SUMMARY Tragedies such as the collapse of both towers of the Skyline Center Project in Virginia (1973), the collapse of the I-35W bridge over the Mississippi River in Mineapolis (2007) and, more recently of the suspended bridge Kutai Kartanegara in Indonesia (2011), reveal the importance and necessity to monitor certain structures, in order to evaluate their structural safety in real time. The success of this work depends fundamentally on two features. On the one hand, the systems and sensors applied in structural analysis must be precise and reliable, and at the same time they should provide a safe, easy-to-use and economic monitoring system. On the other hand, it is necessary to establish a general guideline and topologies for monitoring in order to monitor different structural typologies, as a guide to structure assessment. Within this context, and due to the advantages offered by optical fibre, this doctoral thesis designs and proposes new sensors for structural monitoring based on this technology. The investigation is justified by the limitations of the technologies available to date, and has been carried out in the following phases: * Development of a point fiber optic sensor based on Fiber Bragg Gratting (FBG), to measure strains and temperatures in structures. * Development of a long gauge sensor based on Fiber Bragg Gratting (FBG) to measure strains in structures. * Study and calibration of distributed sensors to measure strains, based on the phenomenon of light dispersion (Stimulated Brillouin Scattering, or SBS). * Tests of the developed sensors with sample tests in the lab. * Testing and optimization of the sensors via numerical models based on finite element analysis. * Testing the behavior of the sensors on real structures, and the improvement of their design. The structures that are monitored cover a wide variety of materials and typologies such as the slab deck in an incrementally launched bridge, a postessed concrete slab, the foundation of a 318 m span suspended bridge or a section in a high speed railway tunnel. In this Tesis, only the works carried out in the high speed railway tunnel near from Mogente (Valencia) are shown. The others can be found in different papers submitted to journals or conferences that are included in the appendices.