Publications

Disaggregation of the seismic hazard has become a popular technique to convey information on the main sources contributing to the hazard at a particular site. Recently published work adopts geographic disaggregation analysis of seismic hazard as a tool to identify dominant rupture scenarios for municipalities in Mainland Portugal. The authors conclude that the seismic hazard in South and Central Portugal is dominated by the seismicity that takes place offshore, around 70km WSW of Cape S. Vicente, both for the return periods of 475 years and 975 years. Whilst recognizing the merits of the approach taken and the utility of the tools developed, we take issue with this last conclusion.We consider that the proposed disaggregation returns a picture of the biases in the hazard analysis, more than any real feature of the distribution of relevant seismogenic sources.

Ao longo da sua história, a cidade de Lisboa tem sofrido os efeitos devastadores de diversos sismos que foram responsáveis por danos e perdas relevantes no seu parque edificado e seus habitantes. Os objectivos do presente artigo englobam a identificação, a análise e a avaliação do risco sísmico deste concelho, cumprindo-se, desta forma, algumas das etapas do processo de gestão do risco. Efectuou-se a análise de risco para uma perigosidade sísmica regida por mais do que um cenário probabilístico de ocorrência de sismos. Para o efeito, caracterizou-se a perigosidade sísmica das 53 freguesias de Lisboa, considerando dois cenários de ocorrência construídos sobre os mesmos pressupostos em que se fundamentou a acção sísmica que serviu de base ao Anexo Nacional do Eurocódigo 8. Avaliou-se ainda a exposição do parque habitacional e habitantes deste concelho, classificou-se e caracterizou-se a vulnerabilidade sísmica dos elementos expostos, traçaram-se as curvas de risco sísmico para a cidade de Lisboa e estimaram-se os valores esperados anuais das perdas económicas e sociais nas freguesias desta cidade. Da análise efectuada ressalta que as perdas totais são condicionadas essencialmente pelo cenário de acção sísmica próximo, que as freguesias mais antigas são aquelas em que o risco relativo esperado anual é mais elevado e que as freguesias responsáveis pelos maiores valores de risco absoluto são as que apresentam a vulnerabilidade sísmica mais elevada e os maiores valores de exposição.A apreciação do risco sísmico efectuada para Lisboa permite concluir que o risco de morte anual devido a sismos a que os habitantes desta cidade estão expostos se situa na zona ALARP (As Low As Reasonably Practicable).

Decisions to mitigate seismic risk require a consistent approach to evaluate the effects of future earthquakes on population, on civil engineering structures and infrastructures. The mathematical and probabilistic methods that are the support to those approaches are generally called Risk Analysis; in the particular case of seismic events and mitigation strategies it will be named Seismic Risk and Mitigation Analysis, SRMA. The paper will address the subject of estimating the seismic risk and evaluate mitigation strategies for the existing building stock of the metropolitan area of Lisbon by describing the methods and showing preliminary results obtained with LNECloss numerical tool. Even though such a sophisticated tool needs validation on some parameters to become more reliable, it is shown that it is possible to compare results of different mitigation strategies.

The paper addresses two complex case studies of modal and structural identification of monuments in Portugal: the Clock Tower of Mogadouro and the Church of Jero´nimos Monastery, in Lisbon. These are being monitored by University of Minho with vibration, temperature and relative air humidity sensors. Operational modal analysis is being used to estimate the modal parameters, followed by statistical analysis to evaluate the environmental effects on the dynamic response. The aim is to explore damage assessment in masonry structures at an early stage by vibration signatures, as a part of a health monitoring process that helps in the preservation of historical constructions. The paper presents the necessary preliminary dynamic analysis steps before the monitoring task, which includes installation of the monitoring system, system identification and subsequent FE model updating analysis, automatic modal identification and investigation of the influence of the environment on the identified modal parameters.

Probabilistic seismic hazard for Mainland Portugal was re-evaluated in order to perform its disaggregation. Seismic hazard was disaggregated considering different spaces ofrandom variables, namely, univariate conditional hazard distributions of M (magnitude), R (source-to-site distance) and

Probabilistic seismic hazard for Mainland Portugal was re-evaluated in order to perform its disaggregation. Seismic hazardwas disaggregated considering different spaces of random variables, namely, univariate conditional hazard distributions of M (magnitude), R (source-to-site distance) and

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Decisions to mitigate seismic risk require a consistent approach to evaluate the effects of future earthquakes on population, on civil engineering structures and infrastructures.The mathematical and probabilistic methods that are the support to those approaches are generally called Risk Analysis; in the particular case of seismic events andmitigation strategies it will be named Seismic Risk and Mitigation Analysis, SRMA. The paper will address the subject of estimating the seismic risk and evaluate mitigation strategies for the existing building stock of the metropolitan area of Lisbon by describing the methods and showing preliminary results obtained with LNECloss numerical tool. Even though such a sophisticated tool needs validation on some parameters to become more reliable, it is shown that it is possible to compare results of different mitigation strategies.

This paper describes the shaking table tests, and their main results, of an asymmetric limestone masonry building, under different reinforcement conditions. The work was performed in the aim of the project

No âmbito de um projecto denominado

Utilizam-se modelos estocásticos para a simulação dos movimentos sísmicos intensos do solopara construção de uma base de dados sintética de registos que se crêem representativos dosmovimentos do solo no Arquipélago dos Açores, no substrato rochoso.De modo a considerar a influência das condições locais do terreno, foram considerados: (i)perfis geotécnicos sintéticos, para cada tipo de terreno do Anexo Nacional do Eurocódigo 8, (ii)o modelo de propagação vertical de ondas S com polarização horizontal associado a umacoluna estratigráfica com interface inferior materializada por um semi-espaço elástico rochoso e(iii) o método linear equivalente para considerar de forma aproximada a resposta não linear dossolos.Tais simulações permitiram criar uma base de dados sintética de registos sísmicos à superfície,para as gamas de frequência, magnitude e distância hipocentral de interesse para aengenharia, permitindo a elaboração de equações de previsão dos movimentos do solo, paraos diferentes tipos de terreno referidos no Anexo Nacional do EC8, para o Arquipélago dosAçores.

The objective of this paper is to analyse the evolution of expected earthquake losses in Portuguese residential buildings, to determine if their natural regeneration originates the mitigation of the seismic risk, although exposure in the region increased over time. To achieve this goal, the evolution of quantified risk measures was evaluated, based on the surveys of the residential building stock obtained in the 2001 and 2011 Portuguese census. This study provides a global perspective of the seismic risk on the Portuguese mainland, and makes possible the comparison of risk levels between different regions and epochs. The comparison of economic losses obtained in these two different moments in time, took into consideration the inflation rate, and led to the conclusion that the natural regeneration of the residential housing stock contributed to the mitigation of seismic risk, even if there was a significant increase in the exposure.

In the scope of the transnational access activities of the European research project SERIES, the Laboratório Nacional de Engenharia Civil (LNEC) has provided access to its 3-D shaking table to the international construction company Wienerberger AG and to a group of European experts, in order to perform full-scale seismic tests on an industrial solution for buildings using a modern unreinforced thermal insulation clay block masonry structure.Such solution represents a very common construction method in Central Europe and, although there are cyclic shear test results available, its effective dynamic response under seismic events still requires experimental validation. For this purpose, two full-scale mock-ups with different geometries were tested on the 3-D shaking table using a series of seismic records with increasing intensity.This paper focuses on the most relevant experimental results regarding the structural response of the specimens, e.g., the dynamic response evolution, the collapse mechanism identified and the maximum drift values measured. The paper closes with the main conclusions drawn and with proposals for future developments.

A avaliação dos movimentos sísmicos à superfície, contemplando os efeitos de sítio, estádependente das caraterísticas geológicas dos terrenos no local em análise.Para o Arquipélago dos Açores a informação geotécnica disponível não permite umaavaliação geograficamente global da resposta sísmica dos terrenos caraterísticos destaregião.Assim, após levantamento e síntese de toda a informação disponível, foram idealizadosperfis estratigráficos sintéticos, representativos da variabilidade dos solos da região,permitindo posteriormente modelar a propagação da energia sísmica, materializada naforma de ondas de corte S, através de um meio estratificado representado por umasequência de camadas, e consequentemente, avaliar a alteração do movimento sísmicodevido à influência daquela.

A simulação estocástica tem sido utilizada, com algum grau de sucesso, para a obtenção deacelerogramas em zonas onde não existem muitos registos instrumentais de sismosintensos ocorridos no passado, e pode ser uma ferramenta importante nesse contexto.Contudo, essas simulações deverão, necessariamente, ser previamente validadas atravésde registos de sismos ocorridos no passado, dada a grande incerteza associada à definiçãode cenários sísmicos. É muito difícil prever qualquer um dos processos, complexos, degeração do sismo, de propagação da energia e dos efeitos locais, nomeadamente ascaracterísticas da rotura, designadamente o padrão de deslizamentos e a queda de tensãomédia no plano da falha, a atenuação das ondas sísmicas ao longo do percurso depropagação e a obtenção da amplificação local das camadas de solo superficial.Neste trabalho, são apresentados os resultados de diversas simulações estocásticas dosismo ocorrido nos Açores em 1998, considerando diferentes localizações da rotura,juntamente com os respetivos parâmetros, variação das características da atenuação ediferentes condições geológicas locais. Os acelerogramas simulados, e correspondentesespectros de resposta, foram comparados com os registos instrumentais do sismo, e com osresultados de leis de atenuação obtidas para a Europa e, em particular, para o arquipélagodos Açores.

Earth has been a traditional building material to construct houses in Africa. One of the most common techniques is the use of sun dried or kiln fired adobe bricks with mud mortar. Although this technique is low-cost, the bricks vary largely in shape, strength and durability. This leads to weak houses which suffer considerable damage during floods and seismic events. A solution is the use of dry-stack masonry with stabilized interlocking compressed earth blocks (ICEB). These blocks are manufactured by compacting cement stabilized earth in a manual or hydraulic press into a mould and then air dried. The resulting blocks present uniform shapes and higher values of strength and durability. This work presents the work made in the context of the HiLoTec project. It focuses on the experimental campaign of the project to characterize the strength of ICEBs and the behaviour of dry-stack masonry.

No âmbito do projeto HiLoTec (desenvolvimento de uma tecnologia construtiva simples, inovadora e sustentável para edifícios de pequeno porte em países em desenvolvimento) foi desenvolvido um sistema construtivo baseado na utilização de blocos de terra compactada com estabilização hidráulica e junta seca. O presente artigo apresenta os principais resultados do ponto de vista estrutural obtidos ao longo do projeto, com especial ênfase para o comportamento sísmico, lançando contribuições para a resposta à pergunta se se poderão os blocos de terra compactada com estabilização fazer um sistema sismo-resistente para construções de pequeno porte. A campanha experimental incluiu ensaios de caracterização do sistema a diferentes níveis: material (solo), bloco, prismas de alvenaria, paredes de alvenaria e um protótipo ensaiado na mesa sísmica no Laboratório Nacional de Engenharia Civil, em Lisboa.

A simulação de movimentos intensos do solo torna-se necessária em regiões de sismicidademoderada, onde os registos de interesse para a engenharia são escassos e insuficientes, oupara estudos que exijam especificamente registos de uma determinada magnitude edistância de interesse. O modelo estocástico, partindo do conhecimento das característicasespetrais da fonte e considerando os efeitos de propagação das ondas sísmicas no percursodesde a fonte até ao local, estima os movimentos intensos do solo em termos da suaintensidade, conteúdo em frequência duração e variabilidade espacial.Neste trabalho apresenta-se o procedimento efectuado, com base nos registos obtidos narede acelerográfica nacional, para quantificação dos parâmetros que descrevem osprocessos envolvidos na geração de movimentos intensos do solo e que são necessáriospara a aplicação do modelo estocástico. Estuda-se o processo de propagação das ondassísmicas (atenuação geométrica e inelástica), o processo de atenuação na crusta superior edeterminam-se as caraterísticas espetrais da fonte sísmica.

Reinforced concrete (RC) structures with tri-dimensional asymmetries tend to exhibit torsional effects that are of great concern in the field of earthquake engineering, in particular at large ductility levels where they become more relevant [MAN09]. In nuclear facilities, this issue assumes particular relevance considering that these structures are designed to respond essentially in the elastic range with a controlled level of deformations and accelerations when subjected to strong ground motions. Within the previous framework, the research project SMART 2013 (

Conservation of ancient built heritage plays a leading role for modern societies. Knowledge about ancient building methods, essentially based on the use of natural materials such as earth, stone and wood, is fundamental to plan interventions aimed at preserving the architectural heritage. Due to the growing research on sustainable technologies, the interest in structural systems built using natural materials has been rising more and more. Taking an earthen mock-up construction as model, the paper focuses on the dynamic behaviour of such a system tested on a shaking table. Detailed descriptions of the model, its mechanical features, the seismic test performed and the damage pattern obtained are first presented. Then, the dynamic identification of the structure during damage occurrence is performed through the decomposition of the power spectral density matrix. Damage evolution and localization are also analyzed by an index based on the complex eigenvectors estimated from the matrix. Finally, comparisons between experimental and analytical results are addressed.

This book presents a selection of the best papers from the HEaRT 2015 conference, held in Lisbon, Portugal, which provided a valuable forum for engineers and architects, researchers and educators to exchange views and findings concerning the technological history, construction features and seismic behavior of historical timber-framed walls in the Mediterranean countries. The topics covered are wide ranging and include historical aspects and examples of the use of timber-framed construction systems in response to earthquakes, such as the gaiola system in Portugal and the Bourbon system in southern Italy; interpretation of the response of timber-framed walls to seismic actions based on calculations and experimental tests; assessment of the effectiveness of repair and strengthening techniques, e.g., using aramid fiber wires or sheets; and modelling analyses. In addition, on the basis of case studies, a methodology is presented that is applicable to diagnosis, strengthening and improvement of seismic performance and is compatible with modern theoretical principles and conservation criteria. It is hoped that, by contributing to the knowledge of this construction technique, the book will help to promote conservation of this important component of Europe

The applications of discrete elements models based on rigid block formulations to the analysis of masonry walls under horizontal out-of-plane loading is simplified block pattern are addressed. Two procedures for creating irregular block systems are presented, one using Voronoi polygons, the other based on a bed and cross joint structure with random deviations. A test problem provides a comparison of various regular and random block patterns, showing their influence on the failure loads. The estimation of manual frequencies of rigid block models, and its application to static pushover analyses, is addressed. An example of application of rigid block model to wall capacity problem is presented.

The overall aim of Sub-Project 10 (Earthquake disaster scenario predictions and loss modelling for urban areas) has been to create a tool, based on state-of-the-art loss modelling software, to provide strong, quantified statements about the benefits of a range of possible mitigation actions, in order to support decision-making by urban authorities for seismic risk mitigation strategies. A further larger aim has been to contribute to a seismic risk mitigation policy for future implementation at European level. Among the European cities for which loss estimation studies have been carried out are Istanbul, Lisbon and Thessaloniki, and tools, using GIS mapping, have been developed by research teams in each of these cities; these were made available for further development to examine mitigation strategies within SP10. Related research studies

Much work in Earthquake Engineering was devoted to the improvement of earthquake resistant design of new structures. One European result is EN 1998, which will be in several years the main seismic code for all European countries. But it is well known, that older existing structures cause in many large earthquakes much more casualties and damages than new structures. It is certainly not possible to retrofit all existing structures, but agreement exists, that assessment and retrofit of safety - critical - structures and lifeline structures must have priority. In September 2004 the European Integrated Research Project LESSLOSS on Risk Mitigation for Earthquakes and Landslides was started. The project will run for three years and comprises 13 Sub-Projects (SP´s). The consortium consists of 46 partners (see http:\\www.lessloss.org). LESSLOSS SP5 is on In-situ Assessment, Monitoring and Typification of buildings and Infrastructure. The project partners of SP5 are ARS, CESI, LNEC, RWTH and VCE. This Sub Project focuses mainly on the assessment of important existing structures and tries to integrate experimental methods into the assessment procedure. The progress of SP5 obtained in the first year is summarized in this paper. Highlights presented by all partners are mentioned and the assessment of Hospital Innsbruck is presented in more detail. The most innovative task of LESSLOSS/ SP5 is Update of vulnerability estimates via monitoring, which was also started in the first year.

In order to study the behavior of bridge structures in relation to traffic, wind and seismic loads, it is extremely important to know their actual dynamic properties (natural frequencies, vibration mode shapes and damping). The experimentally identified dynamic properties of bridge structures are also an effective way to characterize their actual global structural behavior. Whether included in the reception load tests of recently built bridges, before they are opened to the traffic, or as part of the inspection works of bridges already in service, LNEC has performed modal analysis studies based on the results of ambient vibration tests. Some of the studies carried out recently in important bridges are reported in this paper.

O sismo de Northridge ocorreu na parte norte da área metropolitana de Los Angeles, Califórnia, às 4:31 h do dia 17 de janeiro, uma segunda-feira coincidente com dia de feriado nacional, tendo atingindo uma magnitude de 6.6 na escala de Richter. O número total de vítimas mortais cifra-se em 57, havendo para cima de 8 000 feridos e 20 000 desalojados.As estimativas de perdas totais, feitas em meados de fevereiro de 1994, apontavam para valores de 15 biliões de US dólares, tendo o Estado da Califórnia apresentado um impacto económico total de ordem dos 30 biliões de dólares, perto do valor do Orçamento Geral do estado Português para 1994. Os prejuízos infligidos na indústria e no comércio são também surpreendentemente elevados, exigindo longos períodos de interrupção das atividades económicas.

Communicating science within disaster risk reduction using methods that encourage two-way dialogue between scientists and laypersons is a challenging task. This paper aims at presenting a methodological strategy of communicating risk and non-structural seismic protection measures through participatory approach. Such methodological strategy is part of a pilot experience of risk communication in two schools in Lisbon (Portugal) under the EU project KnowRISK (Know your city, Reduce seISmic risK through non-structural elements). The efficacy of education for seismic safety is often inhibited by an incomplete understanding of the process by which individuals decide to protect themselves from harm (Becker JS, Paton D,Johnston DM, Ronan KR. Nat Hazards 64(1):107

Most of the Lisbon 18th century timber-framed masonry

Good performance of non-structural elements can be decisive in saving lives and costs when an earthquake strikes. The European project KnowRISK aims to educate and encourage households to take the necessary precautionary measures to protect people, houses, and contents. Preparedness and prevention act on community resilience. Within the KnowRISK project, the idea of a Practical Guide has been conceived suggesting seismic mitigation solutions for non-structural components to non-experts stakeholders. It is intended to guide people into the first steps of prevention in a straightforward manner, minimizing or avoiding injuries, damage, and long-term financial consequences. The novelty of the Guide belongs to his philosophy: a path through increasing challenges corresponds to a growing level of safety. The idea is that anyone can mitigate seismic risk in its own environment by adopting simple and low cost measures. The Practical Guide may contribute to increase risk awareness. This kind of initiatives if undertaken at larger scales may also enhance social resilience.

When one of the dimensions of a structural member is not clearly larger than the two orthogonal ones, engineers are usually compelled to simulate it with refined meshes of shell or solid finite elements that typically impose a large computational burden. The alternative use of classical beam theories, either based on Euler-Bernoulli or Timoshenko

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This text reflects the first of the four lectures that the author has presented at Udine, Italy, at CISM

Um dos principais problemas e interesses da engenharia sísmica é a caracterizaçãoda acção sísmica, envolvendo a estimativa da intensidade, conteúdo em frequência,duração e variabilidade espacial dos movimentos intensos do solo mais gravosos, emtermos dos seus efeitos nas estruturas, que pode ocorrer num local.O presente trabalho de investigação desenvolve e aplica a metodologia estocástica etécnicas de modelação de fonte

Os sismos são encarados frequentemente como desastres naturais inevitáveis. Todavia,deveriam ser considerados fenómenos naturais, cujos efeitos adversos podem ser minimizadoscaso se proceda a uma gestão efectiva do risco sísmico.O objectivo principal do presente trabalho de investigação é o de avaliar o risco sísmicoem Portugal Continental.Sendo um tema de natureza multidisciplinar, apresentam-se e discutem-se modelos deavaliação probabilística da perigosidade sísmica e sua desagregação, de vulnerabilidade efragilidade sísmicas de tipologias construtivas, de danos e de perdas económicas e humanas.Aplica-se a análise probabilística da perigosidade sísmica, e sua desagregação, aPortugal Continental, obtendo-se cenários modais capazes de reproduzir os níveis deperigosidade que os condicionam. Apresenta-se o inventário do parque habitacional e seushabitantes, descriminado por factores de vulnerabilidade, e classifica-se a sua vulnerabilidadesegundo os modelos de dano. Procede-se à actualização e aferição de uma metodologia parasimulação de cenários sísmicos, integrada num Sistema de Informação Geográfico. Avalia-seo risco sísmico, seguindo diversas abordagens, comparando-se os resultados com o risco deoutros países.Construiu-se assim uma ferramenta de avaliação de perdas devidas a sismos, queconstitui uma primeira contribuição para o desenvolvimento de um processo de gestão dorisco sísmico aplicado ao Continente Português.

O parque habitacional de Portugal Continental contém algumas tipologias construtivas deelevada vulnerabilidade sísmica em relação às quais urge actuar no sentido de reduzir o riscosísmico a elas associado. No projecto de investigação

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This report addresses the National Laboratory for Civil Engineering (LNEC) participation in Subproject 10 Earthquake disaster scenario predictions and loss modelling for urban areas. More precisely this report was developed in order to accomplish the 24 months LESSLOSS deliverable nº 85, which achieves loss estimates for the Metropolitan Area of Lisbon (MAL), for pre-defined scenarios earthquake. These loss estimations represent the reference situation to be compared with revised loss estimates after implementing mitigation actions with the ultimate goal of being established, in the next deliverable, the

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The present report describes the construction of a model in limestone masonry for the user Group 3 oh the ECOLEADER Project, led by IRIDEX Construction Group, and the first phase of the experimental program developed in LNEC. The description of the construction, a photographic report and the results obtained on the characteristics tests made on the mortars used in the construction are presented.The construction was carried out by contractor José dos Santos Paixão on the basics of model details and materials specifications proposed by the User group 3, being NESDE/LNEC responsible for the guidance and supervision of the works.

This report describes the first phase activity of the Portuguese group in the Precast Structures EC8 research projet. The Portuguese group is composed by Laboratório Nacional de Engenharia Civil (LNEC) and the Civibral, S.A. Precast Company.In this phase, seismic test were made in the LNEC

The present report addresses the first twelve months of LNEC participation in LESSLOSS

The dynamics of rigid bodies was studies by long time, because this phenomenon is important in the seismic security of some types of structures. However, there are few experimental studies. This job shows the experimental test carried out at the Laboratório Nacional de Engenharia Civil (LNEC) of Portugal. Four blue granites stones were tested, each one with different geometrical characteristics, under harmonic and random motions.A numerical simulation was carried out with the Discrete Element Method (DEM). This method has shown to be a good tool in the study of the dynamics of rigid bodies. It was proposed a new methodology to find the parameters of the DEM by using the parameters of classical theory.

The project LESSLOSS

Análise dos registos históricos de eventos climáticos e o seu impacto no setor da energia da AML, para identificar o grau em que este setor foi afetado por estímulos relacionados com o clima. Avaliação de capacidades adaptativas.

Análise da forma das edificações nas ações do vento

As condicionantes arquitetónicas e de urbanização na ventilação natural

Caracterização do vento. Ações sobre estruturas. Ensaios em túnel de vento