The protection of cultural heritage against natural hazards, such as earthquakes, represents a question of maximum priority, especially in those countries, like Italy, that are characterized by high or medium seismicity and a huge number of historical heritage buildings. A great amount of theoretical and experimental researches has been produced in the last decades in order to mitigate the seismic risk of heritage structures. Such an effort has resulted in some important documents, including deontological standards, guidelines, and regulations. This PhD research focuses on using high performance materials, in the form of cable systems, for the structural and seismic protection of historical building. The overall aim is to propose, and numerically validate, cable system solutions for retrofitting of historical masonry domes, which constitute a widespread typology in Italy and are very susceptible to damage caused by earthquake events. This kind of research, more than other cultural heritage areas, needs a multi-disciplinary approach, involving fields such as structural and earthquake engineering, conservation, geometric modelling and material science. The introductory chapter deals with the main standards and legislation for the protection of cultural heritage, especially in the light of the emerging use of high performance materials for strengthening interventions (§1). This is followed by a more specialised introduction on these innovative materials and their application to cultural heritage buildings. The increasing use of these materials in architectural heritage conservation is described and analysed in terms of their strengths and weaknesses (§2). Most of the literature on strengthening of historical domes concerns the use of steel cables, especially steel hooping systems, which is a widespread type of intervention. Instead, the present research examines and proposes novel solutions, e.g. cable dome systems, in high performance materials. Consequently, both the static and the dynamic behaviour of masonry domes has been investigated to optimise the design of seismic retrofitting cable systems, as well as the system’s structural performance. Special attention is paid to oval masonry domes (§3). Since the experimental validation of retrofitting technologies applied to the historical buildings has proved to be difficult, the use of numerical models here constitutes a useful and fundamental tool. Strengthening in high performance materials requires multiphysics numerical models, and thus different types of data are needed in order to fit the observed structural behaviour of the building, and to finally obtain an accurate and realistic model (§4). The numerical validation of the new technology needs to be conducted on well-established case studies, so that to rely on exhaustive information. Accordingly, the novel cable system solutions in this research were tailored to the Sanctuary of Vicoforte. With its impressive masonry oval dome, the Sanctuary constitutes an ideal case study, and the availability of historical, survey and mechanical information previously accumulated for this monument allowed for the calibration of a model with predictive capabilities (§5). Seismic retrofitting solutions in Kevlar were validated using the multiphysics numerical model of the Sanctuary. Of note, the FE model was updated through a novel thermomechanical methodology that accounts for both static and dynamic monitoring data (§6). The retrofitting system design was optimised with respect to seismic loads, based on strain energy capacity curves (§7). Subsequently, the laws typically used for masonry were introduced in the model, in order to highlight the effective contribution of the retrofitting system to the structural behaviour of the dome (§8). In conclusion, some guidelines for the application of high performance materials for the strengthening of historical domes are proposed.
High performance cable systems for the seismic protection of historical domes / DE LUCIA, Giulia. - (2018 Jul 25).