Contenido Earthquake Engineering for Concrete Dams: Analysis, Design, and Evaluation

A comprehensive guide to modern-day methods for earthquake engineering of concrete dams

Earthquake analysis and design of concrete dams has progressed from static force methods based on seismic coefficients to modern procedures that are based on the dynamics of dam–water–foundation systems. Earthquake Engineering for Concrete Dams offers a comprehensive, integrated view of this progress over the last fifty years. The book offers an understanding of the limitations of the various methods of dynamic analysis used in practice and develops modern methods that overcome these limitations.

This important book:

    Develops procedures for dynamic analysis of two-dimensional and three-dimensional models of concrete dams
    Identifies system parameters that influence their response
    Demonstrates the effects of dam–water–foundation interaction on earthquake response
    Identifies factors that must be included in earthquake analysis of concrete dams
    Examines design earthquakes as defined by various regulatory bodies and organizations
    Presents modern methods for establishing design spectra and selecting ground motions
    Illustrates application of dynamic analysis procedures to the design of new dams and safety evaluation of existing dams.

Written for graduate students, researchers, and professional engineers, Earthquake Engineering for Concrete Dams offers a comprehensive view of the current procedures and methods for seismic analysis, design, and safety evaluation of concrete dams.

Table of contents

Preface

Acknowledgments

1 Introduction

1.1 Earthquake Experience: Cases with Strongest Shaking
1.2 Complexity of the Problem
1.3 Traditional Design Procedures: Gravity Dams
   1.3.1 Traditional Analysis and Design
   1.3.2 Earthquake Performance of Koyna Dam
   1.3.3 Limitations of Traditional Procedures
1.4 Traditional Design Procedures: Arch Dams
   1.4.1 Traditional Analysis and Design
   1.4.2 Limitations of Traditional Procedures
1.5 Unrealistic Estimation of Seismic Demand and Structural Capacity
1.6 Reasons Why Standard Finite-Element Method is Inadequate
1.7 Rigorous Methods
1.8 Scope and Organization

Part I: Gravity Dams

2 Fundamental Mode Response of Dams Including Dam–Water Interaction

2.1 System and Ground Motion
2.2 Dam Response Analysis
   2.2.1 Frequency Response Function
   2.2.2 Earthquake Response: Horizontal Ground Motion
2.3 Hydrodynamic Pressures
   2.3.1 Governing Equation and Boundary Conditions
   2.3.2 Solutions to Boundary Value Problems
   2.3.3 Hydrodynamic Forces on Rigid Dams
   2.3.4 Westergaard’s Results and Added Mass Analogy
2.4 Dam Response Analysis Including Dam–Water Interaction
2.5 Dam Response
   2.5.1 System Parameters
   2.5.2 System and Cases Analyzed
   2.5.3 Dam–Water Interaction Effects
   2.5.4 Implications of Ignoring Water Compressibility
   2.5.5 Comparison of Responses to Horizontal and Vertical Ground Motions
2.6 Equivalent SDF System: Horizontal Ground Motion
   2.6.1 Modified Natural Frequency and Damping Ratio
   2.6.2 Evaluation of Equivalent SDF System
   2.6.3 Hydrodynamic Effects on Natural Frequency and Damping Ratio
   2.6.4 Peak Response

Appendix 2: Wave-Absorptive Reservoir Bottom

3 Fundamental Mode Response of Dams Including Dam–Water–Foundation Interaction

3.1 System and Ground Motion
3.2 Dam Response Analysis Including Dam–Foundation Interaction
   3.2.1 Governing Equations: Dam Substructure
   3.2.2 Governing Equations: Foundation Substructure
   3.2.3 Governing Equations: Dam–Foundation System
   3.2.4 Dam Response Analysis
3.3 Dam–Foundation Interaction
    3.3.1 Interaction Effects
    3.3.2 Implications of Ignoring Foundation Mass
3.4 Equivalent SDF System: Dam–Foundation System
    3.4.1 Modified Natural Frequency and Damping Ratio
    3.4.2 Evaluation of Equivalent SDF System
    3.4.3 Peak Response
3.5 Equivalent SDF System: Dam–Water–Foundation System
    3.5.1 Modified Natural Frequency and Damping Ratio
    3.5.2 Evaluation of Equivalent SDF System
    3.5.3 Peak Response

Appendix 3: Equivalent SDF System

4 Response Spectrum Analysis of Dams Including Dam–Water–Foundation Interaction

4.1 Equivalent Static Lateral Forces: Fundamental Mode
   4.1.1 One-Dimensional Representation
   4.1.2 Approximation of Hydrodynamic Pressure
4.2 Equivalent Static Lateral Forces: Higher Modes
4.3 Response Analysis
   4.3.1 Dynamic Response
   4.3.2 Total Response
4.4 Standard Properties for Fundamental Mode Response
   4.4.1 Vibration Period and Mode Shape
   4.4.2 Modification of Period and Damping: Dam–Water Interaction
   4.4.3 Modification of Period and Damping: Dam–Foundation Interaction
   4.4.5 Generalized Mass and Earthquake Force Coefficient
4.5 Computational Steps
4.6 CADAM Computer Program
4.7 Accuracy of Response Spectrum Analysis Procedure
   4.7.1 System Considered
   4.7.2 Ground Motions
   4.7.3 Response Spectrum Analysis
   4.7.4 Comparison with Response History Analysis

5 Response History Analysis of Dams Including Dam–Water–Foundation Interaction

5.1 Dam–Water–Foundation System
    5.1.1 Two-Dimensional Idealization
    5.1.2 System Considered
    5.1.3 Ground Motion
5.2 Frequency-Domain Equations: Dam Substructure
5.3 Frequency-Domain Equations: Foundation Substructure
5.4 Dam–Foundation System
    5.4.1 Frequency-Domain Equations
    5.4.2 Reduction of Degrees of Freedom
5.5 Frequency–Domain Equations: Fluid Domain Substructure
    5.5.1 Boundary Value Problems
    5.5.2 Solutions for Hydrodynamic Pressure Terms
    5.5.3 Hydrodynamic Force Vectors
5.6 Frequency-Domain Equations: Dam–Water–Foundation System
5.7 Response History Analysis
5.8 EAGD-84 Computer Program

Appendix 5: Water–Foundation Interaction

6 Dam–Water–Foundation Interaction Effects in Earthquake Response

6.1 System, Ground Motion, Cases Analyzed, and Spectral Ordinates
    6.1.2 Ground Motion
    6.1.3 Cases Analyzed and Response Results
6.2 Dam–Water Interaction
    6.2.1 Hydrodynamic Effects
    6.2.2 Reservoir Bottom Absorption Effects
    6.2.3 Implications of Ignoring Water Compressibility
6.3 Dam–Foundation Interaction
    6.3.1 Dam–Foundation Interaction Effects
    h6.3.2 Implications of Ignoring Foundation Mass
6.4 Dam–Water–Foundation Interaction Effects

7 Comparison of Computed and Recorded Earthquake Responses of Dams

7.1 Comparison of Computed and Recorded Motions
    7.1.1 Choice of Example
    7.1.2 Tsuruda Dam and Earthquake Records
    7.1.3 System Analyzed
    7.1.4 Comparison of Computed and Recorded Responses
7.2 Koyna Dam Case History
    7.2.1 Koyna Dam and Earthquake Damage
    7.2.2 Computed Response of Koyna Dam
    7.2.3 Response of Typical Gravity Dam Sections
    7.2.4 Response of Dams with Modified Profiles

Appendix 7: System Properties

Part II: Arch Dams

8 Response History Analysis of Arch Dams Including Dam–Water–Foundation Interaction

8.1 System and Ground Motion 133
8.2 Frequency-Domain Equations: Dam Substructure
8.3 Frequency-Domain Equations: Foundation Substructure
8.4 Dam–Foundation System
    8.4.1 Frequency-Domain Equations
    8.4.2 Reduction of Degrees of Freedom
8.5 Frequency-Domain Equations: Fluid Domain Substructure
8.6 Frequency-Domain Equations: Dam–Water–Foundation System
8.7 Response History Analysis
8.8 Extension to Spatially Varying Ground Motion
8.9 EACD-3D-2008 Computer Program

9 Earthquake Analysis of Arch Dams: Factors to Be Included

9.1 Dam–Water–Foundation Interaction Effects
    9.1.1 Dam–Water Interaction
    9.1.2 Dam–Foundation Interaction
    9.1.3 Dam–Water–Foundation Interaction
    9.1.4 Earthquake Responses
9.2 Bureau of Reclamation Analyses
    9.2.1 Implications of Ignoring Foundation Mass
    9.2.2 Implications of Ignoring Water Compressibility
9.3 Influence of Spatial Variations in Ground Motions
    9.3.1 January 13, 2001 Earthquake
    9.3.2 January 17, 1994 Northridge Earthquake

10 Comparison of Computed and Recorded Motions

10.1 Earthquake Response of Mauvoisin Dam
   10.1.1 Mauvoisin Dam and Earthquake Records
   10.1.2 System Analyzed
   10.1.3 Spatially Varying Ground Motion
   10.1.4 Comparison of Computed and Recorded Responses
10.2 Earthquake Response of Pacoima Dam
   10.2.1 Pacoima Dam and Earthquake Records
   10.2.2 System Analyzed
   10.2.3 Comparison of Computed and Recorded Responses: January 13, 2001 Earthquake
   10.2.4 Comparison of Computed Responses and Observed Damage: Northridge Earthquake
10.3 Calibration of Numerical Model: Damping

11 Nonlinear Response History Analysis of Dams

Part A: Nonlinear Mechanisms and Modeling

11.1 Limitations of Linear Dynamic Analyses
11.2 Nonlinear Mechanisms
   11.2.1 Concrete Dams
   11.2.2 Foundation Rock
   11.2.3 Impounded Water
   11.2.4 Pre-Earthquake Static Analysis
11.3 Nonlinear Material Models
   11.3.1 Concrete Cracking
   11.3.2 Contraction Joints: Opening, Closing, and Sliding
   11.3.3 Lift Joints and Concrete–Rock Interfaces: Sliding and Separation
   11.3.4 Discontinuities in Foundation Rock
11.4 Material Models in Commercial Finite-Element Codes

Part B: Direct Finite-Element Method

11.5 Concepts and Requirements
11.6 System and Ground Motion
   11.6.1 Semi-Unbounded Dam–Water–Foundation System
   11.6.2 Earthquake Excitation
11.7 Equations of Motion
11.8 Effective Earthquake Forces
   11.8.1 Forces at Bottom Boundary of Foundation Domain
   11.8.2 Forces at Side Boundaries of Foundation Domain
   11.8.3 Forces at Upstream Boundary of Fluid Domain
11.9 Numerical Validation of the Direct Finite Element Method
   11.9.1 System Considered and Validation Methodology
   11.9.2 Frequency Response Functions
   11.9.3 Earthquake Response History
11.10 Simplifications of Analysis Procedure
   11.10.1 Using 1D Analysis to Compute Effective Earthquake Forces
   11.10.2 Ignoring Effective Earthquake Forces at Side Boundaries
   11.10.3 Avoiding Deconvolution of the Surface Free-Field Motion
   11.10.4 Ignoring Effective Earthquake Forces at Upstream Boundary of Fluid Domain
   11.10.5 Ignoring Sediments at the Reservoir Boundary
11.11 Example Nonlinear Response History Analysis
   11.11.1 System and Ground Motion
   11.11.2 Computer Implementation
   11.11.3 Earthquake Response Results
11.12 Challenges in Predicting Nonlinear Response of Dams

Part III: Design and Evaluation

12 Design and Evaluation Methodology

12.1 Design Earthquakes and Ground Motions
    12.1.1 ICOLD and FEMA
    12.1.2 U.S. Army Corps of Engineers (USACE)
    12.1.3 Division of Safety of Dams (DSOD), State of California
    12.1.4 U.S. Federal Energy Regulatory Commission (FERC)
    12.1.5 Comments and Observations
12.2 Progressive Seismic Demand Analyses
12.3 Progressive Capacity Evaluation
12.4 Evaluating Seismic Performance
12.5 Potential Failure Mode Analysis

13 Ground-Motion Selection and Modification

Part A: Single Horizontal Component of Ground Motion

13.1 Target Spectrum
    13.1.1 Uniform Hazard Spectrum
    13.1.2 Uniform Hazard Spectrum Versus Recorded Ground Motions
    13.1.3 Conditional Mean Spectrum
    13.1.4 CMS-UHS Composite Spectrum
13.2 Ground-Motion Selection and Amplitude Scaling
13.3 Ground-Motion Selection to Match Target Spectrum Mean and Variance
13.5 Amplitude Scaling Versus Spectral Matching of Ground Motions

Part B: Two Horizontal Components of Ground Motion

13.6 Target Spectra
13.7 Selection, Scaling, and Orientation of Ground-Motion Components

Part C: Three Components of Ground Motion

13.8 Target Spectra and Ground-Motion Selection

14 Application of Dynamic Analysis to Evaluate Existing Dams and Design New Dams

   14.1 Seismic Evaluation of Folsom Dam
   14.2 Seismic Design of Olivenhain Dam
   14.3 Seismic Evaluation of Hoover Dam
   14.4 Seismic Design of Dagangshan Dam

References

Notation

Index