Application of fiber-optic strain sensors for monitoring of a pre-stressed concrete box girder bridge

Fiber-optic strain sensors have been used to qualitatively assess structure health. Here, use of fiber-optic strain sensors for quantitative measurement of concrete strain on a railway bridge is investigated. Concrete strains have historically been measured using electrical resistance strain gages. These strain gages, however, have the disadvantages of low signal-noise ratio and degradation of signal over time in the specific application for railway bridges on electrified routes. Fiber-optic strain sensors, apart from the ease of application to a girder concrete surface, have high signal-noise ratios, and are suitable for long term health monitoring as the optical signal and the concrete surface attachment do not degrade with time. It is conclusively shown that appropriately attached fiber-optic sensors coupled with high sampling rates provide a reasonably accurate measurement of strains on concrete surfaces, and can, thus, be used directly for quantitative condition assessment of bridges.