Resumen de Monitorizacion de la corrosion en estructuras postensadas mediante sensores de fibra optica
Today available models for prediction of the steel corrosion in reinforced and prestressed concrete structures are not yet accurate enough due to the huge number of variables involved in the process and the high uncertainty inherent to many them. There still exists a large discrepancy between the values predicted by the models and the values measured in real structures affected by corrosion attack. This is even more dramatic in the case of the prestressing steel, where the corrosion mechanisms are more complex due to the material manufacturing and properties and the fact that the steel is in tension. Therefore, probabilistic models for the prediction of corrosion in post-tensioned steels are still in the very beginning. To bridge the gap between the theoretical results coming from the available models and the data from real post-tensioned structures, this thesis proposes the up-dating of the models by the use of long-term monitoring techniques. The proposed monitoring technique is based on the redistribution of strain and stress in a post-tensioned strand when any of the wires of the strand is affected by corrosion, its cross-section reduced as a consequence of this corrosion, and finally a break may happen. To measure in the real structure such change in the stresses of the remaining wires and tendons, a monitoring technique is developed based on the fiber-optic technology. The election of fiber optic as the measuring technology is due to the need of a reliable and robust long-term device that is not affected by the environmental aggressive agents present in real structures as well as the necessity of a sensor with very high resolution, because of the small changes in stress that should be measured. Being able to monitor the stresses/strains that are produced in each of the peripheral wires that form the strand, it's possible to detect a corrosion area and simultaneously to obtain information of the tension redistribution in the case a wire breaks.
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