6th European Workshop on Structural Health Monitoring. Dresden. Germany. 2012. Report. During the slack period of precast concrete structures fabrication, the prestressing force is transferred, by adhesion to concrete being the armor compliant behaviors, up today, a still pending matter. To contribute to a better understanding of the subject, a new quasi-distributed optical fiber sensor system is specifically designed, fabricated and embedded into a prestressed concrete prismatic beam. The experimental results are presented, discussed and finally, conclusions are extracted. The fiber transducer is based on Brag grating technology and a new custom encapsulation..