DESIGNERS' GUIDES TO THE EUROCODES DESIGNERS' GUIDE TO EUROCODE 8: DESIGN OF STRUCTURES FOR EARTHQUAKE RESISTANCE 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 AND RETAINING STRUCTURES M. FARDIS, E. CARVALHO, A. ELNASHAI, E. FACCIOLl, P. PINTO and A. PLUMIER Series editor H. Gulanessian thomas telford
Contents Preface Aim of this guide Layout of this guide Acknowledgements Chapter 1 Introduction 1 1.1. Scope of Eurocode 8 1 1.2. Scope of Eurocode 8 - Part 1 1 1.3. Scope of Eurocode 8 - Part 5 2 1.4. Use of Eurocode 8 - Parts 1 and 5 with the other Eurocodes 2 1.5. Assumptions - distinction between Principles and Application Rules 3 1.6. Terms and definitions - symbols 3 Chapter 2 Performance requirements and compliance criteria 2.1. Performance requircments for new designs in Eurocode 8 and associated seismic hazard leels 2.2. Compliance criteria for the performance requirements and their implementation 2.2.]. Compliance criteria for damage limitation 2.2.2. Compliance criteria for the no-(local-)collapse requirement 2.3. Exemption from the application of Eurocode 8 5 5 7 7 7 10 Chapter 3 Seismic actions 3.1. Ground conditions 3.1.1. Identification of ground types 3.2. Seismic action 3.2.1. Seismic zones 3.2.2. Basic representation of the seismic action 3.2.3. Alternatie representations of the seismic action 3.3. Displacement response spectra 13 13 14 15 15 18 24 27 Chapter 4 Design of buildings 4.1. Scope 4.2. Conception of structures for earthquake resistant buildings 4.2.1. Structural simplicity 31 31 3] 31
DESIGNERS' GUIDE TO EN 1998-1 AND EN 1998-5 4.2.2. Uniformity, symmetry and redundancy 32 4.2.3. Bi-directional resistance and stiffness 32 4.2.4. Torsional resistance and stiffness 33 4.2.5. Diaphragmatic behaiour at the storey leel 33 4.2.6. Adequate foundation 34 4.3. Structural regularity and its implications for design 34 4.3.1. Introduction 34 4.3.2. Regularity in plan 35 4.3.3. Regularity in eleation 41 4.4. Combination of graity loads and other actions with the design seismic action 43 4.4.1. Combination for local effects 43 4.4.2. Combination for global effects 43 4.5. Methods of analysis 44 4.5.1. Oeriew of the menu of analysis methods 44 4.5.2. The lateral force method of analysis 44 4.5.3. Modal response spectrum analysis 48 4.5.4. Linear analysis for the ertical component of the seismic action 52 4.5.5. Non-linear methods of analysis 53 4.6. Modelling of buildings for linear analysis 59 4.6.1. Introduction: the leel of discretization 59 4.6.2. Modelling of beams, columns and bracings 60 4.6.3. Special modelling considerations for walls 61 4.6.4. Cracked stiffness in concrete and masonry 62 4.6.5. Accounting for second-order (P-Ll) effects 63 4.7. Modelling of buildings for non-linear analysis 64 4.7.1. General requirements for non-linear modelling 64 4.7.2. Special modelling requirements for non-linear dynamic analysis 66 4.7.3. The inadequacy of member models in 3D as a limitation of non-linear modelling 68 4.8. Analysis for accidental torsional effects 68 4.8.1. Aceidental eccentricity 68 4.8.2. Estimation of the effects of accidental eccentricity through static analysis 69 4.8.3. Simplified estimation of the effects of accidental eccentricity 70 4.9. Combination of the effects of the components of the seismic action 71 4.10. 'Primary' ersus 'secondary' seismic elements 72 4.10.1. Definition and role of 'primary' and 'secondary' seismic elements 72 4.10.2. Special requirements for the design of secondary seismic elements 73 4.11. Verification 74 4.11.1. Verification for damage limitation 74 4.11.2. Verification for the no-(iocal)-collapse requirement 75 4.12. Special rules for frame systems with masonry infills 81 4.12.1. Introduction and scope 81 4.12.2. Design against the aderse effects of planwise irregular infills 82 4.1.2.3. Design against the aderse effects of heightwise irregular infills 83
Chapter 5 Design and detailing mies for concrete buildings 85 5.1. Scope 85 5.2. Types of concrete elements - definition of 'critical regions' 86 5.2.1. Beams and columns 86 5.2.2. Walls 86 5.2.3. Ductile walls: coupled and uncoupled 87 5.2.4. Large lightly reinforced walls 88 5.2.5. Critical regions in ductile elements 89 5.3. Types of structural systems for earthquake resistance of concrete buildings 89 5.3.1. Inerted-pendulum systems 90 5.3.2. Torsionally flexible systems 90 5.3.3. Frame systems 90 5.3.4. Wall systems 91 5.3.5. Dual systems 91 5.3.6. Systems of large lightly reinforced walls 91 5.4. Design concepts: design for strength or for ductility and energy dissipation - ductility classes 92 5.5. Behaiour factor q of concrete buildings designed for energy dissipation 93 5.6. Design strategy for energy dissipation 95 5.6.1. Global and local ductility through capacity design and member detailing: oeriew 95 5.6.2. Implementation of capacity design of concrete frames against plastic hinging in columns 96 5.6.3. Detailing of plastic hinge regions for flexural ductility 101 5.6.4. Capacity design of members against pre-emptie shear failure 105 5.7. Detailing rules for the local ductility of concrete members 111 5.7.1. Introduction 111 5.7.2. Minimum longitudinal reinforcement in beams 111 5.7.3. Maximum longitudinal reinforcement ratio in the critical regions of beams 112 5.7.4. Maximum diameter of longitudinal beam bars crossing beam-column joints 113 5.7.5. Verification of beam-column joints in shear 116 5.7.6. Dimensioning of shear reinforcement in critical regions of beams and columns 120 5.7.7. Confinement reinforcement in the critical regions of columns and ductile walls 123 5.7.8. Boundary elements at section ends in the critical region of ductile walls 127 5.7.9. Shear erification in the critical region of ductile walls 127 5.7.10. Minimum clamping reinforcement across construction joints in walls of DCR 130 5.8. Special rules for large walls in structural systems of large lightly reinforced walls 131 5.8.1. Introduction 131 5.8.2. Dimensioning for the ULS in bending with axial force 131 5.8.3. Dimensioning for the ULS in shear 132 5.8.4. Detailing of the reinforcement 134 5.9. Special rules for concrete systems with masonry or concrete infills 135 5.10. Design and detailing of foundation elements 138 CONTENTS
DESIGNERS' GUIDE TO EN 1998-1 AND EN 1998-5 Chapter 6 Design and detailing rules for steel buildings 141 6.1. Scope 141 6.2. Dissipatie ersus low-dissipatie structures 141 6.3. Capacity design principle 143 6.4. Design for local energy dissipation in the elements and their connections 144 6.4.1. Faourable factors for local ductility 144 6.4.2. Unfaourable factors for local ductility 145 6.5. Design rules aiming at the realization of dissipatie zones 146 6.6. Background of the deformation capacity required by Eurocode 8 147 6.7. Design against localization of strains 148 6.8. Design for global dissipatie behaiour of structures 150 6.8.1. Structural types and behaiour factors 150 6.8.2. Selection of the behaiour factor for design purposes 151 6.9. Moment-resisting frames 152 6.9.1. Design objectie 152 6.9.2. Analysis issues in moment-resisting frames 152 6.9.3. Design of beams and columns 153 6.9.4. Design of dissipatie zones 156 6.9.5. Limitation of oerstrength 157 6.10. Frarnes with concentric bracings 158 6.10.1. Analysis of frames with concentric bracings considering their eolutie behaiour 158 6.10.2. Simplified design of frames with X bracings 159 6.10.3. Simplified design of frames with decoupled diagonal bracings 159 6.10.4. Simplified design of frames with V bracings 160 6.10.5. Criterion for the formation of a global plastic mechanism 160 6.10.6. Partial strength connections 160 6.11. Prames with eccentric bracings 161 6.11.1. General features of the design of frames with eccentric bracings 161 6.11.2. Short links ersus long links 162 6.11.3. Criteria to form a global plastic mechanism 163 6.11.4. Selection of the typology of eccentric bracings 164 6.11.5. Partial strength connections 164 6.12. Moment-resisting frames with infills 165 6.13. Control of design and construction 165 Chapter 7 Design and detailing of composite steel-concrete buildings 167 7.1. Introductory remark 167 7.2. Degree of composite character 167 7.3. Materials 168 7.4. Design for local energy dissipation in elements and their connections 168 7.4.1. Faourable factors for local ductility due to the composite character of structures 168 7.4.2. Unfaourable factors for local ductility due to the composite character of structures 169 7.5. Design for the global dissipatie behaiour of structures 170 7.5.1. Behaiour factors of structural types similar to steel 170 7.5.2. Behaiour factors of composite structural systems 171
CONTENTS 7.6. Properties of composite sections for analysis of structures and for resistance checks 172 7.6.1. Difficulties in selecting mechanical properties for design and analysis 172 7.6.2. Stiffness of composite sections 172 7.6.3. Effectie width of slabs 173 7.7. Composite connections in dissipatie zones 173 7.8. Rules for members 174 7.9. Design of columns 175 7.9.1. Design options 175 7.9.2. Non-dissipatie composite columns 175 7.9.3. Dissipatie composite columns 176 7.9.4. Composite columns considered as steel columns in the model used for analysis 176 7.10. Steel beams composite with a slab 177 7.10.1. Ductility condition for steel beams with a slab under a sagging (positie) moment 177 7.10.2. Ductility condition for steel beams with a slab under a hogging (negatie) moment 177 7.10.3. Seismic reinforcement in the concrete slab in momentresisting frames 178 7.11. Design and detailing rules for moment frames 179 7.11.1. General 179 7.11.2. Analysis and design rules for beams, columns and connections 180 7.11.3. Disregarding the composite character of beams with a slab 180 7.11.4. Limitation of oerstrength 181 7.12. Composite concentrically braced frames 181 7.13. Composite eccentrically braced frames 181 7.14. Reinforced-concrete shear walls composite with structural steel elements 182 7.14.1. General 182 7.14.2. Analysis and design rules for beams and columns 182 7.15. Composite or concrete shear walls coupled by steel or composite beams 183 7.16. Composite steel plate shearwalls 184 Chapter 8 Design and detailing rules for timber buildings 185 8.1. Scope 185 8.2. General concepts in earthquake resistant timber buildings 185 8.3. Materials and properties of dissipatie zones 187 8.4. Ductility c1asses and behaiour factors 187 8.5. Detailing 189 8.6. Safety erifications 189 Chapter 9 Seismic design with base isolation 191 9.1. Introduction 191 9.2. Dynamics of seismic isolation 197 9.3. Design criteria 201 9.4. Seismic isolation systems and deices 201 9.4.1. Isolators 202 9.4.2. Supplementary deices 203
DESIGNERS' GUIDE TO EN 1998-1 AND EN 1998-5 9.5. Modelling and analysis procedures 204 9.6. Safety criteria and erifications 206 9.7. Design seismic action effects on fixed-base and isolated buildings 207 Chapter 10 Foundations, retaining structures and geotechnical aspects 209 10.1. Introduction 209 10.1.1. Scope ofthe Designers' Guide to EN 1998-5 209 10.1.2. Relationship between EN 1998-5 and EN 1997-1 (Eurocode 7: Geotechnical design. Part 1: General rules) 209 10.2. Seismic action 212 10.2.2. Topographie amplification factor 213 10.2.3. 'Artificial' ersus recorded time-history representations 213 10.3. Ground properties 215 10.3.1. Strength parameters 215 10.3.2. Partial factors for material properties 217 10.3.3. Stiffness and damping parameters 217 10.4. Requirements for siting and for foundation soils 218 10.4.1. Siting 218 Example 10.1: calculation of seismically induced displacements in a reallandslide 221 Example 10.2: liquefaction hazard ealuation 228 10.4.2. Ground inestigations and studies 231 10.4.3. Ground type identification for the determination of the design seismic action 231 Example 10.3: ground-type identification at an actual construction ~~ n3 Example 10.4: a further case of ground-type identification at an actual site 234 10.5. Foundation system 236 10.5.1. General requirements - seismically induced ground deformation 236 10.5.2. Rules for conceptual design 236 10.5.3. Transfer ofaction effects to the ground 237 10.5.4. ULS erifications for shallow or embedded foundations 238 Example 10.5: erification of the footing of a iaduct pier against bearing capacity failure 238 Example 10.6: non-linear dynamic analyses of a simple soil-footing model 240 10.5.5. Piles and piers 246 10.6. Soil-structure interaction 250 10.7. Earth-retaining structures 250 10.7.1. General design considerations 250 10.7.2. Basic models 251 10.7.3. Seismic action 252 10.7.4. Design earth and water pressure 252 Example 10.7: simplified seismic analysis of a flexible earth-retaining structure with the pseudo-static approach 253 Example 10.8: non-linear dynamic analysis of the flexible retaining structure of Example 10.7 subjected to earthquake excitation 259 References Index 265 273