Full-Field Bridge Deflection Monitoring with Off-Axis Digital Image Correlation

Video deflectometer based on using off-axis digital image correlation (DIC) has emerged as a robust non-contact optical tool for deflection measurements of bridges. In practice, a video deflectometer often needs to measure the deflections at multiple positions of the bridge. The existing 2D-DIC-base...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2021-07, Vol.21 (15), p.5058
Main Authors: Tian, Long, Zhao, Jianhui, Pan, Bing, Wang, Zhaoyang
Format: Article
Language:English
Subjects:
Accuracy
Bridges
Camcorders
Cameras
Cantilever beams
Civil engineering
Coordinate transformations
Deflection
deflection measurement
Digital imaging
Field tests
full-field determination
Global positioning systems
GPS
initial parameter estimation
Interferometry
Laser range finders
Lasers
Measurement methods
Methods
off-axis DIC
Parameter estimation
Sensors
Straight line fitting
Vision systems
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Summary:Video deflectometer based on using off-axis digital image correlation (DIC) has emerged as a robust non-contact optical tool for deflection measurements of bridges. In practice, a video deflectometer often needs to measure the deflections at multiple positions of the bridge. The existing 2D-DIC-based measurement methods usually use a laser rangefinder to measure the distance from each point to the camera to obtain the scale factor for the point. It is only suitable for the deflection measurements of a few points since manually measuring distances for a large number of points is time consuming and impractical. In this paper, a novel method for full-field bridge deflection measurement based on off-axis DIC is proposed. Because the bridge is usually a slender structure and the region of interest on the bridge is often a narrow band, the new approach can determine the scale factors of all the points of interest with a spatial straight-line fitting scheme. Moreover, the proposed technique employs reliability-guided processing and a fast initial parameter estimation strategy for real-time and accurate image-matching analysis. An indoor cantilever beam experiment verified the accuracy of the proposed approach, and a field test of a high-speed railway bridge demonstrated the robustness and practicability of the technique.
ISSN:1424-8220
1424-8220
DOI:10.3390/s21155058