Publicação
Modelling and safety assessment of the Santa Maria Maddalena Church, Ischia, Italy
| Resumo: | The church of Santa Maria Maddalena in Casamicciola Terme, Ischia Island, Italy, represents one of the very rare examples of the particular building technique of the Borbonic Baraccato system, one of the earliest engineered earthquake resisting systems developed in Southern Italy between the 18th and 19th Centuries. Its unicity lies on the materials adopted. It presents Neapolitan yellow tuff-masonry walls embraced in iron frames, while the traditional Baraccato system utilizes embedded timber frames in the masonry texture. The church was stroke by the recent earthquake of 21st August, 2017 with epicenter in Casamicciola Terme. Though the moderately high seismic intensity of the event, the post-seismic surveys carried out in the frame of the emergency protocols did not evidence relevant structural damage thanks to the constructive system. The present work aimed at developing a better understanding of the structural behavior of the church. The scope was addressed by developing a three-dimensional numerical Finite Element Model (FEM) in order to assess the structural safety of the building under gravitational and seismic loads performing advanced numerical analyses. The modelling workflow has been guided by the following preliminary tasks which are considered mandatory to rely on the outcomes of the numerical analyses: historic review and definition of the territorial framework in terms of geology and seismicity proneness; geometrical overview of the church and description of the structural elements main features, understanding also the level of knowledge reached for the structural details; description of the observed pre- and post-seismic damage; definition of the modelling strategies to adopt in the numerical model and the material characteristics to use; modal identification of the structure through the post-processing of ambient vibration tests performed under operational conditions; calibration of the numerical model. The execution of preliminary safety assessment of the structure was carried out through the application of nonlinear static analyses to different model versions, capable of describing a possible range of responses of the building under horizontal loads. The numerical models considered for the analyses namely involved the response of the structure under the assumption of a behavior mainly governed by the non-linear response of the masonry walls, discarding the contribution of the Baraccato frames (lower-bound response), conversely a second model was analyzed by taking the response of the frames as infinitely elastic (upper-bound response). The work accomplished the full implementation of the numerical model and the performance of sensitivity analyses based on its response with regards to the uncertainties and the modelling strategies adopted. However, the refinement of the knowledge of structural details, deeper investigation of the influence of different modelling strategies for the Baracccato system, more experimental tests, and the improvement of ambient vibration tests are recommended in the scope of executing non-linear dynamic analyses that could comply with the effective observed post-seismic damage and better define the seismic safety assessment of the church. |
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| Autores principais: | Di Napoli, Beatrice |
| Assunto: | Engenharia e Tecnologia::Outras Engenharias e Tecnologias |
| Ano: | 2019 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | The church of Santa Maria Maddalena in Casamicciola Terme, Ischia Island, Italy, represents one of the very rare examples of the particular building technique of the Borbonic Baraccato system, one of the earliest engineered earthquake resisting systems developed in Southern Italy between the 18th and 19th Centuries. Its unicity lies on the materials adopted. It presents Neapolitan yellow tuff-masonry walls embraced in iron frames, while the traditional Baraccato system utilizes embedded timber frames in the masonry texture. The church was stroke by the recent earthquake of 21st August, 2017 with epicenter in Casamicciola Terme. Though the moderately high seismic intensity of the event, the post-seismic surveys carried out in the frame of the emergency protocols did not evidence relevant structural damage thanks to the constructive system. The present work aimed at developing a better understanding of the structural behavior of the church. The scope was addressed by developing a three-dimensional numerical Finite Element Model (FEM) in order to assess the structural safety of the building under gravitational and seismic loads performing advanced numerical analyses. The modelling workflow has been guided by the following preliminary tasks which are considered mandatory to rely on the outcomes of the numerical analyses: historic review and definition of the territorial framework in terms of geology and seismicity proneness; geometrical overview of the church and description of the structural elements main features, understanding also the level of knowledge reached for the structural details; description of the observed pre- and post-seismic damage; definition of the modelling strategies to adopt in the numerical model and the material characteristics to use; modal identification of the structure through the post-processing of ambient vibration tests performed under operational conditions; calibration of the numerical model. The execution of preliminary safety assessment of the structure was carried out through the application of nonlinear static analyses to different model versions, capable of describing a possible range of responses of the building under horizontal loads. The numerical models considered for the analyses namely involved the response of the structure under the assumption of a behavior mainly governed by the non-linear response of the masonry walls, discarding the contribution of the Baraccato frames (lower-bound response), conversely a second model was analyzed by taking the response of the frames as infinitely elastic (upper-bound response). The work accomplished the full implementation of the numerical model and the performance of sensitivity analyses based on its response with regards to the uncertainties and the modelling strategies adopted. However, the refinement of the knowledge of structural details, deeper investigation of the influence of different modelling strategies for the Baracccato system, more experimental tests, and the improvement of ambient vibration tests are recommended in the scope of executing non-linear dynamic analyses that could comply with the effective observed post-seismic damage and better define the seismic safety assessment of the church. |
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