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FEMA P-2012, Assessing Seismic Performance Irregularities, 2018
- FEMA P-2012
- Assessing Seismic Performance of Buildings with Configuration Irregularities: Calibrating Current Standards and Practices
- Foreword
- Preface [Go to Page]
- Preface
- Table of Contents
- List of Figures
- List of Tables
- Ch1: Introduction [Go to Page]
- 1.1 Background
- 1.2 Overview of Irregularities Considered
- 1.3 Target Audience
- 1.4 Content and Organization
- Ch2: Overview of Irregularities [Go to Page]
- 2.1 Literature Search [Go to Page]
- 2.1.1 Observed Performance of Irregular Buildings [Go to Page]
- 2.1.1.1 Earthquake-Related Fatalities
- 2.1.1.2 Causes of Structural Collapse [Go to Page]
- Recent U.S. Earthquakes
- 1995 Kobe Earthquake
- 2010 Maule Earthquake
- 2.1.2 Treatment of Configuration Irregularities in Codes and Standards [Go to Page]
- 2.1.2.1 U.S. Codes and Standards
- 2.1.2.2 International Codes
- 2.1.3 Published Research on Irregularities
- 2.2 Performance Concerns for Irregularities and Corresponding Code Requirements
- 2.3 Treatment of Irregularities in this Report
- Ch3: Archetype Design, Modeling, and Analysis Approach [Go to Page]
- 3.1 Scope of Analytical Studies
- 3.2 Archetype Configurations and Designs [Go to Page]
- 3.2.1 Steel Moment Frame Archetypes
- 3.2.2 Reinforced Concrete Moment Frame Archetypes
- 3.2.3 Reinforced Concrete Shear Wall Archetypes
- 3.3 Structural Modeling of Archetype Buildings [Go to Page]
- 3.3.1 Steel Moment Frame Archetypes [Go to Page]
- 3.3.1.1 System Modeling
- 3.3.1.2 Modeling of Beam and Column Components
- 3.3.1.3 Modeling of Joint Panel Zones
- 3.3.2 Reinforced Concrete Moment Frame Archetypes [Go to Page]
- 3.3.2.1 System Modeling
- 3.3.2.2 Modeling of Beam and Column Components
- 3.3.2.3 Modeling of Joint Panel Zones
- 3.3.3 Reinforced Concrete Shear Wall Archetypes [Go to Page]
- 3.3.3.1 System Modeling
- 3.3.3.2 Modeling of Walls using Fiber Elements
- 3.3.3.3 Material Constitutive Models for Concrete and Rebar
- 3.4 Archetype Analysis Methods [Go to Page]
- 3.4.1 Overview of FEMA P695 Analysis Methods
- 3.4.2 Selection of Ground Motions
- 3.4.3 Incremental Dynamic Analysis
- 3.4.4 Evaluation of MCER Collapse Performance
- 3.4.5 Collapse Evaluation Using Absolute and Relative Measures of Collapse Risk
- 3.4.6 Tracking of Non-Collapse Archetype Response Parameters
- Ch4: Buildings with Torsional Irregularities [H1, H6] [Go to Page]
- 4.1 Overview
- 4.2 Objectives of Studies and Summary of Findings [Go to Page]
- 4.2.1 Objective 1: Evaluate ASCE/SEI 7-16 Torsion Design Provisions
- 4.2.2 Objective 2: Propose Modifications to the ASCE/SEI 7-16 Seismic Torsion Provisions
- 4.2.3 Summary of Findings
- 4.3 Methodology to Assess Torsion Design Provisions
- 4.4 Archetype Design Space [Go to Page]
- 4.4.1 Plan Configurations
- 4.4.2 Baseline Archetypes
- 4.4.3 Proportioning the Lateral System for Seismic Design [Go to Page]
- Method 1: Decoupled strength and stiffness
- Method 2: Coupled strength and stiffness
- 4.5 Results [Go to Page]
- 4.5.1 Collapse Performance under Current Code Requirements
- 4.5.2 Observations about Torsion Design Requirements
- 4.5.3 Recommended Minimum Requirements
- 4.6 Conclusions and Recommendations
- Ch5: Concrete Wall Buildings with Vertical Irregularities [V1, V8] [Go to Page]
- 5.1 Overview and Summary of Findings
- 5.2 Design Procedures and Common Irregularities
- 5.3 Overview of Archetype Designs
- 5.4 Modeling RC Wall Response [Go to Page]
- 5.4.1 Methodology Validation and Comparison Studies
- 5.4.2 Non-Simulated Failure Modes
- 5.5 Assessment of Collapse Risk [Go to Page]
- 5.5.1 Overview
- 5.5.2 Results
- 5.6 Conclusions and Recommendations
- Ch6: Moment Frame Buildings with Vertical Irregularities [V1, V2, V5, V6, V7] [Go to Page]
- 6.1 Overview
- 6.2 Objectives of Studies and Summary of Findings [Go to Page]
- 6.2.1 Objective 1: Assess the Adequacy of ASCE/SEI 7-16 Vertical Irregularity Provisions
- 6.2.2 Objective 2: Assess the Necessity for Expanding the ASCE/SEI 7-16 Vertical Irregularity Provisions
- 6.2.3 Summary of Findings
- 6.3 Methodology to Assess Vertical Irregularity Design Provisions
- 6.4 Archetype Design Space by System
- 6.5 Studies of Weight (Mass) Irregularity [V2] [Go to Page]
- 6.5.1 Archetype Descriptions
- 6.5.2 Results
- 6.5.3 Conclusion and Recommendations
- 6.6 Studies of Soft- and Weak-Story Irregularities [V1/V5] [Go to Page]
- 6.6.1 Archetype Descriptions
- 6.6.2 Results
- 6.6.3 Conclusion and Recommendations
- 6.7 Studies of Strong-Column/Weak-Beam Design Provisions [V6] [Go to Page]
- 6.7.1 Archetype Descriptions
- 6.7.2 Results
- 6.7.3 Conclusion and Recommendations
- 6.8 Studies of Gravity-Induced Lateral Demands [V7] [Go to Page]
- 6.8.1 Previous Studies
- 6.8.2 Archetype Descriptions
- 6.8.3 Results
- 6.8.4 Limitations of the GILD Studies
- 6.9 Overview of Conclusions and Recommendations [Go to Page]
- 6.9.1 Weight (Mass) Irregularity [V2]
- 6.9.2 Soft/Weak Story Irregularity [V1/V5]
- 6.9.3 Strong-Column/Weak-Beam [V6]
- 6.9.4 Gravity-Induced Lateral Demand [V7]
- Ch7: Discussion of Other Irregularities [H2, H3, H4, H5, V3, V4, V8] [Go to Page]
- 7.1 Reentrant Corner [H2] Irregularity
- 7.2 Diaphragm Discontinuity [H3] Irregularity
- 7.3 Out-of-Plane Offset [H4] and In-Plane Discontinuity [V4] Irregularities [Go to Page]
- 7.3.1 Impact of Out-Of-Plane and In-Plane Discontinuities in RC Wall Buildings
- 7.4 Nonparallel System [H5] Irregularity
- 7.5 Vertical Geometric [V3] Irregularity
- 7.6 Wall Discontinuity [V8] Irregularity [Go to Page]
- 7.6.1 Discontinuities Associated with Initiation or Termination of Stacked Openings in Walls
- 7.6.2 Discontinuities Associated with Increased Wall Area to Capture Forces Introduced by New Structural Elements
- Ch8: Recommended Improvements [Go to Page]
- 8.1 Codes and Standards [Go to Page]
- 8.1.1 NEHRP Recommended Provisions and ASCE/SEI 7-16 [Go to Page]
- Revised Triggers and Prohibitions
- Revised Modeling Requirements
- Revised Design Requirements
- Improved Commentary and Other Clarifications
- 8.1.2 ASCE/SEI 41-17
- 8.2 Future Studies and Development [Go to Page]
- 8.2.1 Explicit Collapse Assessment Improvements
- 8.2.2 Design Sensitivity Studies
- 8.2.3 Strong-Column/Weak-Beam Requirements
- 8.2.4 More Detailed Considerations
- AppA: Torsion Studies [Go to Page]
- A.1 Development and Validation of Simplified 3D Models [Go to Page]
- A.1.1 Nonlinear Backbones for Modeling the Seismic-Force-Resisting System
- A.1.2 Scaling of Nonlinear Backbones
- A.1.3 3D Modeling Approach
- A.1.4 Validation of Single-Story 3D Models
- A.2 Torsional Strength Irregularity
- A.3 Importance of Checking Drift and Stability Requirements at the Building’s Edge for Torsionally Irregular Buildings
- A.4 Rationale for Triggering Type 1a Torsional Irregularity When >75% of Strength is on One Side of the CM
- A.5 Application of 5% Mass Offsets to Simulate Accidental Torsion with Modal Response Spectrum Analysis
- A.6 Explanation of Why Some Trends in the Results Plots Double Back on Themselves
- AppB: Concrete Wall Studies [Go to Page]
- B.1 Past Investigations of Concrete Walls with Irregularities [Go to Page]
- B.1.1 Damage of Concrete Walls with Irregularities in Past Earthquakes
- B.1.2 Quantification of Vertical Discontinuities in Concrete Walls Using Field Data
- B.1.3 Laboratory Test Results for Concrete Walls with Vertical Irregularities
- B.2 Investigation of Vertical Irregularity Using Nonlinear Continuum Analysis
- B.3 RC Wall Building Design Process [Go to Page]
- B.3.1 Building Prototype
- B.3.2 Wall Design
- B.3.3 Design of Wall Panel Zone
- B.3.4 Design of Coupling Beams
- B.3.5 RC Wall Building Design Summaries
- B.4 Modeling Wall Response [Go to Page]
- B.4.1 ATENA
- B.4.2 OpenSees
- B.5 Preliminary Analyses to Investigate Modeling Assumptions and Identify a Preferred Modeling Approach [Go to Page]
- B.5.1 Modeling Assumptions Employed for OpenSees and ATENA Analyses
- B.5.2 Pushover Analyses to Compare OpenSees and ATENA Models
- B.5.3 Dynamic Analyses to Compare OpenSees Displacement-Based and Force-Based Beam-Column Element Models
- B.5.4 Dynamic Analyses to Compare Models Comprising OpenSees Displacement-Based Beam-Column Elements and SFI-MVLEM
- B.5.5 Identification of a Preferred Modeling Approach for Assessing the Impact of Vertical Irregularities on the Collapse Risk Posed by RC Wall Buildings
- B.6 Analysis Results
- AppC: Steel Moment Frame Studies [Go to Page]
- C.1 Steel Moment Frame Baseline Designs [Go to Page]
- C.1.1 Low Seismicity Zone (SDC Bmax) – Steel Ordinary Moment Frame Design [Go to Page]
- C.1.1.1 3-Story OMF Building
- C.1.1.2 9-Story OMF Building
- C.1.1.3 20-Story OMF Building
- C.1.2 High Seismicity Zone (SDC Dmax) – Steel Special Moment Frame Design [Go to Page]
- C.1.2.1 3-Story SMF Building
- C.1.2.2 9-Story SMF Building
- C.1.2.3 20-Story SMF Building
- C.2 Summary of Steel Moment Frame Results
- AppD: Concrete Moment Frame Studies [Go to Page]
- D.1 Concrete Moment Frame Baseline Designs [Go to Page]
- D.1.1 Low Seismicity Zone (SDC Bmax) – RC Ordinary Moment Frame Design [Go to Page]
- D.1.1.1 4-Story OMF Building
- D.1.1.2 8-Story OMF Building
- D.1.1.3 12-Story OMF Building
- D.1.2 High Seismicity Zone (SDC Dmax) – RC Special Moment Frame Design [Go to Page]
- D.1.2.1 4-Story SMF
- D.1.2.2 8-Story SMF
- D.1.2.3 12-Story SMF
- D.1.2.4 20-Story SMF
- D.2 Summary of Reinforced Concrete Moment Frame Results
- AppE: Results of Quality Control Review [Go to Page]
- E.1 Overview of Quality Control Review
- E.2 Results from Quality Control Review [Go to Page]
- E.2.1 Torsional Studies
- E.2.2 Concrete Shear Wall Studies
- E.2.3 Steel Moment Frame Studies
- E.2.4 Concrete Moment Frame Studies
- AppF: Global Behavior of Buildings with Mass Irregularity [V2] [Go to Page]
- F.1 Background
- F.2 Expanded Design Space and Assessment Method [Go to Page]
- F.2.1 Expanded Design Space
- F.2.2 Assessment Method for Global Behavior
- F.3 Findings
- F.4 Recommendations
- AppG: Story Stiffness and Strength Calculation [Go to Page]
- G.1 Background
- G.2 Calculation of Story Stiffness [Go to Page]
- G.2.1 Simple Hand Calculations and Their Limitations
- G.2.2 SEAOC Story Drift Ratio Method
- G.2.3 Apparent Story Stiffness Method
- G.3 Calculation of Story Strength
- G.4 Recommendations [Go to Page]
- G.4.1 Calculation of Story Stiffness
- G.4.2 Calculation of Story Strength
- AppH: Steel Systems Not Specifically Detailed for Seismic Resistance [Go to Page]
- H.1 Background
- H.2 Configuration
- H.3 Proportioning [Go to Page]
- H.3.1 Strong-Column/Weak-Beam Requirement
- H.3.2 Panel Zone Proportioning
- H.3.3 Connection Design Philosophy
- H.4 Member Local Buckling and Lateral Bracing Requirements
- H.5 Less Stringent Material Specifications and Inspection Requirements
- Symbols
- Glossary [Go to Page]
- Definitions
- References
- Project Participants [Go to Page]
- FEMA Oversight
- ATC Management and Oversight
- Project Technical Committee
- Project Review Panel
- Working Group
- Workshop Participants
- Catalog No. 18166-1 [Go to Page]