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Proceedings Paper

Static and dynamic bridge monitoring with fiber optic sensors
Author(s): Sandra LLoret; Daniele Inaudi; Samuel Vurpillot
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Paper Abstract

In many concrete bridges, deformations due to static and dynamic loading are the most relevant parameters to be monitored in both the short and long term. Strain monitoring give only local information about the material behavior and too many of such sensor are therefore necessary to gain a complete understanding of the bridge evolution. Recent advances in measurement technology have demonstrated that optical fiber sensors are suitable for monitoring full-scale structures. A network of such sensors installed inside a bridges enables the measurement of parameters such as internal deformation and temperature. In the past four years, our laboratory has installed hundreds of fiber optic deformation sensors of varying seizes in concrete and composite steel-concrete bridges. These sensors give useful information during the construction phases and about the long-term geometrical deformations of a bridge under static load. Recently it has been found that these sensors can also be used to measure the quasi-static part of the dynamic deformation of a bridge under traffic load. The measurement technique relies on low-coherent interferometry and it guarantees high resolution, high precision ad long-term stability. Nevertheless each measurement takes a few seconds, thus it is inadequate for monitoring the dynamic behavior of bridges, where measurement frequencies of up to 1 kHz are necessary. This paper also presents a new technique to demodulate at a high frequency of up to 1 kHz are necessary. This paper also presents a new technique to demodulate at a high frequency the signal for the same sensors used for long-term monitoring. With its large dynamic range of several mm it allows for the monitoring of bridges under dynamic loads while maintaining the configuration of the original fiber optic sensor that has been proven to be reliable.

Paper Details

Date Published: 13 August 1998
PDF: 11 pages
Proc. SPIE 3555, Optical and Fiber Optic Sensor Systems, (13 August 1998); doi: 10.1117/12.318201
Show Author Affiliations
Sandra LLoret, Swiss Federal Institute of Technology (Switzerland)
Daniele Inaudi, Swiss Federal Institute of Technology and SMARTEC SA (Switzerland)
Samuel Vurpillot, Swiss Federal Institute of Technology (Switzerland)

Published in SPIE Proceedings Vol. 3555:
Optical and Fiber Optic Sensor Systems
Shanglian Huang; Kim D. Bennett; David A. Jackson, Editor(s)

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