Papers
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Direct displacement-based design for RC structures
In the early nineties, the Performance-Based Seismic Engineering (PBSE) principles have been introduced in the seismic design of structures. Several authors have identified the limitations of traditional force-based design (FBD) procedures widespread in most of the design codes to accomplish the PBSE requirements. Therefore, various contributions were made towards the development of displacement-based seismic design methodologies, in particularly the one proposed by Priestley, known as "Direct Displacement-Based Design" (DDBD). The purpose of this work is to investigate the DDBD approach in its entirety. In particular, the emphasis is set herein on the definition of the equivalent viscous damping and on the concrete impact of choosing one or another expression. Then, the efficiency of applying DDBD to reinforced concrete (RC) plane frames and dual frame-wall structures is assessed and the consequences of using the linear response spectrum suggested in the Eurocode 8 as input data is investigated.
Year: 2018
Number Pages:
67-88pp.
Author(s): Massena, B.; Degée, H.; Candeias, P.; Bento, R.
: Revista Portuguesa de Engenharia de Estruturas (rpee)
Editor: LNEC
Volume:
Série III, N.º 6.
Keywords: Reinforced concrete buildings; Equivalent viscous damping; Direct displacement-based design
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Influência do número de sheds e da distância horizontal entre eles no desempenho da ventilação natural
A ventilação natural é uma eficiente estratégia para o condicionamento térmico passivo de edificações, e muitas vezes o seu potencial está relacionado às decisões em projeto diferentes do modelo convencional. Um exemplo são os sheds, aberturas na cobertura que funcionam como captadores ou extratores de ar, dependendo de sua localização em relação aos ventos dominantes. O objetivo do artigo é avaliar a influência do número de sheds e da distância entre eles no desempenho da ventilação natural. Os ângulos de incidência dos ventos analisados foram 0º, 45º, 135º e 180º. A metodologia adotada foi simulação por Dinâmica dos Fluidos Computacional (CFD), utilizando o software CFX. Os resultados indicam que o aumento do número de sheds reduz a renovação de ar interna para as situações de extração e captação de ar. Por outro lado, o aumento da distância entre esses dispositivos, incrementa o fluxo de ar interno para os sheds captadores. No entanto, teve-se uma redução na renovação de ar para os sheds extratores de ar. Isso ocorre pela redução da área total das abertiras de saída de ar, que apresenta uma influência na vazão volumétrica do edifício. Nos sheds captadores de ar o incremento ocorre, pois, apesar do aumento da distância ter reduzido o número das aberturas de entrada de ar, torna os sheds mais efetivos para captar o fluxo de ar.
Year: 2018
Number Pages:
161-176pp.
Author(s): Lukiantchuki, M.; Shimomura, A.; Marques da Silva, F.; Caram, R.
: Ambiente Construído
Editor: ANTAC (Associação Nacional de Tecnologia do Ambiente Construído)
Volume:
vol.18 no.2.
Keywords: Ventilação Natural; CFD
Info
Seismic vulnerability assessment of a RC pedestrian crossing
The paper addresses the seismic vulnerability assessment of a multispan footbridge, prone to span unseating due to shorter seat lengths. The structure is representative of a series of pedestrian crossings located in the Southern part of Portugal, a region with a relevant seismicity. A probabilistic approach allows considering the variability of the seismic action and uncertainties in the definition of the material properties and/or structural behavior. Based on incremental dynamic analyses and corresponding fragility curves, it is shown that, for code compliance design acceleration, there is a significant probability that the structure will only suffer minor damage.
Year: 2018
Number Pages:
18p.
Author(s): Cismasiu, C.; Santos, F.; Perdigão, R.; Bernardo, V.; Candeias, P.; Carvalho, A. M.; Guerreiro, L.
: Journal of Earthquake Engineering
Editor: Taylor & Francis
Keywords: Dowel connection; Fragility curves; Incremental dynamic analysis; Operational modal analysis; Seismic vulnerability assessment; Rc footbridges
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Seismic vulnerability assessment of a RC pedestrian crossing
The paper addresses the seismic vulnerability assessment of a multi-span footbridge, prone to span unseating due to shorter seat lengths. The structure is representative of a series of pedestrian crossings located in the Southern part of Portugal, a region with a relevant seismicity. A probabilistic approach allows considering the variability of the seismic action and uncertainties in the definition of the material properties and/or structural behavior. Based on incremental dynamic analyses and corresponding fragility curves, it is shown that, for code compliance design acceleration, there is a significant probability that the structure will only suffer minor damage.
Year: 2018
Number Pages:
18p.
Author(s): Cismasiu, C.; Santos, F.; Bernardo, V.; Candeias, P.; Carvalho, A. M.; Guerreiro, L.; Perdigão, Rui A. Silva
: Journal of Earthquake Engineering
Editor: Taylor & Francis
Keywords: Dowel connection; Fragility curves; Incremental dynamic analysis; Operational modal analysis; Seismic vulnerability assessment; Rc footbridges
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Shake table blind prediction tests: Contributions for improved fiber-based frame modelling
Distributed plasticity Euler-Bernoulli fiber beams are regularly used byresearchers and practitioners to simulate the nonlinear seismic responseof reinforced concrete framed structures. This study presents a sensitivityanalysis, combining newly proposed and existing goodness-of-fitmeasures, to identify commonly used engineering modeling optionsthat most critically influence the response accuracy. The dynamic behaviorof three distinct structures tested in international blind predictionchallenges is considered. Sensitivity parameters include equivalent viscousdamping, element formulation, strain penetration effects, andmaterial models. The results are critically discussed in light of theoreticalshortcomings of the model assumptions.
Year: 2018
Number Pages:
42p.
Author(s): Sousa, R.; Almeida, J.P.; Correia, A.A.; Pinho, R.
: Journal of Earthquake Engineering
Editor: Taylor & Francis
Keywords: Material models; Strain penetration; Equivalent viscous damping; Fiber element formulation; Sensitivity analysis; Reinforced concrete frames; Shake table tests; Numerical validation
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Simulation and measurements of wind interference on a solar chimney performance
The solar chimney is a stack-induced ventilation strategy used to improve thermal performance in buildings. Besides operating via a buoyancy-driven airflow, even low velocity winds can affect the chimney functioning in both positive and negative ways. In technical literature, though, few studies have considered the influence of windspeed and direction, as well as discharge coefficients and wind pressure coefficients. This paper investigates the effects of wind interference on a solar chimney performance, through different scenarios of wind speed and direction, over a base case model. Wind tunnel experiments and computer simulations using EnergyPlus were carried out to perform qualitative and quantitative analyses of the airflow, as a function of the combined effect of thermal and wind components. Results showed that the airflow rate and distribution pattern at the outlet openings of the solar chimney are influenced by either the thermal gradients and, mainly, by the outdoor windvelocity and direction. A significant reduction in the volumetric flow rate of the chimney is observed due to wind incidence opposite to the inlet opening, even at low velocities, such as 0.6 m/s.
Year: 2018
Number Pages:
135-145pp.
Author(s): Neves, L.; Marques da Silva, F.
: Journal of wind engineering and industrial aerodynamics
Editor: Elsevier
Volume:
179.
Keywords: Wind tunnel; Buoyancy; Solar chemney
Info
Caracterização do comportamento sísmico de edifícios de betão armado representativos do edificado português sem dimensionamento sismorresistente
Uma parte significativa do edificado em Portugal não foi dimensionada para resistir a ações sísmicas. Como tal, o recente impulso do sector da reabilitação pode representar uma oportunidade única para promover a redução da vulnerabilidade sísmica dos edifícios existentes. Neste contexto, o presente trabalho apresenta uma metodologia para avaliar a vulnerabilidade sísmica duma classe de edifícios de betão armado que permite estabelecer indicadores simplificados do seu desempenho estrutural expectável. A metodologia proposta baseia-se num estudo numérico detalhado do comportamento sísmico de edifícios de betão armado com características representativas duma parte significativa do edificado deste tipo em Portugal, simulando de forma adequada os principais aspetos da sua resposta estrutural. Os resultados obtidos pela metodologia desenvolvida permitem identificar as principais vulnerabilidades do edificado e quantificar indicadores de desempenho estrutural que permitem avaliar de forma expedita a sua segurança estrutural.
Year: 2017
Number Pages:
105-114pp.
Author(s): Sousa, R.; Costa, A.; Campos Costa, A.; Candeias, P.; Romão, X.
: RPEE
Editor: LNEC
Volume:
Série III, N.º 3.
Keywords: Indicador de desempenho estrutural; Comportamento sísmico; Betão armado; Reabilitação
Info
Carga aerodinâmica em sombreamentos em cascata
A arquitetura recorre, por vezes, a dispositivos de sombreamento de grandes dimensões, com formas e configurações de montagem cuja resposta à ação do vento carece de caracterização. Este facto condiciona o correto dimensionamento dos apoios e, em menor escala, a determinação do próprio material de construção dos dispositivos.As dimensões dos elementos constituintes destes dispositivos dificultam o recurso a ensaios com modelos reduzidos pelo que se recorreu a um modelo seccional do dispositivo à escala real, sujeito ao escoamento proveniente de um túnel de vento de jacto livre. As características específicas deste ensaio, nomeadamente a geometria do perfil de sombreamento e respetivos suportes, gama de forças e a necessidade de minimizar a obstrução adicionada pela instrumentação ao escoamento, ditaram o desenvolvimento de uma solução particular para a medição das forças aerodinâmicas.O ensaio permitiu avaliar as cargas induzidas pelo escoamento para vários ângulos de incidência fazendo variar a inclinação do modelo relativamente ao jacto através de um suporte articulado onde se montou o modelo seccional, permitindo assim caracterizar o desempenho aerodinâmico do perfil na aplicação em estudo.
Year: 2017
Number Pages:
8p.
Author(s): Marques da Silva, F.; Morais, P.; Pereira, I.; Bairrão, R.; Morais, J.
: Mecânica Experimental
Editor: APAET
Volume:
nº 29.
Keywords: Cascatas; Ação do vento
Info
Shape memory alloy based dampers for earthquake response mitigation
This paper describes the development process and initial tests performed with a new energy dissipation damper based on Shape Memory Alloy (SMA) wires. The aim of this study was to develop a new iteration of this type of devices, and eventually develop a methodology to properly design them for any type of application. The underlying concept of our device is the use of a double counteracting system of pre-strained SMA wire sections as the dissipating component. By using pre-strained wires, this design focuses on maximizing energy dissipation, partially relinquishing the re-centering capabilities of the device.The experimental part was performed on a downscaled prototype based on this design methodology. The goal of this study was to validate the basic mechanical concepts. The device was subjected to a considerable number of load cycling tests, in order to better characterize the SMA wire behavior when used in this arrangement and to improve our understanding of their influence on the device's capabilities.
Year: 2017
Number Pages:
705-712pp.
Author(s): Morais, J.; Gil de Morais, P.; Santos, C.; Campos Costa, A.; Candeias, P.
: Procedia Structural Integrity
Editor: Elsevier
Volume:
Vol. 5.
Keywords: Earthquake Response; Shape Memory Alloy; Vibration Damper
Info
Application of SASHA to seismic hazard for Portugal mainland.
In the frame of the UPStrat-MAFA
Year: 2016
Number Pages:
1827
Author(s): Carvalho, A. M.; Albarello, D.
: Bulletin of Earthquake Engineering
Editor: Springer
Volume:
Volume 14, Issue 7.
Keywords: Portugal; Macroseismic intensity; Seismic hazard
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Comunicação
Info
Tuned liquid dampers para redução de vibrações em edifícios
A utilização de dispositivos de dissipação de energia é atualmente vista como uma forma eficiente para proteger estruturas contra ações sísmicas. Um número considerável deste tipo de dispositivos tem vindo a ser instalados um pouco por todo o mundo. Muito recentemente dispositivos do tipo Tuned Liquid Dampers (TLD) tem despertado a atenção da comunidade científica internacional como forma simples mas eficaz para reduzir a resposta de edifícios quando sujeitos a ações dinâmicas.Os TLDs são tanques com água, com relações entre comprimento e altura de água tais que a sua frequência natural quase que se ajusta à frequência natural da estrutura cuja amplitude se pretende mitigar. A energia de vibração do edifício é transferida para a água em movimento (sloshing) onde se dissipa. Os princípios básicos de funcionamento são semelhantes aos observados para os Tuned Mass Dampers (TMDs), com a vantagem da instalação ser muito mais fácil e económica. Tanto TLDs como TMDs apresentam bom desempenho para estruturas flexíveis, de frequências naturais pouco elevadas.Em Portugal, devido principalmente à reduzida altura das construções, este tipo de dispositivos não é muito conhecido ou utilizado. Não obstante isso as construções Portuguesas modernas tem uma tendência natural para se tornarem mais flexíveis sendo portanto previsível que o uso de TLDs se torne uma boa opção para redução dos deslocamentos horizontais sofridos pelas estruturas, atendendo aos custos reduzidos associados à construção, colocação e manutenção destes dispositivos. O artigo descreve o estudo experimental sobre TLDs iniciado em Bristol (U. Bristol) e em continuação no LNEC, apresentando alguns dos resultados preliminares obtidos.
Year: 2007
Author(s): Falcão Silva, M. J.; Campos Costa, A.; Symes, J.A.; Macdonald, J.H.G.
Editor: FEUP e SPES
Keywords: Tuned Liquid Dampers (TLD); Dispositivos de dissipação de energia
Info
Damage identification based on vibration measurements applied to masonry structures
The present paper aims to explore damage assessment in the masonry structures at an early stage by vibration measurements. Two replicates of historical constructions were built in virgin state: one arch with 1.5 m span and one shear wall with 1.0 m2. Afterwards, progressive damage was applied and sequential modal identification analysis was performed at each damage stage, aiming to find adequate correspondence between dynamic behavior and internal crack growth. Accelerations and strains in many points were record in the replicates. Eigen frequencies, mode shapes and modal strains were derived from the dynamic measurements. Environmental effects of the temperature and relative humidity on the dynamic response were studied. A first updating process was performed on the results of the undamaged arch to tune a finite element model. Moreover, the tests were repeated with added masses to scale the mode shapes. Finally, a brief analysis of the results of the several damage scenarios are presented in the paper.
Year: 2006
Number Pages:
16p.
Author(s): Ramos, L.; De Roeck, G.; Lourenço, P.; Campos Costa, A.
Editor: Katholieke Universiteit Leuven
Keywords: Masonry structures; Historical constructions
Info
Double-skin façade thermal monitoring.
This paper concerns to the post-occupancy monitoring of a building sited in Lisbon with transparent double-skin façades (DSF). This is the first of an enlarged monitoring program covering other buildings and weather conditions aiming to clarify under which climate and performing conditions this architectural solution is acceptable. Within this campaign an enlarged set of parameters were measured, covering from outdoor conditions to indoor comfort. The present paper focus is the thermal behaviour of the façade.
Year: 2006
Number Pages:
111-116pp.
Author(s): Marques da Silva, F.; Gomes, M.; Pinto, A.; Pereira, I.; Rodrigues. A.
Editor: ISIAQ e IDMEC
Volume:
Vol. 3.
Keywords: Thermal behaviour; Monitoring; Double-skin façade
Info
Dynamical behaviour of rigid block structures subjected to earthquake motion
This paper studies the dynamic behaviour of rigid-block structures under seismic behaviour. For this purpose, an experimental investigation has been carried out on the rocking response of single blocks, and ensembles of two and three blocks structures. These structures were subjected to three different base motions: free rocking, harmonic and random excitations. The tests were performed at the seismic table of the National Laboratory of Civil Engineering (LNEC) of Portugal.
Year: 2006
Number Pages:
8p.
Author(s): Peña, F.; Prieto, F.; Lourenço, P.; Campos Costa, A.
Editor: Macmillan
Keywords: Seismic test; Rigid-block
Info
Ensaios sísmicos a uma solução de edifício de betão armado pré-fabricado
Esta comunicação descreve os ensaios sísmicos efetuados no LNEC a uma estrutura pré-fabricada de betão armado. Os ensaios foram desenvolvidos com o apoio da Comissão Europeia e no âmbito do projeto de investigação PRECAST STRUCTURES EC8
Year: 2006
Number Pages:
16p.
Author(s): Mendes, L.; Coelho, E.; Campos Costa, A.
Editor: LNEC
Keywords: Estruturas pré-fabricadas de betão Armado; Comportamento sísmico
Info
In-situ assessment of important existing structures
Much work in Earthquake Engineering was devoted to the improvement of earthquake resistant design of new structures. In several years EN 1998 will be the main seismic code for all European countries. But it is well known, that in many large earthquakes older existing structures cause 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
Year: 2006
Number Pages:
10p.
Author(s): Flesch, R.; Lu, S.; Eusebio, M.; Campos Costa, A.; Oppe, M.; Veit-Egerer, R.
Editor: Swiss Society for Earthquake Engineering and Structural Dynamics ( SGEB )
Keywords: LESSLOSS; Mitigation
Info
Seismic hazard disaggregation studies. Application to mainland Portugal
Earthquake scenarios are used in different activity domains like: civil protection disaster preparedness, computing overall seismic losses for a portfolio, or evaluating time histories and ground motion duration to be used in seismic design. However, the choice of an earthquake scenario is often based on deterministic arbitrary assumptions, like the region worst historical event reported. The purpose of this work is to overcome the disadvantages of a deterministic approach, in what concerns the choice of earthquake scenarios in Portugal. For each of the 278 Portuguese counties, a scenario ground motion based on a probabilistic seismic hazard disaggregation analysis is evaluated. Portuguese probabilistic seismic hazard analysis is reviewed in order to perform its disaggregation. Probabilistic seismic hazard was disaggregated considering different spaces of random variables. Bivariate conditional hazard distributions in X-Y (seismic source latitude and longitude) are analyzed, as well as multivariate conditional hazard distributions in M-R-
Year: 2006
Number Pages:
9p.
Author(s): Luísa Sousa, M.; Campos Costa, A.
Editor: Swiss Society for Earthquake Engineering and Structural Dynamics ( SGEB )
Keywords: Seismic hazard; Earthquake scenarios
Info
Seismic tests of a RC precast building system
This paper describes and analyses the results of the seismic tests preformed at LNEC in a RC precast structure which is representative of a Portuguese system. This type of precast construction is used mainly for industrial buildings and was designed and constructed by a precast company with their common practice. The precast system can be considered as jointed with dry connections of limited ductility. A scaled 1/3 specimen was tested on LNEC
Year: 2006
Number Pages:
10p.
Author(s): Mendes, L.; Coelho, E.; Campos Costa, A.
Editor: Swiss Society for Earthquake Engineering and Structural Dynamics ( SGEB )
Keywords: Reinforced concrete; Seismic tests
Info
Shake table tests of a 3-storey irregular RC structure without engineered earthquake resistance
With the purpose of assessing the seismic behaviour of a reinforced concrete building structure non-seismically designed, an experimental study was carried out at the LNEC/Lisbon shake table, within the framework of the European project SPEAR. The tested structure was a simplification of a 3-storey building, irregular in plan, representative of older construction in southern Europe, without engineered earthquake resistance. It was designed for gravity loads alone, using the concrete design code used in Greece between 1954 and 1995, with construction practice and materials commonly used in southern Europe in the early 70
Year: 2006
Number Pages:
10p.
Author(s): Coelho, E.; Campos Costa, A.; Falcão Silva, M. J.; Candeias, P.
Editor: Swiss Society for Earthquake Engineering and Structural Dynamics ( SGEB )
Keywords: Reinforced concrete; Shaking table
Info
Shaking table tests on an asymmetric limestone building
This paper describes the shaking table tests of an asymmetric limestone masonry building, under different reinforcement conditions. The work was performed in the aim of the project
Year: 2006
Number Pages:
10p.
Author(s): Bairrão, R.; Falcão Silva, M. J.; Campos Costa, A.; Coelho, E.; Juhasova, E.
Editor: Swiss Society for Earthquake Engineering and Structural Dynamics ( SGEB )
Keywords: Asymmetric limestone building; Shaking table
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Books
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Historical earthquake-resistant timber framing in the mediterranean area
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
Year: 2016
Number Pages:
468p.
Author(s): Cruz, H.; Saporiti Machado, J.; Campos Costa, A.; Candeias, P.; Catarino, J. M.
Editor: Springer
Volume:
Vol. 1.
Keywords: Heart 2015 Conference; Historic Masonry; Performance-based Assessment; Structural Health Monitoring; Timber-Framed Construction Systems; Seismic-Resistant Timber Frames; Historical Constructive Analysis; Historical Timber-Framed Walls
Info
Assessment of the seismic capacity of stone masonry walls with block models
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.
Year: 2011
Number Pages:
221-236pp.
Author(s): Lemos, J. V.; Campos Costa, A.; Bretas, E. M.
: Computational Methods in Earthquake Engineering
Editor: Springer
Volume:
Vol. 21.
Keywords: RTigid blocks; Discrete elements; Seismic assessment; Masonry structures
Info
Earthquake disaster scenario prediction and loss modelling for urban areas
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
Year: 2007
Number Pages:
180p.
Author(s): Campos Costa, A.; Carvalho, A. M.
Editor: IUSS Press
Keywords: Shaking scenarios
Info
European manual for in-situ assessment of important existing structures. LessLoss Sub Project 5-In-situ assessment, monitoring and typification of buildings and infrastructure
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.
Year: 2007
Number Pages:
195p.
Author(s): Campos Costa, A.; Candeias, P.; Mendes, L.; Flesch, R.; Pellegrini, R.; Friedl, H.; Hoffmeister, B.; Oppe, M.; Veit-Egerer, R.; Wenzel, H.; Eusebio, M.
Editor: IUSS Press
Keywords: Structures; Earthquake
Info
Modal analysis from ambient vibration survey of bridges: LNEC experience
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.
Year: 1999
Number Pages:
712-718pp.
Author(s): Rodrigues, J.; Campos Costa, A.
: Proceedings of the 17th International Modal Analysis Conference : February 8 - 11, 1999 / IMAC XVII.
Editor: SEM
Volume:
Vol. 3727.
Keywords: Dynamic properties; Bridge structures
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O Sismo de Northridge, Los Angeles, de 17 Janeiro de 1994. Ensinamentos para Portugal.
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.
Year: 1995
Number Pages:
165p.
Author(s): Oliveira, C.S.; Costa, A.; Campos Costa, A.; Azevedo, J.; Delgado, R.M.
Editor: IST e FEUP
Keywords: Northridge earthquake; Earthquake effects
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Capítulo de Livro
Info
Shaping favorable beliefs towards seismic protection through risk communication: A pilot-experience in two Lisbon schools (Portugal).
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
Year: 2019
Number Pages:
445-458pp.
Author(s): Silva, D. S.; Vicente, M.; Pereira, A.; Candeias, P.; Ferreira, M.A.; Oliveira, C.S.; Bernardo, R.; Lopes, M.; Henriques, P.
: Proceedings of the International Conference on Earthquake Engineering and Structural Dynamics
Editor: Springer Link
Volume:
Volume 47.
Keywords: Non-structural; Protective behaviours; Risk communication; Seismic risk
Info
Characterization of timber masonry walls with dynamic tests
Most of the Lisbon 18th century timber-framed masonry
Year: 2018
Number Pages:
299-309pp.
Author(s): Gonçalves, A.; Candeias, P.; Guerreiro, L.; Ferreira, J.; Campos Costa, A.
: Historical earthquake-resistant timber framing in the mediterranean area
Editor: Springer
Volume:
Vol. 1.
Keywords: Shaking table tests; Timber-masonry walls;
Info
KnowRISK practical guide for mitigation of seismic risk due to non-structural components
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.
Year: 2018
Number Pages:
309-321pp.
Author(s): Ferreira, M.A.; Oliveira, C.S.; Lopes, M.; Musacchio, G; Candeias, P.; Vicente, M.; Silva, D. S.; O
: Proceedings of the International Conference on Earthquake Engineering and Structural Dynamics
Editor: Springer Link
Volume:
Volume 47.
Keywords: Practical guide; Community resilience; Preparedness; Non-structural elements
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Elastic and inelastic analyses of frames with a force-based higher-order 3D beam element accounting for axial-flexural-sheartorsional interaction
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
Year: 2016
Number Pages:
109-128pp.
Author(s): Correia, A.A.; Almeida, J.P.; Pinho, R.
: Computational Methods in Applied Sciences
Editor: Springer
Volume:
Vol. 3.
Keywords: Inelastic response; Boundary conditions; Flexural-shear-torsional interaction; Higher-order; Force-based; Beam element
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A finite-fault modeling of the 1755 Lisbon earthquake sources
A non
Year: 2009
Number Pages:
433-454.
Author(s): Carvalho, A. M.; Campos Costa, A.; Sousa Oliveira, C.
Editor: L.A. Mendes-Victor et al. (eds)
Keywords: Earthquake scenarios; Finite-fault modeling
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Simulating earthquake scenarios in the european project Lessloss: the case of Lisbon
N/A
Year: 2009
Number Pages:
233-243.
Author(s): Zonno, G.; Carvalho, A. M.; Franceschina, G.; Akinci, A.; Campos Costa, A.; Coelho, E.; Cultrera, G.; Pacor, F.; Pessina, V.; Cocco, M.
Editor: L.A. Mendes-Victor et al. (eds)
Keywords: Earthquake scenarios
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Shaking table testing
This text reflects the first of the four lectures that the author has presented at Udine, Italy, at CISM
Year: 2008
Number Pages:
165-196pp.
Author(s): Bairrão, R.
Editor: Springer Verlag
Keywords: Shaking table testing
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Tese de Doutoramento
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Modelos estocáticos para a caracterização da acção sísmica em Portugal Continental
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
Year: 2009
Author(s): Carvalho, A. M.
Keywords: Portugal continental; Risco sísmico; Fonte sísmica; Modelos estocásticos; Acção sísmica
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Risco sísmico em Portugal Continental
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.
Year: 2009
Author(s): Sousa, M. L.
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Avaliação da vulnerabilidade sísmica de edifícios de alvenaria
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
Year: 2008
Author(s): Candeias, P.
Keywords: Reforço sísmico; Vulnerabilidade sísmica; Ensaios sísmicos; Edifícios
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Relatório Científico
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Earthquake risk scenarios for selected European cities
O Laboratório Nacional de Engenharia Civil (LNEC) participa atualmente numa das sete Tarefas, doprojeto Europeu SHARE- Seismic Hazard Harmonization in Europe, mais precisamente na tarefa nº 2,intitulada Requisitos de engenharia e aplicações.O presente relatório de progresso descreve a participação do LNEC na sub-tarefa 2.5 - Cenários derisco sísmico para cidades Europeias selecionadas
Year: 2012
Number Pages:
44.
Author(s): Luísa Sousa, M.; Carvalho, A. M.
Editor: LNEC
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Actividade experimental na área dos sistemas passivos para a protecção sísmica de estruturas: Experiência do NESDE - Relatório de estágio
N/A
Year: 2011
Number Pages:
74pp.
Author(s): Falcão Silva, M. J.; Campos Costa, A.
Editor: LNEC
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Modelos de comportamento dinâmico aplicáveis a amortecedores de líquido sintonizado - Relatório de estágio
No presente relatório pretendem-se apresentar e definir alguns das linhasorientadoras para a simulação do comportamento dinâmico de fluidos no interior deAmortecedores de Líquido Sintonizado (TLDs), de acordo com o proposto na literatura.O problema da modelação do comportamento de fluidos no interior deAmortecedores de Líquido Sintonizado, à semelhança do que acontece parareservatórios, é complexo, sendo apresentados os principais modelos matemáticos emecânicos utilizados na actualidade.Assim serão descritos modelos de comportamento adoptados no casoparticular dos Amortecedores de Líquido Sintonizado (TLDs) e modelos simplificadosde sistemas de 1 (SDOF) ou mais graus (MDOF) de liberdade com com os referidosdispositivos de mitigação de acções dinâmicas acopladosO presente relatório servirá, à semelhança dos relatórios Sistemas passivos,activos, híbridos e semi-activos: Estado dos conhecimentos, Actividade experimentalna área dos sistemas passivos para a protecção sísmica de estruturas: Experiência doNESDE e Modelos de comportamento dinâmico para fluidos no interior dereservatórios como uma das linhas orientadoras para o desenvolvimento dos trabalhospropostos no âmbito do PIP 2009-2012 do NESDE-DE Protecção Sísmica deEstruturas: Reabilitação, reforço e sistemas inteligentes.
Year: 2011
Number Pages:
159pp.
Author(s): Falcão Silva, M. J.; Campos Costa, A.
Editor: LNEC
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Modelos de comportamento dinâmico para fluidos no interior de reservatórios - Relatório de estágio
N/A
Year: 2011
Number Pages:
176pp.
Author(s): Falcão Silva, M. J.; Campos Costa, A.
Editor: LNEC
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Sistemas passivos, activos, híbridos e semiactivos para a protecção sísmica de estruturas: Estado dos conhecimentos - Relatório de estágio
N/A
Year: 2011
Number Pages:
226pp.
Author(s): Falcão Silva, M. J.; Campos Costa, A.
Editor: LNEC
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Estabelecimento de cenários sísmicos para a região do Algarve com base em metodologias probabilísticas - Relatório de Estágio
N/A
Year: 2010
Number Pages:
89pp.
Author(s): RODRIGUES, I.; Sousa, M. L.
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NEFOREEE PROJECT
This Report corresponds to Task 2 of the NEFOREEE (New Fields of Research inEarthquake Engineering Experimentation) Project and comprises the description of theLNEC triaxial seismic platform and a presentation of the experimental programdeveloped in the scope of this Project.It is presented a description of the facility and the 3D seismic table with graphicalsupport, drawings of sizing and photographs, as well as its control system. The maininstrumentation available at the NESDE laboratory and used for this test is alsoincluded in this report.The model tested is described as well as the sequence of tests and the correspondingobtained results. Finally a brief analysis of the results is made.
Year: 2009
Number Pages:
325pp.
Author(s): Falcão Silva, M. J.; Campos Costa, A.; Bairrão, R.
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RELATÓRIO FINAL DO PROJECTO USUET
O presente relatório final do projecto USuET integra o trabalho já apresentado norelatório de progresso de Sousa & Afonso [2007], nomeadamente no que toca aoscapítulos 2, 3 e parte do capítulo 4 e, adicionalmente, descreve, em detalhe, asactividades desenvolvidas no projecto desde a data desse relatório (secção 4.2, ecapítulos 5 e 6). A parte da investigação conducente à actualização do Simulador deCenários Sísmicos para ambiente WebSIG, aplicado ao Arquipélago dos Açores, não seencontra descrita com o mesmo detalhe, neste relatório, pois enquadra-se na tese demestrado em Sistemas de Informação Geográfica de Afonso [2007], submetida àUniversidade Técnica de Lisboa. A versão definitiva desta tese, cuja discussão se prevêainda em 2008, será enviada oportunamente.
Year: 2008
Number Pages:
90pp.
Author(s): Sousa, M. L.; Afonso, N.
Keywords: Projecto usuet; Análise sistémica
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Cyclic tests of joints from a reinforced concrete precast building system
N/A
Year: 2007
Number Pages:
204pp.
Author(s): Mendes, L.; Coelho, E.; Campos Costa, A.
Info
Cyclic tests of joints from a reinforced concrete precast building system
This report describes the second phase activity of the Portuguese group in the Precast Structures EC8 research project. The Portuguese group is composed by Laboratório Nacional de Engenharia Civil (LNEC) and the Civibral, S.A. precast company. This phase follows the shaking table tests of a 2 stories structure of the same precast system, which is commercialized by Civibral. More information about these tests can be found in the repor.The goal of the work presented in this document is to assess the seismic behaviour of column-foundation and beam-column connections from the same precast system. To help achieve this goal, 4 column-foundation and 10 beam-column connections were tested using quasi-static, monotonic and cyclic tests, which were made imposing displacements to the specimens. The column-foundation connections (CFC) can be categorized as socket connections and the beam-column connections (BCC) as dry connections using only mechanical devices to transmit forces between elements. All the specimens were supplied and mounted by Civibral personal.
Year: 2007
Author(s): Mendes, L.; Coelho, E.; Campos Costa, A.
Keywords: Reinforced concrete; Cyclic tests
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Outro
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Sensibilidade climática, capacidade adaptativa e de vulnerabilidades atuais e futuras da AML
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.
Year: 2019
Author(s): Marques da Silva, F.; Pinto, A.; Machado, P.
Keywords: Energia; Alterações climáticas
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A propósito da forma na engenharia do vento
Análise da forma das edificações nas ações do vento
Year: 2018
Author(s): Marques da Silva, F.
Keywords: Engenharia do vento; Aerodinãmica
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Forma e desenho urbano - efeitos na ventilação
As condicionantes arquitetónicas e de urbanização na ventilação natural
Year: 2018
Author(s): Marques da Silva, F.
Keywords: Engenharia do vento; Ventilação
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Wind and structures
Caracterização do vento. Ações sobre estruturas. Ensaios em túnel de vento
Year: 2017
Author(s): Marques da Silva, F.
Keywords: Wind tunnel; Actions on structures; Wind engineering
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