Navegando por Assunto "Estruturas mistas"

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Acesso aberto (Open Access)
Análise experimental do desempenho de conectores de cisalhamento de vergalhões dobrados para estruturas mistas via ensaios push-out
(Universidade Federal do Pará, 2022-11-25) SOUSA, Vanessa Carolaine de; LIMA NETO, Aarão Ferreira; http://lattes.cnpq.br/0287664572311345; https://orcid.org/0000-0002-5911-1368
Advances in civil engineering have led to the development of new techniques and materials that optimize the construction process. In this context, steel-concrete composite structures have emerged, which use steel and concrete efficiently through the collaborative work of the materials, exposing the metal part to tensile stresses and the concrete to compressive stresses. Shear connectors are essential in steel-concrete composite structures. They ensure the interaction between the materials and the transfer of stresses, making the structures lighter, stronger, and more durable. It is important to understand their operation and to seek new materials and technologies to optimize the structures. In this sense, this research continues the work of Souza (2019) and Barbosa (2016), who studied shear connectors made with CA-50 steel bars bent. The experimental program includes 7 models (varying the bar size, reinforcement rate, and the inclination of the connectors relative to the table of the metal profile) that were tested according to the recommendations of Eurocode 4 (2004). Of these 7 models, 2 were made with 12.5 mm rebar (models A1 and A2), 2 with 10.0 mm (models B1 and B2), 2 with 8.0 mm (models C1 and C2), and 1 model made with 6.3 mm diameter assembled in a single module (model D). When analyzing the load-carrying capacity/steel area ratio of the connectors, the results show that connector A1 (12.5 mm) had the best performance among the models in the study and also stands out when compared to other connectors studied such as those of Barbosa (2016), Souza (2019), and Chaves (2009). No significant evidence was observed that the inclination of the connectors positively affects the load-carrying capacity of the models. Analyzing the relative displacement between the profile and the slabs, it was possible to classify the models by ductility, in increasing order: D, A1, C1, C2, A2, B2, and B1. The 10.0 mm models have the highest ductilities, and the influence of the inclination of the connectors on this aspect is not clear. Analyzing the behavior in relation to uplift, it is noted that the best performances are in connectors B and C (10.0 mm and 8.0 mm) and there is a tendency for worse results in inclined connectors.
Acesso aberto (Open Access)
Análise experimental do desempenho de conectores de cisalhamento feitos em aço CA-50 para uso em estruturas mistas de perfis em aço e concreto armado
(Universidade Federal do Pará, 2019-10-25) SOUZA, João Pedro Nascimento de; LIMA NETO, Aarão Ferreira; http://lattes.cnpq.br/0287664572311345; https://orcid.org/0000-0002-5911-1368
The steel and concrete composite structures began to increase as a construction system over the years, due to their advantages both in their structural behavior and in their constructive aspects. These structures are those in which both materials (steel and concrete) work together, and for this to be possible, it is necessary to use connectors that combat the shear forces generated between the materials. There are several types of these connectors, but their goal is to make the structure solid and work monolithically. This work aims to experimentally analyze the performance of shear connectors, for use in steel and concrete reinforced composite structures, modifying geometries and arrangement of connectors composed of Ø 12.5 mm diameter CA50 steel bar bent in shape close to a truss, making a comparative to define which model offers the greatest contribution in the connection. Therefore, push-out tests were performed, following the procedure described in the European Standard Norm EN 1994-1-1 (2004), in 7 specimens, consisting of an 800 mm high welded I-metal profile, and two slabs of reinforced concrete, with dimensions of (600x600x150) mm, in contact with the top of flanges of the metallic profile, containing the welded connectors. Among the 7 models, 2 of them, named Isósceles Truss (IT) and Rectangular Truss (RT), were used as reference; in 4 of them were made variations on the arrangement of the connectors used on the reference specimens, which were named Slanted Isosceles Truss. (SIT), Slanted Rectangular Truss (SRT), Piramidal Isosceles Truss Type A (PIT A) and Piramidal Isosceles Truss Type B (PIT B), and in 1 was made a change on the geometry, which was named Straight Truss (ST). Regarding the load capacity, the ST connector presented a load gain of 10.82%, 32.94%, 19.53%, 34.51%, 30.98%, 23.14 % in relation to IT, RT, SIT, SRT, PIT A and PIT B, respectively. Taking into account the design resistance calculation (𝑃𝑅𝑑) of each connector according to EN 1994-11 (2004), the tested connectors had a load capacity 46.54% higher than 𝑃𝑅𝑑. The connectors, in their entirety, presented themselves as they are ductile in their breaking mode. Compared to the others, the RT connector presented a more rigid, and, the SRT, a more flexible behavior. Thus, it is observed that the proposed connectors presented a good performance in relation to the load capacity and rupture mode.