Artigos de Revista

The ballast mechanical behavior is one of most important aspects governing the performance and safety conditions of railway track lines. Usually comprised of natural crushed rock, the research for alternative ballast materials becomes interesting both environmentally and economically. This paper presents a comparison between aggregates of steel slag and granite by means of monotonic and cyclic triaxial tests carried out on scaled down ballast specimens. The monotonic triaxial tests were conducted at three different confining pressures to failure and to critical state. The long-term cyclic tests (at least 106 cycles) were conducted in two stress paths compatible with heavy haul loadings. The results showed that the steel slag aggregate has higher values of strength parameters compared to the granite aggregate and better long-term deformability behavior, expressed by lower degradation and particle breakage and a faster tendency for stabilization the permanent deformation.

No 14º Encontro Internacional de Modelação Numérica em Barragens, organizado pela ICOLD, foi proposta a análise numérica de uma barragem de betão em arco localizada na Suécia sujeita a gradientes térmicos significativos ao longo do ano. Neste artigo apresentam-se os resultados numéricos obtidos com base numa discretização mais refinada do corpo da barragem, quando comparada com o modelo adotado no encontro internacional. Os resultados da análise mecânica realizada com um modelo de fenda discreta são comparados com as observações in situ. Verifica--se que o modelo estrutural mais refinado permite obter resultados mais próximos dos observados, nomeadamente a distribuição de fendilhação no paramento de jusante e o campo de deslocamentos. Analisa-se ainda o efeito das armaduras distribuídas colocadas junto ao paramento de montante e ao paramento de jusante no controlo de deformação e fendilhação.

This paper focuses on studying the dynamic behaviour of large dams over time, including identification of modal parameters (natural frequencies, modal damping ratios and mode shapes) and seismic response analysis, based on measured acceleration time histories. A comparison between experimental results obtained from continuous vibration monitoring data and numerical modelling results from 3D FE models is presented. The aim is to emphasize the interest of combining the use of recorded data from continuous dynamic monitoring systems and of numerical modelling software for seismic and structural health monitoring of dams.

Neste artigo, que, de certa forma, antecipa a conclusão de uma ampla reflexão sobre o que se designou como o "Habitar e Viver Melhor", uma designação que, aliás, dá título a uma série editorial da Infohabitar, depois de uma introdução ao que podemos considerar como uma inovação coerente e consistente no espaço doméstico, aborda-se e comenta-se um amplo leque de características de originalidade doméstica e conclui-se a reflexão com um exercício idêntico sobre as características de apropriação e inovação domésticas.

Fluid-dynamic interference among cylindrical structures in arrays, frequently used in engineering, is of fundamental and practical interests since it may considerably change fluid-structure interactions and produce large fluctuating forces on structures that cause vibrations, lock-in and important motions. This paper aims to study the mutual interference between two circular cylinders in tandem arrangement, which is considered the simplest configuration of one array cylinders, elastically mounted in transversal direction and subject to a bi-dimensional uniform laminar flow at low Reynolds numbers. Both cylinders have the same diameter D and the center-to-center spacing is equal to L = 5.25D which corresponds to co-shedding regime. The academic numerical model Ifeinco, which is based on the finite element method and uses a partitioned scheme that considers two-way interaction of fluid flow and structure, has been employed to the analysis. Combinations of upstream and downstream stationary and elastically mounted cylinders are investigated for Reynolds number range from 90 to 140. Differences of flow behaviors drag and lift forces and resonance between single cylinder and cylinders in tandem arrangement were found. Mutual and respective influence of upstream cylinder motion on the downstream cylinder and vice-versa are analyzed. Results show that, in some engineering studies, the consideration of the flexibility of cylindrical structures in arrays is fundamental since it influences significantly the interference between cylinders, mainly the magnitude and direction of forces and characteristics of the resonance range, and, consequently, structural and dynamical behaviors.

Gullies are sewer inlets placed in pavements usually covered by bar grates. They are the most common linking-element used to drain a wide range of flows from surface runoff into the buried drainage system. Their hydraulic behavior and their overall hydraulic performance is dependent on the flow conditions, the gully dimension, geometry, and location of the outlet device. Herein a numerical research based on Volume Of Fluid (VOF) to detect the interface, and on the Shear Stress Transport SSTk-w turbulence model was conducted to study the importance of the outlet location and characterize flows through them in drainage conditions. Results provided detailed information about flow features, discharge coefficients, and efficiencies for different outlet locations. The authors identified three different regimes, R1, R2, and R3, and concluded that the outlet location influences the velocity field along the gully, the discharge coefficient, and the drainage efficiency. This allows for the estimation of uncertainty and its variation for different outlet positions.

Considerando-se, como base de reflexão, a ideia de uma habitação poderá ganhar muito em flexibilidade de uso e capacidade de apropriação se for constituída mais por “microsítios” específicos do que por espaços ditos de/para as “tradicionais” actividades e funções domésticas, importa tirar o máximo partido da aplicação da cor no interior doméstico, tendo-se em conta, designadamente, a relação entre os tons de cor e a orientação solar dos compartimentos, as relações já conhecidas entre o cromatismo e a fruição espacial, as considerações de diferentes autores sobre as cargas emocionais das cores e, naturalmente, o objetivo “central” de uma desejável e afirmada agradabilidade dos acabamentos interiores domésticos.

This paper describes a programme under the responsibility of the National Laboratory for Civil Engineering (LNEC), Portugal for the systematic observation and monitoring of maritime works, termed OSOM+, which has been applied to an extensive number of maritime structures on the Portuguese mainland coast and abroad. The OSOM+ programme comprises the following four main components for each structure: a) Periodic visual inspections by a trained technician; b) Periodic aerial inspections using a UAV/drone; c) The ANOSOM-GIS database, to store and/or query obtained information, as well as to diagnose present, evolution and risk conditions; and d) A mobile, portable, application, for real-time input and visualization of the ANOSOM-GIS database information. This recently updated methodology encompasses a number of tools whose functionalities are illustrated in this paper with an application to a case study: the Ericeira’s breakwater, in Portugal.