Fatigue testing of reinforced concrete beam instrumented with distributed optical fiber sensors (DOFS)

Abstract

The use of fiber optic sensors on civil engineering structural health monitoring (SHM) applications have become quite popular for the past two decades. Within this type of sensors however, the study and use of Optical Backscatter Reflectometry (OBR) based Distributed Optical Fiber Sensors (DOFS) is relatively new. In this way, there is still some uncertainty that would allow the use of this technology in a more systematic and standardized way. Some of this uncertainty is related with the long-term reliability behavior of these sensors when applied on the monitoring of a structure under a large number of load cycles. In this way, the authors conducted a laboratory experiment where a reinforced concrete beam was instrumented with a DOFS that was adhered in a way to allow the measuring of strain on four different longitudinal segments on its bottom surface. A fatigue test was then conducted on this element where the inputted load range was the one expected on a standard highway bridge between its self-weight and the additional traffic load. Furthermore, each longitudinal segment of the DOFS was adhered to the concrete using a different adhesive in order to assess the optimal one in these conditions. The obtained data is then compared with strain gauges that are also instrumented on the concrete beam.