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The effect of wind suction on flat roofs: an experimental and analytical study of mechanically fastened waterproofing systems
Presently, mechanically fastened waterproofing systems are widely used in large roofs, mostly in industrial and commercial buildings. This paper presents a study of this constructive system that included the analysis of the mechanisms of response to wind loads and the effects of the different components on the systems wind resistance. Wind up lift tests were performed on mechanically fastened waterproofing systems, according to the guideline for European technical approval (ETAG 006), in order to evaluate the influence of both the thermal insulation thickness (from 40 mm to 100 mm) and the characteristics of the atactic polypropylene (APP) modified bitumen waterproofing membranes (different constitutions, single/double layer) on the resistance to wind up lift. All tested mock-ups failed due to peeling of the overlapping membranes. Within the range of analysed systems, the thickness of the thermal insulation and the characteristics of the waterproofing membranes did not present a noticeable effect on the resistance of the tested mock-ups. Results obtained in the experimental tests were compared to other results gathered from European technical approvals. Additionally, results were used to define the field of application of the tested systems to a National level, based on the wind loads defined in the Portuguese code and the design procedure presented in Eurocode 1 and ETAG 006.
Ano: 2010
Número Páginas:
105-112 pp.
Autor(es): Grandão Lopes, J.
Revista: Construction and Building Materials
Editor: Elsevier
Volume:
Vol. 24, Issue 1.
Keywords: Testing; Wind suction; Mechanically fastened waterprooging systems; Roofs
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The EU directive on road infrastructure safety management - Research at the national and European levels
In November 2008 the European Parliament and the Council have adopted the Directive 2008/96/EC aiming at the improvement of road infrastructures safety management in the Trans-European Road Network, by setting up appropriate procedures which can be extended to national networks, namely through the application of guidelines by the Member States. Research and dissemination of research results play an important part in this process. At the Transportation Department of the National Laboratory for Civil Engineering (LNEC), in Portugal, a special attention has been given, over the time, to road infrastructure safety issues, either in the scope of European projects in this area or through studies within collaboration agreements with road and traffic administrations. Based upon this experience, in this article a concise description is made of the main aspects of the EU Directive and on related research studies, which provided sound scientific and technical basis for the proposed procedures, thus contributing to the overall objective of a continuous and widespread improvement of road safety.
Ano: 2010
Número Páginas:
4-8pp.
Autor(es): Macedo, A. L.; Cardoso, J. L.
Revista: European Roads Review
Editor: Revue Générale des routes et des aérodromes SAS, éditeur
Volume:
ERR No 16, Spring 2010.
Keywords: Good practice; Road infrastructure; Traffic safety; Research
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The urban flooding case study of Ribeira da Agualva (Azores, Portugal)
The village of Agualva, located in Terceira Island, Azores, Portugal, experienced severe flooding on the early morning of 15th of December 2010. The flooding was caused by a short-duration and extreme intensity rainfall event. In less than four hours a total of 70mm of rain rushed down the catchment, flooding several streets and causing the main water course to transport a mix of mud, rocks and debris.
Ano: 2010
Número Páginas:
1p.
Autor(es): Leandro, J.; Leitão, J. P.
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Tidal changes in estuarine systems induced by local geomorphologic modifications
Although rising global sea levels will affect the estuarine flooded areas over the coming decades, the local and regional-scale processes will also induce important changes in these coastal systems. The main aim of this work is to investigate possible tidal changes in estuarine systems induced by local geomorphologic modifications, analyzing the particular case of Ria de Aveiro which is in risk of inundation. Located in the Portuguese west coast, this tidally driven lagoon has a large area of mostly abandoned salt pans, which are in progressive degradation caused by the lack of maintenance and by the strong currents which erode their protective walls.To explore possible tidal changes the hydrodynamic model ELCIRC was applied to Ria de Aveiro to simulate and analyse the impact in the lagoon hydrodynamics of this degradation which results in the enlargement of the lagoon flooded area. A high-resolution grid (grid spacing of the order of 1 m) was developed in order to represent the narrow channels adjacent to the salt pans. The hydrodynamic model was then successfully calibrated and assessed for skill for the Aveiro lagoon through comparison between measurements and model results and quantification of the numerical accuracy. The model was subsequently used to investigate the effect of the flooded lagoon area enlargement on tidal propagation in Ria de Aveiro. Simulations were performed for three geomorphologic configurations, representing the reference or present situation and two flooded scenarios. Results were compared through the analysis of tidal currents, tidal asymmetry and tidal prism.The increase of the lagoon flooded area results in an intensification of the tidal currents, tidal prism and tidal asymmetry. Results also indicate that the tidal prism further increases when the flooding depth increases. Otherwise, changes in tidal currents and in tidal asymmetry pattern are negligible with the increase of the flooded area depth.These results indicate that modifications of the flooded area of estuarine systems will result in tidal changes, with an intensification of the actual tidal patterns induced by the enlargement of inundation areas.
Ano: 2010
Número Páginas:
1854-1864.
Autor(es): Picado, A.; Dias, J. M.; Fortunato, A. B.
Revista: Continental Shelf Research
Volume:
30/17:.
Keywords: Ria deaveiro; Tidal changes; Tidal prism; Tidal asymmetry; Tidal currents; Numerical model
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Time-dependent behaviour of timber lightweight concrete composite floors
This article presents a study on the time-dependent behaviour of timber lightweight concrete composite floors. The option of using lightweight aggregates in concrete (LWAC), instead of normal weightaggregates, is the focus of this document.The load-slip behaviour of SFS-screwed joints in timber-LWAC structures is analysed both for the short term and the long term cases. The study takes advantage of an experimental programme carried out atthe University of Coimbra where several timber-LWAC specimens were tested for 600 days.The load-slip behaviour of the connections is very important for the behaviour of the whole structure.The last aspect that is developed in this article concerns the time-dependent behaviour of LWAC composite floors. The calculated results obtained through the computer programme proHBV, developedat the University of Stuttgart, proved to be very close to those obtained from tests carried out at the University of Coimbra. As explained in this article, the direct application of the design rules for creepin concrete and timber, as presented in Eurocodes 2 and 5, results in great deviations from the actual behaviour of structures composed of two materials, timber and concrete. To overcome this difficulty, the authors also present a simplified procedure that can be taken as an extension of the Eurocode design philosophy. This simplified procedure does not need the use of computer programme proHBV, and ismuch more accurate than the current Eurocode proposals. The deviation of the simple design procedure from the test (even if a bit higher than that of proHBV) is in the order of usually accepted values forpractical design, however, the advantage of this approach for the practice is decisive.
Ano: 2010
Número Páginas:
9.
Autor(es): Jorge, L.; Schänzlin, J.; Lopes, S.; Cruz, H.; Kuhlmann, U.
Revista: Engineering Structures
Editor: Elsevier
Volume:
volume 32, Issue 12.
Keywords: Wooden structures; Timber construction; Shrinkage; Time dependence; Creep; Composite beams
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Um modelo discreto de partículas para análise da fractura em betão armado
O método dos elementos discretos adoptando partículas para discretização dodomínio tem sido utilizado no estudo do fenómeno da fractura em meios nãohomogéneos, como o betão e a rocha. Neste artigo, é proposto um modelo de análisepara o betão armado no qual as armaduras são modeladas com elementos rígidosunidimensionais ligados por molas. Os elementos rígidos interagem com o betão,modelado por partículas circulares, através de uma interface de contacto. O modelo évalidado com base em ensaios de flexão em viga a três pontos e a quatro pontos,sem armaduras de esforço transverso. No ensaio de flexão a 3 pontos o modelo dáuma boa aproximação do comportamento real em termos do processo de evolução dafractura e da relação carga-deslocamento. No ensaio de flexão a 4 pontos, verifica-seuma boa correlação com os resultados experimentais, nomeadamente o valor dacarga última, o efeito de escala e a evolução do processo de fractura.
Ano: 2010
Autor(es): Azevedo, N.
Revista: Revista Portuguesa de Engenharia de Estruturas
Editor: RPEE
Keywords: Fractura; Betão armado; Elementos discretos
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Uma abordagem Bayesiana à amostra aleatória normal
Apresentam-se, neste artigo, os conceitos da inferência paramétrica Bayesiana, no contexto da estimação dos parâmetros de amostras aleatórias normais. São abordados temas práticos não triviais, tais como as distribuições anteriores informativas e a sua eliciação paramétrica pelo método empírico. A finalizar o artigo, é apresentado um exemplo de aplicação da metodologia Bayesiana a um problema de estimação paramétrica no âmbito da engenharia de estruturas.
Ano: 2010
Número Páginas:
25-31 pp.
Autor(es): Casaca, J. M.; Piteira Gomes, J.
Revista: Revista Portuguesa de Engenharia de Estruturas
Editor: LNEC - DE
Volume:
Série III número 7.
Keywords: Verosimilhança; Hiper-parâmetro; Eliciação paramétrica; Distribuição posterior; Distribuição anterior
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Uma cidade amigável e habitada, feita de fachadas permeáveis e de vida urbana
N/A
Ano: 2010
Número Páginas:
9 p..
Autor(es): Baptista Coelho, A.
Editor: Revista www
Keywords: Habitação; Urbanismo; Cidades amigas; Imagem urbana
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Uma cidade de vizinhanças conviviais
N/A
Ano: 2010
Número Páginas:
8 p..
Autor(es): Baptista Coelho, A.
Editor: Grupo Habitar
Keywords: Vizinhanças; Vizinhança próxima; Habitar o exterior; Habitar a vizinhança; Convívio residencial
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Urban pluvial flooding in Jakarta: applying state-of-the-art technology in a data scarce environment
Available data relating to major pluvial flooding events in Jakarta, Indonesia were used to investigate the suitability of two different levels of sophistication in urban modelling tools for modelling these events. InfoWorks CS v9.0 was employed to build 1D and 1D/2D models of a 541 ha area of inner city Ciliwung River catchment which has a history of being particularly badly affected by flooding during heavy rainfall events. The study demonstrated that a 1D modelwas sufficient to simulate the flood extent of a major event using the limited data available.While the 1D/2D model also performed well, more data and time would have been requiredto match the 1D model
Ano: 2010
Número Páginas:
2246-2255pp.
Autor(es): Hurford, A.; Maksimovic, C.; Leitão, J. P.
Revista: Water Science & Technology - WST
Editor: IWA
Volume:
Vol 62 No 10.
Keywords: 1d/2d; Urban drainage; Surface water flooding; Pluvial flooding; Jakarta; Data scarcity; 1d
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