Dynamic Measurements of the Second Severn Crossing.

Macdonald, John H G; Dagless, EL; Thomas, BT; Taylor, Colin Anthony

doi:10.1680/itran.1997.29978

Cited by 37 publications

(28 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One of the earliest examples of optics-based monitoring at dynamic rates was Tacoma Narrows Bridge (University of Washington, 1954) of optics-based dynamic tracking, e.g., Humber Bridge (Stephen et al, 1993;Brownjohn et al, 1994) and Second Severn Crossing (Macdonald et al, 1997), both of which were operated by University of Bristol researchers. The Bristol "Vision System" used parallel processing hardware and a predictive search algorithm to track an artificial target at dynamic rates in real time (at Second Severn Crossing) or by post-processing (Humber Bridge).…”

mentioning

confidence: 99%

Vision-Based Bridge Deformation Monitoring

Brownjohn

Hester

2017

Front. Built Environ.

View full text Add to dashboard Cite

Optics-based tracking of civil structures is not new, due to historical application in surveying, but automated applications capable of tracking at rates that capture dynamic effects are now a hot research topic in structural health monitoring. Recent innovations show promise of true non-contacting monitoring capability avoiding the need for physically attached sensor arrays. The paper reviews recent experience using the Imetrum Dynamic Monitoring Station (DMS) commercial optics-based tracking system on Humber Bridge and Tamar Bridge, aiming to show both the potential and limitations. In particular, the paper focuses on the challenges to field application of such a system resulting from camera instability, nature of the target (artificial or structural feature), and illumination. The paper ends with evaluation of a non-proprietary system using a consumer-grade camera for cable vibration monitoring to emphasize the potential for lower cost systems where if performance specifications can be relaxed.

show abstract

mentioning

confidence: 99%

Vision-Based Bridge Deformation Monitoring

Brownjohn

Hester

2017

Front. Built Environ.

View full text Add to dashboard Cite

show abstract

“…Efforts have been spent on developing advanced vision-based systems to provide accurate and robust displacement measurement primarily of high-rise buildings, [8] short-span bridges, [9][10][11][12] and long-span bridges. [10,[13][14][15][16] Previous studies have indicated the significant potential of vision-based systems for structural condition evaluation, especially for system identification. [17][18][19] Other applications based on the camera measured displacement include finite element model calibration, [20] damage detection, [21] and bridge weigh-in-motion where another camera is used for the traffic monitoring.…”

Section: Review Of Vision-based Approachesmentioning

confidence: 99%

“…• Correlation-based template matching is a classic and widely used technique, [8,9,13,14,16] which is realised by searching for an area in a new frame most closely resembling the reference (or template) that is predefined as a rectangular subset in the initial frame.…”

Section: Target Tracking Techniquesmentioning

confidence: 99%

A non-contact vision-based system for multipoint displacement monitoring in a cable-stayed footbridge

Brownjohn

Kong

2018

Struct Control Health Monit

169

106

View full text Add to dashboard Cite

SummaryVision-based monitoring receives increased attention for measuring displacements of civil infrastructure such as towers and bridges. Currently, most field applications rely on artificial targets for video processing convenience, leading to high installation effort and focus on only single-point displacement measurement, for example, at mid-span of a bridge. This study proposes a low-cost and non-contact vision-based system for multipoint displacement measurement based on a consumer-grade camera for video acquisition and a custom-developed package for video processing. The system has been validated on a cablestayed footbridge for deck deformation and cable vibration measurement under pedestrian loading. The analysis results indicate that the system provides valuable information about bridge deformation of the order of a few centimetres induced, in this application, by pedestrian passing. The measured data enable accurate estimation of modal frequencies of either the bridge deck or the bridge cables and could be used to investigate variations of modal frequencies under varying pedestrian loads. KEYWORDSbridge displacement, cable vibration, cable-stayed bridge, pedestrian loads, vision-based system | INTRODUCTIONStructural health monitoring is aimed at providing valuable information about structural performance and characterisation of structural defects to the asset owners, especially for those civil infrastructures beyond the design life. Vibrationbased modal tests are a common way for structural condition and serviceability assessment, providing a direct view about the structural stiffness, mass properties, and their distributions. [1] As well as for validating designs of civil structures, modal parameters extracted from vibration data obtained in short-term or long-term measurements are widely believed to have potential for identifying changes in structural condition or "damage." [2] The sensitivity of these parameters to damage depends on the nature of the damage, for example, local deterioration of material, for example, due to corrosion, may not be detectable against background effects of environmental variability, whereas boundary conditions are known to have a relatively strong effect, for example, fixity of bridge supports.[3]This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

show abstract

“…Severn Bridges in 1990s (Macdonald et al, 1997;Stephen et al, 1993), and the recent applications 150 include displacement monitoring tests in a railway bridge , a long-span bridge (Ye et 151 al., 2013) and a high-rise building (Liao et al, 2010 The procedures are demonstrated in Figure 3. The most prominent corners are detected by Shi-Tomasi 163 corner detector (Jianbo Shi and Tomasi, 1994) in the reference frame with their locations updated in the 164 new frame by Eq.(1).…”

Section: Correlation-based Template Matching 139mentioning

confidence: 99%

Vision-based systems for structural deformation measurement: case studies

2018

Proceedings of the Institution of Civil Engineers - Structures

View full text Add to dashboard Cite

Vision-based systems offer a promising way to measure displacement and are receiving increased attention in civil structural monitoring. However, the working performance of vision-based systems, especially their measurement accuracy and robustness to different field conditions, is not fully understood. This study reports three cases studies of vision-based monitoring tests including one in a laboratory, one on a short-span bridge and one on a long-span bridge. The tracking accuracy is quantified in laboratory conditions in the range from 0·02 to 0·20 pixel, depending on the target patterns as well as the tracking method selected. The measurement performance under several field challenges is investigated, including long-range measurement (e.g. camera-to-target distance of 710 m), low-contrast target patterns, changes of target patterns and changes in lighting conditions. Three representative tracking methods for the video processing, namely, correlation-based template matching, Lucas–Kanade optical flow estimation and scale-invariant feature transform were used for the analysis, indicating their advantages and shortcomings for field measurement. One of the main observations in field application is that changes in lighting conditions might cause some low-frequency measurement errors that could be misunderstood without prior knowledge regarding structural loading conditions.

show abstract

Dynamic Measurements of the Second Severn Crossing.

Cited by 37 publications

References 0 publications

Vision-Based Bridge Deformation Monitoring

Vision-Based Bridge Deformation Monitoring

A non-contact vision-based system for multipoint displacement monitoring in a cable-stayed footbridge

Vision-based systems for structural deformation measurement: case studies

Contact Info

Product

Resources

About