MEASUREMENT OF THE DYNAMIC DISPLACEMENTS OF RAILWAY BRIDGES USING VIDEO TECHNOLOGY

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.

[1]  Erin Santini Bell,et al.  Bridge condition assessment using digital image correlation and structural modeling , 2012 .

[2]  Raimundo Delgado,et al.  Finite element model updating of a bowstring-arch railway bridge based on experimental modal parameters , 2012 .

[3]  Rui Calçada,et al.  Non-contact measurement of the dynamic displacement of railway bridges using an advanced video-based system , 2014 .

[4]  David V. Jáuregui,et al.  Noncontact Photogrammetric Measurement of Vertical Bridge Deflection , 2003 .

[5]  Nam-Sik Kim,et al.  Multi-point Displacement Response Measurement of Civil Infrastructures Using Digital Image Processing , 2011 .

[6]  Bridge displacement measurement system using image processing , 2006 .

[7]  Carmelo Gentile,et al.  An interferometric radar for non-contact measurement of deflections on civil engineering structures: laboratory and full-scale tests , 2010 .

[8]  Jean Ponce,et al.  Computer Vision: A Modern Approach , 2002 .

[9]  Chung Bang Yun,et al.  Development and application of a vision-based displacement measurement system for structural health monitoring of civil structures , 2006 .

[10]  Jong-Jae Lee,et al.  A vision-based system for remote sensing of bridge displacement , 2006 .

[11]  Masanobu Shinozuka,et al.  Evaluation of Bridge Load Carrying Capacity Based on Dynamic Displacement Measurement Using Real-time Image Processing Techniques , 2006 .

[12]  Hani Nassif,et al.  Comparison of laser Doppler vibrometer with contact sensors for monitoring bridge deflection and vibration , 2005 .

[13]  Malgorzata Kujawinska,et al.  Monitoring of civil engineering structures using Digital Image Correlation technique , 2010 .

[14]  Chih-Chen Chang,et al.  Flexible Videogrammetric Technique for Three-Dimensional Structural Vibration Measurement , 2007 .

[15]  James M. W. Brownjohn,et al.  Measurements of static and dynamic displacement from visual monitoring of the Humber Bridge , 1993 .