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"Bridge condition evaluation using LDVs installed on a vehicle" presented at IALCCE2018 by Daniel Martinez Otero

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In this paper, a structural health monitoring approach is proposed involving Laser Doppler Vibrometers (LDVs) installed on a vehicle. Relative velocities are measured to obtain the Rate of Instantaneous Curvature of the velocity (RIC). Standard deflection curvature is shown to be sensitive to local damage. Instantaneous Curvature (IC) is likewise sensitive but calculated using measurements provided from a vehicle. RIC is obtained using the first derivative of IC with respect to time.A damage indicator obtained from RIC, the Difference Ratio, is tested both in noise-free and noisy conditions.

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"Bridge condition evaluation using LDVs installed on a vehicle" presented at IALCCE2018 by Daniel Martinez Otero

  1. 1. Reducing Uncertainty in Structural Safety Special Session SS6 Ghent, Belgium 28-31 October 2018
  2. 2. D. Martinez, A. Malekjafarian and E.J. OBrien Bridge Condition Evaluation using LDVs Installed on a Vehicle
  3. 3. Index • Measuring Strategies • What a TSD is? • RIC and MAD for bridge damage location • Conclusions
  4. 4. Measuring Strategies: Visual Inspection • Frequently used in bridges • Worker dependence Measuring Strategies Daniel Martínez Otero / University College Dublin 3
  5. 5. Direct Monitoring • Sensors installed on the bridge • Electricity supply needed • Great number on sensors involved, specially on bridges Hong Kong Stonecutters bridge, 1.6 km length Measuring Strategies Daniel Martínez Otero / University College Dublin 4
  6. 6. Indirect Monitoring (Drive-by) • Sensors installed in a passing vehicle • Quick • Cost affordable • No risk Measuring Strategies Daniel Martínez Otero / University College Dublin 5
  7. 7. What a TSD is? • A Traffic Speed Deflectometer (TSD) is an equipped vehicle that allows us to know the road profile parameters. • Its characteristics make us to think about the suitability of this kind of vehicle for the bridge measurements. What a TSD is? Daniel Martínez Otero / University College Dublin 6
  8. 8. • Doppler Lasers (LDV) oInstalled on a beam. oReference laser between the two axles. oChange in frequency allows to calculate the relative velocity. Main sensors of the TSD 7 What a TSD is? Daniel Martínez Otero / University College Dublin
  9. 9. What is the TSD measuring? 8 What a TSD is? Daniel Martínez Otero / University College Dublin
  10. 10. TSD for Bridge Condition RIC and MAD for Bridge Damage Location Daniel Martínez Otero / University College Dublin 9
  11. 11. Curvature Methods κℎ𝑒𝑎𝑙𝑡ℎ𝑦(𝑥) = 𝑀(𝑥) 𝐸𝐼 κ 𝑑𝑎𝑚𝑎𝑔𝑒𝑑(𝑥) = 𝑀(𝑥) 𝐸𝐼𝑟𝑒𝑑 RIC and MAD for Bridge Damage Location Daniel Martínez Otero / University College Dublin 10
  12. 12. Instantaneous Curvature • In a moving reference situation this curvature cannot be calculated using only one sensor. • Instantaneous Curvature (IC) is calculated using three different sensors. IC x, 𝐭 = v x−∆x,𝐭 −2v x,𝐭 +v x+∆x,𝐭 ∆x2 RIC and MAD for Bridge Damage Location Daniel Martínez Otero / University College Dublin 11 v Deflection
  13. 13. Deflection Contour Plot with IC calculation RIC and MAD for Bridge Damage Location Daniel Martínez Otero / University College Dublin 12
  14. 14. IC calculation from Contour Plot RIC and MAD for Bridge Damage Location Daniel Martínez Otero / University College Dublin 13
  15. 15. Rate of Instantaneous Curvature • Same idea is used for relative velocities ( ሶq). • Rate of Instantaneous Curvature (RIC) is defined similar to IC. RIC x, 𝐭 = ሶq x−∆x,𝐭 −2 ሶq x,𝐭 + ሶq x+∆x,𝐭 ∆x2 ሶq = ሶv 𝑏𝑟𝑖𝑑𝑔𝑒 − ሶv 𝑣𝑒ℎ𝑖𝑐𝑙𝑒 RIC and MAD for Bridge Damage Location Daniel Martínez Otero / University College Dublin 14
  16. 16. Rate of Instantaneous Curvature RIC and MAD for Bridge Damage Location Daniel Martínez Otero / University College Dublin 15
  17. 17. Damage Indicator for Bridge Condition • Moving Average Difference (MAD): MAD x = 1 Z σ n=− (Z−1)×L 2f (Z−1)×L 2f RICDamaged (x+n)− 1 Z σ n=− (Z−1)×L 2f (Z−1)×L 2f RICHealthy(x+n) min RICHealthy × 100 (%) Z is the number of points for the moving average. f is the measuring sampling frequency of the sensors. L is the length of the bridge. RIC and MAD for Bridge Damage Location Daniel Martínez Otero / University College Dublin 16
  18. 18. MovingAverage Difference RIC and MAD for Bridge Damage Location Daniel Martínez Otero / University College Dublin 17
  19. 19. Conclusions Conclusions Daniel Martínez Otero / University College Dublin 18 • Curvature methods have great potential in drive-by monitoring. • Relative velocities can be used in bridge damage detection. • Moving Average Difference (MAD) has the ability of locate damage on bridges.
  20. 20. The TRUSS ITN project (http://trussitn.eu) has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 642453 Thanks for your attention

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