Georadar                                                        IBIS System                              IBIS             ...
Georadar                                                                                   IBIS System                    ...
Georadar                                                                                 IBIS System                    IB...
Georadar                                                                                IBIS System                       ...
Georadar                                                                                       IBIS System                ...
Georadar                                                                                  IBIS System        Measurement a...
Georadar                                                                                                                  ...
Georadar                                                                                                                  ...
Georadar                                                                           IBIS System     Structure Monitoring: s...
Georadar                                                                                                    IBIS System   ...
Georadar                                                                                       IBIS System                ...
Georadar                                                                                    IBIS System                   ...
Georadar                                                                                         IBIS System              ...
Georadar                                                                 IBIS System      Structure Monitoring: static loa...
Georadar                                                                                                                  ...
Georadar                                                                         IBIS System     Structure Monitoring: mas...
Georadar                                                                                                                  ...
Georadar                                                                  IBIS System                    IBIS-S & Cable-st...
Georadar                                                                            IBIS System                    IBIS-S ...
Georadar                                                            IBIS System                    IBIS-S & Cable-stayed b...
Georadar                                                                                                                  ...
Georadar                                                             IBIS System                    IBIS-S & Cable-stayed ...
Georadar                                                                                                        IBIS Syste...
Georadar                                                                                                                  ...
Georadar                                                                                                                 I...
Georadar                                                                                                                  ...
Georadar                                                                                                                  ...
Georadar                                                                               IBIS System   Dynamic Monitoring: C...
Georadar                                                          IBIS System   Dynamic Monitoring: Capriate bridge       ...
Georadar                                                           IBIS System   Dynamic Monitoring: Capriate bridge      ...
Georadar                                                                                               IBIS System        ...
Georadar                                                                                     IBIS System   Dynamic Monitor...
Georadar                                                                                IBIS System   Dynamic Monitoring: ...
Georadar                                                                                                     IBIS System  ...
Georadar                                                                                                      IBIS System ...
Georadar                                                                              IBIS System   Dynamic Monitoring: Ku...
Georadar                                                                                       IBIS System   Dynamic Monit...
Georadar                                                                                 IBIS System   Dynamic Monitoring:...
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A Ground Based Microwave Interferometer with Imaging Capabilities for Remote Measurements of Displacements and vibrations

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A Ground Based Microwave Interferometer with Imaging Capabilities for Remote Measurements of Displacements and vibrations

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A Ground Based Microwave Interferometer with Imaging Capabilities for Remote Measurements of Displacements and vibrations

  1. 1. Georadar IBIS System IBIS Image by Interferometric Survey A Ground Based Microwave Interferometer with Imaging Capabilities for Remote Measurements of Displacements and vibrations February 2009 All rights reserved to IDS 1
  2. 2. Georadar IBIS System IBIS-S System: HW description Sensor unit: • Signal Transmitter and Receiver • View finder and horn antenna equipped Tripod and 3-D rotating head: • Aluminium tripod: • weight: 4.3Kg; • height range: [43;188]cm • 3-D rotating head: • weight: 1,9 kg; • Azimut rotation range : [0;360] deg; • Elevation rotation range: [-90;+ 90]deg; Processing unit: Power supply unit: • PC with management SW • 2 batteries 12VDC 12Ah • Parameter setting: • signal generator • signal acquisition • First result rendering February 2009 All rights reserved to IDS 2
  3. 3. Georadar IBIS System IBIS-S: 1-dimensional range profiles Range Profile: one dimensional image with 0.5m range resolution Welding lines are good reflective points IBIS-S installed at the turbine pillar base (height 60m) February 2009 All rights reserved to IDS 3
  4. 4. Georadar IBIS System Interferometric capability The differential interferometric analysis provides data on object displacement by comparing phase information, collected in different time periods, of reflected waves from the object, providing a measure of the displacement with an accuracy of less than 0.01mm (intrinsic radar accuracy in the order of 0.001 mm.) TX First acquisition RX ϕ1 λ d d = (ϕ 2 − ϕ1 ) 4π TX Second acquisition RX ϕ2 February 2009 All rights reserved to IDS 4
  5. 5. Georadar IBIS System Interferometric capability The displacement is measured in the direction of the line of sight of the system. To calculate the real displacement is needed to know the acquisition geometry R dp h α d dp h R The distance R d= sin(α ) = d = dp ⋅ is measured sin(α ) R h by IBIS-S February 2009 All rights reserved to IDS 5
  6. 6. Georadar IBIS System Measurement accuracy: IBIS vs. Total Station Test objective: comparison between IBIS-S results and a high-performance Total Station in measuring a target displacement Total Station used: Leica TCA2300 Target distance: 33m Forced displacement: • 3 x 1mm step towards IBIS-S and -3mm back • 2 x 0.5mm step towards IBIS-S and -1mm back • 5 x 0.1mm step towards IBIS-S and -0.5mm back February 2009 All rights reserved to IDS 6
  7. 7. Georadar IBIS System Measurement accuracy : IBIS vs. Total Station IBIS-S results Total station results 1mm displacements 0.5 1 mm displacement 0 0,0005 0,0000 1mm steps -0.5 Radial Displacement [mm] -0,0005 Displacement (m) -1 -0,0010 -1.5 -0,0015 -2 -0,0020 -0,0025 -2.5 -0,0030 -3 -0,0035 0 20 40 60 80 100 120 -3.5 0 500 1000 1500 2000 Measure Num ber time [sec] 0.5 mm displacement 0,5 mm displacement 0.4 0,0005 0.2 0.5mm steps 0 Radial Displacement [mm] 0,0000 Displacement (m) -0.2 -0.4 -0,0005 -0.6 -0,0010 -0.8 -1 -0,0015 -1.2 60 80 100 120 140 160 180 0 200 400 600 800 1000 time [sec] Measure Num ber February 2009 All rights reserved to IDS 7
  8. 8. Georadar IBIS System Measurement accuracy : IBIS vs. Total Station IBIS-S results Total station results 0.1 mm displacement 0,1 mm displacement 0,0003 0.10 0.00 0.1mm steps Radial Displacement [mm] 0,0000 -0.10 Displacement (m) -0.20 -0,0003 -0.30 -0.40 -0,0005 -0.50 -0,0008 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 0 500 1000 1500 2000 2500 3000 3500 4000 4500 Measure Num ber time [sec] IBIS-S real time result February 2009 All rights reserved to IDS 8
  9. 9. Georadar IBIS System Structure Monitoring: static load of a bridge Viaducts crossing Forlanini Avenue Bridge beams are good reflecting points (Milan, Italy) Static monitoring of a new bridge: Determination of displacement of the bridge during a static load test February 2009 All rights reserved to IDS 9
  10. 10. Georadar IBIS System Structure Monitoring: static load of a bridge 90 B C 80 A D H E F IBIS-S 70 G installation SNR (dB) 60 50 Range profile of 40 P2-S – P3-S span 30 0 10 20 30 40 50 60 70 Ground-Range (m) February 2009 All rights reserved to IDS 10
  11. 11. Georadar IBIS System Structure Monitoring: static load of a bridge LC1 LVDT 10 displacement (mm) 0 -10 B D -20 F H -30 0 200 400 600 800 1000 1200 1400 time (s) February 2009 All rights reserved to IDS 11
  12. 12. Georadar IBIS System Structure Monitoring: static load of a bridge LC1 LVDT 10 IBIS-S displacement (mm) LVDT 0 -8.84 -10 -15.62 -20.50 -20 -30 0 200 400 600 800 1000 1200 1400 time (s) February 2009 All rights reserved to IDS 12
  13. 13. Georadar IBIS System Structure Monitoring: static load of a bridge LC2 LVDT 10 IBIS-S displacement (mm) 0 LVDT -10 -14.28 -20 -25.20 -30 -32.76 -40 0 200 400 600 800 1000 1200 1400 time (s) February 2009 All rights reserved to IDS 13
  14. 14. Georadar IBIS System Structure Monitoring: static load of a bridge LC1, P2-S – P3-S span: Deformed elastic curve provided by IBIS-S February 2009 All rights reserved to IDS 14
  15. 15. Georadar IBIS System Static settlements of bridge’s pier and beam P2 P1 P3 P4 P4 P3 P2 P1 6,5 m 5m Vertical movements of the 4 points 0,2 0,1 0spostamento [mm] -0,1 -0,2 -0,3 P1 -0,4 P2 -0,5 P3 P4 -0,6 0 500 1000 1500 2000 2500 3000 3500 4000 tempo [s] February 2009 All rights reserved to IDS 15
  16. 16. Georadar IBIS System Structure Monitoring: masonry bridge Measure objective: detect bridge arch displacement due to locomotive load along the transversal section for two different load locations (comparison with LVDT and laser results) IBIS-S and 5 CRs 1 laser and 3 LVDT February 2009 All rights reserved to IDS 16
  17. 17. Georadar IBIS System Mining Monitoring: tunnel displacement monitoring Measurement points on Load location transversal section of the bridge load Load at 1/2 Load at 1/4 CR1 CR2 CR3 CR4 CR5 D1 laser D2 D3 Measured displacement Load LVDT IBIS-S laser location D1 D2 D3 CR1 CR2 CR3 CR4 CR5 [mm] [mm] [mm] [mm] [mm] [mm] [mm] [mm] [mm] 1/2 -0.630 -0.550 -0.220 -0.557 -0.567 -0.543 -0.279 -0.177 -0.701 1/4 -0.450 -0.365 -0.165 -0.423 -0.449 -0.327 -0.208 -0.149 -0.429 Load error location D1-CR1 D2-CR3 D3-CR5 laser-CR2 [mm] [mm] [mm] [mm] 1/2 -0.073 -0.007 -0.043 -0.134 1/4 -0.027 -0.038 -0.016 0.020 February 2009 All rights reserved to IDS 17
  18. 18. Georadar IBIS System IBIS-S & Cable-stayed bridges Application goal: dynamic analysis done through ambient vibration testing (AVT) aimed at: - Identify the amplitude of the cable vibrations; - Identify the natural resonant frequencies and the cable dumping factors - Evaluate the tension and the operating strain of cables to verify the correct distribution of loads and the temporal variation of tensions along the bridge life February 2009 All rights reserved to IDS 18
  19. 19. Georadar IBIS System IBIS-S & Cable-stayed bridges Conventional equipment used today: - Accelerometer: provides accel./velocity mesurements, one acc. for each cable, time-comsuming acquisition, possible logistics difficulties in the installation (need for a crane-truck and traffic shut-done) - Doppler Laser Vibrometer (LDV): provides displacement measurements, one cable at a time, low accuracy on long distances Accelerometer Doppler laser February 2009 All rights reserved to IDS 19
  20. 20. Georadar IBIS System IBIS-S & Cable-stayed bridges Advantages in the use of IBIS-S: - Provide displacement measurements (useful to evaluate the amplitude of vibrations) - Very accurate measurement: an order of magnitude higher than LDV - No traffic shut-done needed (IBIS can be installed under the bridge or beside the bridge towers) - Simultaneuous measurement on a large number of cables (potentially all cables of each side at once) - Rapid installation and measurement set-up February 2009 All rights reserved to IDS 20
  21. 21. Georadar IBIS System IBIS-S & Cable-stayed bridges Economical advantages in the use of IBIS-S: - Example of standard use for a cable stayed bridge with 48 cables Item Test with accelerometers Test with LDV Test with IBIS-S Personnel (n° of units) 3-4 1-2 1-2 Number of devices 10-15 1 1 Install./disinstall. time 30’ for each cable 10’ for each cable 20’ for 12 cables Acquisition duration once 60’ 60’ 60’ installed* Field activity duration 3-4 4-6 1 (days) Personnel costs (Euro)** 7.200-12.800 3.200-9.600 800-1.600 Need for crane truck Yes no no Need for traffic shut-down Yes no no *Once installed all the equipments need at least 60’ of acquisition to obtain reliable results using AVT **Personnel costs are calculated on an average rate of 800 €/day per personnel unit ***Post-Processing times for data acquired by the three equipments are comparable (the output is the same) February 2009 All rights reserved to IDS 21
  22. 22. Georadar IBIS System IBIS-S & Cable-stayed bridges Geometrical sketch of IBIS-S set-up: IBIS on the bridge IBIS below the bridge February 2009 All rights reserved to IDS 22
  23. 23. Georadar IBIS System IBIS-S & Cable-stayed bridges: case studies Example: Bordolano bridge (Italy) IBIS on the bridge Displacement graph of cable n°1 1,5 Range Profile 1,0 Displacements (mm) 0,5 0,0 -0,5 -1,0 -1,5 -2,0 0 500 1000 1500 2000 250 tempo (s) Time (s) Sampling rate: 200 Hz February 2009 All rights reserved to IDS 23
  24. 24. Georadar IBIS System IBIS-S & Cable-stayed bridges: case studies Example: Bordolano bridge (Italy) Frequency Domain Analysis 1 0,1 ASD (mm) Hz 0,01 ASD (mm) 2//Hz from frequency to 1E-3 tension: 2 1E-4 2 ⎛f ⎞ T ( f n ) = 4ρ L ⎜ n ⎟ 1E-5 2 1E-6 ⎝ n⎠ 1E-7 per n = 1, ... ,5 1E-8 0 5 10 15 20 25 frequenza (Hz) Frequency (Hz) Resonant frequencies Tension 25 f (Hz) Cable n°1 f1 = 2.649 20 fi T(fi ) f2 = 5.286 i (Hz) (kN) frequenza [Hz] Frequency (Hz) 15 f3 = 7.959 f = 2.654 n 1 2.649 2713.1 f4 = 10.62 10 2 5.286 2700.8 f5 = 13.29 5 3 7.959 2721.2 f6 = 15.93 4 10.62 2725.4 f7 = 18.58 0 0 1 2 3 4 5 6 7 8 9 10 5 13.29 2731.26 f8 = 21.18 nn February 2009 All rights reserved to IDS 24
  25. 25. Georadar IBIS System IBIS-S & Cable-stayed bridges: case studies Example: Olginate bridge (Italy) IBIS-S set-up Displacement graph 0,8 Range ProfileDisplacements (mm) 0,4 0,0 -0,4 -0,8 -1,2 -1,6 -2,0 Interferometro IBIS-S 0 100 200 300 400 500 600 700 800 900 1000 Time (s) February 2009 All rights reserved to IDS 25
  26. 26. Georadar IBIS System IBIS-S & Cable-stayed bridges: case studies Example: Olginate bridge (Italy) Comparison with accelerometers 800 Acceleration (mm/s2) 600 400 200 0 -200 -400 -600 Sensore WR731A Interferometro IBIS -800 260 270 280 290 300 310 Time (s) 500 400Acceleration (mm/s2) 300 200 100 0 -100 -200 -300 -400 Sensore WR731A Interferometro IBIS -500 260 270 280 290 300 310 Piezo-electric accel. WR 731A Time (s) February 2009 All rights reserved to IDS 26
  27. 27. Georadar IBIS System IBIS-S & Cable-stayed bridges: case studies Example: Olginate bridge (Italy) 26 24 22 Frequency (Hz) Frequency Domain Analysis 20 18 frequenza [Hz] 0 10 -1 Interferometro IBIS 16 f = 3.906 n 10 14 ASD (mm)2/Hz -2 12 10 -3 10 IBIS 10 8 -4 6 10 4 -5 10 2 -6 0 10 -7 0 1 2 3 4 5 6 7 10 -8 10 n n 10 -1 0 5 10 15 20 25 Tension Sensore WR731A ASD (mm)2/Hz -2 10 Cable S09 10 -3 Accel. IBIS-S Accelerometer -4 10 Tension Tension 10 -5 fexp (Hz) fexp (Hz) (kN) (kN) -6 10 3.906 1883.1 3.809 1790.7 -7 10 0 5 10 15 20 25 7.764 1860.0 7.495 1733.3 Frequency (Hz) 11.720 1883.7 11.470 1804.2 Resonant frequencies 15.630 1884.5 f1 (Hz) f2 (Hz) f3 (Hz) f4 (Hz) f5 (Hz) f6 (Hz) 19.510 1879.2 IBIS-S 3.906 7.764 11.720 15.630 19.510 23.460 23.460 1886.9 Accel. 3.809 7.495 11.470 1880 1776 February 2009 All rights reserved to IDS 27
  28. 28. Georadar IBIS System Dynamic Monitoring: Capriate bridge Measurement objective: comparison with accelerometers, resonance frequencies and modal shape retrieval Central arch length (m): 62.5 February 2009 All rights reserved to IDS 28
  29. 29. Georadar IBIS System Dynamic Monitoring: Capriate bridge To make a comparison between the results of IBIS-S system and accelerometers system 6 corner reflector were installed at the same position of accelerometers February 2009 All rights reserved to IDS 29
  30. 30. Georadar IBIS System Dynamic Monitoring: Capriate bridge Bridge photograph and range profile February 2009 All rights reserved to IDS 30
  31. 31. Georadar IBIS System Dynamic Monitoring: Capriate bridge Velocity comparison for Test Point 22 Velocity [mm/sec] Zoom on the first 15 sec – direct comparison IBIS-S IBIS-S acc Time [sec] Velocity [mm/sec] accelerometer Time [sec] February 2009 All rights reserved to IDS 31
  32. 32. Georadar IBIS System Dynamic Monitoring: Capriate bridge Frequency analysis acc comparison on 3000sec acquisition duration IBIS-S Acc detected IBIS-S detected Percentage frequency frequency error Hz Hz % 2,617 2,595 0,84 3,164 3,182 -0,57 6,641 6,608 0,50 8,086 8,077 0,11 February 2009 All rights reserved to IDS 32
  33. 33. Georadar IBIS System Dynamic Monitoring: Capriate bridge Modal shape obtained by accelerometer data f = 2.617 Hz f = 3.164 Hz f = 6.641 Hz f = 8.086 Hz February 2009 All rights reserved to IDS 33
  34. 34. Georadar IBIS System Dynamic Monitoring: Capriate bridge Modal shapes comparison 1.2 Normalized Mode Shape Accelerometer IBIS-S sensor 0.6 0.0 f=2.617Hz -0.6 -1.2 0 23 46 69 92 115 Distance along deck (m) 1.2 Normalized Mode Shape Accelerometer IBIS-S sensor 0.6 0.0 f=3.164Hz -0.6 -1.2 0 23 46 69 92 115 Distance along deck (m) February 2009 All rights reserved to IDS 34
  35. 35. Georadar IBIS System Dynamic Monitoring: Capriate bridge Modal shapes comparison 1.2 Normalized Mode Shape Accelerometer IBIS-S sensor 0.6 0.0 f=6.641Hz -0.6 -1.2 0 23 46 69 92 115 Distance along deck (m) 1.2 Normalized Mode Shape Accelerometer IBIS-S sensor 0.6 0.0 f=8.086Hz -0.6 -1.2 0 23 46 69 92 115 Distance along deck (m) February 2009 All rights reserved to IDS 35
  36. 36. Georadar IBIS System Dynamic Monitoring: Kuranda Scenic Railway Measurement objective: measurement of the vertical displacements induced by the train passage and resonance frequencies Kuranda train (Cairns, Australia) Measurement set-up February 2009 All rights reserved to IDS 36
  37. 37. Georadar IBIS System Dynamic Monitoring: Kuranda Scenic Railway Radar range profile of the illuminated rail ¼ bridge ½ bridge Steel pillar length length Steel pillar End of IBIS bridge Measurement parameters • measurement lenght: 10’ across the train passage. 2 train passages made. • sampling frequency: 71 Hz • Length of bridge: ~ 50 m. • Height of bridge deck above radar: 2.7 m. February 2009 All rights reserved to IDS 37
  38. 38. Georadar IBIS System Dynamic Monitoring: Kuranda Scenic Railway Time history displacement of a selected points (first train passage) zoom ¼ bridge length ¼ bridge length ½ bridge length ½ bridge length L.o.s. displacement projected along the vertical direction, according to the radar to bridge measured distance (2.7 m.) February 2009 All rights reserved to IDS 38

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