Issue 51

F. Clementi et alii, Frattura ed Integrità Strutturale, 51 (2020) 313-335; DOI: 10.3221/IGF-ESIS.51.24 323 Model Friction masonry structure Friction structure - foundation With Steel Chains 0.30 to 0.5 with increment of 0.05 0.90 Without Steel Chains 0.30 to 0.5 with increment of 0.05 0.90 Table 1 : Different friction values used for the dynamic nonlinear analyses However, for the interface between structure and foundation, we assigned a value equal to µ = 0.90. Several analyses were implemented applying first the gravity loads to the system and afterward the different ground accelerations: the dynamical behaviour was elaborated on the shocks’ actions of real events imported on the three main directions of the tower base. The main shocks considered have various specifications; all of these are obtained by the records of seismic events occurred with the Central Italy sequence of 2016. In particular, the recordings were taken by the station AMT, which is the nearest to the location of the Amatrice civic clock tower, and in this paper, all its three components, i.e. two on the horizontal and one on the vertical directions, are used. In order to have a better perception of the real damage, we decided not to put at the base of the tower a single time history which, although natural, fails to provide the effect of a sequence composed by the main shock and several aftershocks. With this idea, in this paper it has been considered four shocks events which belong to the seismic sequence of 2016, that took place in the highly active seismological area of Central Italy, where is located the analysed civic tower of Amatrice (i) 24 th August 2016 Amatrice with M L =6.0 and M W =6.0 (AMT station in ITACA), (ii) 24 th August 2016 Amatrice with M L =5.4 and M W =5.3 (AMT in ITACA), (iii) 26 th October 2016 Amatrice with M L =5.9 and M W =5.9 (AMT in ITACA), (iv) 30 th October 2016 Amatrice with M L =6.1 and M W =6.5 (AMT in ITACA). Figure 11 : Views of the particular components of the numerical models of the civic clock tower of Amatrice (Rieti, Italy) with the NSCD method. With the aim to optimize the calculation times without losing information on the induced damage, strong motions of the four Time-Histories (THs) were isolated, which generally have a duration of 10 seconds for each shock, and then applied