Noncontact Bridge Deformation Monitoring Using Laser Tracking Technology – Technology Evaluation and Field Implementation

Bridge deformation monitoring under static and temperature loads is vital to understanding structural behavior and performance. Use of traditional technology such as potentiometers requires having a fixed reference. This entire operation is tedious and requires time to mount the sensors and provide power supply and data acquisition. This operation becomes complicated when longer spans or wider bridges are to be monitored. Also, when the bridge is over a river or a highly congested road use of traditional sensors becomes challenging. Today’s focus is to identify technologies that can be used in the field for bridge monitoring, with confidence and minimum or no disturbance to the public and developing no hazardous conditions. Further, it should be a mobile technology that can be easily operated under field conditions, during day or night. Laser based metrology equipment with micrometer accuracy in distance measurement, Laser Tracker, was identified. Capabilities and limitations of the technology were evaluated under various field conditions. Field implementation includes monitoring of a 42-degree skew bridge behavior under thermal loads and deflections under static loads. This paper will discuss basics of laser technology, Laser Tracker working principles, evaluation results, capabilities and limitations of the technology, and field implementation results.

References
1. Sugisaki, K., M. Abe, M. Abe and M. Shimamura. “Development of health monitoring indicators for steel bridges and its implementation to sensing systems,” Bridge Maintenance, Safety and Management – IABMAS ‘10, Proceedings of the Fifth International IABMAS Conference. CRC Press 2010. pp. 2775-2782. 2. Aktan, A.E., F.N. Catbas, K.A. Grimmelsman and M. Pervizpour. Development of a Model Health Monitoring Guide for Major Bridges, Drexel Intelligent Infrastructure and Transportation Institute, Drexel University, Philadelphia, PA. 2002. 3. Hou, X., X. Yang and Q. Huang. “Using Inclinometers to Measure Bridge Deflection,” Journal of Bridge Engineering, Volume 10, Issue 5, 2005, pp. 564-569. 4. Ouyang, J.F., W.L. Liu, D.X. Sun and Y.G. Yan. Laser Tracker Calibration Using Coordinate Measuring Machine, 20th ASPE Annual Meeting, Norfolk, VA, October 9-14, 2005. 5. Leica Geosystems. www.leica-geosystems.com (Accessed: July 2010).
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