Revistas Universidad del Bío-Bío
Not a member yet
3557 research outputs found
Sort by
Changes in wood properties of chestnut wood structural elements with natural aging
Get PDFKnowing the effects of natural aging on wood properties is important both for the conservation of historical wooden material and for reuse of aged wood. The aim of this study was to investigate the wood properties of old wooden elements not impregnated with any protective chemicals and taken from different parts of Zeytinlik houses in Giresun, Turkey. Test samples were prepared from old wooden elements and freshly cut chestnut timber. The anatomical, chemical, physical and mechanical properties were determined according to standard procedure, and the results were compared with those of recent wood specimen. As a result of the anatomical identification, it was determined that the wooden elements used in traditional Zeytinlik houses belong to species of Anatolian chestnut (Castanea sativa), and after an average service life of 88, 113 and 120 years, there was no change in the anatomical structure of the old wooden elements. Fourier transform infrared band characterization of old wood specimens revealed that hemicelluloses degraded and lignin structure changed on the surface of almost all specimens. Especially, the wood density values of the facade elements were smaller than that of recent wood specimen. Except for the modulus of rupture of window sill and rafter, all mechanical properties were significantly greater compared with those of recent wood specimen. The results of this research showed that old wood not damaged by fungi and insects could be evaluated for reuse
Flooring characteristics of thermo-mechanical densified wood from three hardwood tropical species in costa rica
Get PDFDensification is one method used to modify low-density woods to make them achieve the hardness required for flooring application. The purpose of this study was to investigate the effect of thermo-mechanical densification with pre-heating in wood of Alnus acuminata, Vochysia ferruginea and Vochysia guatemalensis from, seeking to stabilize and reduce spring-back of the densified wood and evaluate its performance in flooring applications. The results showed that the wood of the three species turned dark. This is because brightness diminished and yellowness and redness increased. Weight loss due to pre-heating was statistically higher in V. ferruginea and V. guatemalensis. The final density and spring-back were statistically similar in the three species. The percentage of densification of A. acuminata and V. guatemalensis were statistically higher than for V. ferruginea and the degree of compression was statistically higher in V. guatemalensis. As for flooring evaluation, the percentage of densification, temperature and time of pre-heating affected the behavior of densified wood flooring. The low percentage of densification and high weight loss in the pre-heating stage caused greater values of wear, wear index, residual deformation, residual indentation for the falling ball indentation test, and more damages in the surface indentation test in wood of V. ferruginea
Juvenile-mature wood evaluation along the bole considering the influence of silvicultural treatments
Get PDFWood use for structural purposes has increased in the last decade in Spain. However, as a raw material, wood needs to comply with requirements that are not always present. Knowledge about the wood quality from the trees on the stand is essential for providing feedback to forest managers and for taking the required actions to obtain suitable silviculture treatments. Two of the main wood species used in construction in Spain, Pinus nigra and Pinus sylvestris, have been studied in order to determine the amount of juvenile wood, which has been identified as a harmful characteristic for its decrease in quality of the physical-mechanical properties of these species. Being relevant for the best quality of timber in the part along the bole where the logs are obtained, the distribution of juvenile wood at different heights and the effect of several silvicultural treatments have had on juvenile wood formation has been considered. The juvenile-mature wood boundary (transition year) was calculated through segmented linear mixed models employing as variables annual latewood density, obtained through micro X-ray densitometry, silvicultural practices, and a drought index. The results show how juvenile and mature wood is distributed along the bole and the proportion of juvenile wood. Its reduction according to the different thinning and pruning silvicultural practices is presented
Influence of silicone oil thermal modification on mechanical properties of masson pine wood
Get PDFIn this study, the effect of silicone oil thermal modification at different treatment temperatures (150 ºC, 180 ºC and 210 ºC for 2 h and 4 h.) on the mechanical properties of masson pine (Pinus massoniana L.) wood was investigated. The density, modulus of elasticity (MOE), modulus of rupture (MOR), impact bending, compressive strength, and hardness of silicone oil thermal treated samples were evaluated and compared with those of untreated samples. Results showed the mechanical properties of masson pine wood reduces after silicone oil thermal modification. The higher the modification temperature, the lower the mechanical properties of Mason pine wood. At 210 ºC for 4 h, mechanical properties of the modified samples were two times lower than the mechanical properties of the untreated. Higher modification temperature and longer treatment time contributed to lower mechanical properties
Glulam connections assembled with screws in different installation angles
Get PDFSelf-tapping screws are the recognized state-of-the-art in fastener technology for timber structures. Combining fasteners of different stiffness, such as self-tapping screws with different installation angles, can be advantageous to simultaneously achieve high connection stiffness and ductility. In this paper, experimental investigations on a total of 65 glued-laminated timber joints assembled with a variety of installation angles including several combinations of self-tapping screws acting axially in withdrawal with self-tapping screws acting laterally are presented. The connection performance was analyzed in terms of the load-carrying capacity, the deformation capacity, the stiffness, and the ductility. The findings demonstrated that joint assemblies with self-tapping screws loaded primarily laterally exhibit low stiffness but high ductility, whereas joint assemblies with self-tapping screws loaded primarily in withdrawal are very stiff but exhibit low ductility. Combining screws in different installation angles created glued-laminated timber connections that combine high stiffness with high ductility. Existing analytical expressions were deemed suitable to estimate load-carrying capacity through simple summation of the different screws’ individual resistances
Efecto en las propiedades mecánicas de una resina pinífera modificada biodegradable, al utilizarla como compatibilizante o acoplante en formulaciones elastoméricas sin o con fibra de agave y hule de poli(estireno-butadieno). Un paso hacia la formulación
Get PDFEn este trabajo se valora la eficiencia de una resina de pino modificada biodegradable (A-30), al utilizarla como compatibilizante o acoplante para sustituir al resorcinol (que es tóxico y no es biodegradable), comparando las propiedades mecánicas (contra formulaciones preparadas usando el sistema resorcinol-hexametilentetramina (R-HMT) en: a) polímeros elastoméricos reticulados de estireno-butadieno (SBR), y: b) compósitos de SBR reforzados con fibra de agave de desecho. Para la comparación como compatibilizante, aquí se preparan formulaciones equivalentes con A-30 o R-HMT. Para la comparación de los compósitos equivalentes, se varía el agente de acoplamiento (R-HMT o A-30) y la cantidad de azufre como agente de entrecruzamiento (2,5 partes por cien de elastómero (phr), 7,5 phr o 15 phr). En las pruebas de tracción a temperatura ambiente, y el análisis mecanodinámico con barridos de temperatura (de - 70 °C a 40 °C) y frecuencia (de 0,4 Hz a 40 Hz), se obtuvieron incrementos en módulos (hasta un 74 % en módulo de Young) y en capacidad de deformación (hasta 260 %), para los materiales conteniendo el agente A-30, por encima de las formulaciones en las que se usó el resorcinol. El mejor desempeño como compatibilizante o acoplante del A-30, se reflejó también con claridad morfológicamente mediante microscopía electrónica de barrido, al mostrar mayor compacidad en la matriz formulada y mayor cercanía entre fibra y matriz en muestras fracturadas criogénicamente. Se ha demostrado aquí, que el A-30 puede sustituir al par R-HMT con éxito, ya que funciona mejor como agente compatibilizante o acoplante y es biodegradable. Este tipo de agentes tiene un gran potencial para contribuir al desarrollo de elastómeros y compósitos flexibles amigables con el medio ambiente
El sistema social de la casa. En la vivienda informal consolidada de Guayaquil
Get PDFA crise pós-pandémica da moradia contemporânea, desencadeada pela COVID-19, apenas estende a todo o planeta muitas das questões em que estão permanentemente imersas as casas em crise contínua dos países em desenvolvimento. Surge, portanto, a seguinte questão: como tornar as nossas casas mais partilháveis, flexíveis, transformáveis, produtivas, participativas, habitáveis, etc.? Neste sentido, uma abordagem dos problemas habitacionais de populações de baixa renda nestes países permite analisar alternativas aos modelos de moradia atuais que emergem da informalidade como uma resposta às questões que todos nos colocamos hoje. O seguinte documento descreve parte da pesquisa realizada pela Universidade Católica de Santiago de Guayaquil que analisa as transformações físicas e sociais na estrutura habitacional informal consolidada do centro desta cidade equatoriana. As técnicas utilizadas incluem o levantamento planimétrico de casos de estudo, entrevistas aos usuários e o mapeamento do uso das estruturas ao longo do dia. A análise se centra na interação entre os diferentes núcleos familiares da casa e seus objetos, descrevendo, assim, um sistema de transformação e produção de habitat ligado aos objetos no qual a estrutura habitacional é entendida como um sistema social de objetos e pessoas em contínua interação e transformação.La crisis post pandémica de la vivienda contemporánea, desencadenada por la COVID-19, no hace sino extender a todo el planeta muchas de las cuestiones en que se hallan inmersas, de manera permanente, las viviendas en continua crisis de los países en desarrollo. ¿Cómo hacer nuestras casas más compartibles, flexibles, transformables, productivas, participativas, habitables, etc.? Por ello, un acercamiento a la vivienda de bajos recursos de estos países permite analizar alternativas a la vivienda actual, que surgen desde la informalidad como respuesta a aquellas preguntas que nos hacemos hoy todos. El siguiente documento describe parte de la investigación llevada a cabo desde la Universidad Católica de Santiago de Guayaquil, que analiza las transformaciones físicas y sociales en la vivienda informal consolidada del centro de la ciudad. Las técnicas que se utilizan incluyen el levantamiento planimétrico de casos de estudio, entrevistas a los usuarios y el mapeo del uso de las viviendas a lo largo del día. El análisis se centra en la interacción que se ejerce entre los diferentes núcleos familiares de la casa y sus objetos, llegando así a describir un sistema de transformación y producción de hábitat ligado a los objetos, en donde la vivienda es entendida como un sistema social de objetos y personas en continua interacción y transformación.The post-pandemic crisis of contemporary housing, triggered by COVID-19, only but extends, to the entire world, many of the questions in which, permanently, housing is immersed within, in an ongoing crisis of developing countries. How to make houses more shareable, flexible, transformable, productive, participatory, livable, etc.? In that sense, by studying low-income housing in these countries, it is possible to analyze alternatives to the current dwellings, that arise from informality as a response to those questions shared worldwide today. This article describes part of a research carried out at Universidad Católica de Santiago de Guayaquil, which analyzes the physical and social transformations in consolidated informal dwellings within the city center. The techniques used, include planimetric surveys of case studies, interviews to users, and mapping out the use of the dwellings throughout the day. The analysis focuses on the interaction exerted between several nuclear families inside the dwelling and their objects. Thus describing a habitat transformational and production system linked to objects, where the dwelling is understood as a social system of objects and people, in continuous interaction and transformation
Identidade e inclusão. Os conjuntos habitacionais do arquiteto chileno Luciano Kulczewski (1922-1956)
Get PDFLuciano Kulczewski fue un profesional que cumplió un rol clave y distintivo en la primera mitad del siglo XX, período que se considera crucial para el desarrollo de la arquitectura chilena ya que es el momento en que se produce el advenimiento de la modernidad en el país. Una de las ilustraciones más elocuentes a este respecto es el corpus constituido por más de una docena de conjuntos habitacionales destinados a los estratos socioeconómicos medios y populares. Hoy reconocemos en estas soluciones no solo el hecho de que se hallen en sincronía con la trama de procesos sociales, políticos, culturales y económicos que determinaron los comienzos del siglo pasado en Chile, sino que tienen también, entre sus méritos más destacables, el haber sido concebidas en términos de lo que hoy entenderíamos por “inclusión”. El presente artículo busca indagar en estos parámetros, que abarcan desde las propuestas urbanas -que se aproximaban a la ciudad en términos “inclusivos”, en cuanto renunciaban a relegar estas propuestas habitacionales hacia las periferias metropolitanas-, hasta cuestiones más particulares, como era el manejo estilístico de las viviendas a guisa de herramienta puesta al servicio de causas identitarias, con el fin de lograr la integración del usuario con su entorno.Luciano Kulczewski was a professional who played a key and distinctive role in the first half of the 20th century, a period considered as crucial for the development of Chilean architecture, since it is the moment that brought the advent of modernity to the country. One of the most eloquent illustrations in this regard is the corpus, that collects more than a dozen housing complexes aimed for the middle and the working classes. Today, we recognize in these solutions not just the fact that they are in sync with the web of social, political, cultural, and economic processes that characterized the beginnings of the past century in Chile, but that they also have, among their most notable merits, having been conceived in terms of what we would understand today by “inclusion”. This article seeks to investigate these parameters, which range from urban proposals - that approached the city in "inclusive" terms - inasmuch as they did not push for these housing proposals to be in the metropolitan peripheries - to more particular issues, such as the stylistic management of homes as a tool to serve identity causes, in order to achieve the integration of the user with their environment.Luciano Kulczewski foi um profissional que cumpriu um papel fundamental e distintivo na primeira metade do século XX, período considerado crucial para o desenvolvimento da arquitetura chilena por ser o momento em que ocorre o advento da modernidade no país. Uma das ilustrações mais eloquentes a esse respeito é o corpus formado por mais de uma dúzia de conjuntos habitacionais voltados para as camadas socioeconômicas médias e populares. Hoje reconhecemos nessas soluções não apenas o fato de que estão em sintonia com a teia de processos sociais, políticos, culturais e econômicos que marcaram os primórdios do século passado no Chile, mas também, entre seus méritos mais notáveis, o fato de terem sido concebidas em termos do que entenderíamos hoje por “inclusão”. Este artigo busca investigar esses parâmetros, que vão desde as propostas urbanas, que abordaram a cidade em termos “inclusivos” – na medida em que desistiram de relegar essas propostas habitacionais às periferias metropolitanas –, até questões mais particulares, como a gestão estilística das moradias como ferramenta ao serviço das causas identitárias, no intuito de conseguir a integração do usuário com o seu ambiente
Diagnóstico de diseño y uso del espacio vial peatonal: aportes desde el paisaje para la ciudad de La Plata, Argentina
Get PDFIn the context of increasingly more complex urban scenarios, the infrastructure of the city's road spaces is still almost exclusively dedicated to cars. The city of La Plata is no exception, also presenting an interesting contrast between its planned urban areas and those that have grown due to urban sprawl. The concept of pedestrian space is understood starting from the different functions it fulfills, not only insofar as a transport infrastructure, but also as public and strategic spaces that shape the urban landscape. Thus, this article proposes, on one hand, the generation of primary information and, on the other, the construction of a diagnosis about the design and use of the pedestrian space. For this, a survey of the current state of the pedestrian space, its dimensions, morphological characteristics, and landscape elements, is carried out. Although there is an adequate amount of space reserved for pedestrian use, it is confirmed that in many sectors it is still not accessible or pleasant for citizens, due to its poor condition or complete lack of upkeep.En el marco de escenarios urbanos de creciente complejidad, la infraestructura de los espacios viales de las ciudades se encuentra todavía casi exclusivamente dedicada a los autos. La ciudad de La Plata no es la excepción, presentando además un interesante contraste entre sus áreas urbanas planificadas y aquellas que han crecido por expansión del tejido residencial. El concepto de espacio peatonal es entendido a partir de las distintas funciones que cumple no sólo en cuanto infraestructura de transporte sino también en cuanto espacios públicos y estratégicos para la conformación del paisaje urbano. Así, el trabajo se propone, por un lado, la generación de información primaria y, por otro, la construcción de un diagnóstico sobre el diseño y uso del espacio peatonal. Para esto, se realiza un relevamiento del estado actual del espacio peatonal, sus dimensiones, características morfológicas y elementos paisajísticos. Si bien existe una cantidad adecuada de espacio reservado al uso peatonal, se verifica que en muchos sectores aún no resulta accesible ni agradable para los ciudadanos debido a su mal estado o nulo tratamiento
Comparative study on weathering durability property of phenol formaldehyde resin modified sweetgum and southern pine specimens
Get PDFThe effects of low molecular weight phenol formaldehyde resin on weathering durability property of sweetgum (Liquidambar styraciflua) and southern pine (Pinus taeda) specimens were studied using six wet-dry cycles with ultraviolet light accelerated weathering test following ASTM D2898-10 via evaluating the water repellent efficiency, dimensional stability, and crack formation of wood. The results showed that 1) the water repellent efficiency of treated quarter-sawn sweetgum specimens was higher than those of treated quarter-sawn and flat-sawn southern pine specimens; 2) the dimensional stabilities of sweetgum and southern pine specimens were all improved by impregnating low molecular weight phenol formaldehyde resin, especially for sweetgum; 3) there were clearly more cracks on exposed ends and surfaces of all treated sweetgum and southern pine specimens than those on control ones, indicating that the low molecular weight phenol formaldehyde resin modification used in this study were not able to improve the anti-cracking properties of sweetgum and southern pine specimens. Generally, the sweetgum was more suitable to be impregnated with low molecular weight phenol formaldehyde resin than southern pine with the procedure described according to dimensional stability and water repellent efficiency, in order to improve the weathering durability