Papers

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.

O presente trabalho apresenta uma formulação analítica do cálculo dos deslocamentos (rotação, flecha e deslocamento axial) de uma secção transversal qualquer dum elemento estrutural de barra plano (viga ou coluna-viga, p. ex.) de secção rectangular, de aço, submetido a uma força axial constante e a um momento flector em cada uma das suas extremidades. As equações apresentadas fornecem um método de cálculo não linear expedito e exacto, alternativo aos métodos clássicos das “rótulas plásticas” ou da “zona plástica”, e constituem uma base para o posterior desenvolvimento de outros métodos analíticos de cálculo não linear com aplicações mais alargadas, nomeadamente para o cálculo das matrizes de flexibilidade ou de rigidez elastoplástica destes elementos, ou de elementos estruturais de barra com outros tipos de secções transversais (perfis em I ou secções tubulares rectangulares, por exemplo).

double-skin façades (DSF) areused as an architectural solution to improve indoor comfort being characterized by having at least two membranes between the indoor occupied space and the exterior environment, separated by ana ir gap where the shading devices lie. The pressure within he gap plays an important role on i) the glazing structural safety; ii) te sahft ventilation, in particular if a natural ventilation scheme is implemented, but also to promote an efficient gap air change, and; iii) the safety of the maintenence satff, especially when windows may be opened to the interior.Although there are several DSF typologies only the multi-storey case, where no horizontal or vertical partitioning exists between the two skins, will be analised in this paper. Nevertheless, there are still a number of possible layouts for multi-storey DSF that might impose different pressure distributions within the gap. This paper refers to a set of wind tunnel tests made over a building model wit different multi-storey DSF layouts - from open an all edges to fully lateral closure and from naroow to wide gap depths, for an extented range of wind directions. The experimental data showed a layout dependent inner wall pressure distribution that may be considered different from the unsheltered building.

A oferta de produtos de madeira no mercado da construção tem vindo a crescer de forma clara na última década, multiplicando-se a variedade de espécies florestais utilizadas, os tipos de produtos comercializados e, paralelamente, as suas utilizações potenciais. O interesse dos utilizadores e, muito particularmente dos arquitectos, pela madeira prende-se, em grande medida, com o carácter ecológico e o conforto geralmente associados a este material. Interesse que é potenciado pela presente variedade de produtos de construção à base de madeira disponíveis, especialmente na forma de materiais de revestimento de piso e de paredes, para interiores e exteriores. A aplicação de placas de derivados de madeira em painéis de revestimento de fachadas exteriores tem vindo a ser realizada, no nosso País, envolvendo placas de contraplacado marítimo ou placas de laminados a alta pressão (HPL), vulgarmente designadas por placas fenólicas. O mercado tende a considerar o contraplacado como um produto tradicional e menos sofisticado (atendendo à experiência de uso no nosso País), e o HPL um produto sofisticado (face ao pouco conhecimento acerca do seu modo de produção) e inovador (pela ainda reduzida tradição de aplicação). No entanto, ambos são abrangidos pela marcação CE com base em normas harmonizadas (o contraplacado pela EN 13986:2004 e o HPL pela EN 438-7:2005). O desempenho destas placas tem sofrido alguns revezes, que se prendem na maioria das vezes com o desconhecimento da legislação aplicável e com a falta de ensaios de validação da qualidade do produto face à sua utilização (crítica, no caso de investimentos avultados).

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A generalidade das estruturas correntes de madeira actualmente em serviço recorre a ligações por entalhe. Na ausência de elementos metálicos, a transmissão de esforços entre peças é feita principalmente por compressão e corte da madeira, o que limita a sua utilização a situações muito específicas. Elementos metálicos surgem frequentemente adicionados a algumas das ligações, nomeadamente onde é essencial assegurar a transmissão de esforços de tracção, sendo comum os esquadros metálicos, aplicados nas faces dos elementos que convergem na ligação, as braçadeiras, que cintam os elementos em torno da ligação, e as cavilhas, que os atravessam. Em Portugal, ligações de tipo tradicional com recurso a entalhe são encontradas correntemente em asnas de cobertura com vãos geralmente inferiores a 12 metros, verificando-se contudo uma grande diversidade no que se refere à qualidade de execução das respectivas ligações. A avaliação da segurança destas estruturas e a definição de eventuais acções de reparação e reforço levanta frequentemente dificuldades, na medida em que o funcionamento e o dimensionamento destas ligações são claramente dominados pelos técnicos envolvidos.

This study investigates the annual and inter-annual longshore transport at a high-energy dissipative beach (St. Trojan, SW Ole´ron Island, France), over the period 1997–2006. This study is divided in two parts: (1) a short-term study, based on field measurements carried out during, low, moderate and highenergy swell conditions, and permitting to calibrate a wave propagation model and both empirical longshore sediment transport formulas and a hydro-sedimentary numerical model; and (2) a long-term study, combining global optimization methods using WAVEWATCH III (WW3) model outputs and wave numerical modelling to define the nearshore wave climate and then to compute the annual and interannual longshore transport. A good agreement between the different methods was obtained and values for the annual longshore transport ranged from about 50,000720,000m3/yr to 140,000730,000m3/yr. The net annual longshore transport displayed an inter-annual variability, whereas values were always 3–10 times less than those proposed in previous studies. Such differences point out the necessity of calibrating empirical transport formulas and computing accurately the nearshore wave climate. The relatively low values for the net annual longshore transport were explained by a weak contribution of the most energetic swells, which systematically approach the shore with a frontal obliquity and also generate episodes of reverse transport. The methodology itself was also discussed, pointing out the limitations of this study but also the advantages of using WW3 data and simplified wave climates

Moisture is one of the most powerful causes of decay of historic buildings. A lack of understanding concerning the action of moisture and the resulting degradation mechanisms are often preventing efficient repair of ancient walls. Thus, there is a need to develop and systematise a methodology of diagnosis of defects due to moisture, taking into account the characteristics and properties of materials used on those walls. The use of in situ test methods, especially non-destructive methods, is an important tool, but those methods must be adapted to this particular use, calibrated and interrelated in a global approach. As a result of a Research Project developed at LNEC a methodology involving several phases is proposed, based on tests applied to several case studies and on the analysis of their results. This work synthesises the proposed methodology presenting examples of data combinations for the suggested techniques and its interpretation in order to characterise the state of conservation of renderings and to estimate their performance.