Eurocodes Background&applications design of steel buildings The present JRC report contains state-of-the-art training material on the structural design of steel buildings, with emphasis on worked examples. The technical papers here presented focus on specific parts of the structural design, namely basis of design, modelling of structure, design of members, connections, cold-formed steel, seismic and fire design and on sustainability aspects. The report intends to contribute towards the transfer of background knowledge and expertise on the Eurocodes, mainly the EN 1993, from specialists of the European Convention for Constructional Steelwork (ECCS) and of CEN/TC250/Sub Committee 3, to trainers at a national level and to Eurocodes users. The report includes a comprehensive description of Eurocodes rules and worked examples presented by the aforementioned specialists at the workshop “Design of steel buildings with the Eurocodes, with worked examples’’ that was held on 16-17 October 2014, in Brussels, Belgium.
Euroccodes: Ba ackg groun nd & App plica ationss Design of Stee el Bu uildin ngs Worke ed Exa amples Authors: ovic, L Sim mões da Silv va, M Veljko R Simõe es, F Wald , J.-P Jasp part, K Weyna and, D Dubbină, R La andolfo, P Vila Re eal, H Gerrvásio Editors: ovic, M L S Sousa, S Dimova, D M Veljko B Nikolova, M Poljjanšek, A Pinto P 2015 Report EUR 27346 EN European Commission Joint Research Centre Institute for the Protection and Security of the Citizen Contact information Maria Luísa Sousa Address: TP480, Joint Research Centre, Via Enrico Fermi, 2749, 21027 Ispra, VA, Italy E-mail: luisa.sousa@jrc.ec.europa.eu Tel.: +39 0332 78 6381 JRC Science Hub https://ec.europa.eu/jrc Legal Notice This publication is a Science and Policy Report by the Joint Research Centre, the European Commission’s in-house science service It aims to provide evidence-based scientific support to the European policy-making process The scientific output expressed does not imply a policy position of the European Commission Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use which might be made of this publication All images © European Union 2015 JRC96658 EUR 27346 EN ISBN 978-92-79-49573-1 (PDF) ISSN 1831-9424 (online) doi:10.2788/605700 Luxembourg: Publications Office of the European Union, 2015 © European Union, 2015 Reproduction is authorised provided the source is acknowledged Abstract The present JRC report contains state-of-the-art training material on the structural design of steel buildings, with emphasis on worked examples The technical papers here presented focus on specific parts of the structural design, namely basis of design, modelling of structure, design of members, connections, cold-formed steel, seismic and fire design and on sustainability aspects The report intends to contribute towards the transfer of background knowledge and expertise on the Eurocodes, mainly the EN 1993, from specialists of the European Convention for Constructional Steelwork (ECCS) and of CEN/TC250/Sub Committee 3, to trainers at a national level and to Eurocodes users The report includes a comprehensive description of Eurocodes rules and worked examples presented by the aforementioned specialists at the workshop “Design of steel buildings with the Eurocodes, with worked examples’’ that was held on 16-17 October 2014, in Brussels, Belgium CONTENTS DESIGN OF STEEL STRUCTURES 1.1 1.2 Definitions and basis of design 1.1.1 Introduction 1.1.2 Codes of practice and standardization 1.1.3 Basis of design Basic concepts 1.1.3.2 Basic variables 1.1.3.3 Ultimate limit states 1.1.3.4 Serviceability limit states 1.1.3.5 Durability 1.1.3.6 Sustainability Global analysis 1.2.1 Structural modelling 1.2.2 Structural analysis 10 1.2.3 1.3 1.1.3.1 1.2.2.1 Introduction 10 1.2.2.2 Structural stability of frames 11 1.2.2.3 Imperfections 14 1.2.2.4 Classification of cross sections 14 Case-study building – elastic design of a braced steel framed building 19 1.2.3.1 Introduction 19 1.2.3.2 Description of the structure 20 1.2.3.3 General safety criteria, actions and combinations of actions 23 1.2.3.4 Structural analysis 33 Design of members 36 1.3.1 1.3.2 Introduction 36 1.3.1.1 Cross section resistance 36 1.3.1.2 Member resistance 38 Design of tension members 38 1.3.2.1 Code prescriptions 38 1.3.2.2 Worked examples 40 i 1.3.3 1.3.4 1.3.5 Design of columns 42 1.3.3.1 Code prescriptions 42 1.3.3.2 Worked examples 46 Design of beams 48 1.3.4.1 Code prescriptions 48 1.3.4.2 Worked examples 57 Design of beam-columns 62 1.3.5.1 Code prescriptions 62 1.3.5.2 Worked examples 68 BOLTS, WELDS, COLUMN BASE 85 2.1 2.2 2.3 Connections made with bolts, rivets or pins 85 2.1.1 Bolts 85 2.1.2 Positioning of holes for bolts and rivets 86 2.1.3 Design resistance of individual fasteners 88 2.1.4 Long joints 91 2.1.5 Slip-resistant connections 92 2.1.6 Design for block tearing 93 2.1.7 Connections made with pins 95 2.1.8 Worked example - bolted connection of double angle bar 95 Welded connections 97 2.2.1 Geometry and dimensions 97 2.2.2 Design resistance of a fillet welds 99 2.2.3 Design resistance of butt welds 101 2.2.4 Connections to unstiffened flanges 101 2.2.5 Long joints 102 2.2.6 Worked example - welded connection of double angle bar 103 2.2.7 Worked example - header plate simple connection 104 2.2.8 Worked example – fin plate connection 105 Column bases 108 2.3.1 Design resistance 108 2.3.2 Bending stiffness 111 2.3.3 Component base plate in bending and concrete in compression114 2.3.4 Component base plate in bending and anchor bolt in tension 117 2.3.5 Anchor bolts in shear 125 2.3.6 Worked example - simple column base 126 2.3.7 Worked example - fixed column base 127 ii DESIGN OF MOMENT RESISTING JOINTS IN STEEL STRUCTURES 137 3.1 3.2 Introduction 137 3.1.1 The traditional way in which joints are modelled for the design of a frame 137 3.1.2 The semi-continuous approach 137 3.1.3 Application of the “Static approach” 139 3.1.4 Component approach 139 3.2.2 3.2.3 3.2.4 3.2.5 3.4 General 139 3.1.4.2 Introduction to the component method 140 3.1.4.3 Types of design tools for joints 143 Structural analysis and design 144 3.2.1 3.3 3.1.4.1 Introduction 144 3.2.1.1 Elastic or plastic analysis and verification process 145 3.2.1.2 First order or second order analysis 146 3.2.1.3 Integration of joint response into the frame analysis and design process 147 Joint modelling 147 3.2.2.1 General 147 3.2.2.2 Modelling and sources of joint deformability 150 3.2.2.3 Simplified modelling according to Eurocode 150 Joint idealization 150 3.2.3.1 Elastic idealisation for an elastic analysis 151 3.2.3.2 Rigid-plastic idealisation for a rigid-plastic analysis 152 3.2.3.3 Non-linear idealisation for an elastic-plastic analysis 152 Joint classification 153 3.2.4.1 General 153 3.2.4.2 Classification based on mechanical joint properties 153 Ductility classes 154 3.2.5.1 General concept 154 3.2.5.2 Requirements for classes of joints 155 Worked example for joint characterisation 156 3.3.1 General data 156 3.3.2 Determination of the component properties 157 3.3.3 Assembling of the components 170 3.3.4 Determination of the design moment resistance 174 3.3.5 Determination of the rotational stiffness 174 3.3.6 Computation of the resistance in shear 175 Design strategies 176 3.4.1 Design opportunities for optimisation of joints and frames 176 iii 3.4.1.1 Introduction 176 3.4.1.2 Traditional design approach 178 3.4.1.3 Consistent design approach 180 3.4.1.4 Intermediate design approaches 181 3.4.1.5 Economical considerations 182 COLD-FORMED STEEL DESIGN ESSENTIALS 189 4.1 Introduction 189 4.2 Peculiar problems in cold-formed steel design 192 4.3 4.2.1 Peculiar characteristics of cold-formed steel sections (Dubina et al., 2012) 192 4.2.2 Peculiar problems of cold-formed steel design 193 Buckling strength of cold-formed steel members 194 4.2.2.2 Web crippling 197 4.2.2.3 Torsional rigidity 197 4.2.2.4 Ductility and plastic design 198 4.2.2.5 Connections 198 4.2.2.6 Design codification framework 199 4.2.2.7 Fire resistance 200 4.2.2.8 Corrosion 201 4.2.2.9 Sustainability of cold-formed steel construction 201 Resistance of cross-sections 202 4.3.1 Introduction 202 4.3.2 Flange curling 203 4.3.3 Shear lag 204 4.3.4 Sectional buckling modes in thin-walled sections 206 4.3.5 4.4 4.2.2.1 4.3.4.1 Local and distortional buckling 206 4.3.4.2 Buckling of thin flat walls in compression 206 4.3.4.3 Distortional buckling 214 Design against local and distortional buckling according to EN1993-1-3 217 4.3.5.1 General scheme 217 4.3.5.2 Plane elements with edge or intermediate stiffeners 217 4.3.5.3 Design example 222 Resistance of bar members 230 4.4.1 Introduction 230 4.4.2 Compression members 231 4.4.2.1 Interactive buckling of class members 231 4.4.2.2 Design according to EN1993-1-3 232 4.4.2.3 Design example 237 iv 4.4.3 4.4.4 4.4.5 Buckling strength of bending members 243 4.4.3.1 General approach 243 4.4.3.2 Design according to EN1993-1-3 244 4.4.3.3 Design example 247 Buckling of members in bending and axial compression 253 4.4.4.1 General approach 253 4.4.4.2 Design according to EN1993-1-1 and EN1993-1-3 253 4.4.4.3 Design example 254 Beams restrained by sheeting 264 4.4.5.1 4.5 4.6 General approach 264 Connections 267 4.5.1 Introduction 267 4.5.2 Fastening techniques of cold-formed steel constructions 268 4.5.2.1 Mechanical fasteners 268 4.5.2.2 Welding 275 4.5.2.3 Fastening based on adhesive bonding 277 4.5.3 Mechanical properties of connections 277 4.5.4 Design of connections 279 Conceptual design of Cold formed steel structures 280 4.6.1 Introduction 280 4.6.2 Case study: Wall Stud Modular System (WSMS) for residential and non-residential buildings 281 4.6.3 Concluding remarks 285 SEISMIC DESIGN OF STEEL STRUCTURES ACCORDING TO EN 1998-1 293 5.1 Introduction 293 5.2 Performance requirements and compliance criteria 293 5.3 Seismic action 295 5.4 Design requirements for buildings 297 5.5 5.4.1 Design concept and ductility class 297 5.4.2 Analysis procedures and models 299 5.4.2.1 Combination of actions for seismic design situations 301 5.4.2.2 Structural masses 302 5.4.3 Basic principles of conceptual design 303 5.4.4 Damage limitation 304 Design criteria and detailing rules in steel buildings 305 5.5.1 Behaviour factors 305 v 5.5.2 5.6 5.7 Design criteria and detailing rules for dissipative structural behaviour common to all structural types 308 5.5.2.1 Ductility classes and rules for cross sections 308 5.5.2.2 Design rules for connections close to dissipative zones309 5.5.2.3 Design rules and requirements for dissipative connections 309 5.5.3 Design criteria and detailing rules for Moment Resisting Frames309 5.5.4 Design criteria and detailing rules for Concentrically Braced Frames 311 5.5.5 Design criteria and detailing rules for Eccentrically Braced Frames 314 Design worked example: multi-storey building with moment resisting frame 316 5.6.1 Building description 316 5.6.2 Design actions 318 5.6.2.1 Characteristic values of unit loads 318 5.6.2.2 Masses 318 5.6.2.3 Seismic action 318 5.6.3 Calculation model and structural analysis 319 5.6.4 Frame stability and second order effects 322 5.6.5 Design and verification of beams 322 5.6.6 Design and verification of columns 324 5.6.7 Damage limitation check for MRFs 326 Design worked example: multi-storey building with concentric braced frame 327 5.7.1 Building description 327 5.7.2 Design actions 328 5.7.2.1 Characteristic values of unit loads 328 5.7.2.2 Masses 328 5.7.2.3 Seismic action 329 5.7.3 Calculation model and structural analysis 329 5.7.4 Frame stability and second order effects 332 5.7.5 Design and verification of diagonal members for X-CBFs 332 5.7.6 Design and verification of beams 333 5.7.7 Design and verification of columns of X-CBFs 334 5.7.8 Damage limitation check for X-CBFs 335 RESISTANCE OF MEMBERS AND CONNECTIONS TO FIRE 339 6.1 Introduction 339 vi 6.2 6.3 6.4 6.5 6.6 Thermal and mechanical actions 342 6.2.1 Thermal actions 342 6.2.2 Mechanical actions 343 Thermal and mechanical properties of steel 344 6.3.1 Thermal properties of steel 344 6.3.2 Mechanical properties of steel 345 Temperature in steel members 348 6.4.1 Unprotected steel members 348 6.4.2 Protected steel members 349 6.4.3 Worked examples 353 Fire resistance of structural members 356 6.5.1 Classification of cross-sections 357 6.5.2 Members with Class cross-section 357 6.5.3 Concept of critical temperature 359 6.5.4 Worked examples 361 Connections 379 6.6.1 Temperature of joints in fire 380 6.6.2 Strength of bolts and welds at elevated temperature 381 6.6.3 6.6.2.1 Design fire resistance of bolts in shear 382 6.6.2.2 Design fire resistance of bolts in tension 382 6.6.2.3 Design fire resistance of welds 383 Worked examples 383 SUSTAINABILITY ASPECTS OF STEEL BUILDINGS AND COMPONENTS 393 7.1 Introduction to life cycle thinking 393 7.2 Life Cycle Analysis of construction works 394 7.2.1 General methodologies and tools 394 7.2.2 Normative framework for LCA 395 7.2.3 7.2.2.1 Introduction 395 7.2.2.2 Definition of goal and scope 395 7.2.2.3 Life cycle inventory analysis 397 7.2.2.4 Life cycle impact assessment 397 7.2.2.5 Life cycle interpretation 402 7.2.2.6 Illustrative example 402 European standards for LCA of construction works 404 7.2.3.1 Sustainability of construction works 404 7.2.3.2 Product level 404 vii 7.2.3.3 7.3 Sustainability and LCA of steel structures 410 7.3.1 Production of steel 410 7.3.2 Allocation of recycling materials and Module D 411 7.3.3 7.4 7.3.2.1 Introduction 411 7.3.2.2 Allocating processes 411 7.3.2.3 Avoiding scrap allocation 412 Data and tools for LCA of steel structures 414 7.3.3.1 EPDs of steel products 414 7.3.3.2 Simplified methodologies for LCA 414 7.3.3.3 LCA based on the macro-components approach 415 Life cycle analysis of steel products 419 7.4.1 7.5 Building level 409 Worked examples 419 7.4.1.1 Example 1: LCA of a steel beam 419 7.4.1.2 Example 2: LCA of a steel column 423 7.4.1.3 Example 3: Comparative LCA of columns 425 Life cycle analysis of steel buildings 427 7.5.1 Worked examples 427 7.5.1.1 Example 4: LCA of a steel building 427 ANNEX A – DETAILED DATA OF MACRO-COMPONENTS 439 ANNEX B – DETAILED OUTPUT OF MACRO-COMPONENTS 443 viii u # 7, 00 kN/m D Properties of the gross cross-section Area of gross cross-section: A 3502 mm2 Radii of gyration: iy 133,5 mm ; iz Second moment of area about strong axis y-y: Iy 6240, u 104 mm4 Second moment of area about weak axis z-z: Iz 737, 24 u 104 mm4 257 45,9 mm Cold-formed steel design essentials D Dubină Warping constant: Iw 179274 u 106 mm6 Torsion constant: It 10254, mm4 Effective section properties of the cross-section Effective area of the cross-section when subjected to compression only: Aeff ,c 1982,26 mm2 Second moment of area of effective cross-section about strong axis y–y: Ieff ,y 5850, 85 u 104 mm4 Effective section modulus in bending: x with respect to the flange in compression: Weff ,y ,c 319968 mm3 x with respect to the flange in tension: Weff ,y ,t 356448 mm3 Weff ,y ,min Weff ,y ,c ,Weff ,y ,t 319968 mm3 The built-up column has to be designed for the relevant values in NEd and MEd diagrams displayed in Figure 4.46, respectively i.e.: My ,Ed -68.95 -68.95 NEd [kN] MEd [kNm] -46.28 -46.28 Figure 4.46 NEd and My,Ed diagrams Resistance check of the cross-section The following criterion should be met: M 'My ,Ed NEd y ,Ed d1 Nc ,Rd Mcy ,Rd ,com where: Nc ,Rd Aeff fyb J M Mcz ,Rd ,com 'My ,Ed -45.86 -25.30 -44.82 68, 95 kNm -46.48 -44.82 44,82 kN ; -68.95 - the maximum bending moment: -25.30 NEd -16.93 - the axial force (compression): Weff ,comfyb / J M NEd eNy 258 -68.95 Cold-formed steel design essentials D Dubină eNy – is the shift of the centroidal y–y axis; but as the cross-section is doubly symmetric: eNy (§§3.8.9) The resistance check is: 44, 82 u 103 68, 95 u 106 1982 u 350 1, 319968 u 350 1, 0, 680 – OK Buckling resistance check Members which are subjected to combined axial compression and uniaxial bending should satisfy: M 'My ,Ed NEd kyy y ,Ed d1 NRk My ,Rk Fy F LT J M1 J M1 M 'My ,Ed NEd kzy y ,Ed d1 NRk My ,Rk Fz F LT J M1 J M1 where: NRk 350 u 1982 fyb Aeff My ,Rk fybWeff ,y ,min 693, u 103 N 350 u 319968 693,7 kN 112 u 106 Nmm 112 kNm 'My ,Ed – additional moment due to the shift of the centroidal axes; 'My ,Ed F I I I2 O but F d 1,0 0,5 ª1 D O 0, O ẳ D imperfection factor The non-dimensional slenderness is: O Aeff fyb Ncr Ncr – the elastic critical force for the relevant buckling mode 259 Cold-formed steel design essentials D Dubină Determination of the reduction factors Fy, Fz, FT Flexural buckling Aeff fyb OF Aeff A Lcr i Ncr O1 The buckling length: Lcr ,y O1 Lcr ,z H E fyb S 4000 mm 210000 350 Su 76, 95 Buckling about y–y axis Oy Lcr ,y iy Aeff A 1982, 26 3502 4000 u 133,5 76, 95 O1 Dy 0, 21 – buckling curve a Iy 0,5 êơ1 D y Oy 0, Oy º¼ 0, 293 0,5 u ª¬1 0, 21 u 0, 293 0, 0, 2932 º¼ Fy 1 Iy Iy Oy 0,553 0,553 0,5532 0, 2932 0, 978 Buckling about z–z axis Oz Lcr,z Aeff A 1982, 26 3502 4000 u 45, 76, 95 O1 iz Dz 0.34 – buckling curve b Iz 0,5 êơ1 D z Oz 0, Oz ẳ 0, 852 0,5 u êơ1 0, 34 u 0, 852 0, 0, 8522 º¼ Fz I z I z Oz 0, 974 0, 974 0, 9742 0, 8522 0, 692 Torsional buckling Ncr ,T S 2EIw ã Đ GI ă t io â lT where: 260 Cold-formed steel design essentials D Dubină i y i z y o zo io yo , zo – the shear centre coordinates with respect to the centroid of the gross cross-section: yo zo io2 133,52 45, 92 lT H 19929,1 mm2 4000 mm The elastic critical force for torsional buckling is: Ncr ,T § S u 210000 u 179274 u 106 ã u ă 81000 u 10254, 19929,1 â 40002 1206, 96 u 10 N The non-dimensional slenderness is: OT 1982, 26 u 350 1206, 96 u 103 Aeff fyb Ncr DT 0,34 buckling curve b IT 0,5 êơ1 D T OT 0, OT ẳ 0, 758 0,5 u êơ1 0, 34 u 0, 758 0, 0, 7582 º¼ 0, 882 The reduction factor for torsional and flexural-torsional buckling is: FT 1 IT IT OT 0, 882 0, 8822 0, 7582 0, 750 Determination of the reduction factor FLT Lateral-torsional buckling F LT ILT ILT OLT but FLT d 1,0 ILT 0,5 êơ1 D LT OLT 0, OLT º¼ DLT 0,34 – buckling curve b The non-dimensional slenderness is: OLT Weff ,y ,minfyb Mcr Mcr – the elastic critical moment for lateral-torsional buckling Mcr C1 S 2EI z L Iw L2GIt I z S 2EI z 261 Cold-formed steel design essentials D Dubină where C1 1,77 for a simply supported beam under uniform loading 1, 77 u Mcr S u 210000 u 737, 24 u 104 40002 u Mcr 179274 u 106 40002 u 81000 u 10254, 737, 24 u 104 S u 210000 u 737, 24 u 104 282,27 kNm 319968 u 350 268, 27 u 106 Weff ,y ,min fyb OLT ILT u Mcr 0, 646 0,5 êơ1 D LT OLT 0, ... ISISE, University of Coimbra, Portugal Design of steel structures L Simões da Silva and R Simões Design of steel structures 1.1 Definitions and basis of design 1.1.1 Introduction Steel construction... Eurocode 2: Design of Concrete Structures o EN 1993 Eurocode 3: Design of Steel Structures o EN 1994 Eurocode 4: Design of Composite Steel and Concrete Structures o EN 1995 Eurocode 5: Design of Timber... structural design of steel buildings, with emphasis on worked examples The technical papers here presented focus on specific parts of the structural design, namely basis of design, modelling of structure,