The post strengthening of the masonry vaults by the Ω-Wrap technique based on the use of C-FRP

The current technology for the reinforcement of the simple curvature vault masonry structures, by means of composite materials is based on the use of FRP strip directly bonded to the masonry surface. In this study we discuss a technique based on the use of the composite applied using a calibrated shape “Ω-Wrap” around a high resistance mortar core realized at the barrel vault extrados as a supporting rib. The study reports the results obtained both by the numerical and the experimental investigation, the latter carried out on vault specimens scaled to 1:2 size undergoing a monotonic load applied to one fourth of the span. The data were compared to those obtained by the traditional technique based on the use of CFRP directly bonded to the structural masonry element. Wrap system permits us to obtain a relevant increase of the bearing capacity of the vaults as well as a great ability of energy dissipation. This is due to the great resistance and ductility of the mortar ribbing, confined by the composite, with a lower CFRP material quantity in respect to the traditional system. Besides, the strengthening system allows the transfer of the horizontal load from the vault to the masonry bays and at the same time, it is capable, in the case of any subsiding of the abutments of vaults or vertical accelerations, of avoiding the failure of parts of the vault since they remain attached to the ribbings. The numerical data is in very good agreement with experimental data obtained from monotonic tests carried out by the authors on calcareous masonry barrel vaults. So the proposed technology seems to be very suitable in the case of vault retrofitting also in the case of seismic design.