1 Chapter 1Table 1.1 Comparison of sensors for measuring structural vibrations. 2 Chapter 2Table 2.1 Typical hardware components of a vision sensor system. 3 Chapter 3Table 3.1 Measurement errors of the vision sensor in shaking table tests.Table 3.2 Different levels of subpixel resolution.Table 3.3 Measurement errors: NRMSE (%).Table 3.4 Test conditions of eight representative measurements.Table 3.5 Errors between peak displacements measured by different sensors. 4 Chapter 4Table 4.1 Parameters of the three‐story frame structure.Table 4.2 Comparison of identified natural frequencies of the frame structure...Table 4.3 Parameters of the simply supported beam.Table 4.4 Comparison of identified natural frequencies of the beam structure.Table 4.5 Stiffness identification results (×104N/m). 5 Chapter 5Table 5.1 Design parameters of the bridge and track system.Table 5.2 Parameters of the freight train.Table 5.3 Dominant frequencies. 6 Chapter 6Table 6.1 Parameters for the numerical example.Table 6.2 Simulation cases. 7 Chapter 7Table 7.1 Cable length, measured cable frequencies, and tension discrepancies...Table 7.2 Cable geometric and material parameters.Table 7.3 Measured suspender rope frequencies and tension.
List of Illustrations
1 Chapter 1Figure 1.1 Common displacement sensors: (a) LVDT; (b) laser vibrometer; (c) ...Figure 1.2 Vision‐based remote displacement sensor.
2 Chapter 2Figure 2.1 Commercially available video cameras: (a) CMOS image sensor with ...Figure 2.2 Vision‐based multi‐camera measurement system.Figure 2.3 Time synchronization.Figure 2.4 Procedure for 2D vision sensor implementation.Figure 2.5 Defining a template subset in a source image.Figure 2.6 Surface plot of the NCC and template coordinates in image 1.Figure 2.7 Surface plot of the NCC and template coordinates in image 2.Figure 2.8 Schematic of stereo camera calibration.Figure 2.9 Scaling factor determination: (a) optical axis perpendicular to t...Figure 2.10 Error resulting from camera non‐perpendicularity: (a) effect of ...Figure 2.11 Flowchart of the UCC implementation.Figure 2.12 Orientation code (N = 16).Figure 2.13 Matching results for images in ill conditions: (a) searching for...Figure 2.14 Bilinear interpolation for sub‐pixel analysis.Figure 2.15 Flowchart of vision sensor based on OCM.Figure 2.16 User interface of the OCM‐based displacement measurement softwar...
3 Chapter 3Figure 3.1 Shaking table test.Figure 3.2 Comparison of sinusoidal displacements by the LVDT and vision sen...Figure 3.3 Comparison of earthquake displacements by the LVDT and vision sen...Figure 3.4 Shaking table test of a three‐story frame structure: (a) shaking ...Figure 3.5 Subpixel resolution evaluation using a UCC‐based vision sensor: (...Figure 3.6 Comparison of displacements by OCM (artificial target), UCC (arti...Figure 3.7 Comparison of displacements by OCM (natural target), UCC (natural...Figure 3.8 Evaluation of robustness in unfavorable conditions.Figure 3.9 Case 1 comparison: (a) displacements by OCM and UCC; (b) UCC cros...Figure 3.10 Case 2 comparison: (a) displacements by OCM and UCC; (b) UCC cro...Figure 3.11 Case 3 comparison: (a) displacements by OCM and UCC; (b) UCC cro...Figure 3.12 Case 4 comparison: (a) displacements by OCM and UCC; (b) UCC cro...Figure 3.13 A steel building frame model on a seismic shaking table.Figure 3.14 Seismic shaking table setup.Figure 3.15 Experimental results of the seismic shaking table test: (a) meas...Figure 3.16 Test setup for the simply supported beam.Figure 3.17 Schematic of sensor placement.Figure 3.18 Case of a non‐perpendicular camera optical lens axis.Figure 3.19 Images of a marker panel for different camera tilt angles: (a) 3...Figure 3.20 Comparison of displacement measurement at point 16: (a) camera t...Figure 3.21 Field test: (a) Streicker Bridge; (b) artificial target.Figure 3.22 Randomly running pedestrians: displacement measurement by vision...Figure 3.23 Randomly running pedestrians: acceleration measurement: (a) meas...Figure 3.24 Jumping pedestrians: displacement measurement by vision sensor: ...Figure 3.25 Jumping pedestrians: acceleration measurement: (a) measured acce...Figure 3.26 Field test on a highway bridge.Figure 3.27 Experimental results of field tests on a highway bridge: (a) v =...Figure 3.28 View of the two testbed bridges.Figure 3.29 Field tests on the railway bridge: (a) setup of field tests; (b)...Figure 3.30 Target panel and existing features on the railway bridges: (a) H...Figure 3.31 Test H1: comparison of displacements by three sensors (day).Figure 3.32 Test H2: comparison of displacements by three sensors (day).Figure 3.33 Test H3: comparison of displacements by three sensors (day).Figure 3.34 Test H4: comparison of displacements by three sensors (day).Figure 3.35 Test S1: comparison of displacements by two sensors (night).Figure 3.36 Test S2: comparison of displacements by two sensors (night).Figure 3.37 Test S3: comparison of displacements (night).Figure 3.38 Test S4: comparison of displacements (night).Figure 3.39 Schematic illustration of the displacement peak.Figure 3.40 Errors between peak displacements of test H1–H4 of the HCB bridg...Figure 3.41 Errors between peak displacements of the steel bridge in tests S...Figure 3.42 Field test of the Vincent Thomas Bridge: (a) Vincent Thomas Brid...Figure 3.43 Actual images captured by two cameras: (a) artificial target pan...Figure 3.44 Displacement time histories: (a) measurement in the morning; (b)...Figure 3.45 Power spectral distribution: (a) measurement in the morning; (b)...Figure 3.46 Manhattan Bridge: (a) cross‐section; (b) test setup.Figure 3.47 Tracking target on the bridge: (a) one target; (b) simultaneous ...Figure 3.48 Displacement measurement of one target.Figure 3.49 Simultaneous displacement measurements of three targets.Figure 3.50 Tracking targets on the bridge and the background building.Figure 3.51 The camera motion and the mid‐span vertical displacement of the ...
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 Rα: (a)...Figure 5.9 Objective functions w.r.t. normalized rail bed stiffness
