Dissertações em Engenharia de Infraestrutura e Desenvolvimento Energético (Mestrado) - PPGINDE/NDAE/Tucuruí

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/9401

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Acesso aberto (Open Access)
Análise experimental de consolos curtos de concreto armado com fibras e variação da armadura de costura
(Universidade Federal do Pará, 2023-11-23) QUEIROZ, Daniel Pessanha de; LIMA NETO, Aarão Ferreira; http://lattes.cnpq.br/0287664572311345; https://orcid.org/0000-0002-5911-1368
Short armoured concrete consoles are pre-molded structural elements, arranged in balance, which function as a load support. This work aims to analyze experimentally the behavior of short consoles of armed concrete with variation of sewing armour area and application of a fixed content for steel fibers, polyethylene and polypropylene. Ten symmetrical specimens were analyzed, where four speciments did not contain sewing armor and possessed respectively the steel fibers (CA), polyethylene (CPE), polypropylene (CPP) and a fiber-free (CSF). Four specimens with six sewing armor Ø6.3 mm and used steel fibres respectively (C6Ø6.3A), polyethylene (C6Ø6.3PE), polypropylene (C6Ø6.3PP) and a fiber-free (C6Ø6.3SF). One specimen with six armor Ø5.0 mm seam and polyethylene fiber (C6Ø5.0PE). One specimen with eight armor Ø5.0 mm seam with polyethylene fiber (C8Ø5.0PE). They are presented, analyzed and discussed the results of: deformations of concrete and main traction armor and sewing; breaking modes; cracking maps and patterns; end resistance and loads of consoles; as well as the efficiency factors of biela, subsequently these topics above should be compared with those obtained by Abrantes (2019) and with what advocates the regulatory standards ABNT NBR 9062 (2017), NBR 6118 (2023), EUROCODE 2 (2010) and ACI 318 (2014). It is concluded that they have achieved better results compounds that received the addition of fibers. In terms of compression, traction and modulus of elasticity, comparing the matrix without and with fibres, polyethylene was 15%, steel 18% and polypropylene 21% more efficient, respectively. It can be seen that for each test a different fibre performed better. In general, C8Ø5.0PE achieved good results in all analyses, despite not being the specimen with the largest seam reinforcement area. This result is justified by the arrangement of the reinforcement inside the concrete, as well as the presence of the polyethylene fibre.
Acesso aberto (Open Access)
Análise experimental do desempenho à flexão de vigas de concreto armado reforçadas com laminado de fibra de carbono com variação da taxa de armadura existente e do mecanismo de ancoragem
(Universidade Federal do Pará, 2025-06-17) LEÃO JÚNIOR, Paulo Sérgio Barreiros de; LIMA NETO, Aarão Ferreira; http://lattes.cnpq.br/0287664572311345; https://orcid.org/0000-0002-5911-1368
The strengthening of existing reinforced concrete structures with Fiber-Reinforced Polymers (FRP), using techniques such as Externally Bonded Reinforcement and Near-Surface Mounted, is common in practical applications, especially when using Carbon FRP (CFRP). However, in strengthening scenarios that require higher load capacities, these methods may be less effective due to premature debonding failure, highlighting the importance of anchorage systems to improve reinforcement efficiency. There is limited information in the literature regarding the influence of steel reinforcement ratio on the behavior of beams strengthened with anchorage systems. Therefore, this study experimentally investigates the flexural performance of reinforced concrete T-beams strengthened with CFRP, considering two steel ratios (0.44% and 1.12%) and two anchorage systems. Flexural tests were conducted on six T-section beams (2200 mm length, 280 mm height, 180 mm web width, and 80 mm thick by 350 mm wide flange). Each beam had 21 stirrups made of 12.5 mm bars spaced at 100 mm. For each steel ratio, one beam was unstrengthened (reference), and two were strengthened using either a friction-based mechanical anchorage (Hybrid Bonded – HB) or an anchorage system using bonded CFRP strips (FT). Strengthening was more effective in beams with the lower steel ratio, with strength increases of 58% for HB and 11% for FT. For the higher steel ratio, gains were limited to 10% for HB and none for FT. The HB system achieved a flexural capacity of 117.72 kN·m and showed better performance in intermediate displacements, with ductility increases up to 57 times at cracking and up to 100% at steel yielding. At maximum load, all strengthened beams showed reduced ductility. In the HB system, ductility loss increased with steel ratio, from 25% in the less reinforced beam to 49% in the more reinforced one. In the FT system, the trend was reversed, with a 66% loss for the lower steel ratio and 24% for the higher. Failure modes were governed by laminate slip in HB and cover delamination in FT.
Acesso aberto (Open Access)
Influência da substituição de agregados naturais por reciclados de concreto na resistência à punção de lajes lisas de concreto armado com armadura de cisalhamento
(Universidade Federal do Pará, 2023-11-21) PORTILHO, Shara Katharine Melo Silva; LIMA NETO, Aarão Ferreira; http://lattes.cnpq.br/0287664572311345; https://orcid.org/0000-0002-5911-1368
This research experimentally analyzed the mechanical behavior of four reinforced concrete flat slabs with shear reinforcement, when subjected to punching shear forces. Two of these slabs were made using a concrete mixture with a total replacement of natural coarse aggregates (NGA) by recycled concrete coarse aggregates (RCCA), and two slabs served as reference (without replacement). Shear reinforcement had two types: double headed studs and individual stirrups. The specimens were octagonal in shape, with 2,500 mm between opposite faces, thickness of 210 mm, and were supported on square central columns measuring 300 mm on each side. The estimated average concrete strength was 25 MPa, and the flexural and punching shear were 1.4% and 0.34%, respectively. After the laboratory tests, a comparison was made between the experimental behavior and the theoretical predictions from ABNT NBR 6118 (2023), Eurocode 2 (2014), ACI 318 (2019), and the fib Model Code 2010 (2013) models. Regarding the use of shear reinforcement, the results showed that the slabs with double headed studs presented higher punching shear strength when compared to those with individual stirrups. It was also observed that slabs with a total replacement of natural coarse aggregates by recycled concrete aggregates presented lower punching shear strength than slabs with natural aggregates. Regarding the comparison between the estimated punching shear strength of the flat slabs with shear reinforcement using RCCA prescribed by the analyzed codes and the experimental results, it was found that almost all code predictions were very close to the experimental values, except for the Brazilian code, which indicated results against safety.
Acesso aberto (Open Access)
Modelagem da capacidade de infiltração de diferentes cenários de pavimentos permeáveis na bacia do Una - Belém-PA
(Universidade Federal do Pará, 2023-04-06) PALHETA, João Victor Batista; CORDEIRO, Luciana de Nazaré Pinheiro; http://lattes.cnpq.br/9126233381230999; https://orcid.org/0000-0001-7931-4042
Permeable concrete is an important alternative for sustainable construction, being used to preserve water quality and restore soil infiltration properties. To analyze this behavior, a study was conducted to analyze the infiltration capacity of different permeable sidewalk scenarios in the Três de Maio sub-basin located in Belém do Pará using SWMM software. To this end, characteristics were stipulated such as the effect of sidewalk thickness on infiltration rate, base thickness on infiltration rate, the effect of permeable sidewalk area on infiltration rate, and water catchment potential in the proposed scenarios. The scenarios were divided into nine drainage system arrangements, distributed into three thicknesses for the base course (100 mm, 200 mm and 300 mm) and 3 three for the permeable concrete sidewalk reservoir (300 mm, 400 mm and 500 mm). With the insertion of permeable sidewalk it was noticed that all the modeled scenarios obtained significant benefits, however, the application of permeable concrete thickness variation did not obtain significant influence on the infiltration rate keeping its results constant. The use of permeable sidewalk has a great potential for water catchment in all scenarios, showing promise to be applied in areas with a low degree of permeability, especially in the sub-basins that make up the Una basin in Belém do Pará, which suffer from flooding and inundation due to urban sealing and the outdated drainage network.

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