This is a study about the size effect on the methodology with concrete cylinder specimens for analysis of the debonding phenomenon at the interface between concrete and carbon fiber reinforced polymer (FRP). The influence of the concrete specimen size variation is analyzed by maintaining the same geometry in adhered FRP. Direct tensile experiments were performed with three dimensions of cylindrical concrete specimens (diameter × height) for analysis of size effect: 50 mm × 100 mm, 100 mm × 200 mm, and 150 mm × 300 mm. Ten different geometries of the composite material were tested. Two failure modes were observed in the experiments: debonding between the two materials and tensile failure in concrete specimens. In experiments with interface failure, the size of concrete specimens has no significant influence on maximum force, shear stress to peak, and stiffness in debonding between concrete and FRP. However, the use of smaller specimens for analysis of interface collapse is limited because the concrete reaches its normal stress capacity with a lower tensile force, and therefore, the failure often occurs in the concrete.
O presente trabalho se ocupou do estudo das rotinas do sono e do banho em instituições de educação infantil com o objetivo de compreender os processos de construção da identidade corporal das crianças. Os resultados indicaram que estes processos se instauram sob as bases da regulação e não da autonomia. Evidenciaram as precárias condições sob as quais se concretizaram os momentos do sono e do banho, fato que indica que as condições materiais e concretas também determinam a forma como as concepções e práticas institucionais e profissionais conduzem a ação educativa nesta etapa da educação. Palavras-chave: Regulação. Rotinas. Educação Infantil. Corpos.
ABSTRACT. Knowledge obtained in research and project practice contributed to upgrade the Brazilian standard regarding the dimensioning of concrete structures in 2014. The objective of the study is to evaluate the influence in the budget on the structure of an edifice due to changes in the standard ABNT NBR 6118:2014: use of different aggregates and of high-strength concrete. A building structure of reinforced concrete sized according to standards ABNT NBR 6118:2007 and ABNT NBR 6118:2014, considering different hypotheses. The simulations were performed with the software AltoQi Eberick (2014). The quantitative materials (steel, concrete, forms and expanded polystyrene to slabs) and inputs budget for structure were performed for each simulation. The type of aggregate influenced up to 4.60% of cost of the structure and up to 0.82% in overall cost in comparison with previous version of the standard. The use of C60 concrete compared with to C25 increased the budget of the structure (For the same aggregate type, the increase was, in average, of 14%). Although the use of steel and molds reduced (averaged 5%), it was not sufficient to eliminate the difference in the cost of concrete for edifice analyzed.
This study aims to compare methods for the determination of concrete properties by means of the stress diagrams present in the Brazilian standard ABNT NBR 6118: 2014. The area under the stress diagram, the internal reactions, and the application point of the resulting reactions for the parabola-rectangle and rectangular block diagrams are present in order to compare them. Deductions and numerical examples were used, and different results were obtained for each formulation. This is due to non-consideration of the relationship between stress and strain in the simplified rectangular block. The rectangular block is applicable only for cases in which the concrete reaches the ultimate strain. These cases are those that concrete crushing determines the section failure in compression with steel yielding in tension (domain 3) or without steel yielding (domain 4).
This article proposes an alternative method for the structural design of reinforced concrete elements strengthened in bending by metallic plates or fiber-reinforced polymer (FRP) bonded to the concrete substrate. It is proposed a new calculation procedure for the strengthening using thin adhered material bonded to the element surface that dispenses the iterative process generally used in the design. The proposed routine is validated by comparison with other methods. A practical example is also presented, applying the procedure to an element of a building where a load change was foreseen. As result, it was verified that the proposed procedure provides values similar to the trial-and-error method used in the FRP strengthening design. Results are also coherent with other methods available in the literature for metallic plates. Therefore, since this routine obtains similar values without using an iterative method, its applicability in the design becomes advantageous.
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