PSI - Issue 11

Sonia Boschi et al. / Procedia Structural Integrity 11 (2018) 169–176 Author name / Structural Integrity Procedia 00 (2018) 000–000

172

4

The building is made up of load-bearing masonry of different types, plastered in all its parts, except for some limited areas. From the essays and the double flat-jack results, it was possible to identify three different predominant vertical masonry types: M1, M2 and M3. M1 (Fig. 2a) is a stone masonry, 50-60 cm thick, characterized by large blocks, squared in some cases, with a regular presence of shims and full bricks. The mortar is friable to the touch and, accordingly to the results of the mechanical tests, it has a low compressive resistance. The results of the double flat-jack provided an average value of the E modulus equal to 3150 N /mm 2 , amply over the ranges provided by the Italian code (M.I.T. 2009, Tab. C8A.2.1) for the irregular/roughly cut stone masonry. It is worthwhile mentioning that this result could be ascribable to the unfitting positioning of the LVTDs in the masonry, which, by interfering with the stones, have really measured the elasticity of the blocks. The M2 (Fig. 2b) is a solid brick masonry, characterized by variable thicknesses (about 30-55 cm), made up of bricks of varying sizes and mortar with satisfactory mechanical characteristics in relation to the period of construction. The unique double flat-jack carried out on M2 provided a value of E consistent with values given by the Italian code for masonry with the same characteristics and good mortar (about 2700 N/mm 2 ). The M3 masonry (Fig. 2c), a mixed stones and brick masonry, is characterized by barely cut and not worked stones of medium-large size, squared only in few cases. The mortar, generally friable to the touch, is less compact with respect to that of the M1 masonry. In some cases, the M3 walls have voids on the surface and in the wall thickness too. From the three double flat-jack emerges that the average of E modulus is equal to 1057 N/mm 2 , considerably lower than M1 type but in line with the value given for disorganized stone masonry.

a

b

c

Fig. 2. (a) stone masonry; (b) brick masonry (with inserted the double flat-jack); (c) mixed masonry (stone and brick masonry).

There are different types of horizontal elements due to the variety of the structural units and the numerous interventions carried out over time on the building. Spans of the vaults and slabs are generally quite large. There are structural vaults, wooden and steel structures and modern hollow brick and reinforced concrete slabs. In particular, at the ground floor the spaces are covered by cross and barrel vaults, generally made up of brick masonry. Most of the barrel vaults cover large rectangular rooms, have lateral lunette and one or even two orders of transversal chains. These vaults have a rather low profile. In particular, the vault covering the kindergarten - that can be considered representative of all the other of the same typology - has a span of 883 cm and a rise of 148 cm. From a through essay, it emerges that the vault’s thickness is 28 cm from the abutments up to about the haunches, whereas it is halved in the part around the crown, with the exception of the transversal ribs - spaced 110 cm apart - that have both thickness and depth equal to 28 cm. There is not infill, except for a limited zone around the crown; over the vault, a wooden slab rests on the lateral walls and on two brick masonry supports, which develops in the longitudinal direction of the vault, each one at a distance from the crown of about 1 m. Some masonry walls built on some ribs, together with the lunettes, provide a stabilizing and stiffening contribution (Fig. 3 and 4a). The vaults of the cloisters are cross brick masonry vaults (Fig. 4c), with an almost square fields of about 350 cm on a side. Each vault is set on the rear wall and on rectangular piers in the side facing the cloister. A through essay revealed a structural thickness of 15 cm in addition to a filling, made up of mainly loose materials, having a thickness ranging from about 16 to 35 cm on the various sides of the cloister.