Abstract: Fiber Bragg grating(FBG) strain sensorsare calibrated and embedded into the reinforced concrete beams. Operating techniques and protectivemethods suitable for civil engineering structuresare presented. With FBG sensors, internal strainsof the reinforced concrete are determined in laband on construction site. FBG sensors are ad-vantageous with respect to the absolute valuemeasurement and long service life over theconventional electrical strain gauge in experiments.The results indicate that it is possible to build a structural health monitoring system based on fiber optic sensors.