PSI - Issue 29

Mario De Stefano et al. / Procedia Structural Integrity 29 (2020) 71–78 De Stefano and Cristofaro/ Structural Integrity Procedia 00 (2019) 000 – 000

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of the Architecture Department of Firenze. In tota l 51 tests, 13 double fla t-jacks and 20 penetrometric tests were carried out. Samples of natura l and artificia l materia ls were a lso taken from some wa lls and subsequently subjected to compression tests. 2.1. Visual analysis of masonry. The tests were carried out on wa lls identified on the different levels of the building complex. These has been carried out in the corner area or union areas of wa lls belonging to different bodies and/or built in different historica l periods. The tests performed were useful for identifying the different types of wa lls. The wa lls of the various buildings have shown difference from area to area . In particular, the wa lls of the unit that houses the “ Sala dei Gessi ” on the ground floor consist essentia lly of disorganized rubble masonry (Fig. 1a). In some stretches of wa ll, certa in cavities concea led by fa lse wa lls with extremely variable textures were a lso detected with a short distance. On the short sides, the same body instead presents a masonry consisting essentia lly of solid bricks and lime mortar. The buildings that occupy a centra l position in the complex, such as the “ Tribuna del David ” and the front on via Ricasoli, have extremely uneven wa lls. The stone elements turn out to be immersed in mortar beds of varying thickness. Vulnerable zones can a lso be identified as created by old partia lly or completely occluded flues (through coarse filling) and sma ll rooms with reinforced residua lmateria ls (Fig. 1b). The wa lls of the building that runs a long via Ricasoli, have a more uniform texture than those previously described (Fig. 1c). They are characterized by the presence of large blocks of square stone materia l. The wa lls of the building that houses the “Tribuna del David” have shown a good masonry texture, for various sections a lso well organized as well as extremely regular. In the masonry of the short arm and in the one under the David's cross, the masonry is set by a lternating blocks in squared stone and regular applications in solid bricks (Fig. 1d).

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(b)

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Fig. 1. Datasheets of samples of masonry. (a) Sala dei Gessi; (b) Sala del Colosso; (c) Ricasoli street; (d) Tribuna del David;(d).

2.2. Tests with double flat-jacks To investigate the mechanica l properties of the wa lls, tests were carried out with a fla t -jacks (ASTM C 1196-09 (2009) and ASTM C 1197-09 (2009)). The choice took into consideration the type of bonding and their location in the building complex, consistent with the actua l possibility of access to the different spaces, including the museums spaces. Fig. 2 shows the results of two tests. While in Fig. 3a it is shown the maximum va lues of the elastic modulus ( E ) are somewhat variable and fa ll within a range between 1330 MPa and 4616 MPa . The highest va lues were detected in the masonry on the ground floor that separates the room occupied by the “ Sale Fiorentine ” and the courtyard of the “ Opificio delle Pietre Dure ” ( E = 4616 MPa) and the one placed between the “Sale Fiorentine” and the room which houses the “ Sala dei Prigioni ” ( E = 4006 MPa). In the rooms of “ Tribuna del David ” , the va lues of the E , short arm and the long arm, are significantly different from each other. The wa lls of the short arm are characterized by va lues of about 2900 MPa , highlighting higher va lues than those found in the wa lls of the long arm, a lthough lower than what could be expected in a masonry with a uniform and easily recognizable texture. In the long arm, the va lues of the E are around 1500 MPa . The wa lls are in fact extremely uneven, with elements of