The need to reinforce existing structures (degraded structures, modifications in the working conditions of the structure, etc.) is quite common. One of the most commonly used types of reinforcement is laminated composite reinforcement. In previous works, the authors have analyzed the piezoresistive response of nanocomposites based on carbon nanotubes and nanofibers and glass fiber laminates made with nanocomposites. The results have shown their piezoresistive capability. In this work, the ability of these laminates to provide information on the structural state of laboratory demonstrators has been tested. For this purpose, sensitive laminates have been fabricated and bonded to commercial pultrusion beams and subjected to (i) cyclic loading in undamaged and damaged situations and (ii) increased loading until structural failure. The results show that the functionalized resin has a sensitive capability and that the laminates have both sensitive and reinforcing capabilities. Therefore, both solutions are valid for monitoring structural health.