Seismic Retrofit of Existing Reinforced Concrete Buildings

ISBN-13: 9781119987321 / Angielski / Twarda / 2023

Antoniou

Spis treści

Foreword by Rui Pinho xviiAcknowledgments xvix1 Introduction 11.1 General 11.2 Why Do Old RC Buildings Need Strengthening? 31.3 Main Differences Between Assessment and Design Methodologies 41.4 Whom Is this Book For? 71.5 Main Standards for the Seismic Evaluation of Existing Structures 8References 122 Know Your Building: The Importance of Accurate Knowledge of the Structural Configuration 152.1 Introduction 152.2 What Old RC Buildings Are Like 162.2.1 Lack of Stirrups 172.2.2 Unconventional Reinforcement in the Members 182.2.3 Large, Lightly Reinforced Shear Walls or Lack of Shear Walls 192.2.4 Lap Splices 222.2.5 Corrosion 222.2.6 Geometry: Location of Structural Members 252.2.7 Geometry: Bad Alignment of the Columns 252.2.8 Geometry: Arbitrary Alterations During Construction or During the Building's Lifetime 262.2.9 Bad Practices with Respect to the Mechanical and Electrical Installations 262.2.10 Soft Ground Stories 282.2.11 Short Columns 282.2.12 Different Construction Methods 302.2.13 Foundation Conditions 302.2.14 Discussion 322.2.15 One Final Example 342.3 How Come Our Predecessors Were So Irresponsible? 342.4 What the Codes Say - Knowledge Level and the Knowledge Factor 362.5 Final Remarks 39References 393 Measurement of Existing Buildings, Destructive and Nondestructive Testing 413.1 Introduction 413.2 Information Needed for the Measured Drawings 413.3 Geometry 443.4 Details - Reinforcement 463.5 Material Strengths 523.6 Concrete Tests - Destructive Methods 543.7 Concrete Tests - Nondestructive Methods, NDT 553.7.1 Rebound Hammer Test 563.7.2 Penetration Resistance Test 563.7.3 Pull-Off Test 573.7.4 Ultrasonic Pulse Velocity Test, UPV 573.8 Steel Tests 583.9 Infill Panel Tests 583.10 What Is the Typical Procedure for Monitoring an Existing Building? 593.11 Final Remarks 61References 624 Methods for Strengthening Reinforced Concrete Buildings 634.1 Introduction 634.2 Literature Review 644.3 Reinforced Concrete Jackets 674.3.1 Application 674.3.2 Advantages and Disadvantages 744.3.3 Design Issues: Modeling, Analysis, and Checks 764.4 Shotcrete 774.4.1 Introduction 774.4.2 Dry Mix vs. Wet Mix Shotcrete 794.4.3 Advantages and Disadvantages of Shotcrete 804.4.4 What Is It Actually Called - Shotcrete or Gunite? 814.4.5 Materials, Proportioning, and Properties 814.4.5.1 Cement 814.4.5.2 Pozzolans 824.4.5.3 Silica Fume 824.4.5.4 Aggregates 824.4.5.5 Water 834.4.5.6 Fiber Reinforcement 834.4.5.7 Chemical Admixtures and Accelerators 854.4.5.8 Reinforcing Steel 854.4.6 Mix Proportions for the Dry-Mix Process 854.4.7 Equipment and Crew 864.4.7.1 Dry-Mix Process 864.4.7.2 Wet-Mix Process 874.4.8 Curing and Protection 874.4.9 Testing and Evaluation 884.5 New Reinforced Concrete Shear Walls 894.5.1 Application 894.5.2 Foundation Systems of New Shear Walls 974.5.3 Advantages and Disadvantages 984.5.4 Design Issues: Modeling and Analysis 984.6 RC Infilling 994.6.1 Application 994.6.2 Advantages and Disadvantages 1004.7 Steel Bracing 1014.7.1 Application 1014.7.2 Advantages and Disadvantages 1054.7.3 Design Issues: Modeling, Analysis, and Checks 1064.8 Fiber-Reinforced Polymers (FRPs) 1064.8.1 FRP Composite Materials 1064.8.2 FRP Composites in Civil Engineering and Retrofit 1074.8.3 FRP Composite Materials 1094.8.4 FRP Wrapping 1104.8.5 FRP Laminates 1154.8.6 Near Surface Mounted FRP Reinforcement 1194.8.7 FRP Strings 1204.8.8 Sprayed FRP 1224.8.9 Anchoring Issues 1234.8.10 Advantages and Disadvantages of FRP Systems 1234.8.11 Design Issues 1254.9 Steel Plates and Steel Jackets 1274.9.1 Advantages and Disadvantages 1304.9.2 Design Issues 1314.10 Damping Devices 1314.11 Seismic Isolation 1334.11.1 Type of Base Isolation Systems 1364.11.2 Advantages and Disadvantages 1384.11.3 Design Issues 1384.12 Selective Strengthening and Weakening Through Infills 1394.13 Strengthening of Infills 1414.13.1 Glass or Carbon FRPs 1424.13.2 Textile Reinforced Mortars TRM 1434.13.3 Shotcrete 1454.14 Connecting New and Existing Members 1454.14.1 Design Issues 1474.15 Strengthening of Individual Members 1484.15.1 Strengthening of RC Columns or Walls 1484.15.2 Strengthening of RC Beams 1494.15.3 Strengthening of RC Slabs 1534.15.4 Strengthening of RC Ground Slabs 1544.16 Crack Repair - Epoxy Injections 1574.17 Protection Against Corrosion, Repair Mortars, and Cathodic Protection 1584.18 Foundation Strengthening 1604.19 Concluding Remarks Regarding Strengthening Techniques 1634.20 Evaluation of Different Seismic Retrofitting Solutions: A Case Study 1644.20.1 Building Configuration 1644.20.2 Effects of the Infills on the Structural Behavior 1704.20.3 Strengthening with Jacketing 1754.20.4 Strengthening with New RC Walls (Entire Building Height) 1774.20.5 Strengthening with New RC Walls (Ground Level Only) 1824.20.6 Strengthening with Braces 1894.20.7 Strengthening with FRP Wrapping 1924.20.8 Strengthening with Seismic Isolation 1954.20.9 Comparison of the Methods 198References 2005 Criteria for Selecting Strengthening Methods - Case Studies 2215.1 Things Are Rarely Simple 2215.2 Criteria for Selecting Strengthening Method 2225.3 Basic Principles of Conceptual Design 2245.4 Some Rules of Thumb 2265.5 Case Studies 2315.5.1 Case Study 1: Seismic Upgrade of a Five-Story Hotel 2325.5.2 Case Study 2: Seismic Upgrade of a Four-Story Hotel 2365.5.3 Case Study 3: Seismic Upgrade of a Four-Story Hotel 2375.5.4 Case Study 4: Seismic Upgrade of a Three-Story Residential Building 2415.5.5 Case Study 5: Seismic Upgrade of a Three-Story Residential Building for the Addition of Two New Floors 2415.5.6 Case Study 6: Seismic Strengthening of an 11-Story Building 2445.5.7 Case Study 7: Seismic Strengthening of a Five-Story Building 2475.5.8 Case Study 8: Seismic Strengthening of a Three-Story Building 2475.5.9 Case Study 9: Strengthening a Building Damaged by a Severe Earthquake 2485.5.10 Case Study 10: Strengthening of an 11-Story Building 2515.5.11 Case Study 11: Strengthening of a Two-Story Building with Basement 2535.5.12 Case Study 12: Strengthening of a Weak Ground Story with FRP Wraps 2555.5.13 Case Study 13 (Several Examples): Strengthening of RC Slabs 2575.5.14 Case Study 14: Strengthening of a Ground Slab 2605.5.15 Case Study 15: Strengthening of Beam That Has Failed in Shear 2605.5.16 Case Study 16: Demolition and Reconstruction of a RC Beam 2605.5.17 Bonus Case Study 1: Strengthening of an Industrial Building 2615.5.18 Bonus Case Study 2: Strengthening of an Industrial Building 2625.5.19 Bonus Case Study 3: Strengthening of a Residential Building 263References 2686 Performance Levels and Performance Objectives 2696.1 Introduction 2696.1.1 Selection of Performance Objectives in the Design of New Buildings 2696.1.2 Selection of Performance Objectives in the Assessment of Existing Buildings 2706.2 Seismic Assessment and Retrofit Procedures 2706.2.1 Seismic Assessment Procedures 2706.2.2 Seismic Retrofit Procedures 2716.3 Understanding Performance Objectives 2726.3.1 Target-Building Performance Levels 2726.3.1.1 Structural Performance Levels 2736.3.1.2 Nonstructural Performance Levels 2766.3.1.3 Target Building Performance Levels 2796.3.2 Seismic Hazard Levels 2806.3.3 Performance Objectives 2826.3.4 Eurocode 8, Part 3, and Other Standards 2846.3.5 The Rationale for Accepting a Lower Performance Level for Existing Buildings 2866.4 Choosing the Correct Performance Objective 287References 2897 Linear and Nonlinear Methods of Analysis 2917.1 Introduction 2917.2 General Requirements 2947.2.1 Loading Combinations 2947.2.2 Multidirectional Seismic Effects 2957.2.3 Accidental Torsional Effects 2957.3 Linear Static Procedure 2967.4 Linear Dynamic Procedure 2967.5 Nonlinear Structural Analysis 2987.5.1 Nonlinear Structural Analysis in Engineering Practice 2987.5.2 Challenges Associated with Nonlinear Analysis 3007.5.3 Some Theoretical Background 3017.5.3.1 Introduction 3017.5.3.2 Sources of Nonlinearity 3017.5.3.3 Solving Nonlinear Problems in Structural Analysis 3027.5.3.4 Convergence Criteria 3057.5.3.5 Numerical Instability, Divergence, and Iteration Prediction 3067.5.4 Implications from the Basic Assumptions of Nonlinear Analysis 3077.5.5 How Reliable Are Numerical Predictions from Nonlinear Analysis Methods? 3097.5.6 Final Remarks on Nonlinear Analysis 3107.6 Nonlinear Static Procedure 3117.6.1 Pushover Analysis 3117.6.2 Information Obtained with Pushover Analysis 3127.6.3 Theoretical Background on Pushover Analysis 3137.6.4 Target Displacement 3147.6.5 Applying Forces vs. Applying Displacements 3167.6.6 Controlling the Forces or the Displacements 3177.6.6.1 Load Control 3177.6.6.2 Response Control 3187.6.7 Control Node 3187.6.8 Lateral Load Patterns 3197.6.9 Pushover Analysis Limitations 3197.7 Nonlinear Dynamic Procedure 3207.7.1 Information Obtained with Nonlinear Dynamic Analysis 3227.7.2 Selecting and Scaling Accelerograms 3227.7.2.1 Natural Scaled and Matched Accelerograms 3247.7.2.2 Artificial and Synthetic Accelerograms 3267.7.3 Advantages and Disadvantages of Nonlinear Dynamic Analysis 3277.8 Comparative Assessment of Analytical Methods 3287.8.1 Advantages and Disadvantages of the Analytical Methods 3287.8.2 Selection of the Best Analysis Procedure for Structural Assessment 329References 3308 Structural Modeling in Linear and Nonlinear Analysis 3338.1 Introduction 3338.2 Mathematical Modeling 3338.3 Modeling of Beams and Columns 3348.3.1 Material Inelasticity 3348.3.2 Geometric Nonlinearities 3368.3.3 Modeling of Structural Frame Elements 3378.3.3.1 Concentrated Plasticity Elements 3388.3.3.2 Advantages and Disadvantages of Concentrated Plasticity Models 3398.3.3.3 Distributed Plasticity Elements - Fiber Modeling 3398.3.3.4 Types of Distributed Plasticity Elements 3408.3.3.5 Advantages and Disadvantages of Distributed Plasticity Models 3418.3.3.6 Considerations Regarding the Best Frame Model for Structural Members 3428.4 Modeling of Shear Walls 3448.5 Modeling of Slabs 3458.6 Modeling of Stairs 3478.7 Modeling of Infills 3488.7.1 A Simple Example: Infilled Frame vs. Bare Frame 3498.7.2 Another Example: Partially Infilled Frame (Soft Story) vs. Bare Frame 3518.7.3 Problems in the Modeling of Infills 3548.8 Modeling of Beam-Column Joints 3568.9 Modeling of Bar Slippage 3588.10 Shear Deformations 3598.11 Foundation Modeling 3598.12 How Significant Are Our Modeling Decisions? 359References 3609 Checks and Acceptance Criteria 3639.1 Introduction 3639.2 Primary and Secondary Members 3649.3 Deformation-Controlled & Force-Controlled Actions 3659.4 Expected Vs. Lower-Bound Material Strengths 3669.5 Knowledge Level and Knowledge Factor 3689.6 Capacity Checks 3699.6.1 Capacity Checks for Linear Methods - ASCE 41 3699.6.1.1 Component Demands 3699.6.1.2 Component Capacities 3709.6.2 Capacity Checks for Nonlinear Methods - ASCE 41 3729.6.2.1 Component Demands 3729.6.2.2 Component Capacities 3729.6.3 Capacity Checks for Linear Methods - Eurocode 8, Part 3 3729.6.3.1 Component Demands 3729.6.3.2 Component Capacities 3729.6.4 Capacity Checks for Nonlinear Methods - Eurocode 8, Part 3 3749.6.4.1 Component Demands 3749.6.4.2 Component Capacities 3749.7 Main Checks to Be Carried Out in an Assessment Procedure 3749.7.1 Bending Checks 3759.7.1.1 Eurocode Framework (EC8: Part 1 and EC8: Part 3) - Nonlinear Methods 3759.7.1.2 US Framework (ASCE 41 and ACI 318) - Nonlinear Methods 3769.7.2 Shear Checks 3769.7.2.1 Eurocodes Framework (EC8, Part 1, and EC8, Part 3) 3769.7.2.2 US Framework (ASCE 41 and ACI 318) 3789.7.3 Beam-Column Joints 378References 37810 Practical Example: Assessment and Strengthening of a Six-Story RC Building 38110.1 Introduction 38110.2 Building Description 38110.3 Knowledge of the Building and Confidence Factor 38310.3.1 Geometry 38310.3.2 Reinforcement 38310.3.3 Material Strengths 38410.4 Seismic Action and Load Combinations 38610.5 Structural Modeling 38710.6 Eigenvalue Analysis 39110.7 Nonlinear Static Procedure 39310.7.1 Lateral Load Patterns 39310.7.2 Selection of the Control Node 39410.7.3 Capacity Curve and Target Displacement Calculation 39410.7.4 Safety Verifications 39810.7.5 Chord Rotation Checks 39810.7.6 Example of the Calculation of Chord Rotation Capacity 39910.7.7 Shear Checks 40010.7.8 Example of the Calculation of Shear Capacity 40110.7.9 Beam-Column Joint Checks 40310.7.10 Example of the Checks for Beam-Column Joints 40310.8 Strengthening of the Building 40610.8.1 Strengthening with Jackets 40610.8.2 Designing the Interventions 40710.8.3 Deliverables 41510.8.4 Strengthening with Shear Walls 415References 421Appendix A Standards and Guidelines 423A.1 Eurocodes 423A.1.1 Performance Requirements 423A.1.1.1 Limit State of Near Collapse (NC) 423A.1.1.2 Limit State of Significant Damage (SD) 423A.1.1.3 Limit State of Damage Limitation (DL) 423A.1.2 Information for Structural Assessment 424A.1.2.1 KL1: Limited Knowledge 424A.1.2.2 KL2: Normal Knowledge 424A.1.2.3 KL3: Full Knowledge 425A.1.2.4 Confidence Factors 425A.1.3 Safety Factors 425A.1.4 Capacity Models for Assessment and Checks 425A.1.4.1 Deformation Capacity 425A.1.4.2 Shear Capacity 428A.1.4.3 FRP Wrapping 429A.1.5 Target Displacement Calculation in Pushover Analysis 429A.1.5.1 Transformation to an Equivalent Single Degree of Freedom (SDOF) System 430A.1.5.2 Determination of the Idealized Elasto-Perfectly Plastic Force-Displacement Relationship 430A.1.5.3 Determination of the Period of the Idealized Equivalent SDOF System 431A.1.5.4 Determination of the Target Displacement for the Equivalent SDOF System 431A.1.5.5 Determination of the Target Displacement for the MDOF System 432A.2. ASCE 41-17 432A.2.1 Performance Requirements 432A.2.1.1 Performance Level of Operational Level (1-A) 433A.2.1.2 Performance Level of Immediate Occupancy (1-B) 433A.2.1.3 Performance Level of Life Safety (3-C) 433A.2.1.4 Performance Level of Collapse Prevention (5-D) 433A.2.2 Information for Structural Assessment 433A.2.2.1 Minimum Knowledge 434A.2.2.2 Usual Knowledge 434A.2.2.3 Comprehensive Knowledge 434A.2.3 Safety Factors 434A.2.4 Capacity Models for Assessment and Checks 434A.2.4.1 Deformation Capacity 435A.2.4.2 Shear Capacity 435A.2.4.3 FRP Wrapping 441A.2.5 Target Displacement Calculation in the Nonlinear Static Procedure 441A.2.5.1 Determination of the Idealized Elasto-Perfectly Plastic Force-Displacement Relationship 443A.2.5.2 Determination of the Fundamental Period 444References 444Appendix B Poor Construction and Design Practices in Older Buildings 445B.1 Stirrup Spacing 445B.2 Lap Splices 445B.3 Member Alignment 445B.4 Pipes inside RC Members 445B.5 Bad Casting of Concrete 449B.6 Footings 449Appendix C Methods of Strengthening 455C.1 Reinforced Concrete Jackets 455C.2 New Shear Walls 465C.3 Fiber-Reinforced Polymers 468C.3.1 FRP Wrapping of Columns 468C.3.2 FRP Fabrics in Slabs 473C.3.3 FRP Wraps for Shear Strengthening 473C.3.4 FRP Laminates 476C.3.5 FRP Strings 482C.4 Steel Braces 485C.5 Steel Jackets 487C.6 Steel Plates 488C.7 Infills 491C.8 Foundations 493C.9 Dowels and Anchorages 500C.10 Demolition with Concrete Cutting 502C.11 Reinforcement Couplers 506C.12 EpoxyInjections 507Index 509

O autorze

Stelios Antoniou, Ph.D, is Managing Director of Seismosoft Ltd., a company that develops state-of-the-art software tools for nonlinear analysis, structural assessment, and structural strengthening, as well as CEO and Director of the Repair and Strengthening Section of Alfakat S.A., a construction company specializing in seismic load strengthening and retrofits. He holds degrees in civil engineering and earthquake engineering from the National Technical University of Athens, Greece, as well as both an MSc in Earthquake Engineering and a Ph.D. in advanced structural analysis from Imperial College, London, UK.