DESIGNERS’ DESIGNERS’ G U I D E S T O T H E G U I D E S T O T H E EUROCODES EUROCODES an initiative an initiative This series of Designers’ Guides to the Eurocodes provides Tom Lennon has worked at the British Research Establishment for over 20 years. He was responsible for comprehensive guidance in the form of design aids, indications the programme of ful-scale fire tests caried out at BRE’s Designers’ guide to EN1991-1-2, for the most convenient design procedures and worked large-scale test facility at Cardington on steel, concrete and examples. The books also include background information to otimf tbher Sfrtarumcetudr abl uEiludrioncgos.d Mesr. LHeen niso an phraosm eixnteennts mive mexbpeer roiefn ce aid the designer in understanding the reasoning behind and the British Standards commite B525/-/32 the miror group for EN1992-1-2, EN1993-1-2 objectives of the code. All individual guides work in conjunction the fire part of EC1 responsible for the implementation of the with the Designers’ Guide to EN1990 Eurocode: Basis of rceosdpeo nins itbhle UfoKr .d Mevr eLloepnninogn t hise a d mraeftm Nbaetrio onfa tlh Aen pnreoxje fcotr tuesaem structural design. with EN 191-1-2. He is author of a number of papers, design and EN1994-1-2 guides and journal articles on the subject of structural fire Designers’ Guide to EN1991-1-2, EN1992-1-2, EN1993-1-2 and engineering design. EN1994-1-2 differs from the other Eurocode guides available in that it is not concerned with a single design standard. The UK DBri tDisah vCido nBs.t rMucotoiornea ils S thtee Dlwiroerckt oArs osof cEinagtionne earnindg h ats t hoev er 25 T. Lennon, D. B. Moore, Y. C. Wang and C. G. Bailey standard for the design of steel structures encompasses the years experience of research and specialist advisory work in Series editor Haig Gulvanessian rules for both structural steelwork and for composite steel and 5th0e taercehan oicfa sl tpruacpteurrsa lo enn ag iwneideeri nragn agned o hf es uhbajse cptusb mlisahneyd o of ver concrete construction. The fire design procedures for reinforced them in international journals. He has also made a significant and prestressed concrete structures are contained in the relevant contribution to a number of specialised design guides and part of the National code. However, the structural Eurocodes pbeusbtl icparaticotnicse a greu iudseesd f odra tihlye b syt eperla icntdisuinsgtr ys. tMruacntuyr aolf etnhgesinee ers consider steel, composite and concrete construction in isolation and steelwork fabricators. and each material therefore has its own corresponding fire part. Dr Yong C. Wang teaches fire engineering at the University The design methodology, as set out in the fire parts of the of Manchester and has been engaged in research on fire resistance of steel and composite structures for a number structural Eurocodes, is based on the principles adopted for of years. He was Senior Research Engineer at the Building normal temperature design. One of the aims of this book is to Research Establishment and was a member of the working demystify the subject so that it can be readily understood and gthreo uapu trheosrp ofn sSitbele l faonr dth ceo ammpeonsditme estnrtu cotfu BreSs5 –9 5b0e hPaavrito 8u.r aHned i s used by structural engineers used to the underlying principles design for fire safety. and assumptions of design for the ambient condition. This present Designers’ Guide provides guidance on the nature aCto tlhine GU.n iBvearilseityy ios fc Murarenncthlye sPteror.f eHses ohra os fp Sretrvuioctuusrlayl wEnogrkineede froinrg of the loading that must first be understood before applying the design consultants Lovell Construction, Cameron Taylor the structural engineering principles set out in the Eurocodes. Bedford and Clarke Nicholls Marcel, where he designed and supervised the construction of a number of concrete, For this reason the book is meant as a guide to four separate steel and masonry structures. He has also worked for The documents EN1991-1-2, EN1992-1-2, EN1993-1-2 and EN1994- Steel Construction Institute and The Building Research 1-2 with reference, where appropriate, to the Eurocode covering Eresstualbtelidsh imn seingtn, iwfichaenret dheisv eplroapcmticeanlt sa nind sretrsuecaturcrahl eexnpgeinrieenrcineg basis of design. design. His main specialties are fire safety engineering of structures, membrane action, wind loading, and steel– This guide is essential reading for: concrete composite systems. ■ civil and structural engineers ■ code-drafting committees ■ clients ■ structural-design students ■ public authorities in fact, everyone who will be affected by the Eurocodes. www.eurocodes.co.uk www.thomastelford.com/books Coyp rigth ©ECI urEoc uPodlb ies Eih nNg19, 9a1l-1l -r2i.ginthdsd r 1eserved. 18/12/06 15:33:53 Designers’ Guide to EN1991-1-2, Lennon, Moore, Wang & Bailey EN1992-1-2, EN1993-1-2 and EN1994-1-2 DESIGNERS’ GUIDES TO THE EUROCODES DESIGNERS’ GUIDE TO EN 1991-1-2, 1992-1-2, 1993-1-2 and 1994-1-2 HANDBOOK FOR THE FIRE DESIGN OF STEEL, COMPOSITE AND CONCRETE STRUCTURES TO THE EUROCODES CopyrightI ' CEP ublishing,a llr ightsr eserved. Eurocode Designers’ Guide Series Designers’ Guide to EN 1990. Eurocode: Basis of Structural Design. H. Gulvanessian, J.-A. Calgaro and M. Holicky´. 0 7277 3011 8. Published 2002. Designers’ Guide to EN 1994-1-1. Eurocode 4: Design of Composite Steel and Concrete Structures. Part 1.1: General Rules and Rules for Buildings. R. P. Johnson and D. Anderson. 0 7277 3151 3. Published 2004. Designers’ Guide to EN 1997-1. Eurocode 7: Geotechnical Design – General Rules. R. Frank, C. Bauduin, R. Driscoll, M. Kavvadas, N. Krebs Ovesen, T. Orr and B. Schuppener. 0 7277 3154 8. Published 2004. Designers’ Guide to EN 1993-1-1. Eurocode 3: Design of Steel Structures. General Rules and Rules for Buildings. L. Gardner and D. Nethercot. 0 7277 3163 7. Published 2004. Designers’ Guide to EN 1992-1-1 and EN 1992-1-2. Eurocode 2: Design of Concrete Structures. General Rules and Rules for Buildings and Structural Fire Design. A. W. Beeby and R. S. Narayanan. 0 7277 3105 X. Published 2005. Designers’ Guide to EN 1998-1 and EN 1998-5. Eurocode 8: Design of Structures for Earthquake Resistance. General Rules, Seismic Actions, Design Rules for Buildings, Foundations and Retaining Structures. M. Fardis, E. Carvalho, A. Elnashai, E. Faccioli, P. Pinto and A. Plumier. 0 7277 3348 6. Published 2005. Designers’ Guide to EN 1995-1-1. Eurocode 5: Design of Timber Structures. Common Rules and for Rules and Buildings. C. Mettem. 0 7277 3162 9. Forthcoming: 2007 (provisional). Designers’ Guide to EN 1991-4. Eurocode 1: Actions on Structures. Wind Actions. N. Cook. 0 7277 3152 1. Forthcoming: 2007 (provisional). Designers’ Guide to EN 1996. Eurocode 6: Part 1.1: Design of Masonry Structures. J. Morton. 0 7277 3155 6. Forthcoming: 2007 (provisional). Designers’ Guide to EN 1991-1-2, 1992-1-2, 1993-1-2 and EN 1994-1-2. Eurocode 1: Actions on Structures. Eurocode 3: Design of Steel Structures. Eurocode 4: Design of Composite Steel and Concrete Structures. Fire Engineering (Actions on Steel and Composite Structures). Y. Wang, C. Bailey, T. Lennon and D. Moore. 0 7277 3157 2. Forthcoming: 2007 (provisional). Designers’ Guide to EN 1992-2. Eurocode 2: Design of Concrete Structures. Bridges. D. Smith and C. Hendy. 0 7277 3159 9. Forthcoming: 2007 (provisional). Designers’ Guide to EN 1993-2. Eurocode 3: Design of Steel Structures. Bridges. C. Murphy and C. Hendy. 0 7277 3160 2. Forthcoming: 2007 (provisional). Designers’ Guide to EN 1991-2, 1991-1-1, 1991-1-3 and 1991-1-5 to 1-7. Eurocode 1: Actions on Structures. Traffic Loads and Other Actions on Bridges. J.-A. Calgaro, M. Tschumi, H. Gulvanessian and N. Shetty. 0 7277 3156 4. Forthcoming: 2007 (provisional). Designers’ Guide to EN 1991-1-1, EN 1991-1-3 and 1991-1-5 to 1-7. Eurocode 1: Actions on Structures. General Rules and Actions on Buildings (not Wind). H. Gulvanessian, J.-A. Calgaro, P. Formichi and G. Harding. 0 7277 3158 0. Forthcoming: 2007 (provisional). www.eurocodes.co.uk CopyrightI ' CEP ublishing,a llr ightsr eserved. DESIGNERS’ GUIDES TO THE EUROCODES DESIGNERS’ GUIDE TO EN 1991-1-2, 1992-1-2, 1993-1-2 and 1994-1-2 HANDBOOK FOR THE FIRE DESIGN OF STEEL, COMPOSITE AND CONCRETE STRUCTURES TO THE EUROCODES T. LENNON, D. B. MOORE, Y. C. WANG and C. G. BAILEY Series editor H. GULVANESSIAN CopyrightI ' CEP ublishing,a llr ightsr eserved. Published by Thomas Telford Publishing, Thomas Telford Ltd, 1 Heron Quay, London E14 4JD URL: www.thomastelford.com Distributors for Thomas Telford books are USA: ASCE Press, 1801 Alexander Bell Drive, Reston, VA 20191-4400 Japan: Maruzen Co. Ltd, Book Department, 3–10 Nihonbashi 2-chome, Chuo-ku, Tokyo 103 Australia: DA Books and Journals, 648 Whitehorse Road, Mitcham 3132, Victoria First published 2007 Eurocodes Expert Structural Eurocodes offer the opportunity of harmonized design standards for the European construction market and the rest of the world. To achieve this, the construction industry needs to become acquainted with the Eurocodes so that the maximum advantage can be taken of these opportunities Eurocodes Expert is a new ICE and Thomas Telford initiative set up to assist in creating a greater awareness of the impact and implementation of the Eurocodes within the UK construction industry Eurocodes Expert provides a range of products and services to aid and support the transition to Eurocodes. For comprehensive and useful information on the adoption of the Eurocodes and their implementation process please visit our website or email Preface Many structural engineers will be unfamiliar with the principles of structural fire engineering design. In recent years a number of specialist consultants have emerged offering fire engineer- ing solutions, largely for prestigious projects where the potential benefits of adopting a fire engineering design approach outweigh the additional design cost to the client. There is a fundamental lack of understanding of the principles of structural fire engineering design. In reality the design methodology, as set out in the fire parts of the structural Eurocodes, is based on the principles adopted for normal temperature design. One of the aims of this book is to demystify the subject so that it can be readily understood and used by structural engineers used to the underlying principles and assumptions of design for the ambient condition. This book differs from many of the other Eurocode guides available in that it is not concerned with a single design standard. The UK standard for the design of steel structures encompasses the rules for both structural steelwork and for composite steel and concrete construction. The fire design procedures for reinforced and prestressed concrete structures are contained in the relevant part of the National Code. However, the structural Eurocodes consider steel, composite and concrete construction in isolation and each material therefore has its own corresponding fire part. In this case a clause-by-clause examination of the material codes would not be sufficient to allow designers to use these documents. The nature of the loading must first be understood before applying the structural engineering principles set out in the Eurocodes. For this reason the book is meant as a guide to four separate documents – EN 1991-1-2, EN 1992-1-2, EN 1993-1-2 and EN 1994-1-2 – with reference where appropriate to the Eurocode covering basis of design. Copyright © ICE Publishing, all rights reserved. Contents Preface v Chapter 1. Introduction 1 1.1. Introduction to this handbook 1 1.2. Introduction to structural fire design 1 1.3. Scope of EN 1991 Part 1.2, EN 1992 Part 1.2, EN 1993 Part 1.2 and EN 1994 Part 1.2 4 1.4. Distinction between principles and application rules 5 1.5. National annexes and Nationally Determined Parameters 5 1.6. Definitions and symbols 8 Chapter 2. Design methods 13 2.1. Introduction 13 2.2. Design of concrete structures to EN 1992-1-2 16 2.3. Design of steel structures to EN 1993-1-2 16 2.4. Design of composite structures to EN 1994-1-2 17 2.5. Design assisted by testing 18 Chapter 3. Design fires 19 3.1. Introduction 19 3.2. General rules for calculating atmosphere temperatures 19 3.3. Nominal temperature–time curves 20 3.3.1. Standard temperature–time curve 20 3.3.2. External fire curve 20 3.3.3. Hydrocarbon curve 20 3.4. Equivalent time of fire exposure 21 3.5. Parametric temperature–time curves 23 3.6. External atmosphere temperature 26 3.7. Advanced fire models 26 Chapter 4. Member temperatures 27 4.1. Introduction 27 4.2. Section factors for steel and composite construction 27 4.3. Unprotected steelwork 27 4.4. Steelwork insulated by fire protection 28 4.5. Unprotected composite slabs 30 Copyright © ICE Publishing, all rights reserved. DESIGNERS’ GUIDE TO EN 1991-1-2, 1992-1-2, 1993-1-2 AND 1994-1-2 4.5.1. Steel decking 30 4.5.2. Reinforcement bars 31 4.5.3. Concrete slab over steel decking 32 4.6. Temperature profile for concrete members 33 Chapter 5. Static loads 35 5.1. Introduction 35 5.2. Partial safety factors for loads 35 5.3. Design values of loads 36 5.3.1. Loading 37 5.3.2. Ambient temperature design loads 37 5.3.3. Fire limit state design loads 37 5.3.4. Design values of actions – ultimate limit state accidental design situation 37 5.4. Definition of load level, load intensity and degree of utilization 37 5.4.1. Load level (n) 37 5.4.2. Degree of utilization (fi) 38 Chapter 6. Thermal and mechanical properties of materials 39 6.1. Introduction 39 6.2. Steel 39 6.2.1. Hot-rolled carbon steel 39 6.2.2. Stainless steel 43 6.2.3. Light-gauge steel 47 6.3. Concrete 48 6.3.1. Normal-weight concrete 48 6.3.2. Lightweight concrete 52 6.3.3. High-strength concrete 53 6.4. Reinforcing steel 54 6.5. Bolts and welds 55 Chapter 7. Design of tension members 57 7.1. Introduction 57 7.2. Design resistance method 57 7.2.1. Non-uniform temperature distribution 58 7.2.2. Uniform temperature distribution 60 7.3. Critical temperature method 60 Chapter 8. Design of compression members 63 8.1. Introduction 63 8.2. Effective length of columns in fire 64 8.3. Axially loaded steel columns 64 8.3.1. Uniformly heated column with class 1, 2 or 3 cross-section 65 8.3.2. Uniformly heated column with class 4 cross-section 67 8.3.3. Uniformly heated column with combined axial load and bending moment 67 8.3.4. Non-uniformly heated steel columns 67 8.4. Axially loaded composite column 67 8.4.1. General design method 68 8.4.2. Alternative design method for composite column with partially encased steel section 71 viii CopyrightI ' CEP ublishing,a llr ightsr eserved. CONTENTS 8.4.3. Alternative design method for composite columns with concrete-filled hollow sections 78 8.5. Reinforced concrete columns 79 8.5.1. 5008C isotherm method 80 8.5.2. Zone method 80 8.5.3. Additional comments 81 Chapter 9. Design of bending members 83 9.1. Introduction 83 9.2. Steel beams 83 9.2.1. Bending moment capacity 83 9.2.2. Shear resistance 85 9.2.3. Lateral torsional buckling 86 9.2.4. Control of deformation 86 9.3. Steel beam exposed to fire on three sides with concrete slab on the fourth side 87 9.4. Composite beams comprising steel beams with partial concrete encasement 88 9.5. Reinforced concrete beam 91 9.6. Comments on EN 1992-1-2 tabulated data 92 Chapter 10. Design of slabs 93 10.1. Introduction 93 10.2. Composite slabs 93 10.3. Reinforced concrete slabs 101 Chapter 11. Other forms of construction 103 11.1. Introduction 103 11.2. Slim floor beams 103 11.3. Shelf angle beams 103 11.4. Blocked infilled columns 106 Chapter 12. Connections 109 12.1. Introduction 109 12.2. Concrete connections 109 12.2.1. Increase in support moment for continuous structures 110 12.2.2. Forces due to restrained thermal expansion 110 12.2.3. Eccentricity of loading due to large deflection 110 12.3. Steel and composite connections 111 Chapter 13. General discussion 121 13.1. Introduction 121 13.2. Guidance on selection of appropriate design method 121 References 123 Index 127 ix CopyrightI ' CEP ublishing,a llr ightsr eserved. CHAPTER 1 Introduction 1.1. Introduction to this handbook In writing this handbook the authors have been aware that many designers will be unfamiliar with the principles of structural fire engineering design. In recent years a number of specialist consultants have emerged offering fire engineering solutions largely for prestigious projects where the potential benefits of adopting a fire engineering design approach outweigh the additional design cost to the client. The subject is shrouded in mystery and is viewed by many engineers as a black art. One of the aims of this book is to demystify the subject so that it can be readily understood and used by civil and structural engineers familiar with the underlying principles and assumptions of design for the ambient condition. This book differs frommany other Eurocode guides in that it is not concerned with a single design standard. The UK standard for the design of steel structures encompasses the design rules for both structural steelwork and for composite steel and concrete construction, albeit in different parts.1ÿ3 The fire design procedures for reinforced and prestressed concrete structures are contained in the relevant parts of the national code, BS 8110.4;5 However, the structural Eurocodes consider steel, composite and concrete construction in isolation and each material therefore has its own corresponding fire part. In this case a clause-by- clause examination of the fire parts of the material codes would not be sufficient to allow designers to use these documents. The nature of the loading must first be understood before applying the structural engineering principles set out in the Eurocodes. For this reason this book is meant as a guide to four separate documents, namely EN 1991 Part 1.2, EN 1992 Part 1.2, EN 1993 Part 1.2 and EN 1994 Part 1.2, with reference where appropriate to the Eurocode covering the basis of design, namely EN 1990.6 The guide will take the form of an introduction to the procedures required to achieve design solutions for a typical range of structural elements and assemblies. Worked examples will be included along with the text where appropriate to illustrate the use of the Eurocodes for specific design scenarios. As a way of setting the scene for those unfamiliar with the basic principles of structural fire engineering design, the next section provides an overview of the regulatory framework and a description of the commonly used methods for ensuring compliance with the regulations in the UK. 1.2. Introduction to structural fire design In the UK the fire resistance requirements for buildings are specified in the Building Regula- tions for England and Wales7 with regional differences covered in separate documents for construction in Scotland8 and Northern Ireland.9 All buildings must meet certain functional requirements covering means of escape, internal fire spread, external fire spread and access and facilities for the Fire Service as laid down in the regulations. It is important to note that the Building Regulations are only intended to ensure reasonable standards of health and CopyrightI ' CEP ublishing,a llr ightsr eserved.