Cover
Foreword
Preface
Chapter 1: Seismic Design Principles in Structural Codes
1.1 INTRODUCTION
1.2 FUNDAMENTALS OF SEISMIC DESIGN
1.3 CODIFICATION OF SEISMIC DESIGN
Chapter 2: EN 1998-1: General and Material Independent Parts
2.1 INTRODUCTION
2.2 PERFORMANCE REQUIREMENTS AND COMPLIANCE CRITERIA
2.3 SEISMIC ACTION
2.4 CHARACTERISTICS OF EARTHQUAKE RESISTANT BUILDINGS
2.5 METHODS OF STRUCTURAL SEISMIC ANALYSIS
2.6 STRUCTURAL MODELLING
2.7 ACCIDENTAL TORSIONAL EFFECTS
2.8 COMBINATION OF EFFECTS INDUCED BY DIFFERENT COMPONENTS OF THE SEISMIC ACTION
2.9 CALCULATION OF STRUCTURAL DISPLACEMENTS
2.10 SECOND ORDER EFFECTS IN SEISMIC LINEAR ELASTIC ANALYSIS
2.11 DESIGN VERIFICATIONS
Chapter 3: EN 1998-1: Design Provisions for Steel Structures
3.1 DESIGN CONCEPTS FOR STEEL BUILDINGS
3.2 REQUIREMENTS FOR STEEL MECHANICAL PROPERTIES
3.3 STRUCTURAL TYPOLOGIES AND BEHAVIOUR FACTORS
3.4 DESIGN CRITERIA AND DETAILING RULES FOR DISSIPATIVE STRUCTURAL BEHAVIOUR COMMON TO ALL STRUCTURAL TYPES
3.5 DESIGN CRITERIA AND DETAILING RULES FOR MOMENT RESISTING FRAMES
3.6 DESIGN CRITERIA AND DETAILING RULES FOR CONCENTRICALLY BRACED FRAMES
3.7 DESIGN CRITERIA AND DETAILING RULES FOR ECCENTRICALLY BRACED FRAMES
Chapter 4: Design Recommendations for Ductile Details
4.1 INTRODUCTION
4.2 SEISMIC DESIGN AND DETAILING OF COMPOSITE STEEL-CONCRETE SLABS
4.3 DUCTILE DETAILS FOR MOMENT RESISTING FRAMES
4.4 DUCTILE DETAILS FOR CONCENTRICALLY BRACED FRAMES
4.5 DUCTILE DETAILS FOR ECCENTRICALLY BRACED FRAMES
Chapter 5: Design Assisted by Testing
5.1 INTRODUCTION
5.2 DESIGN ASSISTED BY TESTING ACCORDING TO EN 1990
5.3 TESTING OF SEISMIC COMPONENTS AND DEVICES
5.4 APPLICATION: EXPERIMENTAL QUALIFICATION OF BUCKLING RESTRAINED BRACES
Chapter 6: Multi-storey Building with Moment Resisting Frames
6.1 BUILDING DESCRIPTION AND DESIGN ASSUMPTIONS
6.2 STRUCTURAL ANALYSIS AND CALCULATION MODELS
6.3 DESIGN AND VERIFICATION OF STRUCTURAL MEMBERS
6.4 DAMAGE LIMITATION
6.5 PUSHOVER ANALYSIS AND ASSESSMENT OF SEISMIC PERFORMANCE
Chapter 7: Multi-storey Building with Concentrically Braced Frames
7.1 BUILDING DESCRIPTION AND DESIGN ASSUMPTIONS
7.2 STRUCTURAL ANALYSIS AND CALCULATION MODELS
7.3 DESIGN AND VERIFICATION OF STRUCTURAL MEMBERS
7.4 DAMAGE LIMITATION
Chapter 8: Multi-storey Building with Eccentrically Braced Frames
8.1 BUILDING DESCRIPTION AND DESIGN ASSUMPTIONS
8.2 STRUCTURAL ANALYSIS AND CALCULATION MODELS
8.3 DESIGN AND VERIFICATION OF STRUCTURAL MEMBERS
8.4 DAMAGE LIMITATION
Chapter 9: Case Studies
9.1 INTRODUCTION
9.2 THE BUCHAREST TOWER CENTRE INTERNATIONAL
9.3 SINGLE STOREY INDUSTRIAL WAREHOUSE IN BUCHAREST
9.4 THE FIRE STATION OF NAPLES
References
End User License Agreement
List of Tables
Chapter 2: EN 1998-1: General and Material Independent Parts
Table 2.1 – Importance factors for each building category
Table 2.2 – EC8 recommended values of the parameters describing both Type 1 and Type 2 elastic response spectra
Table 2.3 – EC8 recommended values of parameters describing the vertical elastic response spectra
Table 2.4 – Recommended values for ψ 2,i . coefficient used to determine the quasi-permanent fraction of the variable action according to EN 1990 (CEN, 2002a)
Table 2.5 – EC8 Recommended φ coefficient values used to determine ψE,i
Table 2.6 – Consequences of structural regularity on seismic analysis
Chapter 3: EN 1998-1: Design Provisions for Steel Structures
Table 3.1 – Acceptance criteria for interstorey drift ratios according to FEMA 356
Table 3.2 – Upper limits of q factors for systems regular in elevation
Table 3.3 – Upper limits of q factors for dual systems regular in elevation
Table 3.4 – Requirements on cross-sectional class of dissipative elements depending on Ductility Class and reference behaviour factor
Chapter 4: Design Recommendations for Ductile Details
Table 4.1 – Resistance of components
Table 4.2 – Effective Length Factors K of continuous X-bracings
Chapter 5: Design Assisted by Testing
Table 5.1 – Annex D procedure
Table 5.2 – Tests for Displacement Dependant Devices (selected from EN 15129, Table 17)
Chapter 6: Multi-storey Building with Moment Resisting Frames
Table 6.1 – Material properties and partial factors
Table 6.2 – Characteristic values of vertical permanent and live loads
Table 6.3 – Combination coefficients for both loads and masses in seismic design condition
Table 6.4 – Seismic weights and masses
Table 6.5 – Coordinates of the centre of stiffness (CS), centre of mass (CM), structural eccentricity eo , torsional radius (r) and verifications for each floor
Table 6.6 – Periods and participating mass per mode of vibration
Table 6.7 – Accidental torsional moments per floor
Table 6.8 – Global sway imperfections
Table 6.9 – Stability coefficients calculated in X direction
Table 6.10 – Stability coefficients calculated in Y direction
Table 6.11 – Classification of beam cross sections
Table 6.12 – Stable length of beam between the section at a plastic hinge location and the adjacent lateral restraint
Table 6.13 – Flexural checks for beams belonging to MRF in X direction
Table 6.14 – Flexural checks for beams belonging to MRF in Y direction
Table 6.15 – shear checks for beams belonging to MRF in X direction
Table 6.16 – shear checks for beams belonging to MRF in Y direction
Table 6.17 – Flexural checks for columns “A” in X direction
Table 6.18 – Flexural checks for columns “G” in Y direction
Table 6.19 – Shear checks for columms belonging to vertical “A” in X direction
Table 6.20 – Shear checks for columms belonging to vertical “G” in Y direction
Table 6.21 – Local hierarchy criterion for external and inner columns in X direction
Table 6.22 – Verification of shear panel zone and design of additional web plates for external joints of column A in X direction
Table 6.23 – Verification of shear panel zone and design of additional web plates for internal joints of column B in X direction
Table 6.24 – Damage limitation check for MRFs in X direction
Table 6.25 – Damage limitation check for MRFs in Y direction
Table 6.26 – Response parameters and acceptance criteria for plastic hinges
Table 6.27 – Yield rotation for plastic hinges of beams (MRF in X direction)
Table 6.28 – Yield rotation for plastic hinges of columns (MRF in X direction)
Table 6.29 – Lateral force distributions (pushover in X direction)
Table 6.30 – Overstrength ratios au /al
Table 6.31 – Yield rotation for plastic hinges of columns (MRF in X direction)
Chapter 7: Multi-storey Building with Concentrically Braced Frames
Table 7.1 – Material properties and partial factors
Table 7.2 – Characteristic values of vertical permanent and live loads
Table 7.3 – Seismic weights and masses
Table 7.4 – Global sway imperfections in the X and Y directions
Table 7.5 – Stability coefficients for X-CBFs (i.e. frame in X direction)
Table 7.6 – Stability coefficients for inverted V-CBFs (i.e. frame in Y direction)
Table 7.7 – Cross section properties of X-braces
Table 7.8 – Design checks of X-braces
Table 7.9 – Axial strength checks of beams in X-braced bays
Table 7.10 – Combined bending-axial strength checks of beams in X-braced bays
Table 7.11 – Shear strength checks of beams in X-braced bays
Table 7.12 – Axial strength checks for columns in + X direction
Table 7.13 – Axial strength checks for columns in – X direction
Table 7.14 – Inverted V-brace cross section properties
Table 7.15 – Design checks of Inverted V-braces (D1) in tension
Table 7.16 – Design checks of Inverted V-braces (D1) in compression
Table 7.17 – Design checks of Inverted V-braces (D2) in tension
Table 7.18 – Design checks of Inverted V-braces (D2) in compression
Table 7.19 – Seismic induced axial forces into brace-intercepted beams (see Figure 7.18)
Table 7.20 – Axial strength checks of brace-intercepted beams
Table 7.21 – Combined bending-axial strength checks of brace-intercepted beams
Table 7.22 – Shear checks of brace-intercepted beams
Table 7.23 – Axial strength checks for the external columns of the braced cantilever
Table 7.24 – Axial strength checks for the central column of the braced cantilever
Table 7.25 – Damage limitation check for X-CBFs
Table 7.26 – Damage limitation check for inverted V-CBFs
Chapter 8: Multi-storey Building with Eccentrically Braced Frames
Table 8.1 – Material properties and partial safety factors
Table 8.2 – Characteristic values of vertical permanent and live loads
Table 8.3 – Seismic weights and masses
Table 8.4 – Global sway imperfections in both X and Y direction
Table 8.5 – Stability coefficients for EBF in X direction
Table 8.6 – Stability coefficients for EBF in Y direction
Table 8.7 – Link sections, upper bound shear length and selected length per storey (X and Y direction)
Table 8.8 – Strength verifications of links of frames in X direction
Table 8.9 – Strength verifications of links of frames in Y direction
Table 8.10 – Verification of braces in compression (X direction)
Table 8.11 – Verification of braces in compression (Y direction)
Table 8.12 – Axial strength checks for columns of EBF in X direction
Table 8.13 – Axial strength checks for columns of EBF in Y direction
Table 8.14 – Damage limitation check for EBF in X direction
Table 8.15 – Damage limitation check for EBF in Y direction
Chapter 9: Case Studies
Table 9.1 – Comparison between the configurations in the preliminary analysis
Table 9.2 – Wind direction on the scaled model
Table 9.3 – Periods of vibration and modal participating mass ratio
Table 9.4 – Acceptance criteria
Table 9.5 – Plastic rotation in beams and columns (in rad) and plastic deformation in braces (in %) at SLS, ULS and CPLS, average values
Table 9.6 – Choice of quality class according to EN 10164
Table 9.7 – Deviations from the theoretical position
Table 9.8 – Main dimensions of the buildings
Table 9.9 – Recommended values of external pressure coefficients for vertical walls of rectangular plan buildings
Table 9.10 – External pressure coefficients for flat roofs and sharp eaves
Table 9.11 – Values of the parameters describing the Type 1 elastic response spectrum
Table 9.12 – Modal participating mass ratio, structure A1
List of Illustrations
Chapter 1: Seismic Design Principles in Structural Codes
Figure 1.1 – Ductility of a chain with brittle and ductile rings
Figure 1.2 – Ductility of frames: a) high and b) poor displacement capacity
Figure 1.3 – Dissipative capacity of frames: a) high and b) poor energy absorption
Figure 1.4 – Strength vs. displacement demand relationship
Figure 1.5 – Seismic performance design objective matrix (SEAOC, 1995)
Figure 1.6 – ESC-SESAME European-Mediterranean seismic hazard map for the peak ground acceleration with 10 % probability of exceedance in 50 years for rock site (Solomos et al , 2008)
Figure 1.7 – ESHM13 European Seismic Hazard Map for the peak ground acceleration with 10 % probability of exceedance in 50 years for rock site (SHARE, 2013)
Figure 1.8 – Seismic protection strategies (Rai, 2000)
Chapter 2: EN 1998-1: General and Material Independent Parts
Figure 2.1 – Performance levels according to EC8-1
Figure 2.2 – Fundamental chart of the necessary elements for the structural analysis
Figure 2.3 – Displacement (Sde ), pseudo-velocity (Sve ) and pseudo-acceleration (Sae ) elastic response spectra for the Castelnuovo-Assisi station seismic record of the Umbria-Marche earthquake (26 September 1997)
Figure 2.4 – The schematic representation of the procedure to derive the displacement elastic spectrum for the Castelnuovo-Assisi station seismic record of the Umbria-Marche earthquake (26 September 1997)
Figure 2.5 – Concept of equivalent static force
Figure 2.6 – The shape of displacement (Sde ), pseudo-velocity (Sve ) and pseudo-acceleration (Sae ) elastic response spectra in EC8
Figure 2.7 – EC8 representation of seismic action acting upon a point on the ground surface: two horizontal response spectra (Sae,x and Sae,y ) and the vertical response spectrum (Sae,z )
Figure 2.8 – EC8 Elastic acceleration response spectra: Type 1 (a) and 2 (b)
Figure 2.9 – Elastic vs. design acceleration spectrum according to EC8
Figure 2.10 – Multi-storey building with perimeter primary moment-resisting frames (i.e. bold lines) and secondary members
Figure 2.11 – Typical examples of irregular structures sensitive to torsional deformations
Figure 2.12 – Plan regularity requirement for setback area (a); Plan regularity requirement for plan slenderness of building (b)
Figure 2.13 – Favourable (a) and unfavourable (b) plan position of lateral forces resisting systems
Figure 2.14 – Criteria for regularity of buildings with setbacks
Figure 2.15 – Consequences of plan regularity: regular (a) and irregular (b) structure
Figure 2.16 – The schematic representation of horizontal forces determined by lateral force method
Figure 2.17 – The fundamental scheme of the modal response spectrum analysis
Figure 2.18 – The correlation factor ρij vs. the modal circular frequencies ratio βij = ωi /ωj
Figure 2.19 – Moment resisting frame – bending moment diagrams induced by seismic action, calculated by lateral forces method (a) and modal response spectrum analysis method (b)
Figure 2.20 – Moment resisting frame – bending moment diagrams by combination of gravity and seismic effects using the modal response spectrum analysis
Figure 2.21 – Generalized force-deformation representation for the nonlinear behaviour of steel elements or components in case of nonlinear static analysis
Figure 2.22 – Nonlinear static analysis principle
Figure 2.23 – Lateral forces distribution variation function of structural plastic deformations
Figure 2.24 – Uniform (a) and modal (b) distribution of lateral forces for the nonlinear static analysis
Figure 2.25 – αu /α 1 factor – structural redundancy (a) and plastic mechanism (b) obtained using a nonlinear static analysis
Figure 2.26 – Non-linear hysteretic modelling of structural elements: a) bracing member under cyclic axial loading (D’Aniello et al , 2013); b) beam under cyclic bending (Tenchini et al , 2014)
Figure 2.27 – Lateral forces resisting systems: moment resisting frames with rigid joints (a), centrically braced frames (b), structural walls (c); combined gravitational and seismic resisting system (d)
Figure 2.28 – Example of gravitational and lateral loads resisting systems
Figure 2.29 – Distributed mass in a planar frame (a), its model with masses lumped into structural nodes (b) and with masses lumped at each floor (c)
Figure 2.30 – Masses lumped into the structural nodes in case of flexible slab (a); mass concentrated into the centre of masses in case of rigid diaphragms (b); mass mi and distance di to compute the moment of inertia of masses (c)
Figure 2.31 – Variation of modal damping with circular frequency: mass and stiffness proportional damping (a); Rayleigh damping (b)
Figure 2.32 – Structural model for elastic analysis of either X concentrically braced frame (a) and diagonal braced frame (b)
Figure 2.33 – The concept of leaning column to account for P -Δ effects in 2D models
Figure 2.34 – Modelling of a structural member with lumped plastic hinges at both ends
Figure 2.35 – Some examples of constitutive relations for modelling the cyclic behaviour of structural components by means of plastic hinges
Figure 2.36 – Modelling of a structural member with distributed plasticity approach
Figure 2.37 – Torsional effects simulated by means of accidental eccentricity eai in 3D structural models
Figure 2.38 – Torsional effects simulated by means of the magnification factor δ
Figure 2.39 – Accidental eccentricity effects modelled using torsional moments applied to the centroid of mass at each storey
Figure 2.40 – Example of effects induced by two horizontal components of seismic action
Figure 2.41 – Calculation of structural displacements according to EN 1998-1
Figure 2.42 – Elastic vs secant lateral stiffness for calculation of stability coefficients according to Eurocodes
Chapter 3: EN 1998-1: Design Provisions for Steel Structures
Figure 3.1 – Design Concepts according to EN 1998-1 (CEN, 2004a)
Figure 3.2 – The structural schemes considered in EC8: a) Moment resisting frames (dissipative zones in the beams and at the bottom of the columns); b) Frames with diagonal concentric bracings (dissipative zones in tension diagonals only); c) Frame with V bracings (dissipative zones in both tension and compression diagonals); d) Frames with eccentric bracings (dissipative zones in bending or shear links); e) K-braced frames (not allowed); f) Structures with concrete cores or concrete walls; g) Moment resisting frame combined with concentric bracing (dissipative zone in moment frame and in tension diagonals); h) Moment resisting frames combined with infills; i) Inverted pendulum with dissipative zones at the column base; j) Inverted pendulum with dissipative zones in columns
Figure 3.3 – The behaviour factor q according to EC8-1
Figure 3.4 – Examples of gravity load resisting bolted beam-to-column connections
Figure 3.5 – Design shear forces for girders of MRF span: combination of gravity loads with plastic bending moments at both ends of the beam
Figure 3.6 – Beam deflection for the calculation of θp
Figure 3.7 – Shear forces acting on the column web panel
Figure 3.8 – Example of application of requirement given by equation (3.19)
Figure 3.9 – Calculation models of X and Diagonal CBFs
Figure 3.10 – Capacity design criterion for brace-intercepted beams in chevron CBFs
Figure 3.11 – Capacity design criterion for columns in Diagonal CBFs
Figure 3.12 – Theoretical limit for link length (perfectly plastic behaviour no bending-shear interaction)
Figure 3.13 – M-V interaction domain: classification of seismic links
Figure 3.14 – The link rotation angle θp for the EBF configurations given in Figure 3.2
Figure 3.15 – Allowable link deformation capacity θp
Chapter 4: Design Recommendations for Ductile Details
Figure 4.1 – Compatibility transfer forces into the diaphragms
Figure 4.2 – Force distribution into the floor systems: deep beam analogy
Figure 4.3 – Secondary effects induced by horizontal distributed shear forces in collector beams (Burmeister and William, 2008)
Figure 4.4 – Floor diaphragm
Figure 4.5 – Typical potential surfaces of shear failure for composite slab according to section 6.6.6.4 of EN 1994-1-1
Figure 4.6 – Details of reinforcements and seating of the steel sheeting oriented both orthogonally and longitudinally to the spandrel beams (Clifton and El Sarraf, 2005)
Figure 4.7 – Beam of MRF with fly bracings and composite slab
Figure 4.8 – Details of MRF beams to avoid composite action
Figure 4.9 – Details of beam-to-beam splices in plastic hinge zone
Figure 4.10 – The types of welded and bolted joints most commonly used in European practice
Figure 4.11 – Position of plastic hinge and corresponding design lever arm sh
Figure 4.12 – Influence of the stiffener slope on the force transfer mechanism from beam to joint
Figure 4.13 – Geometry of dog-bone or reduced beam section (RBS)
Figure 4.14 – Prequalified beam-to-column joints (Landolfo, 2016)
Figure 4.15 – Details of welds on the beam side
Figure 4.16 – Details of weld access hole in accordance to AISC 358-16
Figure 4.17 – Details of welds on the column side
Figure 4.18 – Haunched beam-to-column joint
Figure 4.19 – Haunched beam-to-column joint: position of plastic hinge
Figure 4.20 – Equivalent double T-section at haunch
Figure 4.21 – Dissipative double-extended end-plate beam-to-column joint
Figure 4.22 – Example of rigid base assemblies for MRFs with extended columns into the basement
Figure 4.23 – Examples of rigid base assemblies for MRFs with grade beams: a) column base embedded in a concrete grade beam (adapted from Cochran, 2003); b) column rigidly connected to a steel moment resisting grade beam
Figure 4.24 – Examples of rigid base assemblies for MRFs with plate directly sitting on top of foundation
Figure 4.25 – Examples of pinned base assemblies for MRFs
Figure 4.26 – Weak-axis bending in the gusset plate due to out-of-plane buckling of braces (adapted from Cochran, 2003)
Figure 4.27 – Out-of-plane buckling mode of braces and formation of yield line in the gusset plate (adapted from Cochran, 2003)
Figure 4.28 – Bracing centrelines and gusset plate yield lines (adapted from Cochran, 2003)
Figure 4.29 – Gusset plate yield line and offset requirements (adapted from Cochran, 2003)
Figure 4.30 – Not recommended gusset plate yield line in both welded (a) and bolted (b) gussets: inadequate off-set and potential tears along gusset plate restraints (adapted from Cochran, 2003)
Figure 4.31 – Welded (a) and bolted (b) gusset plate with yield line isolated from concrete slab: brace with circular or square hollow cross section
Figure 4.32 – Welded (a) and bolted (b) gusset plate with yield line isolated from concrete slab: brace with wide flange cross section (adapted from Astaneh-Asl et al , 2006)
Figure 4.33 – Edge stiffener for welded (a) and bolted (b) gusset plate (adapted from Cochran, 2003)
Figure 4.34 – Critical angle concept: a) on beam side; and b) on column side for welded gusset; c) on beam side and d) on column side for bolted gusset (adapted from Cochran, 2003)
Figure 4.35 – The effective width Wd calculated with Whitmore’s method
Figure 4.36 – Elliptical clearance with 8t band width (Lehman et al , 2008) for welded (a) and bolted (b) gussets
Figure 4.37 – Details of brace-to-beam mid-span connection (adapted from Cochran, 2003)
Figure 4.38 – Details of lateral torsional bracing to restrain the brace-intercepted beam
Figure 4.39 – Example of continuous brace-to-brace connection
Figure 4.40 – Example of discontinuous X-CBFs using different types of mid-length splices: a) welded and b) hybrid welded/bolted connection
Figure 4.41 – Example of brace-to-brace connection using two discontinuous bracing members and a stiffened central core
Figure 4.42 – Possible out-of-plane buckling modes for continuous X-Braces
Figure 4.43 – Possible out-of-plane buckling modes for discontinuous X-Braces
Figure 4.44 – Examples of brace-to-column base connections (adapted from Astaneh-Asl et al , 2006)
Figure 4.45 – Examples of eccentricity between brace and frame centrelines (adapted from Cochran, 2003)
Figure 4.46 – Examples of additional plates to increase the strength of the net area of tubular braces
Figure 4.47 – Examples of additional plates to increase the strength of the net area of tubular braces
Figure 4.48 – Details for web stiffeners in short links
Figure 4.49 – Details for web stiffeners in long links
Figure 4.50 – Suitable details for link length
Figure 4.51 – Lateral bracings to restrain the link against lateral torsional buckling: full disconnected slab
Figure 4.52 – Lateral bracings to restrain the link against lateral torsional buckling: partially connected slab
Figure 4.53 – Full rigid brace-to-link connection
Figure 4.54 – Pinned brace-to-link connection
Figure 4.55 – Recommended detail for link-to-column connections
Chapter 5: Design Assisted by Testing
Figure 5.1 – Reliability index β (CEN, 2002a)
Figure 5.2 – Scatter due to “epistemic uncertainty” (i.e. error of the theoretical design model rt vs. the experimental evidence re )
Figure 5.3 – Example of hysteretic response of a beam-to-column connection obtained as result of quasi-static cyclic testing
Figure 5.4 – Deformed shape of a moment resisting frame under seismic loading (a) and a close-up view of an exterior beam-column joint (b)
Figure 5.5 – Possible idealizations of boundary conditions of an exterior beam to column joint specimen in moment resisting frames: neglecting axial force in the column (a) or accounting for it (b)
Figure 5.6 – Test setup for a beam-to-column joint specimen: conceptual scheme (a) and its implementation (b) for a rotated position and unrotated position ((c) and (d))
Figure 5.7 – Load-displacement curve illustrating static values occuring at regular stops of loading (Dekker et al , 2015)
Figure 5.8 – Cyclic loading protocol (a); determination of yielding displacement Dy (b)
Figure 5.9 – Determination of ultimate rotation according to EC8-1
Figure 5.10 – Loading protocol specified in EN 15129
Figure 5.11 – Loading protocol specified in AISC 341-10 for testing beam-to-column connections
Figure 5.12 – Loading protocol specified in AISC 341-10 for testing link-to-column connections
Figure 5.13 – Loading protocol specified in AISC 341-10 for testing buckling restrained braces
Figure 5.14 – Scheme of PSD testing principle (Pseudo Dynamic Tests)
Figure 5.15 – Pseudo-dynamic testing on a full-scale 3D steel building Frame (Sabau et al , 2014) performed at ELSA, Italy
Figure 5.16 – Shaking tables at University of Naples Federico II (a) and test on a 2-storey building (b, c)
Figure 5.17 – Details and geometry of BRB (debonding material – polyethylene foil, 1mm thick)
Figure 5.18 – Subassembly test setup: a) schematic of test setup; b) specimen installed and the loading arrangement
Figure 5.19 – ECCS vs. AISC cyclic loading protocols
Figure 5.20 – The monotonic behaviour of the BRB specimens (compression vs. tension)
Figure 5.21 – Hysteretic behaviour of BRB with polyethylene film debonding material, AISC and ECCS loading protocols
Figure 5.22 – Monotonic tests vs. the envelopes from AISC and ECCS loading protocols, specimens with polyethylene film debonding material
Figure 5.23 – General view of the specimen after the test (top) and connecting details (bottom)
Chapter 6: Multi-storey Building with Moment Resisting Frames
Figure 6.1 – Architectural plan of the typical floor
Figure 6.2 – Structural plan of the typical floor
Figure 6.3 – Structural elevation of the primary MRFs
Figure 6.4 – Elastic and design response spectra
Figure 6.6 – Numerical model: 3D model (a) MRFs in X (b) and in Y (c) directions
Figure 6.7 – Modal shapes of the main modes of vibrations
Figure 6.8 – Internal forces due to gravity loads. (N.B. the Plots were scaled using different factors, but the same value was used for each type of internal force)
Figure 6.9 – Internal forces due to seismic actions (N.B. the Plots were scaled using different factors, but the same value was used for each type of internal force; in addition, all action effects are defined positive due to the application of SRSS rule)
Figure 6.10 – Fly braces to avoid lateral torsional buckling of beams in MRFs and details of shear connectors to avoid composite action in the plastic hinge zone
Figure 6.11 – Detail of beam-to-column joint: a) stocky and b) supplementary web plate
Figure 6.12 – Lateral displacement shapes: X (a) and Y (b) directions
Figure 6.13 – Position and types of plastic hinges
Figure 6.14 – Generalized force-deformation relationship of plastic hinge (a) and relevant acceptance criteria (b)
Figure 6.15 – M-N domain for plastic hinges of columns
Figure 6.16 – Refined model for the column web panel zone
Figure 6.17 – Modelling of P-Δ effects in 2D model
Figure 6.18 – Capacity curves for both modal and uniform pushover
Figure 6.19 – Damage pattern for both modal (a) and uniform (b) force distribution
Figure 6.20 – Capacity curve of MDOF (a) and SDOF (b) system
Figure 6.21 – Idealized elastic-perfectly plastic force vs displacement behaviour
Figure 6.22 – Pushover response at dt = 0.290 m
Chapter 7: Multi-storey Building with Concentrically Braced Frames
Figure 7.1 – Structural plan of the typical floor
Figure 7.2 – Vertical layout of CBFs
Figure 7.3 – Elastic and design response spectra
Figure 7.4 – Cross sections of X-braces
Figure 7.5 – Cross sections of beams and columns in X-CBFs
Figure 7.6 – Braces of Inverted V-CBFs
Figure 7.7 – Cross sections of beams and columns in inverted V-CBFs
Figure 7.8 – X-CBFs: numerical models of the calculation example with only tension braces tilted in +X direction (a) and in −X direction (b)
Figure 7.9 – Inverted V-CBFs: numerical models of the calculation example
Figure 7.10 – Fundamental dynamic properties of the examined structures
Figure 7.11 – Internal forces for X-CBFs (N.B. the Plots were scaled by the same factor per type of effort)
Figure 7.12 – Internal forces for inverted V-CBFs (N.B. the Plots were scaled by the same factor per type of effort)
Figure 7.13 – Cross sections of X-braces
Figure 7.14 – Cross sections of beams and columns in X-CBFs
Figure 7.15 – Calculation scheme for seismically induced axial forces into the beam of X-CBFs (Mazzolani et al , 2006)
Figure 7.16 – Braces of Inverted V-CBFs
Figure 7.17 – Cross sections of beams and columns in inverted V-CBFs
Figure 7.18 – Seismic induced forces into brace-intercepted beams
Figure 7.19 – Lateral displacement shapes: X-CBFs (a); Inverted V-CBFs (b)
Chapter 8: Multi-storey Building with Eccentrically Braced Frames
Figure 8.1 – Structural plan of the typical floor
Figure 8.2 – Vertical layout of EBF in X direction
Figure 8.3 – Vertical layout of EBF in Y direction
Figure 8.4 – Elastic and design response spectra
Figure 8.5 – EBFs calculation models in X direction (a) and in Y direction (b)
Figure 8.6 – Fundamental dynamic properties of the examined structures
Figure 8.7 – Internal forces for EBFs in X direction (N.B. the Plots were scaled by the same factor per type of effort)
Figure 8.8 – Internal forces for EBFs in Y direction (N.B. the Plots were scaled by the same factor per type of effort)
Figure 8.9 – Lateral displacement shapes: X direction (a); Y direction (b)
Chapter 9: Case Studies
Figure 9.1 – Structural rendering (a), external view of the building (b) and interior of the building (c)
Figure 9.2 – Structural system: a) end transversal frame; b) current transversal frame; c) end longitudinal frame; d) current floor; e) infrastructure and soil layers
Figure 9.3 – Cross section of the members: a) columns; b) beams; c) braces
Figure 9.4 – Typical connections
Figure 9.5 – Wind load vs. seismic load (Taranath, 2005)
Figure 9.6 – The preliminary analysis considering three structural systems
Figure 9.7 – Pressure coefficients for different wind directions on the building
Figure 9.8 – Rigid wind model, length scale 1:100
Figure 9.9 – Mean wind profile, experimental vs. theoretical
Figure 9.10 – Design pressure coefficients, E-W
Figure 9.11 – Distribution of the pressure coefficients on the envelope of the rigid model scaled to 1:100, NE direction of the wind
Figure 9.12 – Turbulence and roughness treatments
Figure 9.13 – Normalised response spectrum for Bucharest
Figure 9.14 – 3D model, south view (left) and north view (right)
Figure 9.15 – First three modes of vibration: a) mode 1, T = 2.86 s; mode 2, T = 2.68 s; c) mode 3, T = 1.76 s
Figure 9.16 – Normalised elastic response spectrum of the site and periods of first three vibration modes
Figure 9.17 – Total lateral displacement under wind load, transverse and longitudinal directions
Figure 9.18 – Response of bracing members
Figure 9.19 – Elastic acceleration response spectra of the semi artificial accelerograms and design spectra (P100-1/2006, ag = 0.24g, Tc = 1.6s)
Figure 9.20 – Plastic hinges: a) side transversal frame; b) current transversal frame
Figure 9.21 – Peak interstorey drift ratio vs. storey level for transversal direction, average of records
Figure 9.22 – Detail of a beam-to-column joint in the MRF of TC1 structure
Figure 9.23 – Some details of the brace connections
Figure 9.24 – Views of the building in successive phases of the construction
Figure 9.25 – Strengthened connection with plastic hinge located in the beam (left) and correction of the design bending moment (right)
Figure 9.26 – Connection between columns of infrastructure and superstructure
Figure 9.27 – Ultrasonic testing report: principle (left); the defect in the thick plate during the inspection on site (right)
Figure 9.28 – Erection of the structure: a) columns are continuous over 3 stories and are hoisted first; b) multiple lift rigging
Figure 9.29 – GPS system to control the position of members: a) reference points serving as fixed points for the total station; b) positioning the antenna of the receiver in a point to be surveyed
Figure 9.30 – General view with the two buildings
Figure 9.31 – General view with the production unit
Figure 9.32 – Main transverse frame
Figure 9.33 – Intermediate transverse frame
Figure 9.34 – Longitudinal frame
Figure 9.35 – General view with the warehouse unit
Figure 9.36 – Main transverse frame
Figure 9.37 – Intermediate transverse frame
Figure 9.38 – Marginal longitudinal frame
Figure 9.39 – Snow load shape coefficients – pitched roofs, for undrifted load arrangement
Figure 9.40 – Snow load shape coefficients - roofs abutting to taller construction, for drifted load arrangement
Figure 9.41 – Variation of exposure factor ce (z ) for different terrain categories and flat terrain (orography coefficient c 0 = 1.0, turbulence factor ki = 1.0)
Figure 9.42 – Zones for vertical walls: a) plan view; b) elevation for e < d ; elevation for e ≥ d ; elevation for e ≥ 5d
Figure 9.43 – The velocity pressure should be assumed to be uniform over each horizontal strip considered
Figure 9.44 – Zones for flat roofs
Figure 9.45 – Wind flow around a low-rise building
Figure 9.46 – Type 1 elastic response spectrum for ground types D (5 % damping)
Figure 9.47 – First mode of vibration
Figure 9.48 – The Fire Station of Naples
Figure 9.49 – The building A of the Fire Station of Naples under construction
Figure 9.50 – The steel skeleton of building B (a) and its final configuration (b)
Figure 9.51 – a) The shock block transmitter; b) the connection between the beam end to the core column
Figure 9.52 – The structural scheme of building C (a) and its main entrance (b)
Figure 9.53 – The building D: the Scaffolding
Figure 9.54 – The Guard House at the entrance of the Centre
Figure 9.55 – The façade of the Head Quarter
Figure 9.56 – The stair-case system connecting Buildings G and H
Figure 9.57 – Structure of the Gymnasium
Figure 9.58 – Longitudinal and transverse sections of Building A
Figure 9.59 – Plan lay-out of Building A
Figure 9.60 – The building A under constructions
Figure 9.61 – Erection phases of the top truss girders
Figure 9.62 – Design sheets of longitudinal and transversal girders
Figure 9.63 – The connection between the top girders
Figure 9.64 – Floor decks sustained by steel ties to the top transversal trusses
Figure 9.65 – Floor bracings
Figure 9.66 – Steel trapezoidal sheeting for covering of the floor structures
Figure 9.67 – The suspended skeleton composed of steel ties and bracing on the facade
Figure 9.68 – Workshop fabrication (a), transportation (b), lifting on the top of the r.c. cores (c, d) and connection of the steel girder to special supports (e, f) (continuation)
Figure 9.69 – Connection of transversal to longitudinal girders: global view a) and detail b)
Figure 9.70 – The detail of the top suspension of ties
Figure 9.71 – Some details of the structural joints: a) intermediate and b) lateral node
Figure 9.72 – Plan location of the top supports and maximum design loads (in tons)
Figure 9.73 – (a) vertical section and (b) plan of the special support device
Figure 9.74 – Constructional details of the support device between two adjacent structural meshes: (a) vertical section; (b) plan
Figure 9.75 – Real view of the device between two adjacent structural meshes
Figure 9.76 – Energy dissipation elements of the device
Figure 9.77 – Details of the device used for avoiding pounding effects between the r.c. walls and the suspended floors
Figure 9.78 – Lateral (a) and plane (b) views of the device used to avoid pounding effects between the cores and the suspended floors
Figure 9.79 – Lower view of the device used to avoid pounding effects between the cores and the suspended floors
Guide
Cover
Table of Contents
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e1
ECCS Eurocode Design Manuals
ECCS Editorial Board
Luís Simões da Silva (ECCS )António Lamas (Portugal )Jean-Pierre Jaspart (Belgium )Reidar Bjorhovde (USA )Ulrike Kuhlmann (Germany )
Design of Steel Structures – 2nd Edition
Luís Simões da Silva, Rui Simões and Helena Gervásio
Fire Design of Steel Strcutures – 2nd Edition
Jean-Marc Franssen and Paulo Vila Real
Design of Plated Structures
Darko Beg, Ulrike Kuhlmann, Laurence Davaine and Benjamin Braun
Fatigue Design of Steel and Composite Structures
Alain Nussbaumer, Luís Borges and Laurence Davaine
Design of Cold-formed Steel Structures
Dan Dubina, Viorel Ungureanu and Raffaele Landolfo
Design of Joints in Steel and Composite Structures
Jean-Pierre Jaspart and Klaus Weynand
Design of Steel Structures for Buildings in Seismic Areas
Raffaele Landolfo, Federico Mazzolani, Dan Dubina, Luís Simões da Silva and Mario D’Aniello
ECCS – SCI EUROCODE DESIGN MANUALS
Design of Steel Structures, UK Edition
Luís Simões da Silva, Rui Simões, Helena Gervásio
Adapted to UK by Graham Couchman
Design of Joints in Steel Structures, UK Edition
Jean-Pierre Jaspart and Klaus Weynand
Adapted to UK by Graham Couchman and Ana M. Girão Coelho
ECCS EUROCODE DESIGN MANUALS – BRAZILIAN EDITIONS
Dimensionamento de Estruturas de Aço
Luís Simões da Silva, Rui Simões, Helena Gervásio, Pedro Vellasco, Luciano Lima
Information and ordering details
For price, availability, and ordering visit our website www.steelconstruct.com.
For more information about books and journals visit www.ernst-und-sohn.de.
Design of Steel Structures for Buildings in Seismic Areas
Eurocode 8: Design of structures for earthquake resistance
Design of Steel Structures for Buildings in Seismic Areas
1st Edition, 2017
Published by:
ECCS – European Convention for Constructional Steelwork
publications@steelconstruct.com
www.steelconstruct.com
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Wilhelm Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin
All rights reserved. No parts of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying,
recording or otherwise, without the prior permission of the copyright owner.
ECCS assumes no liability with respect to the use for any application of the material and information contained in this publication.
Copyright © 2017 ECCS – European Convention for Constructional Steelwork
ISBN (ECCS): 978-92-9147-138-6
ISBN (Ernst & Sohn): 978-3-433-03010-3
Legal dep.: 432199/17 Printed in Sersilito, Empresa Gráfica Lda, Maia, Portugal
Photo cover credits: Dan Dubina
There are many seismic areas in Europe. As times goes by, regional seismicity is better known and the number of places where earthquake is an action to consider in design increases. Of course, there are substantial differences in earthquake intensity between regions and the concern is much greater in many areas of Italy, for instance, than in most places in Northern Europe. However, even in Northern Europe, for structures for which a greater level of safety is required, like Seveso industrial plants, hospitals and public safety facilities, seismic design can be the most requiring design condition.
Designing for earthquake has original features in comparison with design for classical loading like gravity, wind or snow. The reference event for Ultimate Limit State seismic design is rare enough for an allowance to permanent deformations and structural damages, as long as people’s life is not endangered. This means that plastic deformations are allowed at ULS, so that the design target becomes a global plastic mechanism. To be safe, the latter requires many precautions, on global proportions of structures and on local detailing. The seismic design concepts are completely original in comparison to static design. Of course, designing for a totally elastic behaviour even under the strongest earthquake remains possible but, outside of low seismicity areas, this option is generally left aside because of its cost.
This book is developed with a constant reference to Eurocode 8 or EN 1998-1:2004; it follows the organization of that code and provides detailed explanations in support of its rather dry expression. Of course, there are many other seismic design codes, but it must be stressed that there is nowadays a strong common thinking on the principles and the application rules in seismic design so that this book is also a support for the understanding of other continents codes.
Chapter 1 explains the principles of seismic design and their evolution throughout time, in particular the meaning, goals and conditions set forward by capacity design of structures and their components, a fundamental aspect of seismic design.
Chapter 3 focuses on design provisions specific to steel structures: ductility classes, requirements on steel material, structural typologies and design conditions related to each of them; an original insight on design for reparability is also included.
Chapter 4 provides an overview about the best practice to implement the requirements and design rules for ductile details, particularly for connections in moment resisting frames (MRF), concentrically braced frames (CBF) and eccentrically braced frames (EBF), and for other structural components like diaphragms.
Chapter 5 describes the guidance provided for design assisted by testing by EN 1990 and the specific rules for tests, a necessary tool for evaluating the performance characteristics of structural typologies and components in the plastic field and in cyclic/dynamic conditions.
Chapter 6 illustrates and discusses the design steps and verifications required by EN 1998-1 for a multi-storey Moment Resisting Frame.
Chapter 7 and 8 do the same respectively for buildings with CBF’s and EBF’s.
Chapter 9 presents three very different examples of real buildings erected in high seismicity regions: one tall building, one industrial hall and one design using base isolation. These examples are complete in the sense that they show the total design, where seismic aspects are only one part of the problem. These examples are concrete, because they illustrate practical difficulties of the real world with materials, execution, positioning…
The concepts, design procedures and detailing in seismic design may seem complex. This publication explains the background behind the rules, which
This book will serve the structural engineering community in expanding the understanding and application of seismic design rules, and, in that way, constitute a precious tool for our societies safety.
André Plumier
Honorary Professor, University of Liege
This manual aims to provide its readers with the background and the explanation of the main aspects dealing with the seismic design of steel structures in Europe. Therefore, the book focuses on EN 1998-1 (usually named part 1 of Eurocode 8 or EC8-1) that is the Eurocode providing design rules and requirements for seismic design of building structures. After 10 years from its final issue, both the recent scientific findings and the design experience carried out in Europe highlight some criticisms. In the light of such considerations, this book complements the explanation of the EC8-1 provisions with the recent research findings, the requirements of renowned and updated international seismic codes (e.g. North American codes and design guidelines) as well as the design experience of the Authors. Although the manual is oriented to EC8-1, the book aims to clarify the scientific outcomes, the engineering and technological aspects rather than sticking to an aseptic explanation of each clause of the EC8-1. Indeed, as shown in Chapter 4, the proper detailing of steel structures is crucial to guarantee adequate ductility of seismic resistant structures and the current codes does not give exhaustive guidelines to design ductile details since it only provides the fundamental principles. In addition, the practice of earthquake engineering significantly varies between European regions, reflecting the different layouts of each national seismic code as well as the level of knowledge and confidence with steel structures of each country. With this regard, a large number of European engineers believe that steel structures can withstand severe earthquakes without requiring special details and specifications as conversely compulsory for other structural materials like reinforced concrete and masonry. This belief direct results from the mechanical features of the structural steel, which is a high performance material, being stronger than concrete but lighter (if comparing the weight of structural members) and also very ductile and capable of dissipating large amounts of energy through yielding when subjected to cyclic inelastic deformations. However, although the material behaviour is important, the ductility of steel alone is not enough to guarantee ductile structural response. Indeed, as demonstrated by severe past earthquakes (e.g. Northridge 1994,
Therefore, this book primarily attempts to clarify all these issues (from Chapter 1 to 4) for European practising engineers, working in consultancy firms and construction companies. In addition, the examples of real buildings (see Chapter 9) are an added value, highlighting practical and real difficulties related to both design and execution.
Chapter 678Chapter 5
The Authors
Raffaele Landolfo
Federico Mazzolani
Dan Dubina
Luís Simões da Silva
Mario D’Aniello
