Dongming Feng - Computer Vision for Structural Dynamics and Health Monitoring

4 Chapter 4Figure 4.1 Typical modal testing and SHM systems using accelerometers: (a) m...Figure 4.2 Comparison of identified mode shapes of the frame structure.Figure 4.3 Displacement measurements at points 2–31 by the vision sensor.Figure 4.4 Comparison of displacement measurements (a) at point 9; (b) at po...Figure 4.5 Frequency results from (a) displacements at points 2–31 by the vi...Figure 4.6 Comparison of mode shapes between the vision sensor and accelerom...Figure 4.7 Stiffness optimization evolution using measurements taken by the ...Figure 4.8 Test setup: (a) beam; (b) camera; (c) schematics of intact and da...Figure 4.9 Displacement measurements at points 2–31.Figure 4.10 Identified first two mode shapes of the intact and damaged beams...Figure 4.11 Damage indices of the damaged beam: (a) MSC damage index; (b) MM...

5 Chapter 5Figure 5.1 Railway bridge for model updating: (a) side view; (b) plan view; ...Figure 5.2 Freight train configuration.Figure 5.3 Displacement history with train speed 8.05 km/h.Figure 5.4 Schematic representation of the bridge‐track‐vehicle interaction ...Figure 5.5 Measured vs. simulated displacement using the initial FE model.Figure 5.6 Sensitivity analysis procedure.Figure 5.7 Objective functions w.r.t. normalized bridge equivalent stiffness...Figure 5.8 Objective functions w.r.t. normalized bridge damping R α: (a)...Figure 5.9 Objective functions w.r.t. normalized rail bed stiffness : (a) di...Figure 5.10 Objective functions w.r.t. normalized rail bed damping (a) dis...Figure 5.11 Objective functions w.r.t. normalized train suspension stiffness...Figure 5.12 Objective functions w.r.t. normalized train suspension damping :...Figure 5.13 Two‐step FE model‐updating procedure.Figure 5.14 After Step 1: train speed update.Figure 5.15 After Step 2: equivalent bridge stiffness update.Figure 5.16 Bridge under a moving train.Figure 5.17 Power spectral density (PSD) of measured displacement histories:...Figure 5.18 Computed displacement and acceleration time histories and their ...Figure 5.19 Computed displacement and acceleration time histories and their ...Figure 5.20 Computed displacement and acceleration time histories and their ...Figure 5.21 Mid‐span maximum displacements and accelerations w.r.t. differen...

6 Chapter 6Figure 6.1 Schematics of the output‐only simultaneous identification problem...Figure 6.2 Output‐only time‐domain identification procedure.Figure 6.3 Numerical example.Figure 6.4 Effect of the number of sensors and noise level on the evolution ...Figure 6.5 Identification errors for bridge stiffness.Figure 6.6 Comparison of identified and reference impact forces considering ...Figure 6.7 Comparison of predicted and reference/measured displacement respo...Figure 6.8 Effect of the initial stiffness value on the evolution of bridge ...Figure 6.9 Effect of the damping estimate on the evolution of bridge stiffne...Figure 6.10 Comparison of identified and reference impact forces considering...Figure 6.11 Impact test setup.Figure 6.12 Measurement points.Figure 6.13 Comparison of displacement measurements: (a) displacement at poi...Figure 6.14 Beam stiffness identification from different initial stiffness v...Figure 6.15 Identified and measured hammer impact forces.Figure 6.16 Comparison of the predicted and measured beam displacement: (a) ...

7 Chapter 7Figure 7.1 Outline of vision‐based cable tension measurement.Figure 7.2 Hard Rock Stadium.Figure 7.3 Typical cable assembly.Figure 7.4 Implementation of the computer vision sensor in Hard Rock Stadium...Figure 7.5 Measured vibration and PSD function of TD_A cable at Quad A.Figure 7.6 Measured vibration and PSD function of TD_B cable at Quad B.Figure 7.7 Measured vibration and PSD function of TD_C cable at Quad C.Figure 7.8 Measured vibration and PSD function of TD_D cable at Quad D.Figure 7.9 Measured tension forces vs. reference forces for TD cables: (a) Q...Figure 7.10 Measured vibration and PSD function of SLLB cable at Quad C.Figure 7.11 Measured vibration and PSD function of EZUB cable at Quad C.Figure 7.12 Measured vibration and PSD function of EZF cable at Quad C.Figure 7.13 Measured vibration and PSD function of SLF cable at Quad C.Figure 7.14 Measured tension forces for inclined cables using the vision sen...Figure 7.15 Bronx‐Whitestone Bridge.Figure 7.16 Suspender replacement locations.Figure 7.17 Field suspender replacement: (a) jacking apparatus; (b) new tens...Figure 7.18 Vision sensor setup for measuring suspender tension.Figure 7.19 Measured vibration time histories and PSD amplitudes for suspend...

8 Chapter 8Figure 8.1 Bridge inspection: (a) conventional visual inspection; (b) UAV in...Figure 8.2 Examples of visible damage.

9 Appendix 1Figure A.1 Examples of image types: (a) binary image; (b) grayscale image; (...Figure A.2 The 2D Cartesian coordinates of an M × N grayscale image.Figure A.3 Noise‐removal example.Figure A.4 Edge‐detection example.Figure A.5 Discrete Fourier transform of a grayscale image.

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