THE BEHAVIOUR UNDER THERMAL LOADS OF THE "W-WRAP" STRATEGY FOR THE STRENGTHENING OF MASONRY VAULT STRUCTURES

The paper reports the results obtained by a theoretical study carried out on the barrel vaults strengthened by an innovative method based on the use of C-FRP. Recent use of CFRP as proposed by CNR-DT2004 rules suggests the use of fiber sheets bonded to the intrados and/or to extrados of the simple curvature vault structures, in order to avoid all the mechanisms characterized by the formation of four or five plastic hinges for asymmetric or symmetric loads. In the case of symmetric loading history, both the experimental and theoretical tests have shown a greater efficiency of the strengthening applied at the intrados, but, often, it is not possible to work at the intrados for architectonical reasons, mainly in the case of the monumental and historical buildings(i.e. pictures of great value ecc.). Besides, even the intrados strengthening seems inconvenient because there is a premature crisis for the debonding of CFRP, caused by the co-presence of the shear and normal stresses generated by the curvature,. The proposed technique suggests the application of the CFRP layer as to assume an Ω shape wrapped around a concrete core, the latter, placed at the vault extrados, in order to obtain a supporting rib. The proposed system was investigated under thermal gradient.