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O risco refere-se à probabilidade de ocorrerem danos causados pela manifestação de um determinado perigo, sendo função da perigosidade, da exposição (de pessoas e bens) e da vulnerabilidade dos elementos expostos face a esse perigo.Um componente essencial da avaliação do risco è a análise da perigosidade associada aos perigos identificados num dado território, sejam de origem natural ou decorrentes da ação humana. Outro componente essencial é a análise dos elementos (pessoas e bens) expostos ...
In the transport infrastructures context, the support layers have a fundamental role in the degradation of the track condition, both in structural aspects and in terms of fouling of the materials that comprise them. Particularly in the field of railway research, ballast is the key element, and its fouling leads to track deterioration. Thus, the main focus of this work is based on the evaluation of the ballast fouling using Ground Penetrating Radar (GPR). In order to determine the applicabi...
This article presents the main concepts and the application of the discrete element method (DEM) for evaluating the seismic performance of historical buildings. Furthermore, the out-of-plane behavior of an adobe church with thick walls, in which the morphology of the cross-section can have an influence on the response, was evaluated by the DEM. The performance of rigid and deformable blocks models was compared, and the sensitivity of the numerical model to the variation of critical parameters...
Discrete element models are a powerful tool for the analysis of masonry, given their ability to represent the discontinuous nature of these structures, and to simulate the most common deformation and failure modes. In particular, discrete elements allow the assessment of the seismic behavior of masonry construction, using either pushover analysis or time domain dynamic analysis. The fundamental concepts of discrete elements are concisely presented, stressing the issues related to masonry mode...
Masonry arch bridges form a significant portion of the European transport infrastructure network. Many of these bridges are relatively old but still in service. Increasing vehicle loads and speeds have highlighted the need for reliable estimates of their service condition. Past research demonstrated that load-carrying capacity of a masonry arch bridge is a function of the soil response. However, today, the approaches used for the simulation of soil in masonry arch bridges are over-simplistic ...
Earthquakes represent one of the major threats to cultural heritage monuments, such as classical ancient columns. Understanding the behaviour and dynamic response of such historic structures is useful for the assessment of the conservation and rehabilitation techniques to be used for their preservation. The behaviour of ancient multi-drum and monolithic columns subjected to dynamic loads is characterized by highly nonlinearity since both rocking and sliding phenomena can occur. Analytical stu...
Over the last 50 years, a significant amount of effort has been taken to develop numerical approaches and tools for the structural analysis of masonry. These range from considering masonry as an anisotropic continuum (macro-models) to the more detailed ones considering masonry as an assemblage of units and joints (micro-models). In this paper, a detailed micro-modelling approach for the analysis of masonry couplets and prisms is proposed. The approach represents masonry units and mortar joint...
Abstract: Rigid block models are widely used in the analysis of masonry structures, as they provide a sound and efficient approximation of the observed behaviour, namely for modelling collapse modes that do not involve the internal failure of the units. The options available for the numerical representation of contact in rigid block models are discussed, in particular the well-known point contact approaches. The accuracy of the various options is compared for static and dynamical test problem...
Esta dissertação pretende ser um contributo para o desenvolvimento de uma metodologia de abordagem do problema da renovação de plataformas ferroviárias em serviço, em particular no que se refere à avaliação da capacidade de carga e técnicas de reforço. A referida metodologia foi desenvolvida com o objectivo de apoiar os projectos de renovação das vias férreas. Os principais aspectos abordados são os mecanismos que contribuem para a degradação das vias férreas, a caracterização “in situ” das p...
O desempenho exigido atualmente ao transporte ferroviário e, por consequência, às vias-férreas, no que se refere à qualidade de circulação, ao volume e tipo de tráfego a suportar e à durabilidade e eficiência económica da infraestrutura, exigem que a sua conceção e construção sejam feitas com base numa abordagem mecanicista e que os processos de manutenção e de reabilitação sejam conduzidos de forma eficiente, com base nas necessidades reais e no conhecimento do desempenho da estrutura. O Pro...
The Mozambican Roads Administration (ANE) has embarked on a project to establish a Road Research Centre (RRC) in Mozambique aiming to provide the basis for improving the long-term capacity to undertake relevant, high quality research relating to the road sector of Mozambique. This project forms part of the Africa Community Access Programme (AFCAP), which is a research programme supported by the Department of International Development (DFID) of the Government of the United Kingdom and managed ...
The Mozambican Roads Administration (ANE) has embarked on a project to establish a Road Research Centre (RRC) in Mozambique aiming to provide the basis for improving the long-term capacity to undertake relevant, high quality research relating to the road sector of Mozambique. This project forms part of the Africa Community Access Programme (AFCAP), which is a research programme supported by the Department of International Development (DFID) of the Government of the United Kingdom and managed ...
Executive Summary Infrastructure is the backbone of our society. Citizens, companies and governments have come to rely on and expect uninterrupted availability of the road network. Climate change is an important topic within the context of designing, maintaining and operating traffic networks. Most transport infrastructure is intended to be available (in service) to the public for several decades. The life cycles of assets in transport are long enough to take the full strain that comes with c...
O trabalho apresenta o estudo de uma escavação escorada num maciço de argila mole simulada numericamente com recurso a um modelo de cálculo elastoplástico baseado no método dos elementos finitos. Na análise dos resultados são postas em destaque as redistribuições de tensões por efeito de arco no maciço interessado pela escavação e identificados os parâmetros que contribuem para tal fenómeno. É proposta uma analogia estrutural simples para interpretar a interacção solo-estrutura.
O LNEC encontra-se a prestar assessoria ao Ministério da Defesa Nacional (MDN) num conjunto de questões técnico-ambientais suscitadas pela presença, nos últimos 60 anos, do contingente da Força Aérea Americana (USAFE) na Base das Lajes, nos Açores, relacionadas essencialmente com a eventual contaminação de solos e de águas subterrâneas decorrentes do armazenamento e manuseamento de reservas de combustíveis e de outras substâncias, tendo em atenção as práticas adotadas no passado. No âmbito d...
Portugal, embora possuindo um reduzido número de barragens, tem uma vasta experiência no projecto, construção e avaliação da segurança de barragens, em particular devido ao contributo dos estudos realizados no Laboratório Nacional de Engenharia Civil (LNEC). Neste país existem 7 barragens de enrocamento com cortina a montante, 4 delas construídas nos últimos 15 anos. Os autores do artigo têm desenvolvido vários estudos de investigação para todas estas barragens, nomeadamente no âmbito da obse...
LNEC's Scientific Repository
The LNEC Scientific Repository has the purpose of publicizing and allowing free access to the scientific production of its research community in the fields of civil engineering and related areas, promoting the sharing and visibility of scientific information and assuring the preservation of the institution's intellectual memory.
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