Issue 45

F. Brandão et alii, Frattura ed Integrità Strutturale, 45 (2018) 14-32; DOI: 10.3221/IGF-ESIS.45.02 27 With respect to the vertical displacements, represented in Fig. 18.(e) and 18.(f), the back side of the lateral tower near the top, presents displacements of about 1.70 mm in the positive Z direction. The front side of the lateral tower also presents displacement of 1.95 mm, in module, along the negative Z direction. In addition, the wall of the region of the central arches connected to the side tower exhibits displacement of approximately 1.10 mm in the positive Z direction. As a gen- eral comment, analyzing the displacements exhibited by the church during the earthquake, it is possible to observe the ab- sence of a box-behavior: the church behaves as a combination of independent macro-elements with first and second mode potential failures. The principal stresses are shown in Fig. 19. The maximum tensile stress, reported in Fig. 19.(a) and 19.(b), reached the value of 1.37 MPa, in correspondence of the connections of the lateral tower with the wall of the south lateral façade and the wall of the central arches. A similar value was found in correspondence of the connection of the wall of the north lat- eral façade with the wall of the main façade. These values are higher than the assumed tensile strength and denote poten- tial collapse (and/or possible pounding) of this connection. A region of the wall of the north lateral façade with traction of about 0.74 MPa is also observed. The walls of the central arches and the wall of the south lateral façade reached a ten- sile stress of about 0.244 MPa, that indicate potential cracks. The minimum principal stresses (compressive stress) are re- ported in Fig. 19.(c) and 19.(d). The higher value of about 0.65 MPa, occurs in many regions of the structure, namely: i) in the upper left corner of the west main façade, just above of the door opening; ii) in the first arc in contact to the lateral tower; iii) in the inferior central region, situated at the base of the door aperture and iv) in the upper left corner of the north lateral façade. In the front side of the lateral tower, the same west main façade, compressive stress ranging from 0.03 MPa to 0.51 MPa were observed. Figure 19 : Principal stress after Earthquake 2: (a) and (b) maximum principal stress; (c) and (d) minimum principal stress. Unit in MPa. During the Earthquake 2, a maximum principal stress peak was observed as reported in Fig. 20. The peak is a tensile stress of about 5.54 MPa at t=10.34 s and is obtained at the base section of a column of the central wall of the structure. The high value denotes a potential collapse the column due to overturning. Other critical zones can be identified, namely: i) the region of connection of the wall of the central arches with the wall of the triumphal arch in front of the altar (which is subjected to a tensile stress of about 2.19 MPa); ii) the region of connection of the wall of central arches with the lateral tower, just above the first arch (with a peak of tensile stress of about 3.30 MPa); iii) the region of connection of the wall of the west main façade with the lateral tower (with a tensile stress of about 1.64 MPa); iv) the upper region of the central arches and the inferior region of the smaller arc, located at the end of the smaller nave (about 2.19 MPa and 3.30 MPa, respectively). In all these regions cracks and/or local collapses are potentially expected during the seismic loading. The time-history of the minimum principal stress is reported in Fig. 21. It is possible to observe a peak of stress of about 5.66 MPa at t = 10.66 s at the base of the column of the central arch. This region is the same that presented a peak of traction (see Fig. 20), and this result is a confirmation of the potential overturning of this central wall during the earth- quake. Other regions present high compressive stresses, namely: i) the upper part of the first arc in contact with the lateral tower (a compression of about 3.94 MPa is recorded); ii) the region of connection between the upper part of the wall of the central arches with the wall of the arch in front of the altar and iii) the internal wall of the south lateral façade in (a) (b) (c) (d)