In this paper, we demonstrate a modified time of flight fiber optic sensor interferometer that provides global strain information for large-scale FRP strengthened structures with significantly increased strain sensitivity. With the originally continuous signals being reconstructed from the discretely sampled points using a sinc interpolation function, the sensing resolution of the interferometer is demonstrated to be significantly higher than through direct interrogation. To easily embed the FOS in structures and effectively increase the fiber sensing length, a commercially available prefabricated fiber ribbon is used. The results of bending tests of FRP beams with the embedded ribbon demonstrate the increase in strain sensitivity as well as no detectable loss in strength of the FRP plates due to the embedded fiber ribbons. Results from static loading test of a FRP strengthened beam with embedded fiber ribbons show the feasibility of this technique for self-monitoring FRP retrofits.

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