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In this paper the actual dynamic behavior of the civic Clock tower of Rotella, a little village in central Italy heavily damaged by the recent 2016 seismic sequence, is thoroughly investigated by means of a detailed numerical model built and calibrated using the experimental modal properties obtained through Ambient Vibration Tests. The goal is to update the uncertain parameters of two behavioral material models applied to the Finite Element Model (elastic moduli, mass densities, constraints, and boundary conditions) to minimize the discrepancy between experimental and numerical dynamic features. A sensitivity analysis was performed with the definition of a metamodel to reduce the computational strain and try to define the necessary parameters to use for the calibration process. Due to the high nonlinear dependency of the objective function of this optimization problem on the parameters, and the likely possibility to get trapped in local minima, a machine learning approach was meant. A fully automated Finite Element Model updating procedure based on genetic algorithms and global optimization is used, leading to tower uncertain parameters identification. The results allowed to create a reference numerical replica of the structure in its actual health state and to assess its dynamic performances allowing better control over their future evolution. [ABSTRACT FROM AUTHOR]

Medieval defensive walls are a distinctive feature of Italian cultural heritage. These structures testify the origins of historical centres and, in some cases, the consequences of the events occurred over time. The typical configuration of medieval defensive walls, generally characterized by high slenderness ratios, out-of-plumb, the absence of deep and adequate foundations, made these elements particularly vulnerable toward seismic actions. This study focused on the assessment of the seismic safety of Italian medieval defensive walls toward out-of-plane failure mechanisms induced by seismic actions. To this end, a simple approach based on the use of generalized dimensionless capacity curves is presented. These curves, derived by the Authors from a calibration process involving a set of selected real cases, allows for a rapid preliminary seismic assessment of masonry walls particularly useful for getting an initial idea of the condition of the walls with respect to seismic actions also considering the presence of pre-existing out-of-plumb configurations. The proposed approach has been applied in the paper to the real case study of medieval walls of Cittadella, a town in northern Italy, considering the pre-existing out-of-plumb configuration. The obtained results have shown the vulnerability of these walls in case of occurrence of masonry disaggregation and, consequently, the importance of performing specific surveys finalized to investigate this phenomenon. The application of the proposed approach has clearly shown its feasibility and usefulness for the seismic evaluation. Moreover, the comparison with the corresponding results obtained by using the actual capacity curves, rather than the generalized ones, has underlined its good level of reliability. [ABSTRACT FROM AUTHOR]