Concretos de alta resistência têm sido usados em estruturas, atualmente, em diversas partes do mundo. Entretanto, no Brasil, pouco se conhece sobre seu comportamento. Este trabalho fornece uma visão geral das aplicações, dos materiais empregados na produção, das propriedades mecânicas e do comportamento estrutural dos concretos de alta resistência. Resultados experimentais obtidos por alguns pesquisadores, para pilares com carga axial e para vigas sujeitas a flexão e a cisalhamento, são comparados com valores teóricos, calculados com procedimentos usuais relativos a concretos de resistência usual. Para os pilares, é inquestionável a necessidade do confinamento do núcleo de concreto, utilizando armadura de cintamento. Na flexão das vigas, as taxas mínimas para armadura longitudinal, sugeridas pelas normas para concretos usuais, não são suficientes; é importante ter valores maiores que esses. E para cisalhamento, as recomendações das normas são satisfatórias. / Nowadays, high-strength concrete has been used in structures all over the world. However, in Brazil, not much is known about its behavior. This work provides an overview of the applications, the materials employed in production, the mechanical properties, and the structural behavior of high-strength concrete. Experimental results obtained by several researchers, for columns under axial load and beams under flexure and shear, are confronted with theoretical values, computed by normal procedures relative to normal strength concrete. For columns, it is unquestionable the need of confinement of the concrete core by transverse reinforcement. In beams under flexure, the minimum rates for longitudinal reinforcement, suggested by the codes for usual concrete, are not enough; it is important to have values greater than those. And for shear, the codes requirements are satisfactories.

The goal of this study was to revise the development length equation of ACI 318- 05 and to better reflect test results for high-strength concrete. The revision of the equation was accomplished using test results tabulated in the Database 10-2001maintained by ACI committee 408. Equations for development length in ACI 318-05 and ACI 408.3 examined to understand the issues to be considered for revision on the variability of test data. The development length equation in ACI 318-05 was very conservative for [compressive strength of concrete][less than or equal to]14,000 psi based on the experimental data in Database 10-2001 of ACI Committee 408. On the contrary, the ACI 318-05 may be less conservative for high-strength concrete, [compressive strength of concrete] [greater than or equal to]14,000 psi . Thus, modified design equations were proposed to provide realistic values for normal strength concrete and conservatively for high-strength concrete. The ACI 318-05 equation was modified for 1) compressive strength of concrete and 2) confinement as expressed by the term [minimum side cover, cover over the bar or wire, or one-half the center-to-center spacing of the bars or wires] + [contribution of confining reinforcement across potential splitting planes] / [normal diameter of bar] in ACI 318-05. The basic assumption is that bar stress is a linear function of development length, and development length is the length required for bar stresses to reach the yield. / text

published_or_final_version / Civil and Structural Engineering / Master / Master of Philosophy

published_or_final_version / Civil Engineering / Master / Master of Philosophy

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Thesis (Ph.D.)--University of Adelaide, Dept. of Civil and Environmental Engineering, 2002. / "June 2002" Includes bibliographical references (leaves 349-374).