Fire design of steel structures : Eurocode 1 : actions on structures, part 1-2: General actions - Actions on structures exposed to fire : Eurocode 3 : design of steel structures, part 1-2: General rules - Structural fire design

This book explains and illustrates the rules that are given in the Eurocodes for designing steel structures subjected to fire. After the first introductory chapter, Chapter 2 explains how to calculate the mechanical actions (loads) in the fire situation based on the information given in EN 1990 and EN 1991. Chapter 3 is dedicated to the models which represent the thermal actions created by the fire. Chapter 4 describes the procedures to be used to calculate the temperature of the steelwork from the temperature of the compartment and Chapter 5 shows how the information given in EN 1993-1-2 is used to determine the load bearing capacity of the steel structure. Chapter 6 presents the essential features that characterize the advanced calculation models, for thermal and mechanical response. The methods used to evaluate the fire resistance of bolted and welded connections are described in Chapter 7. Chapter 8 describes a computer program called'Elefir-EN,'which is based on the simple calculation model given in the Eurocode and allows designers to quickly and accurately calculate the performance of steel components in the fire situation. Chapter 9 looks at the issues that a designer may be faced with when assessing the fire resistance of a complete building. This is done via a case study and addresses most of the concepts presented in the previous chapters. For this second edition the content has been revised and extended. The book contains some new sections, e.g. a comparison between the simple and the advanced calculation, as well as additional examples. Cover 1 Series Page 4 Title Page 5 Copyright 6 TABLE OF CONTENTS 7 FOREWORD 15 PREFACE TO THE 2ND EDITION 17 PREFACE 1ST EDITION 19 NOTATIONS 21 Chapter 1. INTRODUCTION 29 1.1. RELATIONS BETWEEN DIFFERENT EUROCODES 29 1.2. SCOPE OF EN 1993-1-2 31 1.3. LAYOUT OF THE BOOK 31 Chapter 2. MECHANICAL LOADING 35 2.1. GENERAL 35 2.1.1. General rule 35 2.1.2. Simplification 1 38 2.1.3. Simplification 2 38 2.1.4. Simplification 3 40 2.2. EXAMPLES 41 2.3. INDIRECT ACTIONS 42 Chapter 3.THERMAL ACTION 45 3.1. GENERAL 45 3.2. NOMINAL TEMPERATURE-TIME CURVES 46 3.3. PARAMETRIC TEMPERATURE-TIME CURVES 49 3.4. ZONE MODELS 57 3.5. CFD MODELS 59 3.6. LOCALISED FIRES 60 3.7. EXTERNAL MEMBERS 67 Chapter 4. TEMPERATURE IN STEEL SECTIONS 73 4.1. INTRODUCTION 73 4.2. THE HEAT CONDUCTION EQUATION AND ITS BOUNDARY CONDITIONS 73 4.3. ADVANCED CALCULATION MODEL. FINITE ELEMENT SOLUTION OF THE HEAT CONDUCTION EQUATION 75 4.3.1. Temperature field using the finite element method 76 4.4. SECTION FACTOR 79 4.5. TEMPERATURE OF UNPROTECTED STEELWORK EXPOSED TO FIRE 82 4.6. TEMPERATURE OF PROTECTED STEELWORK EXPOSED TO FIRE 89 4.7. INTERNAL STEELWORK IN A VOID PROTECTED BY HEAT SCREENS 104 4.8. EXTERNAL STEELWORK 106 4.8.1. General principles 106 4.8.2. Example 108 4.9. VIEW FACTORS IN THE CONCAVE PART OF A STEEL PROFILE 116 4.10. TEMPERATURE IN STEEL MEMBERS SUBJECTED TO LOCALISED FIRES 120 4.10.1. Unprotected steel members 120 4.10.2. Protected steel members 121 4.10.3. Thermal response of steel members in case of multiple localised fires 123 4.10.3.1. Multiple localised fires due to simultaneously burning cars: an example of a car park 123 4.10.3.1.1. Characterization of the fire and definition of the fire scenarios 123 4.10.3.1.2. Temperature of the main beam 126 4.11. TEMPERATURE IN STAINLESS STEEL MEMBERS 129 4.11.1. Example 132 Chapter 5. MECHANICAL ANALYSIS 133 5.1. BASIC PRINCIPLES 133 5.2. MECHANICAL PROPERTIES OF CARBON STEEL 138 5.3. CLASSIFICATION OF CROSS SECTIONS 143 5.3.1. Cross section under combined bending and axial-compression at normal temperature 148 5.3.1.1. First methodology for Class 1 and Class 2 cross sections 151 5.3.1.2. Second methodology for the case of Class 1 and Class 2 cross sections 153 5.3.1.3. First methodology for Class 3 cross sections 155 5.3.1.4. Second methodology for Class 3 cross sections 156 5.3.1.5. Advantages and disadvantages of the two presented methodologies 158 5.3.2. Cross section under combined bending and tension at normal temperature 160 5.3.3. Classification under fire conditions 160 5.4. EFFECTIVE CROSS SECTION 162 5.5. FIRE RESISTANCE OF STRUCTURAL MEMBERS 164 5.5.1. General 164 5.5.2. Members with Class 4 cross sections 166 5.5.3. Tension members 167 5.5.4. Compression members 168 5.5.5. Shear resistance 171 5.5.6. Laterally restrained beams 173 5.5.6.1. Uniform temperature distribution 173 5.5.6.2. Non-uniform temperature distribution 175 5.5.6.3. Bending and shear 178 5.5.7. Laterally unrestrained beams 180 5.5.7.1. The elastic critical moment for lateral-torsional buckling 180 5.5.7.2. Resistance to lateral-torsional buckling 184 5.5.8. Members subjected to combined bending and axial compression 187 5.5.9. Some verifications of the fire resistance not covered by EN 1993-1-2 191 5.5.9.1. Shear buckling resistance for web without intermediate stiffeners 191 5.5.9.2. Cross section verification of a member subjected to combined bending and axial force (compression or tension) 192 5.5.9.2.1. Class 1 and 2 rectangular solid sections 193 5.5.9.2.2. Class 1 and 2 doubly symmetric I- and H-sections 194 5.5.9.2.3. Class 3 doubly symmetric I- and H-sections 196 5.5.9.2.4. Class 4 cross sections 197 5.5.9.3. Bending, shear and axial force 197 5.6. DESIGN IN THE TEMPERATURE DOMAIN. CRITICAL TEMPERATURE 198 5.7. DESIGN OF CONTINUOUS BEAMS 208 5.7.1. General 208 5.7.2. Continuous beams at room temperature 209 5.7.3. Continuous beams under fire conditions 212 5.8. FIRE RESISTANCE OF STRUCTURAL STAINLESS STEEL MEMBERS 214 5.9. DESIGN EXAMPLES 221 Chapter 6. ADVANCED CALCULATION MODELS 301 6.1. GENERAL 301 6.2. THERMAL RESPONSE MODEL 303 6.3. MECHANICAL RESPONSE MODEL 310 6.4 SOME COMPARISONS BETWEEN THE SIMPLE AND THE ADVANCED CALCULATION MODELS 316 6.4.1 Shadow factor 317 6.4.2 Buckling curves 321 6.4.3 Factor κ2 323 6.4.4 Factor κ1 324 Chapter 7 JOINTS 327 7.1. GENERAL 327 7.2. STRENGTH OF BOLTS AND WELDS AT ELEVATED TEMPERATURE 328 7.3. TEMPERATURE OF JOINTS IN FIRE 329 7.4. BOLTED CONNECTIONS 330 7.4.1. Design Fire Resistance of Bolts in Shear 331 7.4.1.1. Category A: Bearing Type 331 7.4.1.2. Category B (slip resistance at serviceability) and Category C (slip resistance at ultimate state) 331 7.4.2. Design Fire Resistance of Bolts in Tension 331 7.4.2.1. Category D and E: Non-preloaded and preloaded bolts 331 7.5. DESIGN FIRE RESISTANCE OF WELDS 332 7.5.1. Butt Welds 332 7.5.2. Fillet Welds 332 7.6. DESIGN EXAMPLES 332 Chapter 8. THE COMPUTER PROGRAM "ELEFIR-EN" 343 8.1. GENERAL 343 8.2. BRIEF DESCRIPTION OF THE PROGRAM 344 8.2.1. Available thermal calculations 344 8.2.2. Available mechanical calculations 350 8.3. DEFAULT CONSTANTS USED IN THE PROGRAM 357 8.4. DESIGN EXAMPLE 357 Chapter 9. CASE STUDY 371 9.1. DESCRIPTION OF THE CASE STUDY 371 9.2. FIRE RESISTANCE UNDER STANDARD FIRE 372 9.2.1. Thermal calculations 372 9.2.2. Structural calculation 373 9.2.2.1. Loading 373 9.2.2.2. Fire resistance by the simple calculation model 377 9.2.2.3. Fire resistance by the general calculation model 379 9.3. FIRE RESISTANCE UNDER NATURAL FIRE 381 9.3.1. Temperature development in the compartment 381 REFERENCES 387 Annex A THERMAL DATA FOR CARBON STEEL AND STAINLESS STEEL SECTIONS 397 A.1. THERMAL PROPERTIES OF CARBON STEEL 397 A.1.1. Specific heat 397 A.1.2. Thermal conductivity 398 A.1.3. Thermal elongation 399 A.2. SECTION FACTOR Am / V [m-1] FOR UNPROTECTED STEEL MEMBERS 400 A.3. SECTION FACTOR Ap / V [m-1] FOR PROTECTED STEEL MEMBERS 402 A.4. TABLES AND NOMOGRAMS FOR EVALUATING THE TEMPERATURE IN UNPROTECTED STEEL MEMBERS SUBJECTED TO THE STANDARD FIRE CURVE ISO 834 403 A.5. TABLES AND NOMOGRAMS FOR EVALUATING THE TEMPERATURE IN PROTECTED STEEL MEMBERS SUBJECTED TO THE STANDARD FIRE CURVE ISO 834 408 A.6. THERMAL PROPERTIES OF SOME FIRE PROTECTION MATERIALS 412 A.7. THERMAL PROPERTIES OF STAINLESS STEEL 413 A.7.1. Specific heat 413 A.7.2. Thermal conductivity 413 A.7.3. Thermal elongation 414 A.8. TABLES AND NOMOGRAMS FOR EVALUATING THE TEMPERATURE IN UNPROTECTED STAINLESS STEEL MEMBERS SUBJECTED TO THE STANDARD FIRE CURVE ISO 834 415 A.9. THERMAL PROPERTIES OF SOME FIRE COMPARTMENT LINING MATERIALS 422 Annex B. INPUT DATA FOR NATURAL FIRE MODELS 423 B.1. INTRODUCTION 423 B.2. FIRE LOAD DENSITY 423 B.3. RATE OF HEAT RELEASE DENSITY 426 B.4. VENTILATION CONTROL 431 B.5. FLASH-OVER 434 Annex C. MECHANICAL PROPERTIES OF CARBON STEEL AND STAINLESS STEEL 435 C.1. MECHANICAL PROPERTIES OF CARBON STEEL 435 C.1.1. Mechanical properties of carbon steel at room temperature (20 oC) 435 C.1.2. Stress-strain relationship for carbon steel at elevated temperatures (without strain-hardening) 438 C.1.3. Stress-strain relationship for carbon steel at elevated temperatures (with strain-hardening) 446 C.1.4. Mechanical properties to be used with class 4 cross sections and simple calculation models 447 C.2. MECHANICAL PROPERTIES OF STAINLESS STEEL 449 Annex D. TABLES FOR SECTION CLASSIFICATION AND EFFECTIVE WIDTH EVALUATION 457 Annex E. SECTION FACTORS OF EUROPEAN HOT ROLLED IPE AND HE PROFILES 463 Annex F. CROSS SECTIONAL CLASSIFICATION OF EUROPEAN HOT ROLLED IPE AND HE PROFILES 471 F.1. CROSS SECTIONAL CLASSIFICATION FOR PURE COMPRESSION AND PURE BENDING 471 F.2. CROSS SECTIONAL CLASSIFICATION FOR COMBINED COMPRESSION AND BENDING MOMENT 478 ELEFIR - EN 505 EULA 506