PSI - Issue 44

Mariateresa Guadagnuolo et al. / Procedia Structural Integrity 44 (2023) 878–885 M. Guadagnuolo et al. / Structural Integrity Procedia 00 (2022) 000–000

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3.1. The quality of mortar According to Borri’s classification method, mortar quality plays a fundamental role. In severe degradation, a 30% reduction of Borri’s index is applied by means of parameter m . The only visual judgement appears quite approximative and could easily carry out a wrong masonry classification. It is possible to introduce an effective and simple method for evaluating the m parameter by using the results of penetrometer tests, assuming the value 2 MPa as discriminating. The f mm values under 2 Mpa could be judged as mortars of poor quality. According to such an assumption, the MQIv values have been recalculated. Table 3 proves that by updating the method with the penetrometer test results, the MQIv values for M3 and M8 change, even though for both cases the walls remain in class C.

Table 3. MQI method applied to ten masonries updated with penetrometer test results Masonry M1 M2 M3 M4 M5 M6 M7 M8

M9

M10

MQIv

3.90

2.73

0.74

2.94

0.34

4.50

1.62

1.12

3.60

1.12

SCORE

B

B

C

B

C

B

C

C

B

C

4. Discussion 4.1. F m -E correlations

The following figures show the correlation between the MQIv values of table 3, and the resistance f m (Fig. 2a), and between the same value and the elastic modulus E (Fig. 2b) of the masonry obtained by the double flat jacks tests. In both figures, blue curves represent min, mean and max correlations curves (equations 2 and 3). In Figure 2a, there is a fitting between experimental values and blue curves, while Figure 2b, which refers to the modulus of elasticity E, highlights that the curves of equations 3 don’t match correctly the yellow tuff masonries. It could signify that the correlation curve between fm and E is quite different for yellow tuff masonries. For this reason, in a following step, the E parameter has also been calculated using the Italian Code correlation between f m and E. In particular, within the eight masonries described in the Code, two categories match with yellow tuff masonries. Table 4 reports an extract of the Code classification of masonries regarding the interest categories. In Guadagnuolo et al. (2020) f m and E values fully corresponded to those proposed by the Italian Code for irregular tuff walls but were lower than those recommended for regular walls. Therefore, two categories have been merged in this paper.

(a)

(b)

Fig. 2. a) MQIv vs f m ; b) MQIv vs E