Ercolino, Marianna (2014) Seismic behavior of one-story precast buildings. [Tesi di dottorato]

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Abstract

The seismic behavior of RC one-story precast buildings is investigated in this thesis. Precast structures (mainly one-story) constitute the most widespread solution that accommodates industrial buildings in Europe. Recently, precast structures have been also increasingly used for buildings where many people are gathering together (i.e. most shopping centers, sports stadiums and apartment buildings), causing an increase of the risk related to these structures. Moreover, the safety of industrial precast buildings is a complex problem, that is related not only to the usual structural performance demand of the ordinary buildings but that is also related to functionality and production issues. The recent severe earthquakes demonstrated all these crucial features. The 20th and 29th May Emilia earthquakes, for example, hit several industrial precast structures, causing a huge economic loss (about 1 billion euros), injuries and fatalities. Moreover, the consequences become more serious if the functionality interruption (production interruption, job missing) as well as the loss of the contents (equipment, provisions, plants) are also taken into account. The exhibited vulnerability and the central role of this structural typology motivate the development of this work. The first part of this thesis deals with the global response of precast structures. This study focuses on both the evaluation of the main structural features (geometrical and dynamic) and the design code evolution. The experience of the earthquake (Emilia, 2012) is also described. Benchmark structures and existing buildings are investigated by means of nonlinear analyses in order to justify the recorded damages and to evaluate the effect of the most common deficiencies, observed in these buildings. These results are achieved by means of detailed structural models, proposed and validated in this work. These models are efficient tools, capable to take into account the most crucial aspects (connection systems and nonstructural elements influence) in the seismic response of this construction typology. The topic of the seismic safety of industrial bindings is of great interest at regional and national level. It should be managed with a systematic procedure, especially for those economically developed areas, where the late seismic classification caused a significant vulnerability of these structures. As a consequence of above, the described research provided the collaboration in the redaction of two important emergency documents for the retrofitting actions and for the damage assessment of industrial structures after a seismic event. The local response of the connection systems is investigated in the second part of this thesis. The dowel connections between the precast beams and the columns and the connections between the panels and the main structure are selected due to their evidenced vulnerability and their key role in the global response. Concerning the beam-to-column connections, the results of an experimental campaign are presented and discussed in order to evaluate the behavior of the system. The experimental results are also used to develop a FEM model of the connection that allows to evaluate the influence of some geometrical and design parameters. The behavior of the connection between the structural elements and the cladding panels systems is also studied. A novel model is proposed in order to take into account the possible interaction between the panels and the structure under seismic action. The results of the performed nonlinear dynamic analyses demonstrate the high influence of these nonstructural components in the response of the whole structure, as well as the inadequacy of the typical approach, used for the connections design. The influence of the cladding systems is also investigated by means of a seismic risk study that confirms their strong influence on the global behavior of precast structures. In the last part of the work, the model with cladding panels is further developed in order to record the progressive collapse of the panels during an earthquake; this model could be an interesting tool to evaluate the actual response of a one-story precast structure interacting with the cladding panel system.

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