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FEMA P 1050 1 2015

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FEMA P-1050-1, NEHRP Provisions Volume I: Part 1 Provisions, Part 2 Commentary

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FEMA 2015 555
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PDF Pages PDF Title
1 FEMA P-1050-1: NEHRP Recommended Seismic Provisions for New Buildings and Other Structures – Volume I: Part 1 Provisions, Part 2 Commentary
3 Title Page
4 Disclaimer
5 Foreword
7 Preface and Acknowledgements
9 Table of Contents
33 Introduction
39 INTENT
1.1 Intent
1.1.1 Structure Collapse
40 1.1.2 Nonstructural Damage
41 1.1.3 Hazardous Materials
1.1.4 Preservation of Egress
1.1.5 Functionality of Critical or Essential Facilities
1.1.6 Repair Costs
1.1.7 Reference Document
42 2.1 Commentary to Section
2.1.1 Structure Collapse
44 2.1.2 Nonstructural Damage
2.1.3 Hazardous Materials
2.1.4 Preservation of Egress
2.1.5 Functionality of Critical or Essential Facilities
45 2.1.6 Repair Costs
47 PART 1, PROVISIONS
49 Chapter 1, General
Section 1.2.1
1.2.1 Definitions
51 Chapter 11, Seismic Design Criteria
Section 11.2
11.2 Definitions
Section 11.3
11.3 SYMBOLS
52 SECTION 11.4.2
11.4.2 Site Class
Section 11.4.3
11.4.3 Site Coefficients and Risk-Targeted Maximum Considered Earthquake (MCER) Spectral Response Acceleration Parameters
53 Section 11.4.7
11.4.7 Site-Specific Ground Motion Procedures
54 Section 11.5 and 11.6
11.5 IMPORTANCE FACTOR AND RISK CATEGORY
11.5.1 Importance Factor
11.5.2 Protected Access for Risk Category IV
11.6 SEISMIC DESIGN CATEGORY
55 Section 11.8.3
11.8.3 Additional Geotechnical Investigation Report Requirements for Seismic Design Categories D through F
57 Chapter 12, Seismic Design Requirements For Building Structures
SECTION 12.1.5
12.1.5 Foundation Design
SECTION 12.2
12.2 Structural System Selection
12.2.1 Selection and Limitations
12.2.1.1 Alternative Seismic Force-Resisting Systems
58 12.2.1.2 Substitute Elements
SECTION 12.3.1.3
12.3.1.3 Calculated Flexible Diaphragm Condition
59 FIGURE 12.3-1 Flexible Diaphragm
SECTION 12.4.2.2
12.4.2.2 Vertical Seismic Load Effect
60 SECTION 12.8.1.3
12.8.1.3 Maximum SDS Value in Determination of Cs and Ev
SECTION 12.8.4.2
12.8.4.2 Accidental Torsion
61 Section 12.9
SECTION 12.9.1.1
12.9.1.1 Number of Modes
62 SECTION 12.9.1.4
12.9.1.4 Scaling Design Values of Combined Response.
12.9.1.4.1 Scaling of Forces
12.9.1.4.2 Scaling of Drifts
SECTION 12.9.1.8
12.9.1.8 Structural Modeling
SECTION 12.9.2
12.9.2 Linear Response History Analysis
12.9.2.1 General Requirements
63 12.9.2.2 General Modeling Requirements
12.9.2.2.1 P-Delta Effects
12.9.2.2.2 Accidental Torsion
12.9.2.2.3 Foundation Modeling
12.9.2.2.4 Number of Modes to Include in Response History Analysis
12.9.2.2.5 Damping
12.9.2.3 Ground Motion Selection and Scaling
12.9.2.3.1 Procedure for Spectrum Matching
12.9.2.4 Application of Ground Acceleration Histories
65 12.9.2.6 Enveloping of Force Response Quantities
12.9.2.7 Enveloping of Displacement Response Quantities
SECTION 12.10
12.10 Diaphragms, Chords, and Collectors
SECTION 12.10.1.1
12.10.1.1 Diaphragm Design Forces
SECTION 12.10.3
66 12.10.3 Alternative Provisions for Diaphragms Including Chords and Collectors
12.10.3.1 Design
12.10.3.2 Seismic Design Forces for Diaphragms including Chords and Collectors
12.10.3.2.1 Design acceleration coefficients Cp0 and Cpn
67 FIGURE 12.10-2 Calculating the Design Acceleration Coefficient Cpx in Buildings with n ≤ 2 and in Buildings with n ≥ 3
12.10.3.3 Transfer Diaphragms
12.10.3.4 Collectors – Seismic Design Categories C through F
68 12.10.3.5 Diaphragm Design Force Reduction Factor
SECTION 12.13
12.13 FOUNDATION DESIGN
12.13.1 Design Basis
12.13.2 Materials of Construction
12.13.3 Foundation Load-Deformation Characteristics
12.13.4 Reduction of Foundation Overturning
69 SECTION 12.13.5
12.13.5 Strength Design for Nominal Foundation Geotechnical Capacity
12.13.5.1 Nominal Strength
12.13.5.2 Resistance Factors
70 12.13.5.3 Acceptance Criteria
SECTION 12.13.5 and 12.13.6
12.13.6 5 Requirements for Structures Assigned to Seismic Design Category C
12.13.7 6 Requirements for Structures Assigned to Seismic Design Category D through F
SECTION 12.13.8
12.13.8 Requirements for Structure Foundations on Liquefiable Sites
12.13.8.1 Foundation Design
12.13.8.2 Shallow Foundations
71 12.13.8.2.1 Shallow Foundation Detailing
12.13.8.2.1.1 Foundation Ties
72 12.13.8.2.1.2 Mat Foundations
12.13.8.3 Deep Foundations
12.13.8.3.1 Downdrag
12.13.8.3.2 Lateral Resistance
12.13.8.3.3 Concrete Deep Foundation Detailing
73 12.13.8.3.4 Lateral Spreading
12.13.8.3.5 Foundation Ties
SECTION 12.14.1.1
12.14.1.1 Simplified Design Procedure
75 Chapter 14, Material Specific Seismic Design and Detailing Requirements
Section 14.2.2.1
14.2.2.1 Definitions
Section 14.2.4
14.2.4 Additional Design and Detailing Requirements for Precast Concrete Diaphragms
14.2.4.1 Diaphragm Seismic Demand Levels
76 FIGURE 14.2.4-1 Diaphragm Seismic Demand Level
14.2.4.1.1 Diaphragm Span
14.2.4.1.2 Diaphragm Aspect Ratio
14.2.4.1.3 Diaphragm Shear Amplification Factor
14.2.4.2 Diaphragm Design Options
14.2.4.2.1 Elastic Design Option
77 14.2.3.2.2 Basic Design Option
14.2.3.2.3 Reduced Design Option
14.2.4.3 Diaphragm Connector or Joint Reinforcement Deformability
14.2.4.3.1 Low Deformability Element (LDE).
14.2.4.3.2 Moderate Deformability Element (MDE)
14.2.4.3.3 High Deformability Element (HDE)
14.2.4.3.4 Connector/ Joint Reinforcement Classification
14.2.4.3.5 Special Inspection
14.2.4.4 Precast Concrete Diaphragm Connector and Joint Reinforcement Qualification Procedure
78 14.2.4.4.1 Test Modules
14.2.4.4.2 Number of Tests
14.2.4.4.3 Test Configuration
14.2.4.4.4 Instrumentation
14.2.4.4.5 Loading Protocols
79 14.2.4.4.6 Measurement Indices, Test Observations and Acquisition of Data
FIGURE 14.2.4-2 Backbone Qualification Curve
80 FIGURE 14.2.4-3 Deformation Curve Types
14.2.4.4.7 Response Properties
14.2.4.4.8 Test Report
81 14.2.4.4.9 Deformed Bar Reinforcement
83 Chapter 15, Seismic Design Requirements for Nonbuilding Structures
Section 15.4.1
15.4.1 Design Basis
85 Chapter 16, Seismic Response History Procedures
16.1 GENERAL REQUIREMENTS
16.1.1 Design
16.1.2 Documentation
86 16.2 GROUND MOTIONS
16.2.1 Level of Ground Motion
16.2.2 Development of the Target Response Spectrum
16.2.2.1 Method 1
16.2.2.2 Method 2
16.2.3 Ground Motions Selection
16.2.3.1 Minimum Number of Ground Motions
16.2.3.2 Components of Ground Motion
87 16.2.3.3 Selection of Ground Motions
16.2.4 Ground Motion Scaling
16.2.4.1 Period Range for Scaling
16.2.4.2 Scaling of Ground Motions
16.2.4.3 Spectral Matching of Ground Motions
16.2.5 Application of Ground Motions to the Structural Model
88 16.2.5.1 Orientation of Ground Motions
16.2.5.2 Application of Input Ground Motion over Subterranean Levels
16.3 MODELING AND ANALYSIS
16.3.1 System Modeling
16.3.2 Gravity Load
16.3.3 P-delta Effects
16.3.4 Seismic Mass
16.3.5 Diaphragm Modeling
16.3.6 Torsion
89 16.3.7 Stiffness of Elements Modeled with Elastic Properties
16.3.8 Nonlinear Modeling
16.3.9 Damping
16.3.10 Soil-Structure Interaction (SSI)
16.4 ANALYSIS RESULTS AND ACCEPTANCE CRITERIA
16.4.1 Global Acceptance Criteria
16.4.1.1 Unacceptable Response
90 16.4.1.2 Story Drift
16.4.2 Element-Level Acceptance Criteria
16.4.2.1 Force-Controlled Actions
16.4.2.2 Deformation-Controlled Actions
91 16.4.2.3 Components of the Gravity System
16.5 DESIGN REVIEW
16.5.1 Reviewer Qualifications
16.5.2 Review Scope
93 Chapter 17, Seismic Design Requirements For Seismically Isolated Structures
17.1 GENERAL
17.1.2 Definitions
17.1.3 Notation
96 17.2 GENERAL DESIGN REQUIREMENTS
17.2.1 Importance Factor
17.2.2 Configuration
17.2.3 Redundancy
17.2.4 Isolation System
17.2.4.1 Environmental Conditions
17.2.4.2 Wind Forces
17.2.4.3 Fire Resistance
97 17.2.4.4 Lateral Restoring Force
17.2.4.5 Displacement Restraint
17.2.4.6 Vertical-Load Stability
17.2.4.7 Overturning
17.2.4.8 Inspection and Replacement
98 17.2.4.9 Quality Control
17.2.5 Structural System
17.2.5.1 Horizontal Distribution of Force
17.2.5.2 Minimum Building Separations
17.2.5.3 Nonbuilding Structures
17.2.5.4 Steel Ordinary Concentrically Braced Frames
17.2.5.5 Steel Grid Frames
17.2.6 Elements of Structures and Nonstructural Components
17.2.6.1 Components at or above the Isolation Interface
99 17.2.6.2 Components Crossing the Isolation Interface
17.2.6.3 Components below the Isolation Interface
17.2.7 Seismic Load Effects and Load Combinations
17.2.7.1 Isolator Unit Vertical Load Combinations
17.2.8 Isolation System Properties
17.2.8.1 Isolation System Component Types
17.2.8.2 Isolator Unit Nominal Properties
17.2.8.3 Bounding Properties of Isolation System Components
100 17.2.8.4 Property Modification Factors
101 17.2.8.5 Upper-Bound and Lower-Bound Force-Deflection Behavior of Isolation System Components
17.2.8.6 Isolation System Properties at Maximum Displacements
17.3 SEISMIC GROUND MOTION CRITERIA
17.3.1 Site-Specific Seismic Hazard
102 17.3.2 MCER Response Spectra and Spectral Response Acceleration Parameters, SMS, SM1
17.3.4 MCER Ground Motion Records
17.4  ANALYSIS PROCEDURE SELECTION
17.4.1 Equivalent Lateral Force Procedure
103 17.4.2 Dynamic Procedures
17.4.2.1 Response Spectrum Analysis Procedure
17.4.2.2 Response History Analysis Procedure
17.5  EQUIVALENT LATERAL FORCE PROCEDURE
17.5.1 General
17.5.2 Deformation Characteristics of the Isolation System
104 17.5.3 Minimum Lateral Displacements Required for Design
17.5.3.1 Maximum Displacement
17.5.3.2 Effective Period at the Maximum Displacement
105 17.5.3.3 Total Maximum Displacement
17.5.4 Minimum Lateral Forces Required for Design
17.5.4.1 Isolation System and Structural Elements below the Base Level
106 17.5.4.2 Structural Elements above the Base Level
107 17.5.4.3 Limits on Vs
17.5.5 Vertical Distribution of Force
108 17.5.6 Drift Limits
17.6 DYNAMIC ANALYSIS PROCEDURES
17.6.1 General
17.6.2 Modeling
17.6.2.1 Isolation System
17.6.2.2 Isolated Structure
109 17.6.3 Description of Procedures
17.6.3.1 General
17.6.3.2 MCER Ground Motions
17.6.3.3 Response-Spectrum Analysis Procedure
17.6.3.4 Response-History Analysis Procedure
17.6.3.4.1 Accidental Mass Eccentricity
110 17.6.4 Minimum Lateral Displacements and Forces
17.6.4.1 Isolation System and Structural Elements below the Base Level
17.6.4.2 Structural Elements above the Base Level
17.6.4.3 Scaling of Results
111 17.6.4.4 Drift Limits
17.7  DESIGN REVIEW
17.8  TESTING
17.8.1 General
17.8.1.2 Qualification Tests
112 17.8.2 Prototype Tests
17.8.2.1 Record
17.8.2.2 Sequence and Cycles
17.8.2.3 Dynamic Testing
113 17.8.2.4 Units Dependent on Bilateral Load
17.8.2.5 Maximum and Minimum Vertical Load
17.8.2.6 Sacrificial Wind-Restraint Systems
17.8.2.7 Testing Similar Units
114 17.8.3 Determination of Force-Deflection Characteristics
115 FIGURE 17.8.3-1 Nominal Properties of the Isolator Bilinear Force-Deflection Model
17.8.4 Test Specimen Adequacy
116 17.8.5 Production Tests
117 Chapter 18, Seismic Design Requirements For Structures with Damping Systems
18.1 GENERAL
18.1.1 Scope
18.1.2 Definitions
18.1.3 Notation
121 18.2 GENERAL DESIGN REQUIREMENTS
18.2.1 System Requirements
122 18.2.1.1 Seismic Force-Resisting System
18.2.1.2 Damping System
18.2.2 Seismic Ground Motion Criteria
18.2.2.1 Design Earthquake and MCER Response Spectra
123 18.2.2.2 Design Earthquake and MCER Ground Motion Records
18.2.3 Procedure Selection
18.2.3.1 Response-Spectrum Procedure
124 18.2.3.2 Equivalent Lateral Force Procedure
18.2.4 Damping System
18.2.4.1 Device Design
18.2.4.2 Multiaxis Movement
18.2.4.3 Inspection and Periodic Testing
125 18.2.4.4 Nominal Design Properties
18.2.4.5 Maximum and Minimum Damper Properties
126 18.2.4.6 Damping System Redundancy
18.3 NONLINEAR RESPONSE-HISTORY PROCEDURE
18.3.1 Damping Device Modeling
127 18.3.2 Accidental Mass Eccentricity
18.3.3 Response Parameters
18.4 SEISMIC LOAD CONDITIONS AND ACCEPTANCE CRITERIA FOR NONLINEAR RESPONSE-HISTORY PROCEDURE
18.4.1 Seismic Force-Resisting System
18.4.2 Damping System
18.4.3 Combination of Load Effects
128 18.4.4 Acceptance Criteria for the Response Parameters of Interest
18.5 DESIGN REVIEW
18.6 TESTING
18.6.1 Prototype Tests
129 18.6.1.1 Data Recording
18.6.1.2 Sequence and Cycles of Testing
130 18.6.1.3 Testing Similar Devices
18.6.1.4 Determination of Force-Velocity-Displacement Characteristics
18.6.1.5 Device Adequacy
131 18.6.1.5.1 Displacement-Dependent Damping Devices
18.6.1.5.2 Velocity-Dependent Damping Devices
132 18.6.2 Production Tests
18.7 ALTERNATE PROCEDURES AND CORRESPONDING ACCEPTANCE CRITERIA
18.7.1 Response Spectrum Procedure
18.7.1.1 Modeling
133 18.7.1.2 Seismic Force-Resisting System
18.7.1.2.1 Seismic Base Shear
18.7.1.2.2 Modal Base Shear
18.7.1.2.3 Modal Participation Factor
18.7.1.2.4 Fundamental Mode Seismic Response Coefficient
134 18.7.1.2.5 Effective Fundamental Mode Period Determination
18.7.1.2.6 Higher Mode Seismic Response Coefficient
18.7.1.2.7 Design Lateral Force
18.7.1.3 Damping System
135 18.7.1.3.1 Design Earthquake Floor Deflection
18.7.1.3.2 Design Earthquake Roof Displacement
18.7.1.3.3 Design Earthquake Story Drift
18.7.1.3.4 Design Earthquake Story Velocity
136 18.7.1.3.5 MCER Response
18.7.2 Equivalent Lateral Force Procedure
18.7.2.1 Modeling
137 18.7.2.2 Seismic Force-Resisting System
18.7.2.2.1 Seismic Base Shear
18.7.2.2.2 Fundamental Mode Base Shear
18.7.2.2.3 Fundamental Mode Properties
138 18.7.2.2.4 Fundamental Mode Seismic Response Coefficient
18.7.2.2.5 Effective Fundamental Mode Period Determination
18.7.2.2.6 Residual Mode Base Shear
139 18.7.2.2.7 Residual Mode Properties
18.7.2.2.8 Residual Mode Seismic Response Coefficient
18.7.2.2.9 Design Lateral Force
18.7.2.3 Damping System
140 18.7.2.3.1 Design Earthquake Floor Deflection
18.7.2.3.2 Design Earthquake Roof Displacement
18.7.2.3.3 Design Earthquake Story Drift
18.7.2.3.4 Design Earthquake Story Velocity
141 18.7.2.3.5 MCER Response
18.7.3 Damped Response Modification
18.7.3.1 Damping Coefficient
142 18.7.3.2 Effective Damping
143 18.7.3.2.1 Inherent Damping
18.7.3.2.2 Hysteretic Damping
18.7.3.2.2.1 Hysteresis Loop Adjustment Factor
18.7.3.2.3 Viscous Damping
144 18.7.3.3 Effective Ductility Demand
145 18.7.3.4 Maximum Effective Ductility Demand
18.7.4 Seismic Load Conditions and Acceptance Criteria for RSA and ELF Procedures
18.7.4.1 Seismic Force-Resisting System
146 18.7.4.2 Damping System
18.7.4.3 Combination of Load Effects
18.7.4.4 Modal Damping System Design Forces
18.7.4.5 Seismic Load Conditions and Combination of Modal Responses
148 18.7.4.6 Inelastic Response Limits
149 Chapter 19, Soil Structure Interaction for Seismic Design
19.1 General
19.1.1 Scope
19.1.2 Definitions
19.1.2 Notation
150 19.2 SSI Adjusted Structural Demands
19.2.1 Equivalent Lateral Force Procedure
193 Chapter 24, Alternative Seismic Design Requirements For Seismic Design Category B Buildings
24.1 GENERAL
24.1.1 Scope and Applicability
24.2 STRUCTURAL DESIGN BASIS
24.2.1 Basic Requirements
24.2.2 Member Design, Connection Design, and Deformation Limit
24.2.3 Continuous Load Path and Interconnection
194 24.2.4 Connection to Supports
24.2.5 Foundation Design
24.2.6 Material Design and Detailing Requirements
24.3 STRUCTURAL SYSTEM SELECTION
24.3.1 Selection and Limitations
24.3.2 Combinations of Framing Systems in Different Directions
195 24.3.3 Combinations of Framing Systems in the Same Direction
24.3.3.1 R, Cd, and Ω0Values for Vertical Combinations
24.3.3.2 Two Stage Analysis Procedure
24.3.3.3 R, Cd, and Ω0 Values for Horizontal Combinations
196 24.3.4 Combination Framing Detailing Requirements
24.3.5 System Specific Requirements
24.3.5.1 Dual System
24.3.5.2 Cantilever Column Systems
24.3.5.3 Inverted Pendulum-Type Structures
24.3.5.4 Shear Wall-Frame Interactive Systems
24.4 DIAPHRAGM FLEXIBILITY AND CONFIGURATION IRREGULARITIES
24.4.1 Diaphragm Flexibility
24.4.1.1 Flexible Diaphragm Condition
197 24.4.1.2 Rigid Diaphragm Condition
24.4.1.3 Calculated Flexible Diaphragm Condition
24.4.2 Irregular and Regular Classification
24.4.2.1 Horizontal Irregularity
24.4.2.2 Vertical Irregularity
24.4.3 Limitations and Additional Requirements for Systems with Structural Irregularities
24.4.3.1 Extreme Weak Stories
24.4.3.2 Elements Supporting Discontinuous Walls or Frames
198 24.5 SEISMIC LOAD EFFECTS AND COMBINATIONS
24.5.1 Applicability
24.5.2 Seismic Load Effect
24.5.2.1 Seismic Load Combinations
24.5.3 Seismic Load Effect Including Overstrength Factor
199 24.5.3.1 Load Combinations with Overstrength Factor
24.5.3.2 Allowable Stress Increase for Load Combinations with Overstrength
24.6 DIRECTION OF LOADING
24.7 ANALYSIS PROCEDURE SELECTION
200 24.8 MODELING CRITERIA
24.8.1 Foundation Modeling
24.8.2 Effective Seismic Weight
24.8.3 Structural Modeling
24.8.4 Interaction Effects
201 24.9 EQUIVALENT LATERAL FORCE PROCEDURE
24.9.1 Seismic Base Shear
24.9.2 Period Determination
24.9.2.1 Approximate Fundamental Period
202 24.9.3 Vertical Distribution of Seismic Forces
24.9.4 Horizontal Distribution of Forces
24.9.4.1 Inherent Torsion
203 24.9.4.2 Accidental Torsion
24.9.5 Overturning
24.9.6 Story Drift Determination
24.9.6.1 Minimum Base Shear for Computing Drift
24.9.6.2 Period for Computing Drift
24.9.7 P-Delta Effects
204 24.10 MODAL RESPONSE SPECTRUM ANALYSIS
24.10.1 Number of Modes
24.10.2 Modal Response Parameters
24.10.3 Combined Response Parameters
205 24.10.4 Scaling Design Values of Combined Response
24.10.4.1 Scaling of Forces
24.10.5 Horizontal Shear Distribution
24.10.6 P-Delta Effects
24.11 DIAPHRAGMS, CHORDS, AND COLLECTORS
24.11.1 Diaphragm Design
24.11.1.1 Diaphragm Design Forces
206 24.11.2 Collector Elements
24.12 STRUCTURAL WALLS AND THEIR ANCHORAGE
24.12.1 Design for Out-of-Plane Forces
24.12.2 Anchorage of Structural Walls
207 24.13 DRIFT AND DEFORMATION
24.13.1 Story Drift Limit
24.13.2 Diaphragm Deflection
24.13.3 Structural Separation
24.13.4 Members Spanning between Structures
208 24.14 FOUNDATION DESIGN
24.14.1 Design Basis
24.14.2 Materials of Construction
24.14.3 Foundation Load-Deformation Characteristics
24.14.4 Reduction of Foundation Overturning
24.15 SEISMIC DESIGN REQUIREMENTS FOR EGRESS STAIRWAYS AND PARAPETS
24.15.1 Scope
24.15.2 General Design Requirements
24.15.2.1 Submittal Requirements
209 24.15.2.2 Construction Documents
24.15.3 Seismic Design Force
24.15.4 Design of Egress Stairways for Seismic Relative Displacements
210 24.15.4.1 Displacements within Structures
24.15.4.2 Displacements between Structures
211 24.15.5 Out-of-Plane Bending
24.15.6 Anchorage
24.15.6.1 Design Force in the Attachment
24.15.6.2 Anchors in Concrete or Masonry
24.15.6.3 Installation Conditions
24.15.6.4 Multiple Attachments
24.15.6.5 Power Actuated Fasteners
217 PART 2, COMMENTARY
219 Commentary to Chapter 11, Seismic Design Commentary
C11.1 GENERAL
220 C11.1.1 Purpose
C11.1.2 Scope
221 C11.1.3 Applicability
C11.1.4 Alternate Materials and Methods of Construction
C11.2 DEFINITIONS
222 FIGURE C11-1 Examples of Components, Supports, and Attachments
223 FIGURE C11-2 Base for a Level Site
FIGURE C11-3 Base at Ground Floor Level
224 FIGURE C11-4 Base at Level Closest to Grade Elevation
FIGURE C11-5 Base Below Substantial Openings in Basement Wall
FIGURE C11-6 Base at Foundation Level Where There Are Full-Length Exterior Shear Walls
226 FIGURE C11-7 Building with Tie-Back or Cantilevered Retaining Wall That Is Separate from the Building
FIGURE C11-8 Building with Vertical Elements of the Seismic Force-Resisting System Supporting Lateral Earth Pressures
FIGURE C11-9 Building with Vertical Elements of the Seismic Force-Resisting System Supporting Lateral Earth Pressures
227 FIGURE C11-10 Illustration of Definition of Story above Grade Plane
C11.3 SYMBOLS
C11.4 SEISMIC GROUND MOTION VALUES
228 C11.4.1 Mapped Acceleration Parameters
C11.4.2 Site Class
C11.4.3 Site Coefficients and Risk-Targeted Maximum Considered Earthquake (MCER) Spectral Response Acceleration Parameters
231 C11.4.4 Design Spectral Acceleration Parameters
C11.4.5 Design Response Spectrum
232 C11.4.7 Site-Specific Ground Motion Procedures
234 FIGURE C11.4-1 Comparison of ELF and Multi-Period Design Spectra – Site Class C Ground Motions (vs,30 = 1,600 ft/s)
FIGURE C11.4-2 Comparison of ELF and Multi-Period Design Spectra – Site Class D Ground Motions (vs,30 = 870 ft/s)
235 FIGURE C11.4-3 Comparison of ELF and Multi-Period Design Spectra – Site Class E Ground Motions (vs,30 = 510 ft/s)
236 C11.5 IMPORTANCE FACTOR AND RISK CATEGORY
237 FIGURE C11-11 Expected Performance as Related to Risk Category and Level of Ground Motion
C11.5.1 Importance Factor
C11.5.2 Protected Access for Risk Category IV
C11.6 SEISMIC DESIGN CATEGORY
240 C11.7 DESIGN REQUIREMENTS FOR SEISMIC DESIGN CATEGORY A
C11.8 GEOLOGIC HAZARDS AND GEOTECHNICAL INVESTIGATION
244 REFERENCES
245 Commentary to Chapter 12, Seismic Design Requirements for Building Structures
C12.1 STRUCTURAL DESIGN BASIS
C12.1.1 Basic Requirements
246 FIGURE C12.1-1 Inelastic Force–Deformation Curve
248 FIGURE C12.1-2 Typical Hysteretic Curves
249 C12.1.2 Member Design, Connection Design, and Deformation Limit
C12.1.3 Continuous Load Path and Interconnection
C12.1.4 Connection to Supports
C12.1.5 Foundation Design
250 C12.1.6 Material Design and Detailing Requirements
C12.2 STRUCTURAL SYSTEM SELECTION
C12.2.1 Selection and Limitations
251 C12.2.1.1 Alternative Structural Systems
252 C12.2.1.2 Substitute Elements
C12.2.2 Combinations of Framing Systems in Different Directions
253 C12.2.3 Combinations of Framing Systems in the Same Direction
C12.2.3.1 R, Cd, and Ω0 Values for Vertical Combinations
C12.2.3.2 Two-Stage Analysis Procedure
C12.2.3.3 R, Cd, and Ω0 Values for Horizontal Combinations
C12.2.4 Combination Framing Detailing Requirements
C12.2.5 System-Specific Requirements
C12.2.5.1 Dual System
254 C12.2.5.2 Cantilever Column Systems
C12.2.5.3 Inverted Pendulum-Type Structures
C12.2.5.4 Increased Structural Height Limit for Steel Eccentrically Braced Frames, Steel Special Concentrically Braced Frames, Steel Buckling-Restrained Braced Frames, Steel Special Plate Shear Walls, and Special Reinforced Concrete Shear Walls
C12.2.5.5 Special Moment Frames in Structures Assigned to Seismic Design Categories D through F
255 C12.2.5.6 Steel Ordinary Moment Frames
C12.2.5.6.1 Seismic Design Category D or E
256 C12.2.5.6.2 Seismic Design Category F
C12.2.5.7 Steel Intermediate Moment Frames
257 C12.2.5.7.1 Seismic Design Category D
C12.2.5.7.2 Seismic Design Category E
C12.2.5.7.3 Seismic Design Category F
C12.2.5.8 Shear Wall–Frame Interactive Systems
C12.3 DIAPHRAGM FLEXIBILITY, CONFIGURATION IRREGULARITIES, AND REDUNDANCY
C12.3.1 Diaphragm Flexibility
258 C12.3.1.1 Flexible Diaphragm Condition
C12.3.1.2 Rigid Diaphragm Condition
C12.3.1.3 Calculated Flexible Diaphragm Condition
C12.3.2 Irregular and Regular Classification
259 C12.3.2.1 Horizontal Irregularity
260 FIGURE C12.3-1 Horizontal Structural Irregularity Examples
C12.3.2.2 Vertical Irregularity
261 FIGURE C12.3-2 Vertical Structural Irregularities
C12.3.3 Limitations and Additional Requirements for Systems with Structural Irregularities
C12.3.3.1 Prohibited Horizontal and Vertical Irregularities for Seismic Design Categories D through F
262 C12.3.3.2 Extreme Weak Stories
C12.3.3.3 Elements Supporting Discontinuous Walls or Frames
FIGURE C12.3-3 Vertical In-Plane-Discontinuity Irregularity from Columns or Perpendicular Walls (Type 4)
FIGURE C12.3-4 Vertical In-Plane-Discontinuity Irregularity from Walls with Significant Offsets (Type 4)
263 FIGURE C12.3-5 Discontinued Wood Light-Frame Shear Wall
C12.3.3.4 Increase in Forces Because of Irregularities for Seismic Design Categories D through F
C12.3.4 Redundancy
264 C12.3.4.1 Conditions Where Value of ρ is 1.0
C12.3.4.2 Redundancy Factor, ρ, for Seismic Design Categories D through F
265 FIGURE C12.3-6 Calculation of the Redundancy Factor, ρ
266 C12.4 SEISMIC LOAD EFFECTS AND COMBINATIONS
C12.4.1 Applicability
C12.4.2 Seismic Load Effect
267 C12.4.2.1 Horizontal Seismic Load Effect
C12.4.2.2 Vertical Seismic Load Effect
C12.4.2.3 Seismic Load Combinations
C12.4.3 Seismic Load Effect Including Overstrength Factor
C12.4.3.1 Horizontal Seismic Load Effect with Overstrength Factor
268 C12.4.3.2 Load Combinations with Overstrength Factor
C12.4.3.3 Allowable Stress Increase for Load Combinations with Overstrength
C12.4.4 Minimum Upward Force for Horizontal Cantilevers for Seismic Design Categories D through F
C12.5 DIRECTION OF LOADING
C12.5.1 Direction of Loading Criteria
C12.5.2 Seismic Design Category B
269 C12.5.3 Seismic Design Category C
270 C12.5.4 Seismic Design Categories D through F
C12.6 ANALYSIS PROCEDURE SELECTION
271 C12.7 MODELING CRITERIA
C12.7.1 Foundation Modeling
272 C12.7.2 Effective Seismic Weight
C12.7.3 Structural Modeling
273 C12.7.4 Interaction Effects
FIGURE C12.7-1 Undesired Interaction Effects
C12.8 EQUIVALENT LATERAL FORCE PROCEDURE
274 C12.8.1 Seismic Base Shear
C12.8.1.1 Calculation of Seismic Response Coefficient
FIGURE C12.8-1 Seismic Response Coefficient Versus Period
275 C12.8.1.2 Soil–Structure Interaction Reduction
C12.8.1.3 Maximum SS Value in Determination of Cs
C12.8.2 Period Determination
277 FIGURE C12.8-2 Variation of Fundamental Period with Structural Height
C12.8.2.1 Approximate Fundamental Period
278 C12.8.3 Vertical Distribution of Seismic Forces
FIGURE C12.8-3 Basis of Eq. (12.8-12)
FIGURE C12.8-4 Variation of Exponent k with Period T
279 C12.8.4 Horizontal Distribution of Forces
C12.8.4.1 Inherent Torsion
280 C12.8.4.2 Accidental Torsion
281 C12.8.4.3 Amplification of Accidental Torsional Moment
282 FIGURE C12.8-5 Torsional Amplification Factor for Symmetric Rectangular Buildings
C12.8.5 Overturning
C12.8.6 Story Drift Determination
283 FIGURE C12.8-6 Displacements Used to Compute Drift
284 C12.8.6.1 Minimum Base Shear for Computing Drift
C12.8.6.2 Period for Computing Drift
C12.8.7 P-Delta Effects
FIGURE C12.8-7 Idealized Response of a One-Story Structure with and without P-Δ
288 C12.9 MODAL RESPONSE SPECTRUM ANALYSIS AND LINEAR RESPONSE HISTORY ANALYSIS
C12.9.1 Modal Response Spectrum Analysis
289 C12.9.1.1 Number of Modes
C12.9.1.2 Modal Response Parameters
C12.9.1.3 Combined Response Parameters
290 C12.9.1.4 Scaling Design Values of Combined Response
C12.9.1.4.1 Scaling of Forces
C12.9.1.4.2 Scaling of Drifts
C12.9.1.5 Horizontal Shear Distribution
291 C12.9.1.6 P-Delta Effects
C12.9.1.7 Soil–Structure Interaction Reduction
C12.9.1.8 Structural Modeling
292 C12.9.2 Linear Response History Analysis
C12.9.2.1 General Requirements
12.9.2.2 General Modeling Requirements
C12.9.2.2.1 P-Delta Effects
293 C12.9.2.2.2 Accidental Torsion
C12.9.2.2.3 Foundation Modeling
C12.9.2.2.4 Number of Modes to Include in Response History Analysis
C12.9.2.2.5 Damping
294 C12.9.2.3 Ground Motion Selection and Scaling
FIGURE C12.9-1 Spectral Matching vs. Amplitude Scaled Response Spectra
C12.9.2.3.1 Procedure for Spectrum Matching
295 C12.9.2.4 Application of Ground Acceleration Histories
C12.9.2.5 Modification of Response for Inelastic Behavior
C12.9.2.6 Enveloping of Force Response Quantities
296 C12.10 DIAPHRAGMS, CHORDS, AND COLLECTORS
C12.10.1 Diaphragm Design
FIGURE C12.10-1 Diaphragm with an Opening
297 FIGURE C12.10-2 Diaphragm with a Reentrant Corner
C12.10.1.1 Diaphragm Design Forces
C12.10.2.1 Collector Elements Requiring Load Combinations with Overstrength Factor for Seismic Design Categories C through F
C12.10.3 Diaphragms Including Chords and Collectors
298 C12.10.3.1 Diaphragm Design
C12.10.3.2 Seismic Design Forces for Diaphragms including Chords and Collectors
299 figure 12.10-3 Comparison of Factors Γm1 and Γm2 Obtained from Analytical Models and Actual Structures with Those Predicted by Eqs. 12.10-11 and 12.10-12
300 figure 12.10-4 Comparison of Measured Floor Accelerations and Accelerations Predicted by Eq. 12.10-4 for a 7-Story Bearing Wall Building (Panagiotou et al., 2011)
301 figure 12.10-5 Comparison of Measured Floor Accelerations and Accelerations Predicted by Eq. 12.10-4 for a 5-Story Special MRF Building (Chen et al., 2013)
figure 12.10-6 Comparison of Measured Floor Accelerations with Proposed Eqs. 12.10-4 and 12.10-5 for Steel BRBF and Special MRF Buildings (Adapted from Choi et al. 2008)
302 figure 12.10-7 Diaphragm Design Acceleration Coefficient Cpx for Buildings with Non-Uniform Mass Distribution
C12.10.3.3 Transfer Diaphragms
303 C12.10.3.4 Collectors
C12.10.3.5 Diaphragm Design Force Reduction Factor
304 FIGURE 12.10-8 Diaphragm Inelastic Response Models for (a) a Diaphragm System that is not Expected to Exhibit a Distinct Yield Point and (b) a Diaphragm System that does Exhibit a Distinct Yield Point
307 FIGURE C12.10-9 Relationships: (a) global-local and (b) Rdia-global
308 FIGURE C12.10-10 Diaphragm Shear Overstrength Factor: (a) BDO; (b) RDO (Fleischman et al., 2012)
309 C12.11 STRUCTURAL WALLS AND THEIR ANCHORAGE
C12.11.1 Design for Out-of-Plane Forces
C12.11.2 Anchorage of Structural Walls and Transfer of Design Forces into Diaphragms
310 C12.11.2.1 Wall Anchorage Forces
C12.11.2.2 Additional Requirements for Diaphragms in Structures Assigned to Seismic Design Categories C through F
C12.11.2.2.1 Transfer of Anchorage Forces into Diaphragm
C12.11.2.2.2 Steel Elements of Structural Wall Anchorage System
C12.11.2.2.3 Wood Diaphragms
311 FIGURE C12.11-1 Typical Subdiaphragm Framing
C12.11.2.2.4 Metal Deck Diaphragms
C12.11.2.2.5 Embedded Straps
312 C12.11.2.2.6 Eccentrically Loaded Anchorage System
FIGURE C12.11-2 Plan View of Wall Anchor with Misplaced Anchor Rod
C12.11.2.2.7 Walls with Pilasters
FIGURE C12.11-3 Tributary Area Used to Determine Anchorage Force at Pilaster
313 C12.12 DRIFT AND DEFORMATION
314 C12.12.3 Structural Separation
C12.12.4 Members Spanning between Structures
315 C12.12.5 Deformation Compatibility for Seismic Design Categories D through F
C12.13 FOUNDATION DESIGN
C12.13.1 Design Basis
316 C12.13.3 Foundation Load-Deformation Characteristics
317 C12.13.4 Reduction of Foundation Overturning
C12.13.5 Strength Design of Nominal Foundation Geotechncial Capacity
C12.13.5.1 Nominal Strength
318 C12.13.5.2 Resistance Factors
C12.13.5.3 Acceptance Criteria
319 C12.13.6 Requirements for Structures Assigned to Seismic Design Category C
C12.13.6.1 Pole-Type Structures
C12.13.6.2 Foundation Ties
C12.13.6.3 Pile Anchorage Requirements
C12.13.7 Requirements for Structures Assigned to Seismic Design Categories D through F
C12.13.7.1 Pole-Type Structures
C12.13.7.2 Foundation Ties
C12.13.7.3 General Pile Design Requirement
320 C12.13.7.4 Batter Piles
C12.13.7.5 Pile Anchorage Requirements
C12.13.7.6 Splices of Pile Segments
C12.13.7.7 Pile–Soil Interaction
321 C12.13.7.8 Pile Group Effects
C12.13.8 Requirements for Structure Foundations on Liquefiable Sites
323 C12.13.8.1 Foundation Design
C12.13.8.2 Shallow Foundation
FIGURE C12.13.8-1 Example Showing Differential Settlement Terms δv and L
324 C12.13.8.3 Deep Foundations
325 FIGURE C12.13.8-2 Determination of Ultimate Pile Capacity in Liquefiable Soils
326 C12.14 SIMPLIFIED ALTERNATIVE STRUCTURAL DESIGN CRITERIA FOR SIMPLE BEARING WALL OR BUILDING FRAME SYSTEMS
C12.14.1 General
C12.14.1.1 Simplified Design Procedure
327 FIGURE C12.14-1 Treatment of Closely Spaced Walls
C12.14.3 Seismic Load Effects and Combinations
328 C12.14.7 Design and Detailing Requirements
C12.14.8 Simplified Lateral Force Analysis Procedure
C12.14.8.1 Seismic Base Shear
C12.14.8.2 Vertical Distribution
C12.14.8.5 Drift Limits and Building Separation
REFERENCES
333 Commentary to Chapter 13, Seismic Design Requirements for Nonstructural Components
C13.1 GENERAL
FIGURE C13.1-1 Hospital Imaging Equipment That Fell from Overhead Mounts
334 FIGURE C13.1-2 Collapsed Light Fixtures
FIGURE C13.1-3 Collapsed Duct and HVAC Diffuser
FIGURE C13.1-4 Damaged Ceiling System
335 C13.1.1 Scope
336 FIGURE C13.1-5 Toppled Storage Cabinets
FIGURE C13.1-6 Skid-Mounted Components
C13.1.2 Seismic Design Category
C13.1.3 Component Importance Factor
337 C13.1.4 Exemptions
338 C13.1.5 Application of Nonstructural Component Requirements to Nonbuilding Structures
C13.1.6 Reference Documents
339 C13.1.7 Reference Documents Using Allowable Stress Design
C13.2 GENERAL DESIGN REQUIREMENTS
C13.2.1 Applicable Requirements for Architectural, Mechanical, and Electrical Components, Supports, and Attachments
340 C13.2.2 Special Certification Requirements for Designated Seismic Systems
341 C13.2.3 Consequential Damage
C13.2.4 Flexibility
342 FIGURE C13.2-1 Schematic Plans Illustrating Branch Line Flexibility
C13.2.5 Testing Alternative for Seismic Capacity Determination
343 C13.2.6 Experience Data Alternative for Seismic Capacity Determination
344 C13.2.7 Construction Documents
C13.3 SEISMIC DEMANDS ON NONSTRUCTURAL COMPONENTS
C13.3.1 Seismic Design Force
345 FIGURE C13.3-1 NCEER Formulation for ap as Function of Structural and Component Periods
346 FIGURE C13.3-2 Lateral Force Magnitude over Height
C13.3.2 Seismic Relative Displacements
347 C13.3.2.1 Displacements within Structures
FIGURE C13.3-3 Displacements over Less than Story Height
348 C13.3.2.2 Displacements between Structures
FIGURE C13.3-4 Displacements between Structures
C13.4 NONSTRUCTURAL COMPONENT ANCHORAGE
349 C13.4.1 Design Force in the Attachment
C13.4.2 Anchors in Concrete or Masonry
350 C13.4.3 Installation Conditions
C13.4.4 Multiple Attachments
351 C13.4.5 Power-Actuated Fasteners
C13.4.6 Friction Clips
FIGURE C13.4-1 C-Type Beam Clamp Equipped with a Restraining Strap
352 C13.5 ARCHITECTURAL COMPONENTS
C13.5.1 General
C13.5.2 Forces and Displacements
353 C13.5.3 Exterior Nonstructural Wall Elements and Connections
354 C13.5.5 Out-of-Plane Bending
C13.5.6 Suspended Ceilings
355 C13.5.6.1 Seismic Forces
C13.5.6.2 Industry Standard Construction for Acoustical Tile or Lay-In Panel Ceilings
357 C13.5.6.2.1 Seismic Design Category C
C13.5.6.2.2 Seismic Design Categories D through F
358 C13.5.6.3 Integral Construction
C13.5.7 Access Floors
C13.5.7.1 General
C13.5.7.2 Special Access Floors
C13.5.8 Partitions
359 C13.5.9 Glass in Glazed Curtain Walls, Glazed Storefronts, and Glazed Partitions
C13.5.9.1 General
C13.5.9.2 Seismic Drift Limits for Glass Components
C13.6 MECHANICAL AND ELECTRICAL COMPONENTS
360 C13.6.1 General
361 C13.6.2 Component Period
C13.6.3 Mechanical Components and C13.6.4 Electrical Components
362 C13.6.5 Component Supports
C13.6.5.1 Design Basis
C13.6.5.2 Design for Relative Displacement
C13.6.5.3 Support Attachment to Component
363 C13.6.5.5 Additional Requirements
FIGURE C13.6-1 Equipment Anchorage with Belleville Washers
C13.6.5.6 Conduit, Cable Tray, and Other Electrical Distribution Systems (Raceways)
364 C13.6.6 Utility and Service Lines
C13.6.7 Ductwork
C13.6.8 Piping Systems
366 C13.6.8.1 ASME Pressure Piping Systems
C13.6.8.2 Fire Protection Sprinkler Piping Systems
367 C13.6.8.3 Exceptions
C13.6.9 Boilers and Pressure Vessels
C13.6.10 Elevator and Escalator Design Requirements
C13.6.10.3 Seismic Controls for Elevators
368 C13.6.10.4 Retainer Plates
C13.6.11 Other Mechanical and Electrical Components
REFERENCES
371 Commentary to Chapter 14, Material-Specific Design and Detailing Requirements
C14.0 SCOPE
C14.1 STEEL
C14.1.1 Reference Documents
C14.1.2 Structural Steel
C14.1.2.1 General
C14.1.2.2 Seismic Requirements for Structural Steel Structures
C14.1.2.2.1 Seismic Design Categories B and C
372 C14.1.2.2.2 Seismic Design Categories D through F
C14.1.3 Cold-Formed Steel
C14.1.3.1 General
C14.1.3.2 Seismic Requirements for Cold-Formed Steel Structures
C14.1.4 Cold-Formed Steel Light-Frame Construction
C14.1.4.1 General
373 C14.1.4.2 Seismic Requirements for Cold-Formed Steel Light-Frame Construction
C14.1.4.3 Prescriptive Cold-Formed Steel Light-Frame Construction
C14.1.5 Steel Deck Diaphragms
374 C14.1.6 Steel Cables
C14.1.7 Additional Detailing Requirements for Steel Piles in Seismic Design Categories D through F
C14.2 CONCRETE
C14.2.2.1 Definitions
C14.2.2.2 ACI 318, Section 7.10
C14.2.2.3 Scope
C14.2.2.4 Intermediate Precast Structural Walls
375 C14.2.2.6 Foundations
C14.2.2.7 Detailed Plain Concrete Shear Walls
C14.2.3 Additional Detailing Requirements for Concrete Piles
C14.2.3.1.2 Reinforcement for Uncased Concrete Piles (SDC C)
C14.2.3.1.5 Reinforcement for Precast Nonprestressed Concrete Piles (SDC C)
376 C14.2.3.1.6 Reinforcement for Precast Prestressed Piles (SDC C)
C14.2.3.2.3 Reinforcement for Uncased Concrete Piles (SDC D through F)
C14.2.3.2.5 Reinforcement for Precast Concrete Piles (SDC D through F)
C14.2.3.2.6 Reinforcement for Precast Prestressed Piles (SDC D through F)
C14.2.4 Additional Detailing Requirements for Precast Concrete Diaphragms
377 C14.2.4.1 Diaphragm Seismic Demand Levels
FIGURE C14.2.4-1 Diaphragm Dimensions
379 FIGURE C14.2.4-2 Diaphragm Shear Amplification Factor Results from NTHA at MCE: (a) BDO; (b) RDO
C14.2.4.2 Diaphragm Design Options
381 FIGURE C14.2.4-3 Diaphragm Maximum Joint Opening in NTHA for Basic Design Option Designs Under the MCE
C14.2.4.3 Diaphragm Connector or Reinforcement Deformability
382 C14.2.4.3.5 Special Inspection
C14.2.4.4 Precast Concrete Diaphragm Joint Connector and Reinforcement Qualification Procedure
383 C14.2.4.4.1 Test Modules
Figure C14.2.4-2 Test Module
C14.2.4.4.3 Test Configuration
FIGURE C14.2.4-3 Possible Test Set-Up
C14.2.4.4.4 Instrumentation
384 C14.2.4.4.5 Loading Protocols
FIGURE C14.2.4-4 Shear Loading Protocol
FIGURE C14.2.4-5 Tension/Compression Loading Protocol
385 C14.2.4.4.6 Measurement Indices
C14.2.4.4.7 Response Properties
386 C14.2.4.4.8 Test Report
C14.2.4.4.9 Deformed Bar Reinforcement
C14.3 COMPOSITE STEEL AND CONCRETE STRUCTURES
C14.3.1 Reference Documents
C14.3.4 Metal-Cased Concrete Piles
C14.4 MASONRY
387 C14.5 WOOD
C14.5.1 Reference Documents
REFERENCES
391 Commentary to Chapter 15, Seismic Design Requirements for Nonbuilding Structures
C15.1 GENERAL
C15.1.1 Nonbuilding Structures
C15.1.2 Design
C15.1.3 Structural Analysis Procedure Selection
394 C15.2 REFERENCE DOCUMENTS
395 C15.3 NONBUILDING STRUCTURES SUPPORTED BY OTHER STRUCTURES
C15.3.1 Less than 25% Combined Weight Condition
396 C15.3.2 Greater Than or Equal to 25% Combined Weight Condition
C15.4 STRUCTURAL DESIGN REQUIREMENTS
397 C15.4.1 Design Basis
398 C15.4.1.1 Importance Factor
C15.4.2 Rigid Nonbuilding Structures
399 C15.4.3 Loads
C15.4.4 Fundamental Period
C15.4.8 Site-Specific Response Spectra
C15.4.9 Anchors in Concrete or Masonry
C15.5 NONBUILDING STRUCTURES SIMILAR TO BUILDINGS
C15.5.1 General
C15.5.2 Pipe Racks
400 C15.5.3 Steel Storage Racks
C15.5.4 Electrical Power Generating Facilities
C15.5.5 Structural Towers for Tanks and Vessels
C15.5.6 Piers and Wharves
402 C15.6 GENERAL REQUIREMENTS FOR NONBUILDING STRUCTURES NOT SIMILAR TO BUILDINGS
C15.6.1 Earth-Retaining Structures
C15.6.2 Stacks and Chimneys
C15.6.4 Special Hydraulic Structures
C15.6.5 Secondary Containment Systems
403 C15.6.5.1 Freeboard
C15.6.6 Telecommunication Towers
C15.7 TANKS AND VESSELS
C15.7.1 General
404 C15.7.2 Design Basis
405 C15.7.3 Strength and Ductility
406 C15.7.4 Flexibility of Piping Attachments
C15.7.5 Anchorage
C15.7.6 Ground-Supported Storage Tanks for Liquids
C15.7.6.1 General
407 C15.7.6.1.1 Distribution of Hydrodynamic and Inertia Forces
C15.7.6.1.2 Sloshing
408 C15.7.6.1.4 Internal Elements
C15.7.6.1.5 Sliding Resistance
409 C15.7.6.1.6 Local Shear Transfer
C15.7.6.1.7 Pressure Stability
C15.7.6.1.8 Shell Support
C15.7.6.1.9 Repair, Alteration, or Reconstruction
C15.7.7 Water Storage and Water Treatment Tanks and Vessels
C15.7.7.3 Reinforced and Prestressed Concrete
410 C15.7.8 Petrochemical and Industrial Tanks and Vessels Storing Liquids
C15.7.8.1 Welded Steel
C15.7.8.2 Bolted Steel
C15.7.9 Ground-Supported Storage Tanks for Granular Materials
C15.7.9.1 General
412 C15.7.9.3.5 Combined Anchorage Systems
C15.7.10 Elevated Tanks and Vessels for Liquids and Granular Materials
C15.7.10.1 General
C15.7.10.4 Transfer of Lateral Forces into Support Tower
C15.7.10.5 Evaluation of Structures Sensitive to Buckling Failure
416 C15.7.10.7 Concrete Pedestal (Composite) Tanks
C15.7.11 Boilers and Pressure Vessels
C15.7.12 Liquid and Gas Spheres
C15.7.13 Refrigerated Gas Liquid Storage Tanks and Vessels
419 C15.7.14 Horizontal, Saddle-Supported Vessels for Liquid or Vapor Storage
REFERENCES
421 Commentary to Chapter 16, Seismic Response History Procedures
C16.1 General Requirements
C16.1.1 Overview
C16.1.2 Collapse Safety Goals and Approaches to Demonstrate Appropriate Collapse Safety
C16.1.3 Framework of the Chapter 16 Response-History Procedure
422 C16.1.4 Treatment of Minimum Base Shear
C16.1.5 Applicability
C16.2 Ground Motions
423 C16.2.1 Level of Ground Motion
C16.2.2 Definition of the Target Response Spectrum
424 FIGURE C16-1 Example Conditional Mean Spectra for the Palo Alto Site Anchored for 2% in 50-year Motion at T = 0.45s, 0.85s, 2.6s, and 5s. (NIST, 2011a)
C16.2.2.1 Method 1
C16.2.2.2 Method 2
425 C16.2.3 Ground Motions Selection
C16.2.3.1 Minimum Number of Ground Motions
C16.2.3.2 Components of Ground Motion
C16.2.3.3 Selection of Ground Motions
427 C16.2.4 Ground Motion Scaling
428 C16.2.4.1 Period Range for Scaling
C16.2.4.2 Scaling of Ground Motions
429 FIGURE C16-2 Ground Motion Scaling for Example A, Showing (a) the Ground Motion Spectra for all 11 Motions and (b) an Example for the Loma Prieta, Gilroy Array #3 Motion
C16.2.4.3 Spectral Matching of Ground Motions
C16.2.5 Application of Ground Motions to the Structural Model
C16.2.5.1 Orientation of Ground Motions
430 C16.2.5.2 Application of Input Ground Motion over Subterranean Levels
431 C16.3 MODELING AND ANALYSIS
C16.3.1 System Modeling
432 C16.3.2 Gravity Load
C16.3.3 P-Delta Effects
C16.3.4 Seismic Mass
433 C16.3.5 Diaphragm Modeling
C16.3.6 Torsion
434 C16.3.7 Stiffness of Elements Modeled with Elastic Properties
C16.3.8 Nonlinear Modeling
435 C16.3.9 Damping
C16.3.10 Soil-Structure Interaction
436 FIGURE C16-3 Illustration of the Method of Inputting Ground Motions into the Base of the Structural Model (Source NIST GCR 11-917-14 (NIST 2011))
C16.4 Analysis Results and Acceptance Criteria
C16.4.1 Global Acceptance Criteria
C16.4.1.1 Unacceptable Responses
438 FIGURE C16-4 Collapse Fragilities for a Building with P[C|MCER] = 10% and βCOL,RTR = 0.40
441 C16.4.1.2 Story Drift
C16.4.2 Element-Level Acceptance Criteria
443 C16.4.2.1 Force-Controlled Actions
FIGURE C16-5 Illustration of Lognormal Distributions for Component Capacity and Component Demand (Normalized to an Average Capacity of 1.0); the Average Component Capacity is Calibrated to Achieve P[C|MCER] = 10%
445 FIGURE C16-6 Expected Shear Strengths (in terms of Fe / Fn,e) for Reinforced Concrete Shear Walls, when Subjected to Various Levels of Flexural Ductility (from Wallace et al. 2013)
447 FIGURE C16-7 Plan View of Sample Building Showing Arrangement of Concrete Shear Walls
FIGURE C16-8 Plan View of Sample Building Showing Components of a Reinforced Concrete Core Shear Wall
448 C16.4.2.2 Deformation-Controlled Actions
451 C16.4.2.3 Components of the Gravity System
C16.5 DESIGN REVIEW
REFERENCES
453 Commentary to Chapter 17, Seismic Design Requirements for Seismically Isolated Structures
C17.1 GENERAL
454 FIGURE C17.1 Idealized Force-Deflection Relationships for Isolation Systems (Stiffness Effects of Sacrificial Wind-Restraint Systems Not Shown for Clarity)
455 C17.2 GENERAL DESIGN REQUIREMENTS
456 C17.2.4 Isolation System
C17.2.4.1 Environmental Conditions
C17.2.4.2 Wind Forces
C17.2.4.3 Fire Resistance
C17.2.4.4 Lateral Restoring Force
C17.2.4.5 Displacement Restraint
C17.2.4.6 Vertical Load Stability
457 C17.2.4.7 Overturning
C17.2.4.8 Inspection and Replacement
C17.2.4.9 Quality Control
C17.2.5 Structural System
C17.2.5.2 Building Separations
C17.2.5.4 Steel Ordinary Concentrically Braced Frames
458 C17.2.6 Elements of Structures and Nonstructural Components
459 FIGURE C17.2.6.1 Definitions of Static Residual Displacement Drm for a Bilinear Hysteretic System
461 C17.2.8 Isolation System Properties
C17.2.8.2 Isolator Unit Nominal Properties
462 FIGURE C17.2.8.3-1 Example of the Nominal Properties of a Bilinear Force Deflection System
C17.2.8.3 Bounding Properties of Isolation System Components
463 C17.2.8.4 Property Modification (λ) Factors
465 C17.2.8.5 Upper-Bound and Lower Bound Lateral Force-Displacement Behavior of Isolation System Components
466 FIGURE C17.2.8.3-2 Example of the Upper and Lower Bound Properties of a Bilinear Force Deflection System
C17.3 GROUND MOTION FOR ISOLATED SYSTEMS
C17.3.1 Site-Specific Seismic Hazard
C17.3.2 MCER Spectral Response Acceleration Parameters, SMS, SM1
C17.3.3 MCER Response Spectrum
C17.3.4 MCER Ground Motion Records
C17.4 ANALYSIS PROCEDURE SELECTION
467 C17.5 EQUIVALENT LATERAL FORCE PROCEDURE
468 C17.5.3 Minimum Lateral Displacements
C17.5.3.1 Maximum MCER Displacements
C17.5.3.2 Effective Period at the Maximum MCER Displacement
C17.5.3.5 Total Maximum MCER Displacement
469 FIGURE C17.5-2 Displacement Terminology
C17.5.4 Minimum Lateral Forces
FIGURE C17.5 Isolation System Terminology
470 FIGURE 17.5-1 Example Nominal, Upper-Bound and Lower-Bound Bilinear Hysteretic Properties of Typical Isolator Bearing
471 C17.5.4.1 Isolation System and Structural Elements below the Base Level
C17.5.4.2 Structural Elements above the Base Level
472 C17.5.4.3 Limits on Vs
C17.5.5 Vertical Distribution of Force
474 FIGURE C17.5-4a “Strongly Bilinear” Example Isolation System Example Loop
FIGURE C17.5-4b “Weakly Bilinear” Example Isolation System Example Loop
475 C17.5.6 Drift Limits
C17.6 DYNAMIC ANALYSIS PROCEDURES
477 C17.7 DESIGN REVIEW
C17.8 TESTING
C17.8.2.2 Sequence and Cycles
478 C17.8.2.3 Units Dependent on Loading Rates
479 C17.8.2.4 Units Dependent on Bilateral Load
C17.8.2.5 Maximum and Minimum Vertical Load
C17.8.2.7 Testing Similar Units
480 C17.8.3 Determination of Force-Deflection Characteristics
481 C17.8.4 Determination of Isolator Unit Test Properties for Design
482 C17.8.6 Production Tests
REFERENCES
485 Commentary to Chapter 18, Seismic Design requirements for Structures with Damping Systems
C18.1 GENERAL
FIGURE C18.1-1 Damping System (DS) and Seismic Force-Resisting System (SFRS) Configurations
C18.2 GENERAL DESIGN REQUIREMENTS
C18.2.1 System Requirements
486 C18.2.1.2 Damping System
C18.2.2 Seismic Ground Motion Criteria
C18.2.3 Procedure Selection
487 C18.2.4.1 Device Design
489 C18.2.4.4 Nominal Design Properties
C18.2.4.5 Maximum and Minimum Damper Properties
491 FIGURE C18.2-1 Force-Velocity Relationship for a Nonlinear Viscous Damper
C18.2.4.6 Damping System Redundancy
492 C18.3 NONLINEAR PROCEDURES
C18.3.2 Accidental Mass Eccentricity
493 C18.4 SEISMIC LOAD CONDITIONS AND ACCEPTANCE CRITERIA FOR NONLINEAR RESPONSE-HISTORY PROCEDURE
C18.4.1 Seismic Force Resisting System
494 C18.5 DESIGN REVIEW
C18.6 TESTING
C18.6.1.2 Sequence and Cycles of Testing
C18.6.1.3 Testing Similar Devices
C18.6.2 Production Testing
495 C18.7 ALTERNATE PROCEDURES AND CORRESPONdING ACCEPTANCE CRITERIA
C18.7.1 Response-Spectrum Procedure and C18.7.2 Equivalent Lateral Force Procedure
FIGURE C18.7-1 Effective Damping Reduction of Design Demand
496 FIGURE C18.7-2 Pushover and Capacity Curves
497 FIGURE C18.7-3 Pushover and Capacity Curves
C18.7.3 Damped Response Modification
C18.7.3.1 Damping Coefficient
498 C18.7.3.2 Effective Damping
C18.7.4.5 Seismic Load Conditions and Combination of Modal Responses
REFERENCES
501 Commentary to Chapter 19, Soil-Structure Interaction for Seismic Design
C19.1 GENERAL
502 C19.2 SSI Adjusted Structural Demands
504 C19.3 Foundation Damping
507 C19.4 Kinematic Interaction Effects
C19.4.1 Base Slab Averaging
FIGURE C19.4-1 Example Base-Slab Averaging Response Spectra Ratios
508 C19.4.2 Embedment
REFERENCES
511 Commentary to Chapter 20, Site Classification Procedure for Seismic Design
C20.1 SITE CLASSIFICATION
C20.3 SITE CLASS DEFINITIONS
C20.3.1 Site Class F
513 Commentary to Chapter 21, Site-Specific Ground Motion Procedures for Seismic Design
C21.0 GENERAL
514 C21.1 SITE RESPONSE ANALYSIS
C21.1.1 Base Ground Motions
C21.1.2 Site Condition Modeling
515 C21.1.3 Site Response Analysis and Computed Results
C21.2 RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION HAZARD ANALYSIS
C21.2.1 Probabilistic (MCER) Ground Motions
516 C21.2.1.1 Method 1
C21.2.1.2 Method 2
C21.2.2 Deterministic (MCER) Ground Motions
C21.2.3 Site-Specific MCER
C21.3 DESIGN RESPONSE SPECTRUM
517 C21.4 DESIGN ACCELERATION PARAMETERS
C21.5 MAXIMUM CONSIDERED EARTHQUAKE GEOMETRIC MEAN (MCEG) PEAK GROUND ACCELERATION
518 REFERENCES
521 Commentary to Chapter 22, Seismic Ground Motion, Long-Period Transition and Risk Coefficient Maps
529 RISK-TARGETED MAXIMUM CONSIDERED EARTHQUAKE (MCER) GROUND MOTION MAPS
530 MAXIMUM CONSIDERED EARTHQUAKE GEOMETRIC MEAN (MCEG) PGA MAPS
LONG-PERIOD TRANSITION MAPS
531 RISK COEFFICIENT MAPS
532 GROUND MOTIONS WEB TOOL
UNIFORM-HAZARD AND DETERMINISTIC GROUND MOTION MAPS
REFERENCES
535 Commentary to Chapter 23A, Vertical Ground Motions for Seismic Design
C23.1 DESIGN VERTICAL RESPONSE SPECTRUM
C23.1.1 General
C23.1.2 General Design Procedure
536 C23.1.3 Detailed Design Procedure
537 C23.1.4 Limits Imposed on Sav
FIGURE C23.1-1 Illustrative Example of the Design Vertical Response Spectrum
REFERENCES
539 Commentary to Chapter 24, ALternative Seismic Design Requirements for Seismic Design Category B Buildings
C24.1 General
C24.2 Structural Design Basis
C24.3 Structural System Selection
540 C24.4 Diaphragm Flexibility and Configuration Irregularities
C24.5 Seismic Load Effects and Combinations
C24.6 Direction of Loading
C24.7 Analysis Procedure Selection
C24.8 Modeling Criteria
541 C24.9 Equivalent Lateral Force Procedure
C24.9.1 Seismic Base Shear
C24.9.2 Period Determination
C24.9.4.2 Accidental Torsion
C24.10 Modal Response Spectrum Analysis
C24.11 Diaphragms, Chords and Collectors
542 C24.13 Drift and Deformation
C24.14 Foundation Design
C24.15 Seismic Design Requirements for Egress Stairways and Parapets
C24.15.2 General Design Requirements
C24.15.3 Seismic Design Force
C24.15.4 Design of Egress Stairways for Seismic Relative Displacements
References
FEMA P 1050 1 2015
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