. v
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1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Design strategy for fire safety of structures . 2
4.1 General design process for fire safety of structures . 2
4.2 Practical design process for fire safety of structures . 2
5 Quantification of the performance of structures in fire . 3
5.1 Step 1: Scope of the project for fire safety of structures . 3
5.1.1 Built-environment characteristics . 3
5.1.2 Fuel loads . 6
5.1.3 Mechanical actions .
...