Papers

This article presents a nonlinear finite element model developed to simulate the load-deformation behavior of wood joints when loaded by a dowel-type fastener. Particular attention was paid to the initial load-deformation behavior that had a significant influence on the joint stiffness, a joint property with a large influence on the mechanical behavior of wood-based composite structures connected with semirigid joints. To obtain accurate predictions of joint deformation, the material models available in the literature were adapted and nonlinear deformations were taken into consideration during very early loading. The proposed model precisely describes the embedding behavior of different wood species and densities. Numerical results compared very well with those obtained in experiments. Based on this analysis, the recommendation is to obtain the material model inputs based on design values available in the literature.

A capacidade do meio ambiente para receber os resíduos gerados diariamente pela sociedade em quantidades muito elevadas e crescentes não é infinita, pelo que se vem procurando minimizar a sua produção e implementar políticas de uma gestão sustentável. Num sistema integrado de gestão de resíduos privilegiam-se a sua prevenção e redução, ou, não sendo estas viáveis, a sua reutilização, podendo ainda recorrer-se à reciclagem ou a outras formas de valorização. Ciente da importância do tema em apreço, a Sociedade Portuguesa de Geotecnia (SPG) decidiu criar a Comissão Técnica para a Valorização de Resíduos em Obras Geotécnicas (CT-VROG). Com a presente comunicação, pretende-se divulgar no meio geotécnico nacional as actividades técnicas desenvolvidas pela CT-VROG, que têm por principal objectivo fomentar a aquisição e divulgação de conhecimentos e promover a adopção de políticas de construção sustentável.

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A study was conducted to evaluate the performance of glued laminated timber (glulam) of maritime pine treated with a copper azole preservative product. Shear strength of glue lines met the requirements of EN 386 (2001) with no influence of clamping pressure and cure temperature. According to the same standard, delamination was satisfactory for higher cure temperatures applied with a clamping pressure of 0.6N/mm2. Finger joints made with treated wood gave satisfactory bending strength. The preservative treatment did not influence the modulus of elasticity of the beams. According to a Monte Carlo simulation and following the requirements of EN 1194 (2202), glulam of class GL 28c can be manufactured if visually graded maritime pine of classes E and EE (NP 4305 1995) is used in the inner and outer lamellas, respectively, and class GL 24h when using both grades in equal proportions randomly distributed through the glulam element.

Em Portugal não se constroem barragens de aterro, nomeadamente de enrocamento, para produção de energia eléctrica. Trata-se de uma singularidade a nível internacional. O presente trabalho debruça-se sobre as prováveis explicações para este facto e chama a atenção para os consequentes prejuízos económicos.

Lead time between rainfall prediction results and flood prediction results obtained by hydraulic simulations is one of the crucial factors in the implementation of real-time flood forecasting systems. Therefore, hydraulic simulation times must be as short as possible, with sufficient spatial and temporal flood distribution modelling accuracy. One of the ways to reduce the time required to run hydraulic model simulations is increasing computational speed by simplifying the model networks. This simplification can be conducted by removing and changing some secondary elements using network simplification techniques. The emphasis of this paper is to assess how the level of urban drainage network simplification influences the computational time and overall simulation results' accuracy. The models used in this paper comprise a sewer network and an overland flow drainage system in both 1D/1D and 1D/2D approaches. The 1D/1D model is used as the reference model to generate several models with different levels of simplifications. The results presented in this paper suggest that the 1D/2D models are not yet suitable to be used in real-time flood prediction applications due to long simulation time, while on the other hand, the simplified 1D/1D models show that considerable reductions in simulation time can be achieved without compromising simulation results (flow and water depth) accuracy.

Recycled aggregates may make an important contribution toward decreasing the adverse consequences of the production and the dumping of construction and demolition waste CDW on the environment. The results of the experimental research work carried out at Lisbon’s Instituto Superior Técnico and Laboratório Nacional de Engenharia Civil are presented in this article. Normalized laboratory tests to assess the performance of standard mortars were used to demonstrate the technical feasibility of recycling the waste produced by the ceramics industry and from the demolition of red-clay bricks or tiles to produce mortars with less/no consumption of natural aggregates. Results are very promising up to a replacement ratio of sand with ceramic waste of at least 20%. The paper presents useful data for the ceramics industry, builders and mortar manufacturing companies in terms of minimizing the impact of CDW and using eco-efficient materials.

The removal of microcystins (MC) by powdered activated carbon adsorption/ultrafiltration (PAC/UF) was investigated, focusing on PAC dose and addition mode, MC initial concentration (expressed as MC-LReq) and on the impact of background natural organic matter (NOM), assessed through model compounds (a mixture of tannic and humic acids) and Microcystis aeruginosa culture. Constant flow experiments were performed with a hydrophilic UF hollow-fibre membrane and a mesoporous fine-powdered activated carbon. In the absence of backgroundNOM,PAC/UF with 10 mg/L PAC and up to 20_g/L MC-LReq feed concentration achieved 93–98% MC removal and a cycle-averaged permeate concentration below the drinking water guideline-value adopted by the World Health Organisation (WHO) for microcystin-LR variant. Single-pulse PAC dosing in the beginning of the UF-cycle allowed slightly lower MC concentration in the permeate compared to the multi-pulse PAC addition whereas no differences were found in terms of transmembrane pressure. Hydraulic retention time of 34 and 55 min resulted in similar permeate quality.NOM type and concentration and MC initial concentration determined the PAC dose to be used. While 10 mg/L PAC effectively controlled ca. 5_g/L MC-LReq in a model water with 2.5 mg/L NOM or with M. aeruginosa culture (cells and algogenic organic matter) 15 mg/L PAC were unable to achieve the WHO quality with a water containing higher concentrations of NOM (5 mg/L) and microcystins (ca. 20_g/L MC-LReq).

The removal of microcystins (MC) by powdered activated carbon adsorption/ultra?ltration (PAC/UF) was investigated, focusing on PAC dose and addition mode, MC initial concentration (expressed as MC-LReq) and on the impact of background natural organic matter (NOM), assessed through model compounds (a mixture of tannic and humic acids) and Microcystis aeruginosa culture. Constant ?ow experiments were performed with a hydrophilic UF hollow-?bre membrane and a mesoporous ?ne-powdered activated carbon. In the absence of background NOM, PAC/UF with 10mg/LPAC and up to 20 µg/LMC-LReq feed concentration achieved 93–98% MC removal and a cycle-averaged permeate concentration below the drinking water guideline-value adopted by the World Health Organisation (WHO) for microcystin-LR variant. Single-pulse PAC dosing in the beginning of the UF-cycle allowed slightly lower MC concentration in the permeate compared to the multi-pulse PAC addition whereas no differences were found in terms of transmembrane pressure. Hydraulic retention time of 34 and 55 min resulted in similar permeate quality. NOM type and concentration and MC initial concentration determined the PAC dose to be used. While 10mg/LPAC effectively controlled ca. 5µg/LMC-LReq in a model water with 2.5mg/LNOM or with M. aeruginosa culture (cells and algogenic organic matter) 15mg/LPAC were unable to achieve the WHO quality with a water containing higher concentrations of NOM (5mg/L) and microcystins (ca.20µg/LMC-LReq).

O facto de a madeira ser um material combustível constitui uma das principais preocupações das pessoas quando se fala de segurança contra incêndio de construções de madeira. Contudo, os edifícios de madeira podem ser concebidos e dimensionados para terem desempenhos adequados em muitas situações, uma vez que a carga de incêndio depende essencialmente do recheio e não do material estrutural. Nos últimos anos, o crescente interesse pela construção em madeira, em particular de habitações unifamiliares, tem levantado algumas questões pertinentes, relativamente à segurança contra incêndio, que importa esclarecer.