PSI - Issue 44

Romina Sisti et al. / Procedia Structural Integrity 44 (2023) 1116–1123 R. Sist et al. / Structural Integrity Procedia 00 (2022) 000 – 000

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1. Introduction In recent years, efforts to increase the resilience of heritage buildings have strongly grown. Monitoring systems have been installed in several buildings to promptly counter any critical issue (De Stefano et al. 2016). BIM technologies are used more and more frequently for the management of interventions on heritage buildings and their maintenance (Malovrh Rebec et al. 2022). Several researches are aiming at developing increasingly efficient reinforcement technologies (Yavartanoo and Kang, 2022) and increasingly accurate design models (Diaferio et al 2021). However, the need for further investments in reducing the vulnerability of heritage buildings strongly emerges after every new seismic event. Indeed, the damage reported by heritage buildings is always higher than that detected on ordinary buildings, regardless of the intensity of the seismic event. The need to preserve the building as much as possible in its original state, without changing its behavior and preserving the original construction features, implies particular attention in the choice of strengthening interventions to be carried out. Furthermore, although strengthening techniques have been tested through accurate laboratory tests, observational data on the real seismic behavior of heritage strengthened buildings is still missing. Some recent research has been published regarding post-earthquake damage observed on ordinary strengthened buildings (Sisti et al. 2021; Saretta et al.2021). However, the outcomes found for ordinary buildings cannot be automatically extended to heritage buildings due to the different architectural and structural characteristics and the limitations in the application of strengthening techniques. This paper shows the results of a study on the seismic performance of Palazzo Comunale in Camerino subjected to actions of the 2016-2017 seismic sequence. This heritage building was repaired and strengthened after the previous earthquake occurred in 1997. The effectiveness of the strengthening measures in improving the seismic behavior was evaluated through in situ surveys, global non-linear static analyses and local kinematic analyses. 2. Historical sequence of earthquakes in Camerino Camerino is a town of about 7000 inhabitants, located on a hilly region of central Italy (Fig. 1a). It was founded in pre-roman times, but its urban layout was strongly modified during the Middle Ages, which was its greatest period of development. Figure 1b depicts the seismic history of Camerino (Locati at al. 2021). It shows the earthquakes with a macro-seismic intensity greater than 3, according to the Mercalli-Cancani-Sieberg scale, that struck the town in the last 1000 years. Despite the low number of events in the pre-1700 (due to a lack of information) several strong earthquakes struck the town in its history. In particular, in the last 25 years Camerino experienced two seismic sequences: the 1997 Umbria-Marche sequence (Guerrieri et al. 2009) and the 2016 Central Italy sequence (Chiaraluce et al. 2017). Figure 2 shows that the macroseismic intensity in 1997 was slightly lower than that recorded in 2016: 6 7 versus 7-8. In particular, during the last seismic sequence the first event at the end of August did not cause diffuse damages in Camerino, while the three events at the end of October damaged a huge number of buildings. The maximum peak ground acceleration in Camerino occurred during the earthquake on the 30th of October and it was equal to 0,16g. a

a b Fig. 1. (a) Aerial view of Camerino (from https://www.ilturista.info/ugc/immagini/camerino/marche/63546/). (b) Historical sequence of earthquakes in Camerino in the period 1000-2020 (blue and green dots represent the 1997 and 2016 seismic sequence respectively).