Advances in fiber optic sensing technology have made possible the installation of an extremely precise and reliable sensor in small structural members. Because of the high sensitivity and fast response of the sensor, low strain and dynamic strain can be measured. In this study, a Fabry-Perot strain sensor was cast in a high performance concrete cylinder, which had been submitted to simple compression and thermal tests. These results were compared with measurements obtained using external linear variable differential transformers fixed on concrete samples having the same composition as the fiber optic instrumented concrete cylinder. Comparisons were also done with results from tests on concrete cylinders instrumented with embedment vibrating wire and electrical strain gauges. In addition, thermal tests were performed on the different concrete cylinders and samples in order to compare the behaviour of the different sensors in high performance concrete submitted to temperature variations. The results show that the concrete strains measured with the Fabry-Perot sensor are in agreement with strain measurements made on concrete samples. Consequently, the presence of the embedded fiber optic sensor does not influence greatly the mechanical properties of concrete. Furthermore, for high stress levels (0.4 f 'c) and rapid stress changes (0.25 MPa/s), the fiber optic sensor measures with higher accuracy the strains of high performance concrete than the vibrating wire strain gauge.Key words: high performance concrete, sensor, vibrating wire, strain, extensometer, Fabry-Perot, fiber optic, instrumentation.
Analysis of a high-speed fiber-optic spectrometer for fiber-optic sensor signal processing