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Authors
Abstract(s)
Os recentes acontecimentos sísmicos ocorridos em centros urbanos em Itália, em agosto e outubro de 2016, e México, em setembro de 2017, revelam uma vez mais a vulnerabilidade do património construído anterior à entrada em vigor dos regulamentos de construção antissísmicos. A reabilitação sísmica é fundamental para aumentar a robustez dos centros urbanos à ação dos sismos, contribuindo para o aumento da resiliência das populações e das cidades face a cenários de catástrofe. No entanto, os intervenientes nessa reabilitação são confrontados com a dificuldade de selecionar as melhores soluções construtivas a adotar e os critérios que devem suportar essa escolha.
Saliente-se que, embora sejam conhecidas as técnicas de reforço mais adequadas a diferentes tipologias construtivas, estas são, geralmente, tratadas considerando o edifício individualmente e não à escala do quarteirão. Importa, no entanto, identificar e estudar as soluções de reforço considerando o edifício e os edifícios adjacentes dada a interação que existe entre eles.
Este trabalho corresponde ao primeiro estudo de estratégias de reabilitação e reforço sísmico para os edifícios em bandas lineares, à escala do quarteirão no bairro de Alvalade, na cidade de Lisboa, e foi realizado com a ajuda do software “LNECLOSS”.
A avaliação do desempenho sísmico dos edifícios do parque edificado e dos respetivos danos estruturais foi feita através de um método mecanicista, o denominado método do espectro de capacidade, em que os edifícios são descritos pelas curvas de capacidade e de fragilidade. Através da análise destas curvas, avaliou-se a vulnerabilidade sísmica dos edifícios e das bandas lineares homogéneas e heterogéneas, e concluiu-se que no caso das bandas homogéneas a vulnerabilidade é a mesma para os edifícios e para as bandas, sendo independente do número de edifícios existentes em cada banda, mas que é diferente no caso das bandas heterogéneas.
Para a avaliação do risco sísmico consideraram-se dois cenários de ação sísmica, o cenário “próximo” e o cenário “afastado” característicos da sismicidade que afeta Portugal, concluindo-se que o cenário “afastado” é mais prejudicial.
Relativamente às estratégias de reforço sísmico adotadas, verificaram-se que as estratégias R1, R3 e R4 conduzem a reduzidos valores de danos à estrutura, e são aquelas que melhor contribuem para a mitigação do risco sísmico do local, tendo em conta a inserção dos edifícios no quarteirão. Pretendeu-se deste modo, contribuir para uma tomada de decisão informada.
Recent seismic events in urban centers as Italy, August and October 2016, and Mexico, September 2017, revealed once more the vulnerability of the built heritage prior to the enforcement of anti-seismic construction regulations. Seismic rehabilitation is fundamental to increase the robustness of urban centers to the action of earthquakes, contributing to increase the resilience of populations and cities in the face of catastrophic scenarios. However, those involved in this rehabilitation face the difficulty choosing the best constructive solutions to adopt and the criteria that should support this choice. It should be noted that although the most suitable reinforcement techniques are known for different construction typologies, they are generally treated by considering the building individually rather than the block scale. It is therefore important to identify and study reinforcement solutions considering the building and adjacent buildings given the interactions that exist between them. This work corresponds to the first study of rehabilitation and seismic reinforcement strategies for buildings in linear bands, at the block scale in the Alvalade neighborhood, in the city of Lisbon, and was carried out with the help of software "LNECLOSS". The evaluation of the seismic performance of the edified buildings and their structural damage was done through a mechanistic method, called the capacity spectrum method, in which buildings are described by capacity and fragility curves. Through the analysis of these curves, it was evaluated the seismic vulnerability of buildings and homogeneous and heterogeneous linear bands, and it was concluded that in the case of homogeneous bands the vulnerability is the same for buildings and for bands, being independent of the number of buildings in each band, but that is different in the case of heterogeneous bands. For the seismic risk assessment, two scenarios of seismic action were considered, the "near" scenario and the "remote" scenario characteristic of seismicity affecting Portugal, concluding that the "remote" scenario is more harmful. With respect to the seismic reinforcement strategies adopted, it was verified that the strategies R1, R3 and R4 lead to reduced values of damage to the structure, and are those that best contribute to the mitigation of the seismic risk of the site, taking into account the insertion of the buildings in the block. In this way, it is intended to contribute to an informed decision-making.
Recent seismic events in urban centers as Italy, August and October 2016, and Mexico, September 2017, revealed once more the vulnerability of the built heritage prior to the enforcement of anti-seismic construction regulations. Seismic rehabilitation is fundamental to increase the robustness of urban centers to the action of earthquakes, contributing to increase the resilience of populations and cities in the face of catastrophic scenarios. However, those involved in this rehabilitation face the difficulty choosing the best constructive solutions to adopt and the criteria that should support this choice. It should be noted that although the most suitable reinforcement techniques are known for different construction typologies, they are generally treated by considering the building individually rather than the block scale. It is therefore important to identify and study reinforcement solutions considering the building and adjacent buildings given the interactions that exist between them. This work corresponds to the first study of rehabilitation and seismic reinforcement strategies for buildings in linear bands, at the block scale in the Alvalade neighborhood, in the city of Lisbon, and was carried out with the help of software "LNECLOSS". The evaluation of the seismic performance of the edified buildings and their structural damage was done through a mechanistic method, called the capacity spectrum method, in which buildings are described by capacity and fragility curves. Through the analysis of these curves, it was evaluated the seismic vulnerability of buildings and homogeneous and heterogeneous linear bands, and it was concluded that in the case of homogeneous bands the vulnerability is the same for buildings and for bands, being independent of the number of buildings in each band, but that is different in the case of heterogeneous bands. For the seismic risk assessment, two scenarios of seismic action were considered, the "near" scenario and the "remote" scenario characteristic of seismicity affecting Portugal, concluding that the "remote" scenario is more harmful. With respect to the seismic reinforcement strategies adopted, it was verified that the strategies R1, R3 and R4 lead to reduced values of damage to the structure, and are those that best contribute to the mitigation of the seismic risk of the site, taking into account the insertion of the buildings in the block. In this way, it is intended to contribute to an informed decision-making.
Description
Dissertação de natureza científica para obtenção do grau de mestre em Engenharia Civil, área de Especialização de Estruturas, no âmbito da colaboração entre o ISEL e o Núcleo de Engenharia Sísmica e Dinâmica de Estruturas (NESDE) do Laboratório Nacional de Engenharia Civil (LNEC)
Keywords
Sismo Earthquake Perigosidade Hazard Vulnerabilidade Vulnerability Risco Risk Avaliação e mitigação do risco Risk assessment and mitigation Estratégias de reforço Reinforcement strategies Banda linear Linear bands Quarteirão Block
Citation
COSTA, Nerysa Alexandra Amaro da - Estratégias de mitigação do risco sísmico de quarteirões no bairro de Alvalade, em Lisboa. Lisboa: Instituto Superior de Engenharia de Lisboa, 2018. Dissertação de mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa