Ambient Vibration Monitoring

AMBIENT VIBRATION MONITORING......Page 3
Contents......Page 7
PREFACE......Page 13
ACKNOWLEDGEMENTS......Page 15
SUMMARY......Page 17
1.1 Scope of Applications......Page 19
1.2 Laws and Regulations......Page 20
1.3 Theories on the Development of the AVM......Page 22
2.1 System Identification......Page 25
2.1.1 Eigenfrequencies and Mode Shapes......Page 26
2.1.3 Deformations and Displacements......Page 29
2.1.4 Vibration Intensity......Page 30
2.2 Stress Test......Page 31
2.2.2 Determination of the Vibration Elements......Page 32
2.2.4 Determination of Forces in Tendons and Cables......Page 33
2.3.1 Structural Safety......Page 35
2.3.3 Maintenance Requirements and Intervals......Page 37
2.4.2 Stress Characteristic......Page 39
2.4.3 Verification of Load Models......Page 41
2.4.5 Determination of Specific Measures......Page 42
2.4.7 Dynamic Effects on Cables and Tendons......Page 43
2.4.8 Parametric Excitation......Page 45
2.5 Monitoring of the Condition of Structures......Page 46
2.5.1 Assessment of Individual Objects......Page 47
2.5.3 BRIMOS® Recorder......Page 49
2.5.4 Permanent Monitoring......Page 52
2.6 Application of Ambient Vibration Testing to Structures for Railways......Page 53
2.6.1 Sleepers......Page 54
2.6.2 Noise and Vibration Problems......Page 57
2.7.1 Limits of Measuring Technology......Page 67
2.7.2 Limits of Application......Page 69
2.7.3 Limits of Analysis......Page 70
2.7.4 Perspectives......Page 71
References......Page 72
3.1 Economic Background......Page 73
3.2.1 Conservative Design......Page 74
3.2.3 Influence of Temperature......Page 75
3.2.4 Displacement......Page 79
3.2.5 Large Bridges versus Small Bridges......Page 82
3.2.6 Vibration Intensities......Page 84
3.2.8 Value of Patterns......Page 86
3.2.10 Dynamic Factors......Page 90
References......Page 93
4 PRACTICAL MEASURING METHODS......Page 95
4.1 Execution of Measuring......Page 96
4.1.2 Levelling of the Sensors......Page 101
4.2.1 Calculation Models......Page 102
4.2.2 State of the Art......Page 106
4.3.1 BRIMOS®......Page 107
4.3.2 Sensors......Page 108
4.3.3 Data-Logger......Page 109
4.3.4 Additional Measuring Devices and Methods......Page 110
4.4 Environmental Influence......Page 111
4.5 Calibration and Reliability......Page 114
4.6 Remaining Operational Lifetime......Page 115
4.6.1 Rainflow Algorithm......Page 116
4.6.2 Calculation of Stresses by FEM......Page 119
4.6.3 S–N Approach and Damage Accumulation......Page 122
4.6.4 Remaining Service Lifetime by Means of Existing Traffic Data and Additional Forward and Backward Extrapolation......Page 123
4.6.5 Conclusions and Future Work......Page 124
References......Page 127
5.1 Plausibility of Raw Data......Page 129
5.2.1 Recording......Page 130
5.2.2 Data Reduction......Page 132
5.2.4 Frequency Analysis, ANPSD (Averaged Normalized Power Spectral Density)......Page 133
5.2.5 Mode Shapes......Page 138
5.2.6 Damping......Page 139
5.2.7 Deformations......Page 141
5.2.8 Vibration Coefficients......Page 143
5.2.9 Counting of Events......Page 144
5.3.1 The Stochastic Subspace Identification (SSI) Method......Page 147
5.3.2 Application to Bridge Z24......Page 148
5.4.1 Finite Element Model Updating Method......Page 152
5.4.2 Application to Bridge Z24......Page 159
5.4.3 Conclusions......Page 165
5.5.1 General Information......Page 167
5.5.3 Practical Implementation......Page 168
5.5.4 State of the Art......Page 169
5.5.6 Assessment......Page 170
5.6 Damage Identification and Localization......Page 171
5.6.1 Motivation for SHM......Page 172
5.6.2 Current Practice......Page 173
5.6.3 Condition and Damage Indices......Page 175
5.6.4 Basic Philosophy of SHM......Page 177
5.7 Damage Prognosis......Page 179
5.7.2 Data Interrogation Procedure for Damage Prognosis......Page 180
5.7.3 Predictive Modelling of Damage Evolution......Page 181
5.8.3 Correlation of Measurement and Calculation (MAC)......Page 182
5.8.5 Complex Eigenvector Measurement......Page 183
5.8.6 Selection of Suitable Check Points using the MAC......Page 184
5.9.2 Applications of the AVM......Page 186
5.9.3 Practical Implementation......Page 187
References......Page 188
6 THEORETICAL BASES......Page 191
6.1 General Survey on the Dynamic Calculation Method......Page 192
6.2 Short Description of Analytical Modal Analysis......Page 194
6.3.1 SDOF System......Page 196
6.3.2 MDOF System......Page 197
6.5.1 Eigenfrequencies......Page 199
6.5.2 Mode Shapes......Page 201
6.6.1 Frequencies of Cables as a Function of the Inherent Tensile Force......Page 203
6.6.2 Influence of the Bending Stiffness......Page 208
6.6.3 Influence of the Support Conditions......Page 210
6.6.4 Comparison of the Defined Cases with Experimental Results......Page 211
6.6.5 Measurement Data Adjustment for Exact Cable Force Determination......Page 215
6.7.1 Mathematical Backgrounds......Page 217
6.7.2 Transfer Functions in the Vibration Analysis......Page 223
6.7.3 Applications (Examples)......Page 232
6.8 Stochastic Subspace Identification......Page 240
6.8.1 Stochastic State-Space Models......Page 241
6.8.2 Stochastic System Identification......Page 244
References......Page 250
7 OUTLOOK......Page 253
7.2.1 State-of-the-Art Sensor Technology......Page 254
7.3 Research Gaps and Opportunities......Page 255
7.4.1 Collaboration Framework......Page 257
7.4.2 Activities......Page 261
8.1 Aitertal Bridge, Post-tensional T-beam (1956)......Page 263
8.2 Donaustadt Bridge, Cable-Stayed Bridge in Steel (1996)......Page 266
8.3 F9 Viaduct Donnergraben, Continuous Box Girder (1979)......Page 268
8.4 Europa Bridge, Continuous Steel Box Girder (1961)......Page 270
8.5 Gasthofalm Bridge, Composite Bridge (1979)......Page 274
8.6 Kao Ping Hsi Bridge, Cable-Stayed Bridge (2000)......Page 276
8.7 Inn Bridge Roppen, Concrete Bridge (1936)......Page 278
8.8 Slope Bridge Saag, Bridge Rehabilitation (1998)......Page 281
8.9 Flyover St Marx, Permanent Monitoring......Page 283
8.10 Mur Bridge in St Michael, Bridge Rehabilitation......Page 288
8.11 Rosen Bridge in Tulln, Concrete Cable-Stayed Bridge (1995)......Page 290
8.12 VOEST Bridge, Steel Cable-Stayed Bridge (1966)......Page 293
8.13 Taichung Bridge, Cable-Stayed Bridge......Page 297
Nomenclature......Page 301
INDEX......Page 307