A estrutura independente e a arquitetura moderna brasileira

Este trabalho tem como objetivo a análise de um conjunto de obras que pertence ao grupo da vertente modernista brasileira, parte da escola carioca e parte da escola paulista. O fator comum entre elas é a independência dos elementos estruturais em relação aos demais que compõem os edifícios. O período delimitado para este estudo começa em 1936 e vai até 1961, de acordo com as datas dos projetos analisados. Como os momentos de consolidação das duas escolas não são coincidentes, o período entre essas datas é o maior, de acordo com o panorama nacional e internacional, que não deve ser considerado isoladamente em relação a cada escola. A Arquitetura Moderna Brasileira, tendo por base os princípios do racionalisma estutural, sob forte influência corbusiana, trilha o caminho de uma produção própria, valendo-se da cultura e tecnologia locais. Utilizando-se os exemplos de Lúcio Costa, Affonso Eduardo Reidy e Vilanova Artigas, de temas diversos, puderam ser analisadas as influências internacionais recebidas e o legado deixado por eles à produção arquitetônica brasileira desde então. Acompanham o texto escrito ilustrações que, além de seu caráter complementar, são imprescindíveis para a compreensão deste trabalho.

A utilização de varões de GFRP nas estruturas de betão armado

A crescente preocupação com a deterioração e consequente reparação e reabilitação das estruturas de betão armado tradicionais, sobretudo devido ao fenómeno da corrosão associada aos varões de aço, que afecta significativamente a durabilidade deste tipo de estruturas, tem impulsionado a introdução dos varões de GFRP na área da engenharia civil. A progressiva utilização dos varões de GFRP, nas estruturas de betão armado, surge não só no sentido de colmatar as deficiências apresentadas pelo aço convencional, mas igualmente, pelas características que lhe são inerentes, das quais se destacam, entre outras, a elevada resistência à tracção e à fadiga, a elevada resistência química, a sua não condutividade electromagnética e corrosibilidade nula e o seu baixo peso próprio. Contudo, o comportamento frágil consequente do reduzido módulo de elasticidade, o custo início elevado e a falta de códigos de dimensionamento, têm tardado a sua aplicação generalizada. Neste contexto, procede-se no presente documento à elaboração de um Estado da Arte, com intuito de analisar o ponto de situação dos conhecimentos, seguida da apresentação da filosofia de dimensionamento e da descrição das propriedades físicas e mecânicas dos varões de GFRP. No sentido de avaliar o Estado Limite Último (E.L.U.) e o Estado Limite de Serviço (E.L.S.), dos elementos de betão armado com GFRP, realiza-se uma exposição dos modelos de dimensionamento sugeridos pelo ACI 440.1R-06 [3], pelo Fib-Bulletin 40 [21] e pelo ISIS Manual No.3 [25]. Por fim, dimensiona-se três elementos estruturais de betão armado com GFRP, com o objectivo de delinear as principais diferenças entre as armaduras de aço e de GFRP. Os exemplos de aplicação efectuados permitiram concluir, que de facto, o E.L.S. é maioritariamente condicionante neste tipo de estruturas, devido ao reduzido módulo de elasticidade, que afecta significativamente a deformação.

Construção com painéis sanduíche de silicato de cálcio, cimento e EPS

A carência de materiais que permitam elementos estruturais leves, de elevada rigidez e resistência na indústria da construção, contribuiu para o desenvolvimento e posterior utilização de materiais compósitos, nos quais incluem-se os painéis sanduíche. Estes são aperfeiçoados e fabricados com o objetivo de obter elevada relação resistência/peso próprio, rigidez/peso próprio e outras vantagens a nível construtivo como a montagem rápida, a redução de custos e boas propriedades de isolamento. Nesta dissertação são apresentados os painéis sanduíche de silicato de cálcio, cimento e EPS, com o intuito de informar os interessados, em métodos construtivos alternativos, sobre uma solução viável, vantajosa a vários níveis e que pode ser adaptada e igualmente adequada às suas necessidades construtivas. Inicia-se com um resumo do desenvolvimento histórico até à necessidade de evolução e utilização de materiais semelhantes, seguindo-se de uma descrição mais detalhada do painel sanduíche e os seus requisitos. A nível de fabrico, sugere-se uma possível disposição de maquinaria em fábrica e pormenoriza-se o processo de fabrico até atingir o produto final. Segue-se o trajeto do painel até ao seu propósito final em obra, onde se descreve o seu processo construtivo. Explicam-se as vantagens e desvantagens dos Painéis acompanhados de vários exemplos de aplicações com sucesso. Para divulgar a qualidade e facilitar a comercialização deste produto, descreve-se detalhadamente o processo moroso da obtenção da marca que atesta a conformidade de um produto a nível europeu e mundial, a marcação CE, e a nível nacional, uma proposta de especificação técnica como comprovativo de qualidade. É ainda realizado um estudo teórico do desempenho esperado dos painéis sanduíche de silicato de cálcio, cimento e EPS, a nível acústico, térmico, a sua resistência à água e fogo, durabilidade a longo prazo e resistência dos Painéis. Por fim, demonstram-se vários pormenores construtivos que eventualmente serão utilizados em obra.

Betões especiais: aplicações em edifícios

Atualmente o betão é o material estrutural mais utilizado a nível mundial no âmbito da construção civil. É composto por água, agregados grossos e finos, com ou sem adjuvantes, cimento e adições. Atendendo ao facto de a sua utilização ter vindo a ser bastante significativa, ao mesmo tempo torna-se uma solução dispendiosa, dada a presença de alguns dos seus constituintes, principalmente o cimento Portland. O aparecimento de novos componentes, capazes de substituírem parte do cimento e de aumentarem as capacidades do betão para responder às expectativas, nomeadamente, as adições e adjuvantes, induziram ao surgimento de betões mais resistentes, duradouros e capazes de responderem melhor às condições que lhes são exigidas em projeto. Neste contexto, desenvolveu-se o presente trabalho, com o objetivo de estudar as soluções em betão com maior viabilidade económica. Ao longo do presente estudo, pretende-se avaliar a possibilidade de recorrer à utilização de betões especiais para a construção de alguns elementos estruturais de edifícios. Nesta perspetiva, numa fase inicial do trabalho, apresenta-se uma breve introdução histórica sobre a evolução do betão, desde a sua descoberta até à atualidade, e, em seguida, discutem-se as vantagens e as desvantagens referentes a cada betão quando aplicado em diferentes elementos estruturais. Posteriormente, é feita uma breve análise, comparação e discussão de resultados referentes aos custos atualmente praticados em Portugal Continental e na Ilha da Madeira relativos a cada tipo de betão. A dissertação termina com a análise dos resultados obtidos.

O projeto de arquitetura de espaços temporários com o uso de sistema construtivo remontável: um estudo exploratório

The purpose of this research is to study the portable or reassemblable architectures, which, different from conventional architecture (whose designs are of permanent buildings), corresponds to the designing of spaces with temporary purposes. The focus of the study is the architectural design of spaces that are produced from building systems that can to be moved to different places (process of assembly / disassembly / reassembly) in order to identify the types of spaces generated and the processes used in their design / projecting. The aim is to investigate relationships between the initial project conceived based on a Reassemblable Construction System (RCS) and its application in the architectural design of professionals and students in order to contribute to the understanding of the specificities of this type of design activity. To this end it was developed the exploratory research based on multimedia methods, which includes: documentary analysis, technical visits, interviews, surveys, academic exercise and documentation by images. Although the study is not conclusive, the results indicate significant differences between the point of view of the RCS´s designers and its users (architects and architecture students) since the users demonstrated to have some difficulty to access the features provided for the first group, in particular the students. It is also demonstrated that the use of RCSs seems to change the appreciation / hierarchization of the conditions of project design, since, unlike what happens in traditional architectural design, the designers who use them seem to be more concerned with constructive issues, especially the structural elements (support and covering), instead of functionality, aesthetics and even physical characteristics of the site

Plásticos reforçados a base de tecidos híbridos: efeitos da anisotropia e geometria normativa na caracterização mecânica e da fratura

As most current studies, reinforced plastics have been, in recent years, a viable alternative in building structural elements of medium and large, since the lightness accompanied by high performance possible. The design of hybrid polymer composites (combination of different types of reinforcements) may enable structural applications thereof, facing the most severe service conditions. Within this class of composite materials, reinforced the underlying tissues hybrid high performance are taking space when your application requires high load bearing and high rigidity. The objective of this research work is to study the challenges in designing these fabrics bring these materials as to its mechanical characterization and fracture mechanisms involved. Some parameters associated with the process and / or form of hybridization stand out as influential factors in the final performance of the material such as the presence of anisotropy, so the fabric weave, the process of making the same, normative geometry of the specimens, among others. This sense, four laminates were developed based hybrid reinforcement fabrics involving AS4 carbon fiber, kevlar and glass 49-E as the matrix epoxy vinyl ester resin (DERAKANE 411-350). All laminates were formed each with four layers of reinforcements. Depending on the hybrid fabric, all the influencing factors mentioned above have been studied for laminates. All laminates were manufactured industrially used being the lamination process manual (hand-lay-up). All mechanical characterization and study of the mechanism of fracture (fracture mechanics) was developed for laminates subjected to uniaxial tensile test, bending in three and uniaxial compression. The analysis of fracture mechanisms were held involving the macroscopic, optical microscopy and scanning electron microscopy

A Tessitura de sentidos: representação social de licenciados do curso deletras da UFRN sobre o ensinar

En esta investigación, se busca comprender los procesos de formación de pregrado del Curso de Cartas da UFRN, de estas representaciones sociales acerca de los estudiantes de enseñanza. Por lo tanto, el objetivo fue conocer y analizar las representaciones sociales de curso de pregrado UFRN Cartas sobre la enseñanza. Por lo tanto, se aplica la Técnica de Libre de Palabras Asociación (TALP) con 20 participantes, después de haber sido probados individualmente, utilizando como estímulo palabra "enseñar" y limitar el número de invocaciones a 03 palabras por participante. Esta técnica fue elegida porque es una técnica proyectiva que permite la reducción y racionalización permite acceder al campo semántico de las representaciones sociales, en nuestro caso, en la enseñanza del de pregrado do Curso de Cartas da UFRN. Por lo tanto, llegamos a total de 60 llamadas, análisis de frecuencia después de 41 y 24 después de un análisis del significado que se utilizaron en otro procedimiento aplicado en esta investigación, las calificaciones de Procedimiento de Múltiples Calificaciones (PCM). Estas palabras, sobre la base de las justificaciones de las evocaciones y significados que atribuyen participantes en la investigación, se dividieron en 4 campos semánticos: Campo 1: Aspectos técnicos de la enseñanza, Campo 2: aspectos volitivos, Campo 3: aspectos relacionales de la enseñanza y de Campo 4: Elementos del campo. El PCM se aplicó de forma individual, con 50 estudiantes. Para el análisis de los datos generados, utilizamos Análisis Multidimensional (MDS) para la Escala Multidimensional de Evaluación Análisis gratuito (MSA: Multidimensional Scalogram Analysis) y el análisis de clasificación selectiva de los espacios menores (SSA: Smallest Space Analysis). El mapa generado por el análisis de MSA fue dividido en tres regiones: Aspectos de los aspectos de enseñanza, capacitación y asistencia técnica de los promotores de la profesionalización, la primera región que tiene una sub-regionalización llamada dimensión negativa. El mapa de la SSA análisis se dividió en dos partes y un subfaceta, llamado el aspecto faceta técnica de la enseñanza y la formación, la segunda faceta llamado Vínculo entre el campo y la enseñanza específica y su nombre subfaceta aspecto relacional. Del análisis del contenido de las justificaciones de la PCM, llegó a 5 categorías, a saber: Hacer la enseñanza, la faceta negativa, Escuela, Formación y faceta afectiva del profesor. El TALP aporta pruebas de que algunos de estos estudiantes ve la oportunidad de adquirir unos conocimientos en esta área, la formación en un nivel superior, como quieran, simplemente tienen un título universitario para realizar licitación abierta. El PCM nos ha hecho comprender que el contenido representacional en cuestión se configura desde el universo consensual conectado a la profesión y la formación. Por lo tanto, podemos decir que los titulares de licencias con respecto al tema estudiado anclar la representación social de "enseñar" a la imagen de ser un maestro y objetivar la imagen de la profesión

Avaliação de concreto com adição de fibras de PET submetido a altas temperaturas

The concrete for centuries constituted an essential structural element in the construction industry due to its relative ease of forming, before the weather durability, low cost, its lower maintenance compared to other materials such as steel. However, when the concrete is exposed to high temperatures tends to lose its mechanical characteristics, and may even result in loss of section, which undermines the stability and mechanical strength of structural elements. The pathologies resulting from exposure to elevated temperatures ranging from cracks, pops up chipping explosives (spalling). Recently, the technology of concrete is closely related to the study of its microstructure. The use of fibers added to concrete has been revealed as a solution to increase the mechanical strength of the concrete, it acts directly on the distribution of efforts to act in the play within the microstructure. In this work we used recycled PET fibers embedded in concrete with 15x2mm fck = 30MPa, water/cement ratio of 0.46, in works made for verification of mechanical strength of this mixture submitted to high temperature. The specimens of concrete with addition of PET fibers were tested after exposure to temperatures: ambient (30ºC), 100°C, 200°C, 300°C, 400°C, 600°C and 900°C. It was found that the concrete loses significant strength when exposed to temperatures above 300°C, however the use of fiber PET may delay the risk of collapse of structures for the formation of a network of channels that facilitate the escape of vapor 'water, reducing the pore pressure inside the structural element

Modelagem numérica de estruturas de contenção atirantadas em areia

A numerical study on the behavior of tied-back retaining walls in sand, using the finite element method (FEM) is presented. The analyses were performed using the software Plaxis 2D, and were focused on the development of horizontal displacements, horizontal stresses, shear forces and bending moments in the structure during the construction process. Emphasis was placed on the evaluation of wall embedment, tie-back horizontal spacing, wall thickness, and free anchor length on wall behavior. A representative soil profile of a specific region at the City of Natal, Brazil, was used in the numerical analyses. New facilities built on this region often include retaining structures of the same type studied herein. Soil behavior was modeled using the Mohr-Coulomb constitutive model, whereas the structural elements were modeled using the linear elastic model. Shear strength parameters of the soil layers were obtained from direct shear test results conducted with samples collected at the studied site. Deformation parameters were obtained from empirical correlations from SPT test results carried out on the studied site. The results of the numerical analyses revealed that the effect of wall embedment on the investigated parameters is virtually negligible. Conversely, the tie-back horizontal spacing plays an important role on the investigated parameters. The results also demonstrated that the wall thickness significantly affects the wall horizontal displacements, and the shear forces and bending moments within the retaining structure. However, wall thickness was not found to influence horizontal stresses in the structure

Estudo numérico do comportamento de muros de arrimo em alvenaria estrutural de blocos vazados

Usually masonry structures has low tension strength, hence the design to flexural efforts can results in high reinforcement ratio, specification of high unit and prism strength, structural members with larger section dimensions and modification in structural arrangement to be possible to use masonry members. The main objective of this study is to evaluate the stiffness, the efforts distribution and the effect of horizontal elements (girders) and vertical elements (counterforts) distribution on the behavior of masonry blocks retaining walls. For this purpose, numerical modeling was performed on typical retaining wall arrangements by varying the amount and placement of horizontal and vertical elements, beyond includes elements simulating the reactions of the soil supporting the foundation of the wall. The numerical modeling also include the macro modeling strategy in which the units, mortar and grout are discretized by a standard volume that represents the masonry elastic behavior. Also, numerical model results were compared with those ones of simplified models usually adopted in bending design of masonry elements. The results show horizontal displacements, principal and shear stresses distribution, and bending moments diagrams. From the analysis it was concluded that quantity and manner of distribution of the girders are both important factors to the panel flexural behavior, the inclusion of the foundation changed significantly the behavior of the wall, especially the horizontal displacements, and has been proposed a new way of considering the flanges section of the counterforts

Compósitos híbridos: desenvolvimento de configuração e efeitos de umidificação

The advantage in using vegetable fibres in place of synthetic fibres such as glass fibre, for reinforcements in composites are: biodegradability, low cost, low density, good tenacity, good thermal properties, low energy content and reduced use of instruments for its treatment or processing. Even though, problems related to low mechanical performance of some of the natural fibres, has caused difficulty in their direct application in structural elements. The use of alternative materials like hybrid composites has been encouraged, thus trying to better the structural performance of the composites with natural fibres. This work presents a comparative study of the strength and stiffness of hybrid composites with orthopthalic polyester matrix reinforced with E-fibre glass, jute and curauá. The experimental part includes uniaxial tension and three point bending tests to determine the mechanical properties of the final product. The hybrid composite was manufactured in a local industry and was in the form of laminates. All the samples were projected to withstand the possible structural applications as reservoirs and pipes. CH (laminated hybrid composite with glass and curauá fibres). The results obtained show clearly the influence of the hybridization in all the types tested and indicate a good mechanical performance of the composite with glass/curauá fibres in relation to the composite with glass fibres. Aspects in relation to the interfaces glass/curauá composites besides the fracture characteristics for all loading types were also analysed

Efeitos do envelhecimento ambiental acelerado em compósitos poliméricos

The advantages of the use of vegetable fibers on the synthetic fibers, such as glass fibers, in the reinforcements in composites are: low cost, low density, good tenacity, good thermal properties and reduced use of instruments for their treatment or processing. However, problems related to poor performance of some mechanical natural fibers, have hindered its direct use in structural elements. In this sense, the emergence of alternative materials such as hybrids composites, involving natural and synthetic fibers, has been encouraged by seeking to improve the performance of structural composites based only on natural fibers. The differences between the physical, chemical and mechanical properties of these fibers, especially facing the adverse environmental conditions such as the presence of moisture and ultraviolet radiation, is also becoming a concern in the final response of these composites. This piece of research presents a comparative study of the strength and stiffness between two composite, both of ortoftalic polyester matrix, one reinforced with fibers of glass-E (CV) and other hybrid reinforced with natural fibers of curauá and fiberglass-E (CH). All the comparative study is based on the influence of exposure to UV rays and steam heated water in composites, simulating the aging environment. The conditions for the tests are accelerated through the use of the aging chamber. The composites will be evaluated through tests of uniaxial static mechanical traction and bending on three points. The composite of glass fiber and hybrid manufacturing industry are using the rolling manual (hand lay-up) and have been developed in the form of composites. All were designed to meet possible structural applications such as tanks and pipes. The reinforcements used in composites were in the forms of short fiber glass-E quilts (450g/m2 - 5cm) of continuous wires and fuses (whose title was of 0.9 dtex) for the curauá fibers. The results clearly show the influence of aging on the environmental mechanical performance of the composite CV and CH. The issues concerning the final characteristics of the fracture for all types of cargoes studied were also analyzed

Laminados compósitos de PRFV: efeitos da descontinuidade geométrica e do envelhecimento ambiental acelerado

The growing demand in the use of composite materials necessitates a better understanding of its behavior related to many conditions of loading and service, as well as under several ways of connections involved in mechanisms of structural projects. Within these project conditions are highlighted the presence of geometrical discontinuities in the area of cross and longitudinal sections of structural elements and environmental conditions of work like UV radiation, moisture, heat, leading to a decrease in final mechanical response of the material. In this sense, this thesis aims to develop studies detailed (experimental and semi-empirical models) the effects caused by the presence of geometric discontinuity, more specifically, a central hole in the longitudinal section (with reduced cross section) and the influence of accelerated environmental aging on the mechanical properties and fracture mechanism of FGRP composite laminates under the action of uniaxial tensile loads. Studies on morphological behavior and structural degradation of composite laminates are performed by macroscopic and microscopic analysis of affected surfaces, in addition to evaluation by the Measurement technique for mass variation (TMVM). The accelerated environmental aging conditions are simulated by aging chamber. To study the simultaneous influence of aging/geometric discontinuity in the mechanical properties of composite laminates, a semiempirical model is proposed and called IE/FCPM Model. For the stress concentration due to the central hole, an analisys by failures criteria were performed by Average-Stress Criterion (ASC) and Point-Stress Criterion (PSC). Two polymeric composite laminates, manufactured industrially were studied: the first is only reinforced by short mats of fiberglass-E (LM) and the second where the reinforced by glass fiber/E comes in the form of bidirectional fabric (LT). In the conception configurations of laminates the anisotropy is crucial to the final mechanical response of the same. Finally, a comparative study of all parameters was performed for a better understanding of the results. How conclusive study, the characteristics of the final fracture of the laminate under all conditions that they were subjected, were analyzed. These analyzes were made at the macroscopic level (scanner) microscope (optical and scanning electron). At the end of the analyzes, it was observed that the degradation process occurs similarly for each composite researched, however, the LM composite compared to composite LT (configurations LT 0/90º and LT ±45º) proved to be more susceptible to loss of mechanical properties in both regarding with the central hole as well to accelerated environmental aging

Descontinuidade na seção transversal em laminados compósitos poliméricos: efeitos e propriedades

The growing demand in the use of composite materials necessitates a better understanding its behavior to many conditions of loading and service, as well as under several ways of connections involved in mechanisms of structural projects. It is know that most of the structural elements are designed with presence of geometric discontinuities (holes, notches, etc) in their longitudinal sections and / or transversals, and that these discontinuities affect the mechanical response of these elements. This work has aims to analyze a study of the mechanical response, when in the presence geometric discontinuity, of polymer matrix composite laminates (orthophthalic polyester) to the uniaxial tensile test. The geometric discontinuity is characterized by the presence of a center hole in the transversal section of the composite. In this study, different kinds of stacking sequences are tested, with and without the presence of the hole, so as to provide better understanding of the mechanical properties. This sense, two laminates were studied: the first is only reinforced by with seven layers short mats of fiberglass-E (CM) and the second where the reinforcement of fiberglass-E comes in the form of bidirectional fabric (CT), with only four layers. The laminate CT has the presence of anisotropy (sense of continuous fibers with respect to the applied load) as the main parameter influencing its mechanical behavior, behavior this, not observed for the CM. In addition to the mechanical properties was also studied the fracture characteristics developed in each composite laminated. The results also showed that the presence of the hole in the transversal section decreased the ultimate strength of laminates and changed the final characteristic of fracture in all kinds of composite laminated studied

Análise de viabilidade técnica de utilização da Fibra de bananeira com resina sintética em Compósitos

This paper aims to present the feasibility of using a composite using discarded material from the cultivation of banana tree (pseudostem), which is fibrillated together with synthetic resin replacing glass fiber to be used in structural elements that do not demand large mechanical stress such as reservoirs, troughs, domes, sewage pipes etc.. For this, there were studies about the mechanical properties of a composite made with polyester resin and fiber of banana tree (Musa sp, musac), in which the splints were removed from the pseudostem, being made fibrillation by hand, with the aid of a brush steel, followed by natural drying. After treatment for cleaning and removal of wax, the fiber was cut into pieces of approximately 60 mm to 100 mm, for, together with synthetic resin, make cards of a features fiber composite with random orientation relative to the weight of the resin. We used three different percentages of fiber (3%, 6% and 9%), in order to make a comparative study between them and what would be the one with the best performance. Were manufactured specimens of each material and then subjected to uniaxial tensile tests, three point bending, moisture absorption and thermal characteristics. The results show that, in general, the use of banana tree fiber is feasible simply by an improvement in the production process (machining of the procedure) and greater care in the manufacture of parts