TY - CONF A1 - Ferraioli, M. A1 - Abruzzese, D. A1 - Miccoli, Lorenzo A1 - Mandara, A. ED - Galea, P. ED - Borg, R. P. ED - Farrugia, D. ED - Agius, M. R. ED - D'Amico, S. ED - Torpiano, A. ED - Bonello, M. T1 - Dynamic identification and seismic safety of two masonry towers N2 - The recent experience of Italian seismic events provided wide observational information about typical behaviour, damage patterns and intrinsic vulnerability of monumental buildings. Evidence indicates that historical constructions are by far the most vulnerable from the seismic point of view. As a consequence, they demand for the definition of urgent strategies for the protection of cultural heritage from seismic hazard. The main goal of an in-depth knowledge of the structure should help to avoid inadequate, unsuitable or dangerous rehabilitation operations, as well as to select non-invasive and reversible techniques for the best exploitation of material and technology features. The definition of reliable models and methods for seismic risk assessment of historical constructions is today a very important topic. Typical problems of masonry structures concern aspects like inherent structural lacks, material degradation, geotechnical problems, buckling behaviour of slender elements and dynamic loading vulnerability. Modelling the mechanical behaviour of masonry may play an important role, due to both inherent material complexity and great scatter in mechanical properties. Effective procedures for the identification of the structural parameters from static and dynamic testing are thus required. In particular, dynamic measurements may be very useful for the identification of mechanical properties and soil restraints and, consequently, for the calibration of advanced numerical finite element models. The paper addresses two case studies of structural monitoring and seismic assessment of medieval masonry towers in Italy: the bell tower of Aversa and the bell tower of Capua. These monuments, placed in the Campania region, were monitored by means of full-scale environmental vibration testing. Measured responses are then used for modal identification with a typical finite element model updating technique based on vibration test results. Parameters optimization is carried out on the basis of a criterion which minimises a weighted error on modal properties. A satisfactory improvement in the determination of modal parameters is thus obtained, resulting in a close agreement between the modal properties observed in dynamic tests and those calculated from numerical model. Seismic assessment is finally performed based on nonlinear static analysis of the tower under multimodal distributions of lateral loads. Results from nonlinear analysis indicate the potential collapse mechanisms and evidence dangerous structural weakness which may play a role in the seismic vulnerability of the towers. T2 - Georisk in the Mediterrean and their mitigation CY - Valletta, Malta DA - 20.07.2015 KW - masonry towers KW - ambient vibration tests KW - dynamic characterisation KW - seismic assessment PY - 2016 SN - 978-88-98161-20-1 SP - 250 EP - 251 PB - Mistral Service AN - OPUS4-37204 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ferraioli, M. A1 - Miccoli, Lorenzo A1 - Abruzzese, D. A1 - Mandara, A. T1 - Dynamic characterisation and seismic assessment of medieval masonry towers N2 - The paper investigates the dynamic characterisation, the numerical model tuning and the seismic risk assessment of two monumental masonry towers located in Italy: the Capua Cathedral bell tower and the Aversa Cathedral bell tower. Full-scale ambient vibration tests under environmental loads are performed. The modal identification is carried out using techniques of modal extraction in the frequency domain. The refined 3D finite element model (FEM) is calibrated using the in situ investigation survey. The FEM tuning is carried out by varying the mechanical parameters and accounting for the restraint offered by the neighbouring buildings and the role of soil–structure interaction. The assessment of the seismic performance of the bell towers is carried out through a nonlinear static procedure based on the multi-modal pushover analysis and the capacity spectrum method. Through the discussion of the case studies, the paper shows that the modal identification is a reliable technique that can be used in situ for assessing the dynamic behaviour of monumental buildings. By utilising the tuned FEM of the towers, the theoretical fundamental frequencies are determined, which coincide with the previously determined experimental frequencies. The results from seismic performance assessment through a pushover analysis confirm that the masonry towers in this study are particularly vulnerable to strong damage even when subjected to seismic events of moderate intensity. KW - masonry towers KW - ambient vibration tests KW - dynamic characterisation KW - seismic assessment PY - 2016 U6 - https://doi.org/10.1007/s11069-016-2519-2 SN - 1573-0840 SN - 0921-030X VL - 86 SP - Suppl. 2, S489 EP - S515 PB - Springer AN - OPUS4-37187 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -