Non-contact measurement of the dynamic displacement of railway bridges using an advanced video-based system

Ribeiro, Diogo; Calçada, Rui; Ferreira, José; Martins, Teresa

doi:10.1016/j.engstruct.2014.04.051

Cited by 221 publications

(142 citation statements)

References 21 publications

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“…For distances to the object in the order of 5 m it is possible to obtain an image resolution of approximately 0.01 mm by selecting a focal length of 3200 mm. For distances in the order of 25 m, to obtain a resolution of 0.01 mm, it is necessary to use a focal length of 3200 mm and apply an image processing technique at subpixel level, in this case, at half pixel level [15]. Under these conditions the illumination of the target should be a critical aspect, since the use of the lens and magnification elements significantly reduces the light entrance into the camera's sensor.…”

Section: Requirements and Performancementioning

confidence: 99%

“…The gain option enables to digitally increase the intensity of the gray levels of the image in situations where the field of view presents low luminosity. The trigger can be internally or externally activated [15]. The brightness and contrast are indicators of image quality monitored at the level of the region of interest.…”

Section: Softwarementioning

confidence: 99%

“…The graphical interface of the developed software, presented in Figure 4, includes several functionalities, namely, the definition of the regions of interest, the definition of the camera's parameters (acquisition frame rate, gain, shutter speed), the selection of the type of trigger, the monitoring of the image quality parameters (brightness and contrast) and the automatic processing of acquired images [15]. The definition of a region of interest of a field of view is performed graphically by selecting a portion of the image using a rectangular window.…”

Section: Softwarementioning

confidence: 99%

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Measurement of the Dynamic Displacements of Railway Bridges Using Video Technology

Ribeiro

Calçada

Ferreira³

et al. 2015

MATEC Web of Conferences

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Abstract. This article describes the development of a non-contact dynamic displacement measurement system for railway bridges based on video technology. The system, consisting of a high speed video camera, an optical lens, lighting lamps and a precision target, can perform measurements with high precision for distances from the camera to the target up to 25 m, with acquisition frame rates ranging from 64 fps to 500 fps, and be articulated with other measurement systems, which promotes its integration in structural health monitoring systems. The system's performance was evaluated based on two tests, one in the laboratory and other on the field. The laboratory test evaluated the performance of the system in measuring the displacement of a steel beam, subjected to a point load applied dynamically, for distances from the camera to the target between 3 m and 15 m. The field test allowed evaluating the system's performance in the dynamic measurement of the displacement of a point on the deck of a railway bridge, induced by passing trains at speeds between 160 km/h and 180 km/h, for distances from the camera to the target up to 25 m. The results of both tests show a very good agreement between the displacement measurement obtained with the video system and with a LVDT.

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Section: Requirements and Performancementioning

confidence: 99%

Section: Softwarementioning

confidence: 99%

Section: Softwarementioning

confidence: 99%

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Measurement of the Dynamic Displacements of Railway Bridges Using Video Technology

Ribeiro

Calçada

Ferreira³

et al. 2015

MATEC Web of Conferences

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“…[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. [22] However, vision-based systems still face several field challenges, such as the requirement for stable camera mounting, [11] measurement error caused by lighting changes, [23] and atmospheric effects affecting light refraction-particularly for long-range measurements.…”

Section: Review Of Vision-based Approachesmentioning

confidence: 99%

“…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.…”

Section: Review Of Vision-based Approachesmentioning

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

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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.

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2020

Computer Vision for Structural Dynamics and Health Monitoring

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Non-contact measurement of the dynamic displacement of railway bridges using an advanced video-based system

Cited by 221 publications

References 21 publications

Measurement of the Dynamic Displacements of Railway Bridges Using Video Technology

Measurement of the Dynamic Displacements of Railway Bridges Using Video Technology

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

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