Effective seismic strengthening and monitoring of a masonry vault by using Glass Fiber Reinforced Cementitious Matrix with embedded Fiber Bragg Grating sensors

The research proposes the combined use of a Glass Fiber Reinforced Cement Matrix (GFRCM) composite with an integrated fiber optic sensing system for innovative seismic retrofitting of masonry vaults. The need of eco-compatibility of bonding material with masonry support implies the use of Hydraulic Lime Mortar (HLM) as bonding matrix that, in contrast, is characterized by lower adhesion capacity respect to polymeric resins and not well-known carrying-load properties. Hence, monitoring of the operating features of the GFRCM reinforcement has been pursued with an advanced fiber optic sensing system realized through Fiber Bragg Grating (FBG) sensors. The use of FBG sensors is justified by a large number of advantages such as small sensor dimensions, low weight as well as high static and dynamic resolution of measured values, distributed sensing feature allowing to detect anomalies in load transfer between reinforcement and substrate. Specifically, the proposed retrofitting and monitoring technique is designed and applied to an old masonry pavilion vault. A nonlinear finite element model of the reinforced structure is developed in order to quantify the effectiveness of the GFRCM strengthening layer and to derive the convenient position of the optic fibers for a correct monitoring of the reinforced vault. An experimental campaign is carried out in order to verify the proper behavior of the proposed strengthening and sensing strategy.