Title Details

Hua-Peng Chen is Professor of Civil Engineering, Head of Innovative and Smart Structures at the University of Greenwich, UK. He has been working for over 20 years on structural health monitoring, advanced numerical modelling and structural performance assessment. He is a Fellow of the Institution of Civil Engineers (UK) and a Chartered Civil Engineer (UK) with extensive experience in civil engineering practice.

Preface xiii

Biography xv

1 Introduction to Structural Health Monitoring 1

1.1 Advances in Structural Health Monitoring Technology 1

1.1.1 Structural Health in Civil Engineering 1

1.1.2 Aims of Structural Health Monitoring 2

1.1.3 Development of SHM Methods 3

1.2 Structural Health Monitoring System and Strategy 4

1.2.1 SHM System and its Components 4

1.2.2 SHM Strategy and Method 6

1.3 Potential Benefits of SHM in Civil Engineering 7

1.3.1 Character of SHM in Civil Engineering 7

1.3.2 Potential Benefits of SHM 9

1.4 Challenges and Further Work of SHM 10

1.4.1 Challenges of SHM in Civil Engineering 10

1.4.2 Further Work on SHM for Practical Applications 11

1.5 Concluding

Remarks 13

References 13

2 Sensors and Sensing Technology for Structural Monitoring 15

2.1 Introduction 15

2.2 Sensor Types 16

2.3 Sensor Measurements in Structural Monitoring 21

2.3.1 Structural Responses 21

2.3.2 Environmental Quantities 24

2.3.3 Operational Quantities 25

2.3.4 Typical Quantities for Bridge Monitoring 25

2.3.5 Example of an SHM System – a Suspension Bridge (I) 27

2.4 Fibre Optic Sensors 33

2.4.1 Classification of Fibre Optic Sensors 33

2.4.2 Typical Fibre Optic Sensors in SHM 33

2.4.3 Fibre Optic Sensors for Structural Monitoring 36

2.5 Wireless Sensors 37

2.5.1 Components of Wireless Sensors 38

2.5.2 Field Deployment in Civil Infrastructure 39

2.6 Optimum Sensor Selection and Placement 39

2.6.1 Factors for Sensor Selection 40

2.6.2 Optimal Sensor Placement 41

2.7 Case Study 42

2.7.1 Sensors and Sensing System for SHM 43

2.7.2 Installation of FBG Sensors 43

2.8 Concluding

Remarks 47

References 48

3 Data Acquisition, Transmission and Management 51

3.1 Introduction 51

3.2 Data Acquisition Systems 52

3.2.1 Data Acquisition for Structural Monitoring 52

3.2.2 Data Acquisition in Bridge Monitoring 53

3.3 Data Transmission Systems 54

3.3.1 Wired Transmission Systems 54

3.3.2 Wireless Transmission Systems 55

3.3.3 Data Transmission in Bridge Monitoring 56

3.4 Data Processing Systems 57

3.4.1 Data Pre?]Processing for SHM 57

3.4.2 Data Analysis and Compression 58

3.4.3 Data Processing in Bridge Monitoring 58

3.5 Data Management Systems 59

3.5.1 Data Storage and File Management 59

3.5.2 Data Management in Bridge Monitoring 60

3.6 Case Study 61

3.7 Concluding Remarks 64

References 66

4 Structural Damage Identification Techniques 69

4.1 Introduction 69

4.2 Damage in Structures 70

4.3 Non?]Destructive Testing Techniques 71

4.3.1 Acoustic Emission 72

4.3.2 Ultrasound 73

4.3.3 Guided (Lamb) Waves 74

4.3.4 Thermography 75

4.3.5 Electromagnetic Methods 76

4.3.6 Capacitive Methods 76

4.3.7 Laser Doppler Vibrometer 77

4.3.8 Global Positioning System 78

4.3.9 Visual Inspection 79

4.4 Comparison of NDT and SHM 79

4.5 Signal Processing for Damage Detection 81

4.5.1 Fourier Based Transforms 81

4.5.2 Wavelet Transforms 81

4.5.3 Hilbert–Huang Transform 83

4.5.4 Comparison of Various Transforms 84

4.6 Data?] Based Versus Model?]Based Techniques 84

4.7 Development of Vibration?]Based Methods 87

4.8 Concluding Remarks 88

References 89

5 Modal Analysis of Civil Engineering Structures 91

5.1 Introduction 91

5.2 Basic Equations for Structural Dynamics 92

5.2.1 Modal Solution 93

5.2.2 Frequency Response Function 94

5.3 Input?]Output Modal Identification 94

5.3.1 Equipment and Test Procedure 95

5.3.2 Modal Identification Techniques 96

5.3.2.1 Frequency?]Domain Techniques 96

5.3.2.2 Time?]Domain Techniques 96

5.3.3 Example for Modal Identification – a Steel Space Frame (I) 96

5.4 Output?]Only Modal Identification 98

5.4.1 Equipment and Test Procedure 98

5.4.2 Operational Modal Identification Techniques 99

5.4.2.1 Frequency?]Domain Methods 99

5.4.2.2 Time?]Domain Methods 100

5.4.3 Damping Estimation 101

5.4.4 Effect of Temperature on Modal Data 101

5.4.5 Comparison of Methods 102

5.4.6 Example for Modal Identification – a Cable?]Stayed Bridge 103

5.5 Correlation Between Test and Calculated Results 104

5.5.1 Modal Assurance Criterion 105

5.5.2 Orthogonality Checks 107

5.5.3 Modal Scale Factor 108

5.5.4 Coordinate Modal Assurance Criterion 108

5.6 Mode Shape Expansion and Model Reduction 109

5.6.1 General Expansion and Reduction Methods 109

5.6.2 Perturbed Force Approach 111

5.6.3 Comparison of Methods 112

5.7 Case Study 114

5.7.1 Operational Modal Analysis 115

5.7.2 Mode Shape Expansion 118

5.8 Concluding Remarks 118

References 120

6 Finite Element Model Updating 123

6.1 Introduction 123

6.2 Finite Element Modelling 125

6.2.1 Stiffness and Mass Matrices 125

6.2.2 Finite Element Modelling Error 125

6.3 Structural Parameters for Model Updating 126

6.3.1 Updating Parameters for Framed Structures 127

6.3.1.1 Updating Stiffness and Mass at Element Level 127

6.3.1.2 Updating Stiffness at Integration Point Level 127

6.3.1.3 Updating Material and Sectional Properties 128

6.3.1.4 Updating Joints and Boundary Conditions 128

6.3.2 Updating Parameters for Continuum Structures 128

6.4 Sensitivity Based Methods 129

6.4.1 Sensitivity Matrix 129

6.4.1.1 Sensitivity of Eigenvalue 130

6.4.1.2 Sensitivity of Eigenvector 130

6.4.1.3 Sensitivity of Input Force 131

6.4.2 Direct Parameter Estimation 131

6.4.3 Residual Minimisation Methods 132

6.4.4 Example for Model Updating – a Cantilever Beam 133

6.5 Dynamic Perturbation Method 135

6.5.1 Governing Equations 135

6.5.2 Regularised Solution Procedure 137

6.6 Use of Dynamic Perturbation Method for Model Updating 139

6.6.1 Use of Frequencies Only 139

6.6.2 Use of Incomplete Modes 140

6.6.2.1 Iterative Solution Method 142

6.6.2.2 Simplified Direct Solution Method 142

6.6.3 Example for Model Updating – a Plane Frame 143

6.6.4 Example for Model Updating – a Steel Space Frame (II) 145

6.7 Case Study 149

6.8 Concluding Remarks 151

References 153

7 Vibration?]Based Damage Identification Methods 155

7.1 Introduction 155

7.2 Structural Modelling for Damage Identification 156

7.3 Methods Using Change of Modal Parameters 159

7.3.1 Natural Frequencies 159

7.3.2 Direct Mode Shape Comparison 160

7.3.3 Mode Shape Curvature 161

7.3.4 Damping 162

7.3.5 Frequency Response Function Curvature 162

7.3.6 Modal Strain Energy 163

7.3.7 Example for Damage Localisation – a Suspension Bridge (II) 165

7.4 Methods Using Change of Structural Parameters 169

7.4.1 Flexibility Matrix 169

7.4.2 Strain Energy Based Damage Index 172

7.4.3 Modal Strain?]Based Damage Index 174

7.4.4 Example for Damage Localisation – a Suspension Bridge (III) 175

7.5 Pattern Recognition Methods 177

7.5.1 Stochastic Pattern Recognition 178

7.5.2 Novelty Detection 179

7.5.3 Example for Damage Detection – a Suspension Bridge (IV) 180

7.6 Neural Network Techniques 182

7.6.1 Back?]Propagation Neural Network 182

7.6.2 Input Parameters and Pre?]Processing 184

7.6.3 Probabilistic Neural Network 185

7.6.4 Example for Damage Localisation – a Suspension Bridge (V) 186

7.7 Concluding Remarks 189

References 190

8 Model?]Based Damage Assessment Methods 195

8.1 Introduction 195

8.2 Characterisation of Damage in Structures 196

8.2.1 Damage in Framed Structures 197

8.2.1.1 Damage Characterisation at Element Level 197

8.2.1.2 Damage Characterisation at Critical Point Level 197

8.2.2 Damage in Continuum Structures 199

8.2.2.1 Damage Characterisation at Element Level 199

8.2.2.2 Damage Characterisation at Integration Point Level 199

8.3 Matrix Update Methods 200

8.3.1 Residual Force Vector Method 200

8.3.2 Minimum Rank Update Method 201

8.3.3 Optimal Matrix Updating Method 202

8.3.4 Example for Damage Assessment – a Plane Truss 203

8.4 Sensitivity Based Methods 204

8.4.1 Eigen?]Parameter Sensitivity Method 204

8.4.2 FRF Sensitivity Method 205

8.4.3 Example for Damage Assessment – a Grid Structure 207

8.5 Damage Assessment Using Dynamic Perturbation Method 207

8.5.1 Use of Frequencies Only 208

8.5.2 Use of Incomplete Modes 209

8.5.3 Examples for Damage Assessment – Simple Framed Structures 211

8.5.3.1 Damage Assessment of a Grid Structure Using Frequencies Only 211

8.5.3.2 Damage Assessment of a Plane Truss Using Incomplete Modes 212

8.6 Numerical Examples 213

8.6.1 Framed Building Structure 213

8.6.2 Gravity Dam Structure 218

8.7 Potential Problems in Vibration?]Based Damage Identification 220

8.7.1 Finite Element Model and Experimental Data 220

8.7.2 Effect of Modelling and Measurement Errors 221

8.7.3 Effect of Environmental Factors 222

8.7.4 Frequency Range and Damage Detectability 222

8.7.5 Damage Diagnosis and Prognosis 223

8.8 Concluding Remarks 224

References 225

9 Monitoring Based Reliability Analysis and Damage Prognosis 227

9.1 Introduction 227

9.2 Usage Monitoring 229

9.2.1 Lifecycle Monitoring 229

9.2.2 Load Monitoring and Evaluation 230

9.2.3 Monitoring of Environmental Factors 231

9.2.4 Example for Usage Monitoring – a Suspension Bridge (VI) 233

9.3 Probabilistic Deterioration Modelling 235

9.3.1 Sources of Deterioration 235

9.3.2 Modelling and Parameter Uncertainty 236

9.3.3 Probabilistic Deterioration Models 237

9.3.3.1 Failure Rate Function 237

9.3.3.2 Markov Process 237

9.3.3.3 Gamma Process 238

9.3.4 Example for Fatigue Cracking Modelling – a Steel Bridge (I) 239

9.4 Lifetime Distribution Analysis 240

9.4.1 Stochastic Gamma Process 240

9.4.2 Weibull Life Distribution Model 241

9.4.3 Data Informed Updating 242

9.4.4 Example for Lifetime Distribution Analysis – a Concrete Bridge 243

9.5 Structural Reliability Analysis 244

9.5.1 Limit States and Reliability Analysis 245

9.5.2 Time?]Variant Reliability 247

9.5.3 Remaining Useful Life 248

9.5.4 Example for Fatigue Reliability Analysis – a Suspension Bridge (VII) 248

9.6 Optimum Maintenance Strategy 250

9.6.1 Lifetime Costs 251

9.6.2 Decision Based on Lifetime Deterioration 253

9.6.2.1 Failure Rate Function Model 253

9.6.2.2 Markov Process Model 253

9.6.2.3 Gamma Process Model 254

9.6.2.4 Survival Function 254

9.6.3 Decision Based on Structural Reliability 255

9.6.4 Example for Optimal Maintenance – a Steel Bridge (II) 256

9.7 Case Study 256

9.7.1 Traffic Loads Monitoring 257

9.7.2 Cable Force Monitoring 260

9.7.3 Stiffening Deck System Stress Monitoring 261

9.8 Concluding Remarks 263

References 264

10 Applications of SHM Strategies to Large Civil Structures 267

10.1 Introduction 267

10.2 SHM System and Damage Identification of a Cable?]Stayed Bridge 268

10.2.1 Sensors and Sensing Network 268

10.2.2 Data Management System 270

10.2.3 Operational Modal Analysis and Mode Identifiability 270

10.2.4 Finite Element Modelling 271

10.2.5 Damage Localisation Using Mode Shape Curvature Index 273

10.2.6 Damage Detection Using Neural Network 275

10.3 In?] Construction Monitoring of a High?]Rise Building 277

10.3.1 Long?]Term SHM System 278

10.3.2 Monitoring During Shoring Dismantlement 279

10.3.3 Wireless Sensing Network for Vibration Monitoring 280

10.3.4 Ambient Vibration Tests and Results 282

10.4 Monitoring of Tunnel Construction Using FBG Sensors 284

10.4.1 Temperature Monitoring of Tunnel Cross Passage Construction 284

10.4.2 Settlement Monitoring of Undercrossing Tunnel Construction 287

10.5 Safety Monitoring of Rail Using Acoustic Emission 288

10.5.1 Rail Track Damage Detection System 289

10.5.2 On?]Site Monitoring Data 290

10.6 Structural Integrity Monitoring of Water Mains 294

10.6.1 FBG Sensory System 294

10.6.2 Implementation of Monitoring System 296

10.6.3 Measurements Under Different Operational Conditions 296

10.7 Concluding Remarks 301

References 302

Index 303