Browsing by Author "Vicente, Romeu"
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- Avaliação da vulnerabilidade sísmica de núcleos urbanos antigosPublication . Vicente, Romeu; Ferreira, Tiago M.; Maio, Rui; Estêvão, João Manuel Carvalho; Costa, Alexandre A.; Varum, Humberto; Costa, Aníbal; Oliveira, Carlos SousaEste artigo reúne alguns dos mais importantes outputs resultantes do projeto URBSIS, financiado pela Fundação para a Ciência e Tecnologia, nomeadamente aqueles relacionados com a avaliação da vulnerabilidade sísmica de núcleos urbanos antigos através da aplicação de uma metodologia simplificada baseada no cálculo de um índice de vulnerabilidade que, consequentemente, possibilita a avaliação de danos e a criação de cenários de perdas. Neste sentido, será aqui apresentada e discutida a aplicação e calibração da metodologia proposta e a sua integração numa plataforma SIG aos núcleos urbanos antigos de Faro e da Horta (ilha do Faial, Açores).
- Casting a new light on the seismic risk assessment of stone masonry buildings located within historic centresPublication . Maio, Rui; Estêvão, João M. C.; Ferreira, Tiago Miguel; Vicente, RomeuIn light of the new legal framework in force in Portugal, which defines the terms for reporting the seismic vulnerability assessment and the need for seismic strengthening of existing buildings, this paper aims at investigating the correlation between two well-known approaches for the seismic risk assessment of stone masonry buildings located within historic centres: the vulnerability index method and nonlinear static seismic analyses. The latter were carried out by using a new three-dimensional macroelement model to numerically represent the considered sample of prototype buildings, together with the application of the N2 Method. In this paper, the original purpose of the vulnerability index method, that of ranking the seismic vulnerability of existing urban cultural heritage (UCH) assets within the same building typology, was numerically validated. However, when reverting the use of the vulnerability index method by replacing the Macroseismic Intensity with a response spectrum, the results were not as interesting as envisaged, since the correlations between the vulnerability index and the main properties of the capacity curves derived from numerical models, presented, in general, a poor fitting. Finally, the possible causes for such poor fitting and future lines of investigation are discussed. Despite these results must be understood with due care and diligence, the authors believe that this exercise might encourage new investigations on this topic that could lead to the development of a new code-oriented methodology for the seismic risk assessment of UCH assets within historic centres.
- Cost-benefit analysis of traditional seismic retrofitting strategies integrated in the renovation of stone masonry buildingsPublication . Maio, Rui; Estêvão, João M. C.; Ferreira, Tiago Miguel; Vicente, RomeuThis study discusses the cost-benefit analysis resulting from the application of traditional seismic retrofitting strategies on four case studies considered representative of both rural and urban stone masonry building stock of Faial Island, in Azores (Portugal). The seismic performance-based assessment was carried out by applying the N2 Method procedure, and the global seismic capacity of each case study estimated by using a three-dimensional model based on the macroelement approach, which combines both the in-plane and out-of-plane response of masonry buildings, to perform nonlinear static analyses. Fragility and loss estimation was evaluated according to the HAZUS methodology. In general terms, the cost-benefit analysis has demonstrated that the studied retrofitting strategies are indeed capable of reducing substantially the seismic vulnerability of the considered case studies, and also that they represent, in fact, a limited amount of the total replacement cost, not compromising, therefore, their economic viability.
- Displacement-based seismic performance evaluation and vulnerability assessment of buildings: the N2 method revisitedPublication . Lopes, Gonçalo Correia; Vicente, Romeu; Ferreira, Tiago Miguel; Azenha, Miguel; Estêvão, João M. C.The so-called N2 method is a widely used nonlinear static method for the seismic design and/or assessment of different building typologies. In this paper, the idea of reversing the so-called N2 method currently adopted in the Annex B of Eurocode 8 (the code on which the present paper is based) in a direct displacement-based procedure is presented in a simple alternative format. In this way, it is possible to obtain the percentage of the seismic action associated to any performance displacement. By doing so, it is also possible to determine the target displacement without the need for an iterative procedure. The proposed method presents several advantages for professional engineering practice in respect to the seismic vulnerability assessment of new and existing buildings. The comparison of the original N2 method with the proposed one is illustrated by means of a test structure example.
- A estabilidade estrutural e a vulnerabilidade dos edifícios em centros históricos face ao risco sísmicoPublication . Vicente, Romeu; Ferreira, Tiago Miguel; Maio, Rui; Estêvão, João M. C.; Rodrigues, HugoPresentemente os países europeus estão a despertar para uma cultura da gestão de risco integrado, quer a nível nacional quer em termos municipais. A gestão de risco é um processo que engloba uma série de ações que apoiam a implementação de medidas que reduzam o potencial de perda na ocorrência de um evento, por exemplo, de natureza sísmica. Porém, a avaliação do risco sísmico é apenas uma das tarefas da teia complexa da gestão de risco e definição de estratégias de intervenção e controlo de um sistema urbano. De entre muitos objetivos que se perspetivam no âmbito do planeamento e gestão urbana, com este artigo abordar a avaliação de risco no domínio específico da segurança estrutural, com enfoque na avaliação do risco sísmico, cujas graves consequências fazem parte da nossa memória coletiva e, infelizmente, em alguns casos, da memória viva de diversas comunidades. A gravidade dos danos que deles decorrem é motivo suficiente para uma forte valorização das estratégias de prevenção, planeamento e mitigação que diminuam a sua probabilidade, limitem as suas consequências e permitam uma ação continuada de melhoria, já que só utopicamente se poderá considerar a possibilidade de transformação integral e imediata das realidades urbanas em situações de risco “zero”.
- Metodologia de avaliação da vulnerabilidade sísmica: calibração e validação macrossísmicaPublication . Vicente, Romeu; Ferreira, Tiago M.; Maio, Rui; Costa, Alexandre A.; Estêvão, João Manuel Carvalho; Varum, Humberto; Costa, Aníbal; Oliveira, Carlos S.As metodologias disponíveis para estudar a vulnerabilidade sísmica do edificado tradicional de alvenaria em centros urbanos antigos, atendendo à escala e ao número de edifícios a avaliar, diferenciam-se marcadamente pelo volume de trabalho associado ao levantamento de informação, e seu tratamento, decorrente do processo de inspeção e do nível de detalhe associado. A metodologia aqui apresentada para a avaliação da vulnerabilidade sísmica de edifícios em alvenaria é baseada em estudos e levantamentos de danos pós-sismo, que evidenciam algumas das características que governam o comportamento das estruturas de alvenaria de edifícios antigos quando sujeitos à ação sísmica. Estas características são posteriormente tratadas como parâmetros a analisar na definição e construção de um índice de vulnerabilidade. Assim, neste artigo, a metodologia original apresentada é calibrada com base na informação recolhida após o sismo dos Açores de 1998, que infligiu graves danos em grande parte do edificado da Ilha do Faial. Esta calibração permitiu redefinir os pesos dos parâmetros e reclassificar as classes de vulnerabilidade de alguns dos parâmetros da metodologia de avaliação da vulnerabilidade sísmica.
- Seismic performance-based assessment of urban cultural heritage assets through different macroelement approachesPublication . Maio, Rui; Ferreira, Tiago Miguel; Estêvão, João M. C.; Pantò, Bartolomeo; Caliò, Ivo; Vicente, RomeuThis paper aims at providing an insightful comparison between three of the most widely used commercially available macroelement models for assessing the global seismic performance of existing masonry structures: the equivalent frame model of 3Muri®, and the two- and three-dimensional discrete macroelements available in 3D-Macro®. To this aim, a stone masonry building, representative of the Urban Cultural Heritage (UCH) typology of the Azores archipelago (in Portugal), was considered as a case study. Firstly, sensitivity analyses were performed to investigate the impact of a few modelling aspects on the seismic performance of the case study building, and ultimately to define the reference model. Secondly, this reference model was analysed both linearly and nonlinearly. Finally, the seismic performance was evaluated by applying the N2 Method. With this comparative study, the authors aim at discussing, from the user viewpoint, the features that these software codes and corresponding macroelement models have in common and those where they most diverge, as well as their main advantages and drawbacks. Results demonstrate that these models should be applied to UCH assets with due diligence, bearing in mind both the particularities of the case study as well as features and limitations associated with the chosen modelling strategy and software.
- Seismic vulnerability assessment of existing masonry buildings: case study of the old city centre of Faro, PortugalPublication . Vicente, Romeu; Ferreira, Tiago; Maio, Rui; Varum, Humberto; Costa, Alexandre A.; Costa, Aníbal; Oliveira, Carlos S.; Estêvão, João Manuel CarvalhoThe seismic vulnerability and risk assessment of old city centre areas is truly essential in urban rehabilitation programs and should not be focused exclusively over recognized historical and patrimonial valuable buildings but also in relation to current old masonry buildings that are highly valued in urban context. In addition, due to their geographical, demographic or historical features some old city centres are particularly interesting and critical, in respect to seismic risk mitigation. An excellent example of this reality is the old city of Faro, Capital of the Algarve, Portugal, which is one of the most popular summer touristic destination in Europe in a prone seismic region. This fact explains the high seasonal flux of population, which together with the moderate to high seismic hazard of the Algarve region and a vulnerable building stock increases both the seismic and tsunami risk in this area. From the exposed, this paper approaches the seismic vulnerability assessment of old building stock through the application of a simplified vulnerability method to the old city centre of Faro. Such method is based on a vulnerability index, which can be used to evaluate physical damage and to create human and economic loss scenarios in a broad sense (Vicente et al., 2011). 191 buildings were evaluated in accordance with the referred methodology and the results obtained were subsequently integrated into a Geographical Information System (GIS) tool, which allows the spatial analysis of results (Ferreira et al., 2013).This tool constitutes a very valuable instrument for city councils and regional authorities, whom can decide in a faster and more accurate way the best risk mitigation strategies to follow at the urban scale.
- Seismic vulnerability assessment of historical urban centres: case study of the old city centre of Faro, PortugalPublication . Maio, Rui; Ferreira, Tiago Miguel; Vicente, Romeu; Manuel Carvalho Estêvão, JoãoThe necessity of implementing seismic vulnerability assessment procedures to the Portuguese building stock has become urgent as recent predictions indicate the possibility of the occurrence of an earthquake similar to the well-known 1755 Lisbon earthquake within the next 50 years. Obviously, at first instance, large-scale procedures should be used rather than more extensive and accurate methodologies suited for individual buildings assessment. Moreover, it is fundamental to operate in the most vulnerable areas in our built environment, typically, the historical urban centres. As it is recognised, it is within these areas, that old masonry buildings are generally concentrated, being both the most representative and vulnerable constructive typology. Comprising 354 buildings, the case study of the old city centre of Faro is herein presented aiming at analysing and evaluating the seismic vulnerability of its old masonry building stock. In order to achieve these objectives, a vulnerability-index-based methodology was used for the assessment of the seismic vulnerability of the old masonry buildings belonging to the historical centre of Faro (Ribeirinha area) carried out through detailed inspection and survey. The results obtained were analysed using a geographical information system tool. The integration of such vulnerability and loss results represents a valuable tool for city councils and/or regional authorities to plan interventions, on the basis of a global view of the site under analysis, leading this way to more accurate and comprehensive risk mitigation strategies which comply with the requirements of safety and emergency planning. The application of this large-scale scoring methodology has confirmed moderate-to-high values for the vulnerability of this particular area, which combined with its high seismicity, may be quite alarming.
- The seismic performance of stone masonry buildings in Faial island and the relevance of implementing effective seismic strengthening policiesPublication . Maio, Rui; Estêvão, João M. C.; Ferreira, Tiago M.; Vicente, RomeuEnhancing the seismic performance of traditional stone masonry buildings is considered a crucial mea- sure towards the preservation and safeguarding of our built heritage, particularly in seismic prone areas such as the Azores archipelago, in Portugal. In this context, the present paper is focused on the seismic vulnerability assessment of two traditional stone masonry building located in the Faial Island, taken as typologically representative of the rural Azorean building stock. The case study buildings were modelled based on the equivalent frame model approach and non-linear static (pushover) analyses were performed to assess their seismic performance. Firstly, results were com- pared in terms of capacity curves, and secondly, two different seismic performance-based assessment methods (N2 and CSM) were used to determine the respective performance points and assess the seismic safety of both structures. The seismic demand was defined by a set of real ground motion records, which the authors assumed as representative of the 1998 Azores earthquake, both in terms of magnitude and epicentral distance. Additionally, a set of traditional retrofitting solutions were implemented to the original models in order to analyse and compare their influence over the building’s global seismic performance. These solutions were adopted in the aftermath of the 1980 and 1998 Azores earthquakes by different design offices and engineering consultants, based on the designing recommendations specifically prepared by the Regional Laboratory of Civil Engineering (LREC) under the scope of the Faial rehabilitation process. Finally, fragility curves were derived based on the spectral response approach, and the results were crit- ically discussed.