PSI - Issue 11

Mariateresa Guadagnuolo et al. / Procedia Structural Integrity 11 (2018) 444–451 Author name / Structural Integrity Procedia 00 (2018) 000–000

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evaluated according to the only one direction because all the examined portions are symmetrical. The safety verification was performed at different heights because it was not possible to identify a priori the most critical section, due to the tapers in wall thickness and the opening impairments. The analyses led to f a values lower than one for the tuff portion number 4 and 6, with values ranging between 0.4 and 0.6, and for the brick portion number 2, where is equal to 0.7. In order to assess the seismic response of the bell tower, a multi-modal simplified analysis was performed, even though the ability of such an analysis to represent the actual behavior of masonry buildings is limited, due to the largely nonlinear behavior under dynamic seismic action. Moreover, the knowledge of eigen-values, eigen-modes and activated masses is needed for determining the shape of the horizontal load forces to utilize within the subsequent pushover procedure. The first three period of vibration are shown in Figure 5. Out-of-plane local analyzes are necessary for an overall seismic evaluation.

Fig. 5. First three period of vibration of the “Corpus Domini” bell tower.

4. Conclusion

Masonry towers constitute a huge amount of the Italian built heritage. They are unique architectural typologies, usually conceived in ancient times exclusively to withstand vertical loads. Therefore, their seismic safety assessment has a significant social importance. This paper presents the retrofit and conservation design, also aimed at the achievement of suitable seismic safety carried out on a seventeen-century masonry tower in Italy, the “Corpus Domini” bell tower in Maddaloni (Italy). The safety indexes obtained by the simplified analysis are larger than unity, except for the tuff portions. It has to be considered, however, that in the model the brick coating of the tuff masonry was not considered, and then the possible increase in strength was not taken into account. Finally, the seismic safety evaluation of masonry towers should be performed both by global seismic analysis, controlling the