Experimental in-plane evaluation of light timber walls panels

In general, the satisfactory seismic performance of timber buildings can be partially attributed to the material characteristics of the wood itself and to the lightness of its own structure. The aim of this paper is to analyze the in-plane behavior of light timber walls panels through a series of monotonic and cyclic tests, and to evaluate how the sheathing material and the fixation to the base influence the overall response of the wall. Five tests are presented and discussed while the reliability of an analytical method to predict the response of the walls is studied. The sheathing material revealed to be important in the overall response of the wall. Moreover, the type of fixation to the base also revealed to be important in the in-plane response of timber walls. In-plane stiffnesses, static ductility, energy dissipation and damping ratio have been quantified.info:eu-repo/semantics/publishedVersio

Fatigue laws for Brazilians asphalt rubber mixtures obtained in 4 point bending tests

The majority of Brazilian roadpavements consistsof thin pavement structures unable to resist the damage caused by heavy loads and an increasing traffic demand. The main structural distress modes found in Brazilians asphalt layers is fatigue cracking. One of the prom-ising techniques to improve the pavement performance is through asphalt rubber mixtures, which make use of crumb rubber from scrap tires to modify and enhance the properties of the asphalt. The inexistence of fatigue laws for asphalt rubber mixtures to be applied in road design encouraged the study presented in this paper, aiming at the development of prediction models for fatigue and dynamic modulus from the results obtained in laboratory tests. Four mixtures (gap and dense graded) containing Brazilian terminal blend asphalt rubbers were assessed through four point bending tests to evaluate their fatigue and stiffness properties

Lateral tests on a two-story CLT house

A two storey full-scale model of a CLT house, of 4.5 m x 9.1 m in-plane, with a height of 5.04 m, was tested under quasi-static monotonic (pushover). The main objectives were to investigate the 3-D system performance of a CLT structure subjected to lateral loads in terms of lateral strength and deformability capacity, global behaviour of the structure, frequency response of the structure, performance of connectors (mainly hold-downs and angle-brackets) and connections between CLT panels. Lateral loads have been applied on the storeys inducing torsion to the building. Loading procedure, number and disposition of connectors varied between tests. With this campaign it is intended to obtain results on: i) load-deformation response of a 3-D CLT structure subjected to lateral loads; ii) global response of the structure, focusing on the performance of CLT slabs subjected to in-plane loads, performance of parallel and perpendicular walls, and response of the structure near openings; iii) failure mechanisms and on the performance of connections between CLT panels and connectors. The outcomes of the full-scale CLT house tests will be used for further analytical and numerical analyses to help implement the new generation of Eurocode 8.- (undefined

Lateral tests on a two-story CLT house

Artigo em ata de conferênciaA two storey full-scale model of a CLT house, of 4.5 m x 9.1 m in-plane, with a height of 5.04 m, was tested under quasi-static monotonic (pushover). The main objectives were to investigate the 3-D system performance of a CLT structure subjected to lateral loads in terms of lateral strength and deformability capacity, global behaviour of the structure, frequency response of the structure, performance of connectors (mainly hold-downs and angle-brackets) and connections between CLT panels. Lateral loads have been applied on the storeys inducing torsion to the building. Loading procedure, number and disposition of connectors varied between tests. With this campaign it is intended to obtain results on: i) load-deformation response of a 3-D CLT structure subjected to lateral loads; ii) global response of the structure, focusing on the performance of CLT slabs subjected to in-plane loads, performance of parallel and perpendicular walls, and response of the structure near openings; iii) failure mechanisms and on the performance of connections between CLT panels and connectors. The outcomes of the full-scale CLT house tests will be used for further analytical and numerical analyses to help implement the new generation of Eurocode 8

Comparação do desempenho de asfaltos produzidos através dos sistemas continuous blend e terminal blend

O processo de fabricação de um asfalto modificado pela adição de borracha de pneus insersíveis é um dos principais fatores que influencia suas propriedades de desempenho. No presente trabalho, a incorporação de borracha de pneus ao asfalto foi feita através do processo úmido (wet process), no qual a borracha foi adicionada asfalto convencional e resultou em um novo produto, o asfalto modificado com borracha ou asfalto-borracha. O estudo investigou o comportamento dos asfaltos modificados com borracha de pneus usados obtidos através dos sistemas continuous blend e terminal blend. Na produção do asfalto-borracha continuous blend utilizou-se o asfalto convencional CAP 50/70 e a borracha de pneus obtida no sistema ambiente. Inicialmente, o estudo comparou as características do asfalto-borracha do sistema continuous blend através da variação da percentagem de borracha e do tempo de digestão, e identificou o asfalto-borracha otimizado. A investigação conduzida em laboratório avaliou o desempenho dos asfaltos-borracha (continuous e terminal blend) através dos seguintes ensaios: (i) penetração; (ii) ponto de amolecimento; (iii) resiliência; (iv) viscosidade Brookfield. Foram produzidas misturas asfálticas com os dois tipos de asfalto-borracha e com o asfalto convencional. O desempenho das misturas foram comparadas através da vida de fadiga obtida por meio de ensaio de flexão em 4 pontos. O resultado mostrou que as misturas produzidas com o asfalto-borracha proveniente do sistema terminal blend possui um desempenho superior quando comparado com as outras misturas confeccionadas com o ligante convencional e proveniente do sistema continuous blend.The production process of modified asphalt by the addition of crumb rubber from waste tires is one of the main factors that have been influenced the asphalt properties. In this present study, the incorporation of crumb rubber into the asphalt was made by wet process, in which one the crumb rubber was added into conventional asphalt and resulted in a new product, the asphalt modified with rubber or asphalt-rubber. The study investigated the performance of the asphalts-rubber, obtained through continuous blend system and terminal blend system. The conventional asphalt CAP 50/70 was used to produce the continuous blend asphalt-rubber, and the rubber from waste tires was obtained in the ambient system. Initially, the study compared the characteristics of the asphalt-rubber produced in continuous blend system through the variation of these variables: crumb rubber percentage and digestion time, in order to identify the optimized asphalt-rubber. The evaluation of the asphalt rubber (terminal blend and continuous blend) was done through following tests: (i) penetration; (ii) softening point; (iii) resilience; (iv) apparent viscosity using a Brookfield viscometer. Asphalt mixtures were produced using two types of asphalt-rubber and the conventional asphalt one. All mixtures were evaluated through fatigue test (four-points flexural beam tests). The results showed that the mixture prepared from terminal blend system presented better performance than the mixtures produced with conventional asphalt and asphalt rubber from continuous blend system

Desempenho de misturas betuminosas com betume modificado com borracha através do processo húmido

Este trabalho apresenta os resultados da avaliação de desempenho mecânico de misturas betuminosas produzidas com betume modificado com borracha de pneus usados através do processo húmido, utilizando o sistema terminal blend e o sistema continuous blend. Os betumes modificados com borracha através dos dois sistemas foram caracterizados através dos seguintes ensaios: (i) penetração; (ii) ponto de amolecimento (método anel e bola); (iii) resiliência; (iv) viscosidade Brookfield. A avaliação do comportamento mecânico das misturas betuminosas inclui a resistência à fadiga, através do ensaio de flexão em quatro pontos e da deformação permanente utilizando o ensaio de corte simples repetido à altura constante (RSST-CH). Para este estudo foram produzidas misturas betuminosas com dois tipos de granulometria: (i) granulometria densa (Instituto do Asfalto Faixa IV) com betume borracha terminal blend; (ii) granulometria descontínua tipo gap graded (Caltrans ARHM-GG), com betume borracha continuous blend. As misturas com betume borracha foram comparadas com a mistura de referência denominada concreto asfáltico usinado a quente (DNIT 031/2006), preparada com betume convencional. Os resultados mostraram que a mistura com betume modificado com borracha através do sistema terminal blend apresentou o melhor desempenho, com maior vida à fadiga e maior resistência às deformações permanentes.Programa de Bolsas de Alto Nível da União Europeia para a América Latina (Programa ALβAN) - bolsa nº E04D040507BRConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ

Consideração da propagação de trincas em camadas de reforço com misturas com asfalto-borracha

A restauração de pavimentos flexíveis trincados através da execução de uma camada de reforço ou da fresagem parcial do revestimento existente e a colocação de uma camada asfáltica convencional são soluções frequentemente adotadas pelos órgãos rodoviários brasileiros. No entanto, tal prática tem mostrado que nem sempre o objetivo proposto é alcançado, uma vez que a camada executada não atinge a vida de projeto prevista devido ao aparecimento prematuro de trincas que têm como origem a propagação das trincas existentes no revestimento antigo. Assim, em pavimentos em que o trincamento predominantemente ocorre de baixo para cima, com a fresagem parcial do revestimento a patologia não é de todo eliminada. Desta forma, ao se executar uma camada de revestimento novo sobre esta superfície, as trincas existentes se comportam como pontas de uma trinca. A elevada concentração de tensões na extremidade das trincas existentes, provocadas pelos movimentos dos seus bordos, é resultante das seguintes ações: (i) tráfego, (ii) variações de temperatura; (iii) variações de umidade no subleito; (iv) qualidade de construção. Para mitigar o problema da propagação de trincas, várias soluções têm sido pesquisadas em diversos países. Dentre elas, misturas asfálticas modificadas com asfalto-borracha têm sido desenvolvidas com o objetivo de inibir a propagação de trincas, além de retardar o aparecimento de patologias como o trincamento por fadiga e o afundamento, comumente encontradas em rodovias brasileiras. No presente trabalho apresenta-se uma simulação numérica utilizando um modelo de propagação de trincas, através de técnica de elementos finitos, para avaliar o dano provocado em uma camada de reforço de um pavimento devido à ação do tráfego e das variações de temperatura. O modelo determina os níveis de extensão desviatória de Von Misses a que uma camada de reforço fica submetida quando assente sobre uma superfície trincada e, utilizando-se as leis de fadiga das misturas pesquisadas, obtidas no ensaio de fadiga por flexão alternada em 4 pontos, avalia-se a vida de fadiga desta camada em termos de seu trincamento. Os resultados mostraram que as misturas com asfalto-borracha prolongam consideravelmente a vida da camada de reforço, em termos de propagação de trincas, em relação a uma mistura convencional

Improvement of the functional pavement quality with asphalt rubber mixtures

Skid resistance and texture are important safety characteristics which need to be considered in flexible pavement design, maintenance and rehabilitation. The main objective of this paper is to optimize surface texture characteristics in asphalt rubber pavements, mainly macrotexture to reduce splash, spray and hydroplaning and microtexture to increase friction at low and high speeds. The objective was accomplished by measuring the friction surface with two different tests: (i) British pendulum; (ii) Volumetric Method. The specimens prepared in the laboratory represent the as-constructed pavement surface. In this study, two different mixtures grading (dense and gap) were produced using three types of binders: (i) conventional asphalt; (ii) asphalt rubber using terminal blend process; (iii) asphalt rubber using continuous blend process. The binder content influence in functional quality was tested by using the same configuration for mixtures with more 1% of asphalt rubber content. The results of this study were carried out to evaluate the effect of asphalt rubber production process and mixtures gradation on the pavement surface characteristics. The results showed that the mixture with gap grading exhibit higher texture in comparison of mixtures with a dense grade gradation. The asphalt rubber mixtures improved the skid resistance compared to conventional mixtures. This research indicates that the CRM (crumb rubber modified) production with rubber from the different processes have significant differences in pavement surface characteristics.União Europeia (UE) - Programme Alban (E04D040507BR)

Conservation Management of EU Priority Habitats after Collapse of Traditional Pastoralism: Navigating Socioecological Transitions in Mountain Rangeland

Agricultural abandonment is a major driver of change in rural landscapes. Assumed to provide beneficial results to the environment and the conservation of biota, rural abandonment triggers landscape and biotic homogenization and loss of valuable species and habitats. This article focuses on the ecological effects and conservation challenges of shifts in extensive grazing regimes on marginal pastureland of Mediterranean mountains. We conceptualize a navigated socioecological transition toward conservation-oriented management after the collapse of historical land systems. The article provides examples from the LIFE+ project “Higro,” developed in mountainous protected areas in Portugal, of how management for conservation could sustain disturbance-dependent habitats. We argue that actively and regularly managing large habitat areas should be envisaged as a short-term approach to limit the immediate effects of rural abandonment. A gradual integration of conservation targets with other activities in changing rural economies is necessary to foster long-term conservation of species and habitats, building on the link between conservation-oriented habitat management and ecosystem services in rural landscapes. Conservation goals should run alongside recovery of social systems and innovation applied to traditional sources of income. This parallel development would contribute to building up social-ecological resilience by maintaining a diversity of social and ecological capital in rural areas.info:eu-repo/semantics/publishedVersio

Electron microprobe analysis of cryolite

Comunicação apresentada em: EMAS 2013 : 13th European Workshop on Modern Developments and Applications in Microbeam Analysis, Centro de Congressos da Alfândega do Porto, Portugal, 12 to 16 May 2013A sample of cryolite was studied with a JEOL JXA 8500-F electron microprobe under several operating conditions. A TAP crystal was used to analyse Na and Al and a LDE1 crystal to analyse F. As F and Na are both highly "volatile" elements, special care must be taken during analysis. The measurement order of Na, F and Al is not irrelevant and optimum conditions may also result in different combinations of accelerating voltage, beam current, beam size or counting times. Relevant X-ray signals were recorded in order to investigate the behaviour of the Na Ka and F Ka counts with elapsed time. The incident beam current was also recorded at the same time. In a clear contrast to what has normally been reported in the EPMA analysis of aluminosilicates and silicate glasses, we found that the Na X-ray counts increase with time. This increment of X-rays intensities for sodium in cryolite depends on the operating conditions and is accompanied by a strong migration of fluorine from the beam excitation volume, leading to a decrease in F X-ray counting rates. It was also observed that higher incident beam currents induce higher radiation damage in the mineral. The current instability is consistent with possible electron induced dissociation in the cryolite structure. An analytical protocol was achieved for 6 kV and 15kV accelerating voltage for the correct EPMA analysis of cryolite