Navegando por Assunto "Sistema de ancoragem"

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Acesso aberto (Open Access)
Análise experimental da influência de ancoragens e taxas de armadura na resistência à flexão de consolos longos reforçados com laminados de fibra de carbono
(Universidade Federal do Pará, 2025-05-29) SILVA, Lucas Carvalho; LIMA NETO, Aarão Ferreira; http://lattes.cnpq.br/0287664572311345; https://orcid.org/0000-0002-5911-1368
For the repair and strengthening of reinforced concrete corbels, solutions are sought that extend the service life of these structures, increase their load-bearing capacity, reduce deformations, and limit crack propagation. Therefore, this study presents tests on experimental models of corbels strengthened with Carbon Fiber Reinforced Polymer (CFRP) laminates to analyze the strength enhancement in these models. All corbels are chamfered and have the same geometry. Thus, the ratio between the load application point (a) and the effective depth (d) is approximately 1.28, allowing the behavior to be characteristic of either a corbel or a cantilever beam. All specimens have a geometric arrangement with 250 mm width, 400 mm embedded height, 200 mm height at the outer face, and 570 mm length. The main objective of this research is to analyze the behavior of the reinforcement according to the variation in the main reinforcement ratio and the anchorage method, to compare the experimental results with current standards, and to verify whether the proposed anchorage systems prevent premature failure modes. The reinforcement dimensions consist of a (50x1440) mm laminate applied to both faces of the corbel. Two configurations of the anchorage system were analyzed. The first anchorage method involves attaching bolts through plates that do not perforate the laminate, known as Hybrid Bonding (HB). The second method, classified as FT (based on the laminate application approach), uses the reinforcement laminates themselves, with overlapping layers — the final one being applied perpendicular to the reinforcement and previous layers. Regarding the results, it was observed that both anchorage methods are effective in increasing the strength of the specimens, with HB being the most suitable anchorage method. Furthermore, depending on the reinforcement ratio, the strength gains provided by the reinforcement vary, being less effective in corbels with higher main reinforcement ratios. Finally, it was noted that the proposed anchorage methods were not entirely effective in preventing debonding along the laminate. However, it is worth highlighting that in the corbels with HB anchorage, even with reinforcement debonding, the anchorage was able to prevent complete slippage, contributing to increased ductility of the corbel even after debonding.
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)
Efeito da taxa de armadura existente e do sistema de ancoragem na resistência à flexão de consolos curtos de concreto armado reforçados com laminados de PRFC
(Universidade Federal do Pará, 2025-06-13) LIMA, Layse Rafaele Furtado; FERREIRA, Maurício de Pina; http://lattes.cnpq.br/4242041552985485; https://orcid.org/0000-0001-8905-9479
Short corbels are elements used in bridges and buildings to support beams, stringers or concentrated loads of great intensity, and are characterized by having a span-to-height ratio of less than one. Over the course of their useful life, these structures can fail to meet basic safety requirements for reasons such as design error, material degradation, overload or change in use, requiring reinforcement techniques that can be applied quickly and efficiently. With this in mind, this work seeks to experimentally analyze short reinforced concrete beams reinforced externally in bending with Carbon Fiber Reinforced Polymer (CFRP) laminates. To this end, six specimens were analyzed, three with a 0.18% flexural reinforcement rate and three with a 0.47% rate. All the models have the same geometry, with the presence of horizontal and vertical stirrups. The reinforcement was positioned on both sides of the cantilever and anchored at the ends, checking the influence of two systems. The first anchoring system is made up of steel plates and bolts, while the second is made up of overlapping laminates, with transverse bonding in the last layer. As a result, it was possible to analyze that the reinforcement proved to be efficient in terms of increased resistance, which ranged from 14,5% to 50,3%, with the hybrid anchorage standing out as having the highest loading value.