ISO/TR TECHNICAL 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 IS0/TR 24679-5:2023(E) ISO @ ISO 2023 IS0/TR 24679-5:2023(E) COPYRIGHT PROTECTED DOCUMENT @IS02023 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 or IsoO's member body in the country of the requester. ISO copyright office CP 401 : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +41 22 749 01 11 Email: [email protected] Website: www.iso.org Published in Switzerland ii @ IS0 2023 - All rights reserved IS0/TR 24679-5:2023(E) @ Contents Page Foreword. .iv Introduction. ..V Scope. 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 ofthe performance of structures in fire .2 5.1 Step 1: Scope of the project for fire safety of structures. 2 5.1.1 Buit-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 Objectivesandfunctionalreguirementsforfiresafetyofstructures .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 34 5.5.1 Charring of timber. 34 5.5.2 Description of the thermal properties 37 5.5.3 Scenario3 38 5.5.4 Temperature beyond the char layer 50 5.6 Step 6: Mechanical response of the structure 51 5.6.1 Description of the mechanical properties 52 5.6.2 Scenario 3 - Beam B1. 52 5.6.3 Scenario3-ColumnC2 56 5.7 Step 7: Assessment against the fire safety objectives 60 5.7.1 Beam B1 60 5.7.2 Column C2 60 5.8 Documentation of the design for fire safety of structures 61 5.9 Factors and influences to be considered in the quantification process 61 5.9.1 Material properties. 61 5.9.2 Effect of continuity and restraint (interaction between elements and materials) 62 5.9.3 Use of test results. 62 5.9.4 Fire spread routes .62 6 Guidance on use of engineering methods 62 6.1 Using calculation methods. 62 6.2 Using experimental methods. 62 6.3 Using engineering judgment. 62 Bibliography .64 @ IS0 2023 - All rights reserved iii IS0/TR 24679-5:2023(E) Foreword Iso (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO member bodies). The work of preparing International Standards is normally carried out through IsO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with IsO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. The procedures used to develop this document and those intended for its further maintenance are describedintheIsO/IEcDirectives,Part1.Inparticular,thedifferentapprovalcriterianeededforthe different types of IsO document should be noted. This document was drafted in accordance with the editorial rules of the ISo/IEC Directives, Part 2 (see www.iso.org/directives). Iso draws attention to the possibility that the implementation of this document may involve the use of (a) patent(s). IsO takes no position concerning the evidence, validity or applicability of any claimed patent ri