Publications

In this study, we simulate and compare ground motion shaking in the city of Lisbon and surrounding counties (metropolitan area of Lisbon (MAL)), using two possible earthquake models: the onshore source area of Lower Tagus Valley, M5.7 and M4.7 and the offshore source area, Marques de Pombal Fault, M7.6, one of the possible source of the 1755 Lisbon earthquake. The stochastic and a new hybrid stochastic-deterministic approach (DSM) are used in order to evaluate the ground shaking and to characterize its spatial variability. Results are presented in terms of response acceleration spectra (PSA) and peak ground acceleration (PGA) with respect to bedrock and surface. Site effects are evaluated by means of equivalent stochastic non-linear one-dimensional ground responses analysis, performed for a set of stratified soil profile units properly designed to cope with the soil site conditions of MAL region. A sensitive study is carried out using different input parameters and different approaches in order to give the basic information to evaluate the range of uncertainty in seismic scenarios.

In this study, we simulate and compare ground motion shaking in the city of Lisbon and surrounding counties (metropolitan area of Lisbon (MAL)), using two possible earthquake models: the onshore source area of Lower Tagus Valley, M5.7 and M4.7 and the offshore source area, Marques de Pombal Fault, M7.6, one of the possible source of the 1755 Lisbon earthquake. The stochastic and a new hybrid stochastic-deterministic approach (DSM) are used in order to evaluate the ground shaking and to characterize its spatial variability.Results are presented in terms of response acceleration spectra (PSA) and peak ground acceleration (PGA) with respect to bedrock and surface. Site effects are evaluated by means of equivalent stochastic non-linear one-dimensional ground responses analysis, performed for a set of stratified soil profile units properly designed to cope with the soil site conditions of MAL region. A sensitive study is carried out using different input parameters and different approaches in order to give the basic information to evaluate the range of uncertainty in seismic scenarios.

This article describes the dynamical behavior of free-standing block structures under seismic loading. A comprehensive experimental investigation has been carried out to study the rocking response of four single blocks of different geometry and associations of two and three blocks. The blocks, which are large stones of high strength blue granite, were subjected to free vibration, and harmonic and random motions of the base. In total, 379 tests on a shaking table were carried out in order to address the issues of repeatability of the results and stability of the rocking motion response. Significant understanding of the rocking motion mechanism is possible from the high quality experimental data. Extensive experimental measurements allowed to discuss the impulsive forces acting in the blocks and the three-dimensional effects presented in the response.

Stone masonry in historical buildings. Ways to increase their resistance and durability

This paper describes the behavior of single rigid-block structures under dynamic loading. A comprehensive experimental investigation has been carried out to study the rocking response of four blue granite stones with different geometrical characteristics under free vibration, and harmonic and random motions of the base. In total, 275 tests on a shaking table were carried out in order to address the issues of repeatability of the results and stability of the rocking motion response. Two different tools for the numerical simulations of the rocking motion of rigid blocks are considered. The first tool is analytical and overcomes the usual limitations of the traditional piecewise equations of motion through a Lagrangian formalism. The second tool is based on the discrete element method (DEM), especially effective for the numerical modeling of rigid blocks. A new methodology is proposed for finding the parameters of the DEM by using the parameters of the classical theory. An extensive comparison between numerical and experimental data has been carried out to validate and define the limitations of the analytical tools under study.

A caracterização do parque habitacional existente em Portugal Continental no que respeita à sua vulnerabilidade sísmica e a sua classificação em tipologias construtivas são os principais objetivos do presente artigo.Esta caracterização e classificação estão enquadradas num estudo de âmbito mais vasto que é o de avaliação do risco sísmico de Portugal Continental [Sousa,2005] que, por sua vez, requer o conhecimento prévio da vulnerabilidade sísmica do seu parque habitacional.Neste contexto, apresenta-se o panorama da construção existente em Portugal Continental, caracteriza-se e evolução das práticas construtivas ao longo do tempo, identificam-se os principais tipos de construção que subsistem e se praticam no Continente, descrevem-se, de forma sumária, os respetivos sistemas estruturais, mencionando as suas principais vulnerabilidades face à ação dos sismos (entendidas como as deficiências do seu desempenho sísmico), e tipificam-se as soluções construtivas mais correntes enquadrando-as nas tipologias identificadas no Censos 2001.

Apresenta-se um método expedito, baseado em ábacos, de estimativa de caudais de ventilação natural considerando as componentes eólica e térmica

Apresentam-se modelos preditivos para a ventilação natural, como contribuição para a redução de sistemas AVAC, mantendo a Qualidade do Ar Interior.

A ventilação natural requer a estimativa adequada dos caudais de ar em circulação, as taxas de renovação, função da velocidade do vento e da distribuição de pressão na envolvente. A turbulância atmosférica introduz perturbações neste processo simplificado induzindo variações na velocidade e direcção do vento, podendo dar origem a reversões do escoamento.

Probabilistic seismic hazards maps have been prepared either for the archipelago of the Azores in general terms, or for the islands of the Central Group using updated seismic information for the region, including a revision of the earthquake catalogue for the period 1522-1998. Two different approaches were used: (i) a standard seismic source model and (ii) a semi-zonified source model based on spatially smoothed seismicity where no delineation of seismic sources is needed. Preliminary data point out that high PGA values were obtained for an area located to the west of the Central Group and for an area between Terceira and the São Miguel Islands. Deaggregation of hazard for some counties was evaluated and results are presented in terms of mean and modal values of magnitude and distance, showing that the main contributions to hazard in all counties are from close-in and not very severe earthquakes.

A group of five Portuguese experts on earthquake engineering visited the Los Angeles region after the 17 January 1994 Northridge earthquake. The observations mad during the field trip are briefly reports. Discussion is made on the behaviour of different types of structures, namely, masonry, wooden, reinforced concrete and steel structures, as well as special structural typologies such as precast parking lots, tilt-ups and bridges. The presentation is illustrated by means of a few cases, for which the causes of malfunctioning were anticipated.Mention is also made to the behaviour of lifelines, such as electricity, gas and water supply, sewage systems and telephones. The damage assessment is viewed under the light of the ground motion severity.A description of the organizational aspects and procedures adopted for the inspection, immediate reinforcement, recovery and reconstruction of the main buildings, bridges and other utilities are also referred.

Esta comunicação apresenta a conceção, o projeto, a instalação e o planeamento da utilização durante os dois primeiros anos do simulador sísmico triaxial que brevemente começará a funcionar no LNEC. Este simulador destina-se ao ensaio dinâmico até á rotura de grandes modelos de edifícios e ponte (até 60t). Este simulador realiza uma conceção inovadora, que se traduz essencialmente pela eliminação dos 3 graus de liberdade de rotação através de 3 sistemas mecânicos constituídos por uma barra de torção, duas manivelas e duas bielas.

The paper presents the results that permit the identification of optimal design methods for building structures in terms of a eccentricity and are calibrated for probability of failure, evaluated for critical scenarios of expected earthquake intensities.

Some fundamental aspects concerning the overall conception and mechanical design of the new LNEC seismic shaking table, which will have three translational degrees of freedom, are presented. Considerations are made regarding its adaptive control, pointing out the interactions between the behaviour of the mechanical and control systems as far the overall performance of the seismic shaking table is concerned. Lastly, some considerations are also presented on the special building that houses the shaking table.

In this paper we an analytical model to study the hysteretic behavior, under cyclic loading, of RC frames infilled with masonry panels.The calibration of the parameters which define the analytical model, was performed according to the experimental results obtained with three infilled RC frames models and one bare frames model tested at the LNEC.With a good selection of parametric values, the fairly good fitting between analytical an experimental results, allows to conclude that this model can be used in the more broader framework of Earthquake Engineering and structural reliability of buildings under large intensity earthquakes.

A stochastic model of earthquake ground motion, with non-stationary amplitude and frequency content, is presented. This model is quantified on the basis of the information available from seismic hazard studies and strong ground motion seismology with the purpose of generating artificial accelerograms to be used in nonlinear analysis and design of structures. The stochastic model is defined by a

This paper presents the las developments on seismic hazard analysis directed to the computation of strong ground motion parameters to be applied to nonlinear structural analysis (Campos Costa,1992). It follows the Ishikama and Kameda approach (1988), and makes an application to the Lisbon site. Inhere, the methodology and the most probable seismic scenarios are presented. In an accompagning paper (Duarte et al, 1992), time series generation is obtained for a long distance and short distance earthquake scenarios.

This paper presents, in the light of LNEC experience in Earthquake Engineering studies, the limitations and advantages of shaking table testing of reinforced concrete and masonry structures. It starts with a general assessment of the contribution of shaking table facilities to the mitigation of earthquake risks and proceeds with a discussion of some specific problems of shaking table performance and testing procedures, like shaking table design alternatives, self-tuning control and numerical evaluation.

A methodology for the definition and quantification of behaviour coefficients to be used in the earthquake design of structure is presented. These coefficients are defined for specific design methods and are quantified by a target value of the probability of collapse. The methodology is quantified through the analysis and safety checking of structures defined by single variable models.

Nesta comunicação apresenta-se uma metodologia de quantificação de coeficientes de ductilidade de edifícios em betão armado que apresentam irregularidades em planta, e que possuem uma dada probabilidade de ruína.Foram considerados edifícios de 8 pisos com dimensões em planta 20x15 m2, os elementos resistentes a forças horizontais são pórticos planos e paredes estruturais, sendo a determinação dos valores resistentes elásticos limites feito em função de um dado processo de dimensionamento.Posteriormente, recorrendo a algoritmos de integração passo a passo, acedeu-se ao comportamento inelástico dos edifícios sob a ação sísmica intensa. Deste modo, obtiveram-se os valores máximos das ductilidades impostas, definidas em termos das relações momentos-curvaturas nas secções extremas dos elementos de barra, e para valores crescentes de ação sísmica.O cálculo dos coeficientes de ductilidade foi efetuado tendo em atenção quer os valores das probabilidades de serem excedidas as ductilidades disponíveis quer os potenciais mecanismos de colapso de cada edifício.

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

O presente estudo teve como objetivo a caracterização dinâmica e do comportamento mecânico da estrutura do edifício Sede I da EDP, para uma adequada simulação do seu comportamento sísmico. Neste relatório descrevem-se os ensaios de identificação dinâmica in situ realizados, com base em vibrações ambiente e em vibrações forçadas, com o objetivo de recolher informação sobre as propriedades dinâmicas da estrutura como um todo e das suas lajes dos pisos elevados em particular. Foi efetuado o registo e a análise dos sinais de aceleração devido a vibração ambiente, medidos em diversos pontos do edifício, bem como devido a vibrações forçadas impostas num dos pisos enterrados do edifício. São também apresentados e analisados os ensaios de caracterização do comportamento mecânico de componentes estruturais relacionadas com a ligação das lajes mistas dos pisos elevados às paredes dos núcleos resistentes de betão armado do edifício. Estes consistem em ensaios destrutivos de troços de laje mista ligados aos núcleos, por meio de varões selados à parede, e em ensaios de arrancamento desses varões, tendo como objetivo caracterizar os materiais e componentes dos elementos estruturais. Esta informação é essencial para a posterior calibração dos modelos numéricos da estrutura e para uma realista simulação do seu comportamento sísmico, bem como para uma eventual deteção de anomalias estruturais decorrentes de patologias que possam comprometer o desempenho do edifício face à ocorrência de sismos.

A avaliação da segurança sísmica de edifícios existentes tem como quadro de referência o Eurocódigo 8

Nos estudos probabilísticos para avaliação da perigosidade sísmica, são estabelecidas zonas de geração sísmica (zonas sismogénicas), representando regiões que partilham as mesmas caraterísticas sismológicas, tectónicas e geológicas e definidas as relações entre a frequência com que aí ocorrem os sismos e as respetivas magnitudes, num dado período de tempo. Em 2006, para o Anexo Nacional do Eurocódigo 8, foram consideradas e caraterizadas 11 zonas Sismogénicas para Portugal continental, adaptadas de estudos previamente elaborados em 1996. Entre 2008 e 2009, no âmbito dos projetos ERSTA e SHARE, foram propostas novas zonas sismogénicas, e estimados os respetivos parâmetros da lei de frequência - magnitude. Estas diferentes propostas resultaram em diferentes mapas de perigosidade sísmica para Portugal continental. A SPES, Sociedade Portuguesa de Engenharia Sísmica, espelhando a inquietude existente na comunidade científica face às diversas expressões da perigosidade sísmica em Portugal, e consciente da necessidade de um consenso perante os agentes decisores, considerou urgente a realização de um estudo criterioso acerca das opções tomadas, nos diferentes estudos, e suas implicações. É nestecontexto que surge este trabalho, que pretende fazer uma análise crítica e comparativa dos resultadosobtidos nos diferentes estudos mencionados e as suas implicações ao nível dos períodos de retorno para sismos de maior magnitude. Numa parte II, serão estudadas as implicações em termos de valores da perigosidade sísmica, para vários períodos de retorno e frequências espetrais.

O presente relatório, elaborado no âmbito de um estudo em curso no LNEC sobre a segurança sísmica das construções nas intervenções de reabilitação, sintetiza os instrumentos jurídicos e os conceitos relevantes para a análise do atual regime jurídico da reabilitação urbana (RJRU), e do regime excecional de reabilitação urbana (RERU).

This document reports the outcomes of the research project

This document reports the outcome of the seismic test on the Rusticasa building, the first in a total of four buildings included in the TIMBER BUILDINGS Project. This building is a log house system (LHS). The goal of the tests was to assess the seismic performance of the building, panel elements and steel connectors, defined in terms of relative displacements and hold-down forces.

This document reports the outcome of the seismic test on the LegnoCase building, the second in a total of four buildings included in the TIMBER BUILDINGS Project. This building is a platform frame system with sheathing assembled by means of OSB panels (PF-OSB). The goal of the tests was to assess the seismic performance of the building, panel elements and steel connectors, defined in terms of relative displacements and hold-down forces.

This document reports the outcome of the seismic test on the RubnerHaus building, the third in a total of four buildings included in the TIMBER BUILDINGS Project. This building is a platform frame system with sheathing assembled by means of gypsum fibre panel (PF-GF). The goal of the tests was to assess the seismic performance of the building, panel elements and steel connectors, defined in terms of relative displacements and hold-down forces.

This document reports the outcome of the seismic test on the TUGraz building, the fourth in a total of four buildings included in the TIMBER BUILDINGS Project. This building is a cross laminated system (CTL). The goal of the tests was to assess the seismic performance of the building, panel elements and steel connectors, defined in terms of relative displacements and hold-down forces.

The TIMBER BUILDINGS Project, led by the University of Trento, included testing of four full scale multi-story timber houses with a realistic horizontal plan and three types of timber housing systems: platform frame system (PFS), log house system (LHS) and cross laminated timber (CLT). The tests were carried in the LNEC-3D shake table under different levels of excitation and different conditions of the structure.The tests were carried with the goal of assessing the seismic performance of the buildings, panel elements and steel connectors, defined in terms of relative displacements and hold-down forces.The results were presented in separate reports, one for each building. This document contains information common to the remaining four reports.

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