PSI - Issue 29

Mario De Stefano et al. / Procedia Structural Integrity 29 (2020) 71–78 De Stefano and Cristofaro / Structural Integrity Procedia 00 (2019) 000 – 000

72 2

1. Introduction Many of the earthquakes that affected Ita ly in the century XX have stra ined the territory, bringing entire countries to their knees. The ma in consequence has been the loss of human lives and subsequently a significant socia l and economic impact. We can a ttribute to our peninsula an earthquake hazard medium-high level, for the frequency and intensity of the phenomena . However, compa red to other countries, such as Ca lifornia or Japan, where the danger is greater, Ita ly has a very high vulnerability, due to the considerable fragility of its building heritage, not least the historica l architectural one. One event to remember, which shocked the sensitivity of the whole world was the earthquake of Umbria and Marche on 26th September 1997 5.8 ML-MEDNET sca le. In this circumstance, the collapse of part of the vaults of the upper “ Basilica of San Francesco ” in Assisi occurred. On 20th May 2012 a 5.9 ML sca le shock with epicenter in Fina le Emilia hit Emilia Romagna . The consequences of the earthquake on the cultura l heritage of the area were enormous and devastating. Entire collapsed towers, such as the “Torre dell’Orologio” , as well as bell towers, ancient buildings, theaters and churches. Even the la test seismic events that took place in centra l Ita ly between 2016 and 2017 did not spare the cultura l heritage, 293 churches, monuments and historic buildings were damaged. In Norcia two places symbol of the ecclesiastica l culture of the city collapsed: the Church of “ San Benedetto ” and the Cathedra l of “ Santa Maria Argentea ” . The earthquake of 18th May 1895, known as the "Great earthquake of Firenze", caused extensive but not serious damage to many historic buildings and museums in the city. In Vannucci et. a l. (2001) it is possible to identify the areas most affected by the event. Even the oldest structures of the Ga lleria Complex, dating back to the end of the fourteenth century, were damaged. Dav id himself, together with other events before 1895, was affected by the effects induced by the earthquake with damages to the ankle (Borri 2005, Lolli and Pascale 2013). The Complex of the Museum of the “Galleria dell’ Accademia di Firenze ” constitutes, together with the various rooms belonging to the institutes adjacent to it, a building organism dating back to different eras, with additions and transformations of various kinds that have changed the origina l construction characteristics, determining an urban aggregate characterized by a structura l behavior of mutua l complexity and interaction between the various parts of which it is composed. The whole complex is to be considered a conta iner of numerous artistic works including Michelangelo's well-known David. These works, both pa inted and sculptura l, are found in rooms dating back to different historica l periods. In particular, it is emphasized that, with the exception of the “ Tribuna del David ” , created ad hoc by De Fabbris (1873-1882) to place the imposing statue, the rema ining rooms are the result of artifacts made and modified in a period that includes over five centuries, destined for different uses. Just think of the “ Sala dei Gessi ” whose plan dates back to the end of the 14th century to house the women's ward of the ancient “Ospedale di San Matteo” (Mignani 1979, Sanpaolesi 1946), today it is one of the best known rooms, with a collection of pa intings and sculptures of 19th century artists in rela tion to the Academy of Fine Arts, including the plaster casts of Lorenzo Bartolini, with the works arranged as they were put by the artist in his studio in Borgo San Frediano in Firenze and those of Luigi Pampa loni. The “Sala del Colosso” and the surrounding rooms, including the “Conservatorio Luigi Cherubini ” , occupy an area once destined for the former “Convento di San Niccolò in Cafaggio ” , as can also be seen froma planof the city of Florenceby Buonsignori in 1584 (AA.VV. 2017). The works preserved in these environments, of undisputed artistic va lue, must be protected from risks of a ll kinds, including the seismic one. For this reason, in 2009 the Direzione genera le per i beni architettonici e il paesaggio launched a first phase of rapid investigation to assess the seismic safety of a part of the Ga llery ( Tribuna del David and adjacent rooms) with the a im of experimenting with the applica tion of the GL for assessing and reducing the seismic risk of cultura l heritage (MIBACT, 2010). This phase was followed by a second one in which not only new bodies were added, but the controls covered a ll three levels of eva luation foreseen by the GL. All the interdisciplinaryactivities that contributed to theachievement of the set objectivesare reported in AA.VV. (2017). 2. The mechanical characterization of masonry The diagnostic campaign has been planned to reach a knowledge of the mechanica l properties of the materia ls. The Complex consists of severa l buildings, dating back to different historica l periods. The activities ma inly concerned in situ tests which were subsequently accompanied by labora tory tests at the Materia l Testing Laboratory