Distributed fiber optic sensing during static and dynamic bridge loading

In order to ensure a safe operation of bridges and other civil infrastructure, efficient methods for condition assessment are necessary. Distributed Fiber Optic Sensing (DFOS) offers highly accurate monitoring and provides significant advantages over point-wise sensors. In order to assess the condition of an Austrian highway bridge, static and dynamic load tests have been performed. Two spans have been equipped with fiber optic cables and point-wise sensors. Through the use of Optical Backscatter Reflectometry (OBR), the strain distribution of the bridge spans under static load was measured. Additionally, the use of Distributed Acoustic Sensing (DAS) enabled the measurement of vibrations along the bridge spans under dynamic load. In this paper we demonstrate that through the use of complementary DFOS techniques, a more comprehensive analysis of the bridge’s behavior can be achieved. The resulting measurements are verified not only by the bridge’s numerical model, but also by co-located pointwise reference sensors.