Repositório UFSCar

O Repositório Institucional da UFSCar (RI UFSCar) é um sistema de informação que visa armazenar, preservar, organizar e disseminar amplamente a produção intelectual dos diversos setores e segmentos da comunidade da UFSCar, provendo o acesso aberto à informação produzida na instituição e registrada como científica, tecnológica, didática, artístico-cultural e técnico-administrativa.

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Comportamento estrutural de pilares de aço preenchidos com concreto de agregado reciclado cerâmico submetidos à compressão axial
(Universidade Federal de São Carlos, 2026-04-23) Prates, Lucas Mognon Santiago; Ferreira, Felipe Piana Vendramell; http://lattes.cnpq.br/5933034803347448; https://orcid.org/0000-0001-8007-789X; Martins, Carlos Humberto; http://lattes.cnpq.br/1665294496138141; https://orcid.org/0000-0001-7342-5665; http://lattes.cnpq.br/7177250247199481; https://orcid.org/0009-0003-0955-1378; Lima, Luciano Rodrigues Ornelas de; Nicoletti, Renato Silva; Bolandim, Emerson Alexandro; Diógenes, Hidelbrando Jose Farkat; http://lattes.cnpq.br/2151919861612154; http://lattes.cnpq.br/3109388079611718; http://lattes.cnpq.br/9169305081866640; http://lattes.cnpq.br/6693686167483212; https://orcid.org/0000-0002-7332-3818; https://orcid.org/0000-0002-3021-0944; https://orcid.org/0000-0001-6220-7646; https://orcid.org/0000-0003-2480-7688
Concrete-filled steel tubular columns are an efficient structural solution for compression members, since the interaction between the steel tube and the concrete core contributes to increased strength, stiffness, and ductility. At the same time, the growing demand for more sustainable solutions in the construction sector has encouraged the use of industrial waste as a replacement for natural aggregates. In this context, the feasibility of using recycled ceramic sanitary ware aggregate as a replacement for natural sand in self-compacting concrete for steel composite columns subjected to axial compression is assessed, considering its effects on material properties, structural behavior, and strength prediction by numerical and design code models. For this purpose, the constituent materials were characterized, and two self-compacting concrete mixes were analyzed, with natural fine aggregate replacement levels ranging from 0 to 100% in the first mix and from 0 to 50% in the second, in 25% increments. Subsequently, 24 experimental axial compression tests were carried out on circular concrete-filled steel tubular columns, comprising 16 short columns and 8 columns of intermediate slenderness. In addition, a finite element numerical model was developed in ABAQUS, validated against the experimental results, and used in a parametric study with 1,442 models, varying geometric and mechanical parameters as well as the recycled aggregate replacement level. The results indicate that the incorporation of recycled aggregate reduces the workability of the mixtures, without preventing the production of self-compacting concretes with satisfactory performance. It was found that increasing the replacement level does not necessarily lead to strength loss, with strength gains observed at certain replacement levels, depending on the mix composition. In the composite columns, the structural behavior was consistent with steel-concrete composite action, with efficient filling of the tube and mobilization of confinement in the short columns, whereas, in the slender members, the response was predominantly governed by global instability. Among the replacement levels evaluated, the 25% replacement level showed the most balanced performance for structural application, as it maintained a more stable response under different conditions. The numerical modeling satisfactorily reproduced the experimental response, and the parametric study confirmed global slenderness as the variable with the greatest influence on member efficiency. It is concluded that the use of recycled sanitary ware ceramic aggregate in self-compacting concrete for filling circular concrete-filled steel tubular columns is technically feasible and structurally promising, combining satisfactory mechanical performance, reuse of industrial waste, and potential application in structural concretes.
Capacidade resistente de vigas celulares mistas de aço de alta resistência e concreto à instabilidade no montante da alma
(Universidade Federal de São Carlos, 2026-03-27) Ferreira, Lucas Gomes; Ferreira, Felipe Piana Vendramell; http://lattes.cnpq.br/5933034803347448; https://orcid.org/0000-0001-8007-789X; Nardin, Silvana De; http://lattes.cnpq.br/5587716781980132; https://orcid.org/0000-0002-8736-4987; https://lattes.cnpq.br/5991867134405037; https://orcid.org/0009-0005-4867-0788; Milani, Margot Fabiana Pereira; Rossi, Alexandre; http://lattes.cnpq.br/9324192204449423; http://lattes.cnpq.br/3946998323160911; https://orcid.org/0000-0001-6432-3931; https://orcid.org/0000-0001-9590-1554
This study aims to investigate the resistance capacity of high-strength steel composite cellular beams with concrete slabs against web-post buckling. To this end, nonlinear geometric and material analyses were performed using the ABAQUS® software. The numerical model was validated against experimental data from physical models of composite cellular beams with concrete slabs. Four reference models were used as a basis for a parametric study carried out in two stages. In the first stage, the influence of the steel yield strength was investigated for S460, S690, and S960 steels (with yield strengths of 460 MPa, 690 MPa, and 960 MPa, respectively), without geometric variations. In the second stage, variations in steel strength were combined with variations in the following ratios: the opening diameter to the unexpanded steel profile height (Do/d), taking values of 0.8, 0.9, 1.0, and 1.1; and the center-to-center spacing to opening diameter ratio (p/Do), taking values of 1.2, 1.3, 1.4, and 1.5. For the variations of the validated symmetric profile models, CCB1 from Nadjai et al. (2007) and CCB3 from Müller et al. (2006), as well as the asymmetric model CCB2 (asymmetry ratio of 1.13) also from Nadjai et al. (2007), web-post buckling remained the predominant failure mode across all steel grades during the first stage, with maximum strength gains ranging from 24.6% to 60.8% for S690 and from 54.0% to 83.4% for S960. For variations of model CCB4, also from Müller et al., (2006), which has a top-to-bottom tee asymmetry ratio of 2.8, only local web buckling of the top tee was observed in the first stage, regardless of yield strength, with strength gains of 28% for S690 and 68% for S960. In the second stage, increasing Do/d tended to reduce the maximum strength, while increasing p/Do generally increased it, although complex interactions between geometry and steel yield strength were observed. For the CCB1, CCB2, and CCB3 variations, as steel strength increased, failure modes shifted toward those involving the formation of Vierendeel plastic mechanisms, either in isolation or combined with web-post buckling. For the CCB4 variations, the failure mode shifted from pure local web buckling of the top tee to an interaction between this failure mode and the Vierendeel plastic mechanism. The numerically obtained maximum strength values were compared with four analytical verification models: Panedpojaman et al. (2014), Grilo et al. (2018), AISC Steel Design Guide 31 (2016), and BS EN 1993-1-13 (2024). The comparison shows that most formulations underestimate the maximum resistance capacity of high-strength steel–concrete composite cellular beams. When analyzing the effect of increasing steel yield strength on maximum strength, the AISC Steel Design Guide 31 (2016) method showed an increase in the F_numerical/F_analytical ratio, while the other methods showed a decrease in this ratio as strength increased. Furthermore, all methods exhibited high coefficients of variation, often exceeding 40%, indicating high relative data dispersion. This level of variability compromises the reliability of predictions for high-strength steels, suggesting that current formulations do not adequately capture the instability and plastification phenomena in composite cellular beams with high-strength steel profiles.
Estimativa da rigidez axial e capacidade de carga de pilares de madeira parcialmente reforçados por materiais compósitos laminados
(Universidade Federal de São Carlos, 2026-06-02) Jardim, Pedro Ignácio Lima Gadêlha; Christoforo, André Luis; http://lattes.cnpq.br/7623383075429186; http://lattes.cnpq.br/6028687809417062; https://orcid.org/0000-0002-4448-6554; Silva, Leandro José da; Bertolini, Marília da Silva; Pedroti, Leonardo Gonçalves; Chahud, Eduardo; http://lattes.cnpq.br/3410027147747579; http://lattes.cnpq.br/0280120880255759; http://lattes.cnpq.br/8770106216994640; http://lattes.cnpq.br/7061747933713446
Wood is a material widely used in construction since antiquity, commonly found in historical buildings around the planet. As wood is a biodegradable material, historical buildings that use it as a structural typology, without the knowledge of current techniques to ensure the durability of this element, require greater care regarding their protection. Several studies have been observed addressing techniques for strengthening and recovering timber structures, with the use of fiber-reinforced polymers (FRP) being a solution of growing interest in the scientific community. A gap was observed in published studies regarding the application of localized FRP reinforcement in timber columns with longitudinal openings. Thus, obtaining an equation to determine the ultimate load and axial stiffness is necessary to make the strengthening method viable. The present study proposed an equation capable of describing the ultimate load of timber columns with longitudinal openings and partial FRP reinforcement, considering multiplying factors related to instability and the confinement effect generated by the reinforcement. Furthermore, a factor for adjusting the axial stiffness was also proposed. For this, a broad parametric study was carried out through finite element method simulations, comprising 1392 models. The following parameters were considered: wood species, column diameter and length, opening proportion, fiber type, number of layers, and FRP spacing. For the model prediction, a 'white-box' evolutionary algorithm was adopted: symbolic regression. This solution was chosen due to its high capacity for data evaluation and physical interpretation, allowing for the topological dynamism of the generated model. The results of the parametric study revealed that the effectiveness of the reinforcement is not universal, being strictly dictated by the dominant collapse mode. In slender members, the application of low FRP rates optimized the structural response by generating local confinement and mitigating early transverse deformations. In contrast, in robust columns, excessive reinforcement demonstrated marginal efficiency due to premature failures induced by stress concentrations at the wood-composite interface. The predictive models generated by symbolic regression show significant statistical robustness (R2 = 0.92 for load capacity) and surpass pre-existing empirical models in the literature by introducing a slightly conservative variance, ensuring that eventual deviations act in favor of structural safety.
Relação entre estrutura e atividade catalítica do cobre na hidrogenação de CO2 para formação do metanol
(Universidade Federal de São Carlos, 2026-04-22) Simionato, Arnaldo Agostinho; Santos, João Batista Oliveira dos; http://lattes.cnpq.br/0285313473901330; http://lattes.cnpq.br/2322073284273845; Moreira, Regina de Fátima Peralta Muniz; Oliveira, Jéssica Ariane de; http://lattes.cnpq.br/8521588947381085; http://lattes.cnpq.br/4765767150921439
In the context of the commitments made under the Paris Agreement to reduce greenhouse gas emissions and limit the global temperature increase to 1.5 °C above pre-industrial levels by mid-century, there is a clear need to transition current energy systems and to develop effective technologies for carbon dioxide (CO2) utilization. Among the strategies under investigation, the hydrogenation of CO2 to methanol has attracted considerable attention, both as a means of mitigating atmospheric CO2 and as a route to convert it into value-added chemicals. Methanol is a key commodity in the chemical industry, with global production exceeding 90 million tons in 2025. It is widely used as a solvent and as a feedstock for the synthesis of numerous chemical products. A variety of catalysts have been explored for methanol synthesis via CO2 hydrogenation, with copper-based systems consistently showing the most promising performance, particularly in terms of cost-effectiveness and activity. However, the relationship between catalyst structure and activity remains a matter of ongoing debate. In this work, the effect of Cu particle size on methanol synthesis was investigated. Cu/Zr-SBA-15 catalysts were prepared by the impregnation method and characterized using X-ray diffraction, nitrogen physisorption, H₂ temperature-programmed reduction, N2O decomposition and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). These analyses confirmed the successful preparation of catalysts with a range of particle sizes, with estimated diameters between 4.1 and 35.3 nm. Catalytic testing showed that CO2 hydrogenation to methanol follows behavior consistent with a class π reaction, although only minor variations were observed across the samples. Mechanistic insights obtained from ME-PSD-DRIFTS (Modulation-Excitation Phase Sensitive Detection Diffuse Reflectance Fourier Transform Spectroscopy) suggest that either the hydrogenation of methoxy species or the desorption of methanol is the slow step in the reaction. Apparent activation energy measurements indicated values below 44 kJ/mol for all catalysts in methanol formation. Taken together, these results suggest that methanol desorption is the rate-limiting step, possibly due to its interaction with oxophilic sites associated with zirconium.
Rastros visuais para experiências (im)possíveis: pedagogias para ver e narrar a cidade
(Universidade Federal de São Carlos, 2025-12-12) Souza, Raquel Salazar Ribeiro e; Costa, Alan Victor Pimenta de Almeida Pales; http://lattes.cnpq.br/5414466437997230; http://lattes.cnpq.br/6401585330796504; Araujo, Arthur Medrado Soares; Scareli, Giovana; Novaes, Marcus Pereira; Santos, Maria Cristina dos; http://lattes.cnpq.br/4366710470670566; http://lattes.cnpq.br/6602683272664282; http://lattes.cnpq.br/3211660362126012; http://lattes.cnpq.br/1095065753077001
This thesis investigates the relationships between memory, experience, and creation based on educational practices of the Olhares (Im)possíveis collective, formed by young people from Ouro Preto since 2017. It analyzes how the images produced and the collective practices reconfigure ways of seeing and narrating the city. The research understands filmmaking as a space of encounter, listening, and invention, where new forms of inhabiting the urban are created. Inspired by Walter Benjamin, Jorge Larrosa, Georges Didi-Huberman, Jacques Rancière, Cezar Migliorin, Paola Berenstein Jacques, and Susan Sontag, it articulates concepts of experience, image, and montage. The study focuses on the productions of the collective between 2017 and 2023 (films, photographs, audio recordings, conversations, and workshops) understood as a living archive that fabulates and reinscribes the city’s memories. The central question guiding this investigation is: how do the audiovisual devices created within Olhares (Im)possíveis enable young people to build new forms of relationship with the city and with themselves? The methodological path is cartographic and essayistic, inspired by research modes that are built through encounters and drift. The investigation is carried out with the group, not only about it, accompanying its creative processes, pauses, and re-beginnings. The procedures include analysis of films and photographs, listening to and transcribing recorded conversations, revisiting personal and collective archives, and writing as a practice of montage. The work assumes an experimental tone, becoming a gesture of montage that reveals the power of audiovisual creation to generate shared narratives, affections, and futures.