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224 results on '"de Andrade Silva, Flávio"'

48. A modeling strategy for the shear and flexural performance prediction of SFRC beams without stirrups accounting for the variability of properties.

Author

Benedito, André Vitor, Vanalli, Leandro, Krahl, Pablo Augusto, Martins, Carlos Humberto, and de Andrade Silva, Flávio

Subjects
FIBER-reinforced concrete, FAILURE mode & effects analysis, STIRRUPS, FIBROUS composites, IMPACT (Mechanics)
Abstract

The behavior of steel fiber reinforced concrete (SFRC) is highly dependent on mix design, where the properties of its components, such as cementitious matrix and fibers, impact the physical and mechanical properties of the composite. Incorporating steel fibers into concrete modifies its physical properties, potentially leading to fiber segregation and resulting in a nonuniform distribution of the fibers within the material. In experimental studies, an increase in fiber volume has been found to change the failure mode of SFRC beams from shear to flexure, and numerical investigations have shown that randomness in fiber distribution can significantly influence the behavior of the composite. Therefore, this study aims to develop a numerical model that considers variations in material properties to simulate the change in the failure mode of SFRC beams due to variations in fiber volume. The failure and yielding parameters were initially established and integrated into the concrete damaged plasticity (CDP). Subsequently, the response of both steel and concrete to tension or compression stresses was ascertained. Finally, the appropriate meshes and finite elements were chosen for the simulation. In the final approach, two methods were employed to introduce randomness into the beam. One divided the beam into different vertical segments: 30, 45, and 90, and the other combined vertical and horizontal segments: 30 vertical with 4 horizontal, 45 vertical with 5 horizontal, and 90 vertical with 10 horizontal. A script was developed in Python to automatically insert the properties. The numerical model successfully captured the change in failure mode from shear to flexure resulting from fiber volume increase. Vertical and horizontal segments increased toughness due to crack deviation, better predicting cracking pattern and loading capacity for the highest fiber contents. [ABSTRACT FROM AUTHOR]

Published
2024
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49. Technological characterization and utilization of recycled aggregate in the fine fraction in substitution to the fine natural aggregate for concrete production

Author

Lopes da Silva Elivone, Leonardo Torem Mauricio, and de Andrade Silva Flávio

Subjects
characterization, aggregates, waste, concrete, Environmental engineering, TA170-171
Abstract

Civil Construction and Demolition Waste (CDW), after screening process, can go through benefication process which enables physical alterations obtaining samples with different granulometry. X-ray diffraction tests were performed in order to identify the mineral components present in the samples. The Scanning Electron Microscopy (SEM) analyzes showed that the samples had rough surface texture with grains present in different formats. The chemical properties are the conditioning factor of the affinity between the aggregate and the binder, and can contribute to the early degradation of the structures. The analysis of physical and mechanical properties is important because, in addition to assessing mechanical strength performance, it also analyzes the performance of CDW concrete. The compression tests and modulus of elasticity of an aggregate are not easy to measure because the particles cannot be tested alone. Test bodies were produced with fractions of 10%, 20%, 30%, 50%, and 100% RCD. As a result of the mechanical tests performed in these test bodies it was observed that the fractions with up to 30 % recycled aggregate obtained good compressive strength ranging from 33 MPa to 46 MPa, with modulus of elasticity varying from 24.96 GPA to 31.54 GPA. However, the same result was not obtained for the fractions that had above 50 % recycled aggregate in the concrete trait that had compressive strength ranging from 10.8 MPa to 15 MPa, with modulus of elasticity varying from 11.82 GPA to 14.45 GPA.

Published
2019

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