## 2 Case Studies
### Basilica of Santa Maria di Collemaggio  
The basilica of Santa Maria di Collemaggio represents one of the most significant Italian historical monuments and, as a result, has been the subject of extensive research in recent years [21, 22]. The church was built in the late 13 th century by Pope [PERSON] and originally exhibited the characteristics of Romanesque architecture. However, over the centuries, the construction process of the basilica has undergone various interventions, primarily due to the consequences of earthquake damage. The church is characterised by the presence of three naves, delineated by two columns of octagonal cross sections (Figure 4a). On the opposite side to the facade is the transport, which contains two chapels and a choir. A low dome covered by a wooden roof and entirely rebuilt in the 20 th century is situated at the intersection between the transport and the central nave. The two altars, located on either side of the transport, are characterised by stucco decoration on the walls, vaults, and chapels. These represent the final sections of the building that underwent baroque decoration, which was removed during the 1970s. The remaining parts of the basilica are characterised by bare walls and wooden trusses, which provide structural support for the wooden roof of the central nave and aisles. One of the most important features of the basilica is its imposing two-tone facade (Figure 4b), as well as the tower, located on the right side of the facade, with an octagonal cross section. The church presents a cross-shaped plan with a length of 93.64 m, having a maximum transversal size equal to 34.26 m in correspondence to the transport (Figure 5). The original layout of the church dates to the 13 th century, but the construction process continued until the 16 th century. During the 17 th century, the basilica underwent significant alterations in response to the damage caused by the 1639 and 1654 earthquakes. These interventions encompassed not only the embellishment in a baroque style but also the enhancement of the seismic response of the main structural elements [23]. Of particular note are the following interventions: (i) the reduction in height of the aisle walls, and (ii) the enhancement of the interconnections between the various structural components (roof, vaults, walls, etc.). The 1915 Fucino earthquake caused significant damage to the church, resulting in the partial collapse of the upper-left corner of the facade. Consequently, a new buttress was constructed in the corresponding location on the facade, with robust tie rods to prevent further out-of-plane movements. Moreover, to improve the out-of-plane stiffness, a new  
Figure 4: Basilica of Santa Maria di Collemaggio. (**a**) Central nave; and (**b**) facade. frame made of reinforced concrete (R.C.) was incorporated into the reconstruction of the upper-left corner of the facade. Subsequently, the basilica was subjected to a further seismic event in 1958. During this seismic event, the pre-existing cracks widened, particularly in correspondence to the transport dome, which was demolished and completely rebuilt using reinforced concrete. The remaining restoration interventions were completed during the 1970s. The baroque style decorations were removed. During the course of this operation, some of the principal original structural elements were revealed, while others were significantly altered compared to their original configuration. In particular, the cross section that characterised the main pillars of the transport was entirely modified, and the two last octagonal columns near the transport were rebuilt using reinforced concrete. The remaining masonry columns were modified, removing the 17 th-century cruciform cover and revealing the original masonry structure. The longitudinal walls, already subject to the above-mentioned height reduction intervention, were raised through the construction of two new R.C. curbs positioned within the thickness of the walls.