Embedded distributed optical fiber sensors for health monitoring of concrete bridges

The idea behind Structural Health Monitoring (SHM) is the identification of early structural malfunctions, which, in the case of concrete bridges, is mainly shown as deformation and cracking and the consequent feedback on the structure’s ability to continue serving its intended purpose. An increasingly popular SHM tool are Distributed Optical Fiber Sensors (DOFS) which boasts clear advantages over the classic ones. Yet, DOFS´s literature reports strain reading issues connected to measurements when the fiber is embedded in RC, in particular when the latter starts cracking. The present paper wants to suggest solutions to such by studying various bonding and protection techniques offered by the literature and integrating them in a laboratory experimental campaign that sees the rebar of four RC tensile members instrumented with DOFS. Different segments of the fiber were bonded with different bonding and protection techniques in an attempt to pin-point which of them leads to the highest quality DOFS strain readings.