Concrete Strain Monitoring with Fabry-Pérot Fiber-Optic Sensor

The field of instrumentation is now going through new developments with the advent of fiber-optic strain gauges. Fabry-Pérot is one type of fiber-optic sensing technology that can be used for microstrain measurement of concrete. However, this new generation of strain gauges first needs laboratory investigation. The Fabry-Pérot type of sensor, specially designed for embedment in concrete, is evaluated. The sensor is protected by a steel sleeve that allows its installation in concrete elements. Laboratory experiments, including compressive and thermal loading, are performed on a high-performance concrete cylinder containing this new type of strain gauge. The fast response of these strain gauges allows monitoring of the dynamic load test up to 5 Hz. The strain gauge sleeve is made of steel, and numerical simulations using a finite-element method are performed to verify strain distribution in a concrete cylinder with an embedment fiberoptic strain gauge. Results show that this type of strain gauge performs well for strain measurement of concrete and seems not to be affected by temperature variations.