http://repositorio.ufc.br/handle/riufc/424 2026-04-05T23:50:44Z 2026-04-05T23:50:44Z Santos, Éden Malveira dos http://repositorio.ufc.br/handle/riufc/85534 2026-03-28T14:49:42Z 2022-01-01T00:00:00Z

Título: Aplicação de programação linear baseada em geração de colunas ao corte de barras de aço destinadas à construção civil Autor(es): Santos, Éden Malveira dos Abstract: The construction companies need to improve their performance by implementing rationality improvements in their processes and management alternatives that led to operating cost reduction. Related to this, the aim was to study the One-Dimensional Cutting Stock Problem (1D-CSP), due to its application in the Civil Construction Industry with propositions to minimize raw material and labor costs, and waste reduction. The main challenge is to compare a linear programming model based on column generation applied to 1D-CSP in steel bars production that meets customer demand to the empirical method used by a company specialized in cutting and bending steel located in the city of Maracanaú/CE. For this purpose, a five-step research strategy was outlined, which was applied in the form of a case study to collect and analyze data from this company. The computational results demonstrated the efficiency of the column generation-based model for obtaining cutting patterns, the computational time required by the solver to return optimal solutions in the projects was 97.45 seconds on average. This represents a considerable gain from a practical point of view, as there is a decrease of more than 45,86% in the effort spent to plan the next cutting patterns to be performed at each requested stop. Regarding the productive capacity, the method predicted an average evolution of 11,03% and 3,98%, for bars with gauges of 12,50mm and 16,00mm, respectively. In monetary terms, annually, minimizing the use of bars in stock brings a reduction of R$ 314.658,46 and the waste reduction reaches the amount of R$ 334.594,39. The results obtained by the implemented model show considerable improvements in the defined objective, as the optimal solutions were found in a low computational time, it is believed that these approaches are promising to be applied in the industries of this segment. It is expected that the studied company analyze the results presented in this thesis as an initiative to restructure the planning methodologies and management stances with a focus on maintaining the competitive standard imposed by the market. Tipo: Dissertação

2022-01-01T00:00:00Z Pinto, Marcelo Freires http://repositorio.ufc.br/handle/riufc/85322 2026-03-13T13:31:53Z 2024-01-01T00:00:00Z

Título: Estabilidade de colunas laminadas de material compósito com seção C Autor(es): Pinto, Marcelo Freires Abstract: The increasing use of composite materials encourages the manufacture of thin-walled elements, due to cost and efficiency. However, these structures are highly slender and susceptible to stability failures when subjected to compressive stresses. Channel profiles have wide applicability as columns and are subject to local and global buckling modes, which makes the structural behavior of these profiles of interest for study. Considering these aspects, this work studies the stability of laminated columns of fiber-reinforced composite material with channel sections subjected to compression. Initially, the Rayleigh-Ritz Method, with one and two degrees of freedom, is used to determine the local buckling load, with these values being compared with results obtained using the Finite Element Method (FEM), in addition to numerical and experimental results available in the literature. Then, the Rayleigh-Ritz Method is also applied to determine the global buckling load, considering the bending-torsion and bending modes around the axis of least inertia. The calculation of cross-sectional equivalent properties of laminated columns is carried out using the theories of Cardoso (1999), Massa and Barbeiro (1998), and Kollar and Pluzsik (2002). The results are compared with those obtained using the Finite Element Method. The proposed approach allows the simple and efficient determination of the signature curve of laminated columns with channel sections subjected to pure compression. This approach is applied to columns with different layups and cross-sectional dimensions, including a parametric study to evaluate the effect of adding layers, consequently increasing the laminate thickness, in addition to different geometric configurations considering the same material consumption. Tipo: Dissertação

2024-01-01T00:00:00Z Silva, Mariana Mohana Rodrigues da http://repositorio.ufc.br/handle/riufc/85019 2026-03-02T13:52:42Z 2025-01-01T00:00:00Z

Título: Novo sistema estrutural pré-fabricado para construção de edifícios de múltiplos pavimentos: análise experimental e analítica da ligação semirrígida Autor(es): Silva, Mariana Mohana Rodrigues da Abstract: The widespread use of precast structures in civil construction offers significant advantages, such as improved quality control, ease of execution, and reduced construction time, in addition to ensuring high strength and durability. However, their application still presents important challenges, particularly regarding the performance of structural connections. Unlike cast-in-place structures, in which the elements are executed as a continuous unit, precast systems are composed of independent components assembled on-site. This hinders the reproduction of the monolithic concept of cast-in-place structures and requires the use of more robust elements and additional devices that, together, form a connection, ultimately increasing the overall construction cost. In light of this context, the main objective of this research is to perform an experimental and analytical investigation of a semi-rigid beam-to-column connection during the assembly stage of a new precast structural system. For this purpose, a full-scale prototype was manufactured, assembled, and tested in the laboratory in collaboration with T&A Pré-fabricados, the company sponsoring the research. The results showed that the beam-to-column connection exhibited good structural performance for this construction stage. The first visible cracks only appeared after a load of 120 kN, whereas the service load is 104.35 kN. Furthermore, the connection demonstrated semi-rigid behavior, with an initial stiffness of 126.07 MN · m/rad, a secant stiffness at the SLS of 70.187 MN·m/rad, and a secant stiffness at the ULS of 40.360 MN·m/rad. In addition, the analytical model developed showed good agreement with the experimental results, presenting an initial stiffness of approximately 136.52 MN ·m/rad, about 8% higher than the initial stiffness obtained from the tests. Tipo: Dissertação

2025-01-01T00:00:00Z Carvalho, Felipe Melo http://repositorio.ufc.br/handle/riufc/84949 2026-02-25T18:19:13Z 2025-01-01T00:00:00Z

Título: Modelagem numérica de uma ligação viga-pilar semirrígida em concreto pré-moldado utilizando cantoneiras soldadas na viga e no pilar Autor(es): Carvalho, Felipe Melo Abstract: In precast concrete structures, the proper design and execution of the beam-to-column connection are essential to ensure overall structural performance. The determination of the stiffness of this connection can be carried out through experimental, analytical, or numerical methods. The use of numerical methods to analyze the performance of beam-to-column connections is highly efficient for understanding the behavior of the connection components. The beam-to-column connection experimentally investigated by Silva (2025) presents several particular characteristics, such as the use of welded angle plates and a relatively low beam height. Therefore, the main objective of this study is to perform a numerical modeling of a semi-rigid beam-to-column connection in precast concrete using welded angles at both the beams and the column. With the aid of the Abaqus software and employing the finite element method, a numerical model was developed and validated through comparison with the results of the reference experimental test. The analysis involved comparing the load–displacement curve, the load–strain curves for the reinforcing bars and angle plates, and the moment–rotation curve of the connection. Regarding the final displacements, the percentage difference was 11.44%, while for the secant stiffness the difference was 18.56%. All curves exhibited similar behavior to those obtained experimentally. Aparametric study was conducted by varying the diameter of the continuity reinforcement to 20 mm,16mm,and12.5 mm. It was observed that smaller bar diameters led to more flexible connections, resulting in reduced stiffness, with a decrease of 39.29% in secant stiffness between the largest and smallest bar diameters. The equation from NBR 9062:2017 was calibrated to determine the secant stiffness under negative bending in beam-to-column connections with continuity reinforcement. Using the experimental model as a reference, the parameters k and Led were obtained for the connection. These values were then applied to calculate the stiffness for the reinforcement diameters used in the parametric study, and the results were compared with those from the numerical method. The differences between both methods were small, ranging from a maximum of 20.41% to a minimum of 3.52%. Therefore, the numerical modeling assumptions proved to be effective in representing the behavior of this connection, the parametric analysis was consistent, and the equation calibration yielded satisfactory results. Tipo: Dissertação

2025-01-01T00:00:00Z