## 2 Knowledge-Based Procedure
### Exhaustive Knowledge Acquisition: KL3  
The masonry building has been the object of a significant knowledge campaign targeted at achieving the highest KL defined by the Italian code, i.e., KL3. To this aim, several investigations and techniques have been conducted, as summarized in Table 1. Remote sensing laser scanning of the whole building was executed to ascertain the architectural consistency of the building in its current state with a high level of accuracy. The laser scanning survey was used to obtain a 3D point cloud which was later used to extract bidimensional drawings of the construction (plans, sections). Diagnostic campaigns have been executed to reveal the structural features of the construction. In this perspective, a hierarchical approach has been adopted. Initially, non-destructive (ND) tests were widely executed in order to globally identify the structural elements of the building. Thermography and ground penetrating radar (GPR) were employed to characterize the structural system of the building. When combined, these tests provide useful information to non-invasively characterize masonry and historical constructions [20; 44; 45]. The hypothesis made on the basis of the interpolation of the two ND tests was later validated by excavating 16 test holes, which have permitted unequivocal identification of the structure of the buildings. Furthermore, visual inspections with an endoscopy have been conducted to investigate the inner layers of horizontal and vertical elements. These methods enable us to define the structural system of the building. The bearing walls of the structure are characterized by rough-block stone masonry for the external panels, with clay brick masonry for the internal partitions (Figure 2). The internal structural walls are made of one single brick layer, leading to particularly slender panels. The external  
Figure 1: (**a**) Areal view of the building; (**b**) image of the structure from the street; (**c**) architectural transversal section of the construction; (**d**) ground floor plan. bearing walls in stone masonry are enriched by the presence of horizontal courses of bricks. The slabs are characterized by RC joists alternated with hollow clay elements, the so-called _sola in latero-cemento_, typical of the modern Italian tradition. Except for the roof, the connection between walls and slabs is characterized by the presence of a concrete ring beam, distributing the load and leading to a box behavior. The ceiling of the roof is made of a clay structure suspended over timber beams (the so-called Perret ceiling), representing a very fragile element. Finally, the roof is a wooden structure covered by clay roof tiles in a traditional Italian fashion. Later, destructive analyses were carried out to characterize the mechanical value of the elements. The investigations focused on load bearing wall structures and the concrete composition of the slabs. Regarding the masonry walls, the analyses assessed the integrity of the masonry and the different components (mortar + resistant elements). Details of the investigations conducted are shown in Table 1.  
Figure 2: (**a**) Thermography investigations; (**b**) test holes on a clay masonry wall; (**c**) structural characterization of masonry walls. Considering the entire masonry panels, double flat-jack tests targeted at defining the Elastic Young's Moduli and shove tests for shear resistance were executed. For the double flat-jack tests, four tests were performed, two for each masonry typology (Figure 3). The results are shown in Table 2.  
Referring to the mechanical values, the obtained parameters were compared with the ranges provided by MIT 2019 [14] for the same masonry typologies. Except for M2, which specifies bigger values, all tests denounce values of Elastic Young's Modulus lower than the minimum range of the code (rough-block stone masonry 1020-1440 MPa, clay brick masonry 1200-1800 MPa, respectively). For the clay brick masonry, it is worth noting that