https://repositorio.ufu.br/handle/123456789/19022 Mon, 17 Aug 2026 15:13:04 GMT 2026-08-17T15:13:04Z https://repositorio.ufu.br/handle/123456789/49238 Title: Comportamento estrutural de vigas celulares mistas de aço e concreto com protensão externa Abstract: Cellular composite steel–concrete beams are defined as the combination of a concrete slab and a steel beam with sequential circular openings, connected through shear connectors, enabling their application in long spans while reducing self-weight. In order to improve structural performance or support rehabilitation strategies, external prestressing emerges as a viable solution to increase load-carrying capacity and reduce serviceability deflections. However, although prestressing is well established in reinforced concrete, and standards such as ABNT NBR 8800:2024 and Eurocode 4 BS EN 1994-1:2026 address the design of composite beams, while Eurocode 3 BS EN 1993-1-13:2024 covers cellular beams, there are still no normative procedures for the application of external prestressing in cellular composite steel–concrete members. In this context, a numerical model was developed using ABAQUS® to investigate the structural behavior of externally prestressed cellular composite beams, based on validation against experimental models available in the literature. A parametric study was carried out to evaluate the influence of cable eccentricity, initial prestressing force, cable profile and span, as well as cross-sectional properties and geometric parameters of the openings. The analysis focused on the serviceability limit state defined by ABNT NBR 8800:2024, adopting a displacement-based criterion corresponding to a maximum deflection of L/350. The results indicated that external prestressing increased the equivalent bending moment under service conditions in all analyzed models, with gains ranging from approximately 20% to 45% compared to non-prestressed beams, depending on the cable profile and eccentricity. Polygonal cable layouts showed superior performance compared to straight profiles, promoting a more efficient redistribution of internal forces. It was also observed that variations in opening diameter influence the elastic behavior of the beams. Overall, external prestressing proved to be an effective strategy to enhance the service performance of cellular composite beams, contributing both to increased load capacity and reduced deflections, particularly when efficient cable layouts are adopted. parameters. Thu, 12 Mar 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/49238 2026-03-12T00:00:00Z https://repositorio.ufu.br/handle/123456789/48855 Title: Uso combinado de fibras de PVA e PP em matriz com fíler calcário e metacaulim: efeito nas propriedades de compósitos cimentícios engenheirados Abstract: Engineered Cementitious Composites (ECC) are fiber-reinforced materials characterized by high ductility and strain-hardening behavior. The typical formulation of these composites employs fly ash as a partial cement replacement and 2% polyvinyl alcohol (PVA) fibers. However, the irregular availability of fly ash in some regions, combined with the high cost of PVA fibers, has driven the search for more viable and sustainable alternatives. In this context, this work aimed to investigate the impact of fully replacing fly ash with a combination of metakaolin and limestone filler in the ECC matrix, as well as to evaluate the effect of hybridizing PVA and polypropylene (PP) fibers on the composite's properties. The experimental program was developed in two stages: (1) formulation of matrices with full replacement of fly ash by metakaolin and limestone filler in proportions (1M1C and 1M2C), determining the superplasticizer content by mini-slump test; and (2) study of the hybridization of PVA and PP fibers at volumetric substitution levels of 0%, 25%, 50%, 75%, and 100% in two distinct matrices. The results showed that the matrix containing metakaolin and limestone filler (1M2C) exhibited workability and mechanical strength similar to the reference matrix (M45), making it a viable alternative. Fiber hybridization significantly affected the composite's behavior. The mixture with 1.5% PVA and 0.5% PP (1.5A_0.5P) offered the best balance between strength and ductility. Increasing the PP content reduced workability and flexural strength but increased deformation capacity. Microstructural analysis confirmed distinct failure mechanisms: rupture of PVA fibers and pull-out of PP fibers. The combined use of metakaolin and limestone filler proved viable for replacing fly ash in ECC production. Fiber hybridization allows the adjustment of ECC properties to meet specific application requirements. Thu, 05 Feb 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48855 2026-02-05T00:00:00Z https://repositorio.ufu.br/handle/123456789/48449 Title: Análise experimental de blocos sobre duas estacas metálicas com armadura metálica e não-metálica de barras de polímeros reforçada com fibra de vidro (GFRP) Abstract: Pile caps are fundamental structural elements in deep foundation systems, responsible for transferring loads from the superstructure to the piles. Due to their typical exposure to aggressive environments, such as high moisture conditions, these elements are prone to deterioration associated with steel reinforcement corrosion, which motivates the investigation of more durable reinforcement alternatives. In this context, this study experimentally evaluated the structural behavior of rigid pile caps supported by two steel piles, designed according to the strut-and-tie method, comparing models reinforced with CA-50 steel bars and glass fiber-reinforced polymer (GFRP) bars. All models were designed with identical geometry, loading conditions, and concrete strength, varying only the type and distribution of the main tensile reinforcement. The experimental program included material characterization tests, load tests up to failure, and detailed instrumentation to monitor strains, displacements, crack development, and load distribution at the supports. The results showed that steel-reinforced pile caps exhibited behavior consistent with rigid block assumptions, presenting lower deformations and better crack control. Conversely, GFRP-reinforced pile caps showed larger deformations and crack widths, indicating a more flexible structural response, even when designed using the same criteria. It was also observed that distributing the GFRP reinforcement along the entire length of the tie resulted in improved structural performance compared to concentrating the reinforcement only in the anchorage region. The study concludes that the use of GFRP bars in pile caps is structurally feasible in terms of ultimate strength; however, additional design criteria related to deformation and crack control are required. Fri, 06 Feb 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48449 2026-02-06T00:00:00Z https://repositorio.ufu.br/handle/123456789/48019 Title: Estudo do coagulante tanfloc e do coagulante sulfato de alumínio no tratamento de efluente de laticínio Abstract: The increase in demand for water and the need for adequate treatment of industrial effluents have encouraged the search for more efficient and sustainable processes. In the dairy industry, which generates effluents with high organic load, color, and turbidity, coagulation and flocculation are essential steps for the removal of particles and organic matter, and the choice of coagulant is decisive for the performance of the treatment. In this context, this study compared the chemical coagulant aluminum sulfate to the natural coagulant Tanfloc in the removal of color and turbidity from dairy effluent, through tests in Jartest equipment and the preparation of coagulation diagrams to define the ideal pH and dosages, complemented by digital image analysis to evaluate the characteristics of the flocs formed and sedimentation behavior. The results indicated that aluminum sulfate showed good removal, but required strict pH correction and higher dosages, implying an increase in input consumption and the production of sludge with a higher metal content. Tanfloc, on the other hand, showed efficiency in wider pH ranges and at lower dosages, in addition to generating less sludge, with biodegradable characteristics. Although Tanfloc has a higher unit cost, its application can reduce indirect operating costs and environmental impacts. It can be concluded that Tanfloc is a promising and sustainable alternative to aluminum sulfate, especially in systems that seek efficiency combined with waste reduction and operational simplification. Fri, 12 Dec 2025 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/48019 2025-12-12T00:00:00Z