21,108 research outputs found
Projeto de vigas de pequeno porte parcialmente protendidas com monocordoalhas engraxadas
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-graduação em Engenharia CivilEsta dissertação estuda a aplicação do sistema de monocordoalhas engraxadas em vigas isostáticas e hiperestáticas de estruturas de edifícios, de acordo com as recomendações da norma NBR6118:2003. Os objetivos gerais resumem-se em apresentar, discutir e sugerir critérios de projeto para dimensionamento e verificação dessas vigas e, em seguida, aplicar esses critérios a alguns exemplos de cálculo. A parte inicial da pesquisa traz uma revisão dos conceitos de graus de protensão, com ênfase especial em protensão parcial, assim como a consideração simplificada das perdas como uma força constante ao longo do cabo. Além disso, discutem-se, em detalhes, a representação da protensão por carregamentos externos equivalentes e o método das cargas balanceadas. Apresenta-se uma proposta para a verificação da capacidade resistente de seções no ELU por meio de um processo iterativo em planilha eletrônica. As definições da NBR6118:2003 para verificação dos estados limites de serviço de abertura de fissuras ELS-W e de deformação excessiva ELS-DEF são analisadas e, a seguir, comparadas com as recomendações do eurocódigo EN1992:2004 e da norma americana ACI318:2002. A segunda parte inicia com a presentação detalhada dos procedimentos de verificação aos ELU e aos ELS de uma viga biapoiada de concreto armado que possui flecha além da permitida. Posteriormente, a essa mesma viga são acrescentadas cordoalhas engraxadas para resolver o problema da deformação. Um segundo exemplo de aplicação analisa a importante influência de pilares e lajes na distribuição dos esforços de protensão na estrutura. O último exemplo mostra as diferenças entre os esforços isostáticos e hiperestáticos obtidos com os modelos de viga contínua e de pórtico plano e sua influência nos estados limites últimos e de serviço da viga em estudo. Em se admitindo perdas constantes e se utilizando o método dos carregamentos equivalentes com modelos elásticos, dimensionar e verificar vigas contínuas com protensão parcial torna-se relativamente simples. This dissertation studies the application of the unbonded strand systems in isostatic and hiperstatic beams of building structures, in accordance with the recommendations of the NBR6118:2003 code. The main objectives are summarized in presenting, commenting and suggesting project criteria for sizing and verifying these beams, and, after that, applying these criteria to some examples of calculation. The initial part of the research brings a revision of the prestressing degrees concepts, with special emphasis in partial prestressing, as well as the simplified consideration of the losses as a constant force throughout the tendon. Moreover, the representation of the post-tensioning by external equivalent loads and the method of balanced loads are discribed in details. It´s presented a proposal for verification of the resistant capacity of sections in the ultimate limit state ULS through an iterative process in electronic spread sheet. The definitions of BR6118:2003 for serviceability limit states SLS verifications, as control of crack width and control of deformation, are analyzed and, afterward, compared with the recommendations of eurocode EN1992:2004 and American code ACI318:2002. The second part initiates with the detailed presentation of the procedures for ULS and SLS verification of a reinforced concrete, single supported beam which presents deflection beyond the allowed value. Later, it is added to that same beam unbonded strands to solve the deflection problem. The second example of application analyzes the important influence of columns and slabs in the distribution of the post-tensioning efforts in the structure. The last example shows the differences between the isostatics and hiperstatics efforts gotten with the continuous beam and plane frame models, and its influence in the ultimate and serviceability limit states of the beam in study. If constant losses are admitted and if the method of equivalent loads are used with elastic models, to size and to verify continuous beams with partial prestressing becomes a relatively simple task
Report on Meteorological Research March 1, 1935 (m-1)
No full textThe object of the report was to elucidate in detail the various features of the research program in meteorology being carried on at the Daniel Guggenheim Airship Institute in Akron, Ohio. Mr. L. J. Fangman, of the U.S. Weather Bureau, was collaborating with the author in carrying out work such as a study of autographic records of the various meteorological elements during frontal passages with a view to the possible prediction of the intensity of the accompanying disturbance as it may affect the operation of aircraft and a study of atmospheric gustiness with a view to finding the dependence between frequency end amplitude of velocity fluctuations and the vertical temperature and velocity gradients
(Fourth) Report on Meteorological Activities at the DGAI (8-1-36)(Weather Bureau Copy)
No full textThis report is on the investigations of frontal phenomena at the Daniel Guggenheim Airship Institute in Akron, Ohio from January 1, 1935 through August 1, 1936. The investigation was carried out with the cooperation of the U.S. Bureau of Aeronautics, the U.S. Weather Bureau, the California Institute of Technology, and the Guggenheim Airship Institute. Mr. R.C. Robinson of the Weather Bureau cooperated with the author in carrying out the investigation. The object of the investigation was to determine the intensity of the atmospheric disturbances (i.e. rapidity of wind shift and gustiness) accompanying the passage of cold fronts, along with a study of the characteristics of the air masses involved and other features which might affect the intensity of the disturbance. The report treated thirty cold fronts which passed the station during 1935 to 1936
Dimensionamento por computador de vigas simplesmente apoiadas de concreto protendido pós-tracionadas
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Civil.O dimensionamento e detalhamento de vigas de concreto protendido é um processo iterativo demandando muito trabalho rotineiro de engenharia. Como conseqüência tem-se a introdução de simplificações com perda de precisão nos resultados. Programas computacionais para o projeto de elementos estruturais de concreto protendido ainda são poucos. Neste trabalho, foram desenvolvidos procedimentos e rotinas computacionais, para o dimensionamento aos Estados Limites de Serviço, de vigas simplesmente apoiadas de concreto protendido, pós-tracionadas. Pretende-se com a disponibilização desta ferramenta computacional estimular a utilização do concreto protendido, além de contribuir para a obtenção de soluções melhores em termos técnicos, econômico-financeiros, sociais e ambientais. Fornecendo o vão e o carregamento da viga, o nível de protensão desejado e as características dos materiais a serem utilizados na sua fabricação, o programa indicará o módulo de resistência mínimo que deve ter a seção transversal. Adotada uma seção transversal para a viga, o programa escolherá automaticamente os cabos de protensão, visando minimizar o consumo de aço. O lançamento dos cabos de protensão é feito de forma semi-automática, ou seja, com a participação do usuário. Com o traçado dos cabos definido serão calculadas as perdas de protensão e a seguir as tensões normais nas bordas das diversas seções, para que possam ser comparadas com as tensões limite. O aplicativo foi desenvolvido na linguagem de programação Visual Basic. As rotinas consideram os conhecimentos atuais da técnica do concreto protendido. São apresentados vários exemplos de vigas resolvidas com o programa desenvolvido. Os resultados, obtidos com o programa, foram comparados aos obtidos por outros autores. Estudou-se a utilização da região delimitada pelas curvas limite para fins de lançamento automático dos cabos de protensão. Com base nos gráficos da força de protensão após as perdas, feitos pelo aplicativo, foram obtidas conclusões importantes com relação às perdas de protensão
Archives and Images as Repositories of Time, Language, and Forms from the Past: A Conversation with Daniel Eisenberg
No full textDaniel Akech
No full textabstract: Daniel was a little boy when the war came to his village. He witnessed people being shot and running for shelter. There was no food or water so he drank urine and ate tree leaves.
“Lost Boys Found” is an ongoing, interdisciplinary project that is collecting, recording and archiving the oral histories of the Lost Boys/Girls of Sudan. The collection is a work-in-progress, seeking to record the oral history of as many Lost Boys/Girls as are willing, and will be used in a future book.Age: 24Region: Upper NileThis picture and bio was donated to the "Lost Boys Found" oral history project from The Arizona Lost Boys Cente
Daniel Emmett postcard
No full textPostcard of Daniel Emmett and his home in Mount Vernon, Ohio. Emmett is considered to be the author of the antebellum song "Dixie," written in 1859, which became the unofficial song of the Confederate soldiers during the American Civil War. He was born in Mount Vernon in 1815 and taught himself the fiddle, and later became associated with minstrel shows and helped to define that genre. Minstrel shows traveled around the United States, presenting skits and musical performances. Emmett also composed many other songs, including "Old Dan Tucker," "Turkey in the Straw," and "The Blue Tail Fly." He died in 1904
Daniel Jau Maper
No full textabstract: Daniel Jau Maper was herding cattle when Arabs attacked his village.
“Lost Boys Found” is an ongoing, interdisciplinary project that is collecting, recording and archiving the oral histories of the Lost Boys/Girls of Sudan. The collection is a work-in-progress, seeking to record the oral history of as many Lost Boys/Girls as are willing, and will be used in a future book.Age: 27Region: Upper NileThis picture and bio was donated to the "Lost Boys Found" oral history project from The Arizona Lost Boys Cente
Daniel A. Ngor
No full textWhen Daniel was five years old Arab soldiers attacked his village.
“Lost Boys Found” is an ongoing, interdisciplinary project that is collecting, recording and archiving the oral histories of the Lost Boys/Girls of Sudan. The collection is a work-in-progress, seeking to record the oral history of as many Lost Boys/Girls as are willing, and will be used in a future book.Age : 23Region: Upper NileThis picture and bio was donated to the "Lost Boys Found" oral history project from The Arizona Lost Boys Cente
Personal Papers (MS 80-0002)
No full textLetter from Mary T. Steyn of The Readers Digest to Daniel W. Kempner providing some information on the author of an article he was asking about
- …
