Programa de Pós-Graduação em Engenharia Civil
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Master Thesis Pontes rodoviárias curvas em concreto com tabuleiros alargados: uma análise da distribuição dos momentos fletores e das forças cortantes devido à carga móvel(Universidade Federal do Rio Grande do Norte, 2021-10-18) Nascimento, Yngrid Rayane Freitas do; Silva Filho, José Neres da; http://lattes.cnpq.br/0915972389480304; Barros, Rodrigo; http://lattes.cnpq.br/6314974214441091; Gomes, Gilberto; http://lattes.cnpq.br/2274734815970506; Trautwein, Leandro Mouta; http://lattes.cnpq.br/8892009084347857A significant fraction of Brazilian bridges is at risk of becoming functionally obsolete and structurally deficient if they are not reinforced and widened to conform to the new dimensional and load patterns. Still, technical literature mainly focuses on designing and constructing new structures, leaving the field of bridge widening relatively unexplored. In this context, this research aims to analyze the distribution of bending moments and shear forces due to the mobile load in curved bridges that have undergone a process of widening. This approach allows an analysis of how the transverse variation of stiffness affects bending moment and shear force distribution. The widenings were performed symmetrically, admitting stiffness equal to or greater than that of the pre-existing deck. The study considered the variation of additional segment's concrete strength, curvature radius, girder number, and cross-section type, as well as diaphragm insertion, 72 models were developed. The results were based on Bending Moment (BMDF) and Shear Force Distribution Factor (SFDF), which were obtained through FEM, using the CsiBridge v21 and the analytical methods proposed in the literature, V-Load and M/R. The analysis considered the design truck in two different positions on the deck: load case 01, with the vehicle-type fixed at the outermost position of the deck, and load case 02, with the vehicle positioned on the centerline of the deck. Regarding load case 02, in general, stresses relocate toward the additional and stiffer areas, relieving the original girders. However, concerning load case 01, more often than not, the additional internal girders also experience stress reduction, which is not desirable. In conclusion, the variations tend to grow with the strengthening of the additional segments. Overall, the results showed that the magnitude of the increases or decreases in the amount of stress experienced by the girders is directly proportional to the widening stiffness.Master Thesis Análise dinâmica de pórticos planos pelo Método dos Elementos Finitos(Universidade Federal do Rio Grande do Norte, 2021-10-29) Lima, Daniel Alves de; Barros, Rodrigo; Mittelbach, Fernanda Rodrigues; 07421809724; http://lattes.cnpq.br/2860863457342608; http://lattes.cnpq.br/6314974214441091; http://lattes.cnpq.br/9414903034223402; Kzam, Aref Kalilo Lima; http://lattes.cnpq.br/4164207970081311; Amorim Neto, Raimundo Gomes de; http://lattes.cnpq.br/4124638187971744The dynamic analysis of 2D frames is a relevant topic for structural engineers, since the civil construction advances, in a quick way, technologically as the time passes. This allows the creation of increasingly taller structures which are highly stressed due to dynamic loads, such as the wind. Thus, this work aims at the development of a computational code using the software MATLAB. The code solves 2D portals problems through the Finite Elements Method (FEM), using frame elements, obtaining the internal efforts of the structure, and in addition it analyzes certain displacements, at the user's discretion, through two methods consolidated in the study of structural dynamics, the methods of Newmark and Houbolt, the study also deals with the use of constant and variable dynamic loads.Master Thesis Análise paramétrica das distribuições de momentos fletores e das reações de apoio devido à carga móvel em tabuleiros de pontes esconsas em vigas (grelha) e em laje(Universidade Federal do Rio Grande do Norte, 2020-07-10) Pujatti, Olimpia Loures Vale; Silva Filho, José Neres da; ; ; Pantoja, João da Costa; ; Barros, Rodrigo;The structural analysis of the bridges with skew longitudinal geometry presents greater complexity when compared to a straight bridge. Therefore, there is a shortage of research on the subject both nationally and internationally. The objective of this work was to perform a parametric study of the bending moment distribution according to the moving load and the support reactions in skew bridges made with grid and slab. To reach this purpose, numerical models were constructed for structural systems of bridges with trays in beams molded in loco and in slab, using the Finite Element Method using the computer program CSiBridge v21, in order to acheive: (a) the influence of the addition of supporting and intermediate crossbeams on the bending moment distribution and on the support reactions of skewed bridges with multiple grids and, (b) the distribution of bending moments and support reactions on the skewed bridges with slabs. The analysis proposal recommended by the American Association of State Highway and Transportation Officials (AASHTO LRFD, 2017) was also applied, in order to compare the results with those obtained in the modeling. The results showed in the situations of the orthogonal bridge with longitudinal girders a symmetrical distribution of the bending moment distribution factor (BMDF’s) due to the mobile load. In all the situations studied on the bridges with side members, with the introduction of the angle of skewed, changes occurred in the distribution of the bending moments. The global analytics of the support reactions due to the mobile load showed that in the orthogonal bridge models, the reactions were evenly distributed, presenting equal values for the supports positioned at the same distance in relation to the central axis. The introduction of obscurity generated an uneven behavior of the reactions, with an increasing trend towards the obtuse angle. For some models, the percentage variation between the support close to the obtuse angle and the support used as a reference, close to the acute angle reached almost 50%. In the hidden bridges in slab, in all the cases analyzed, the obscurity generated a significant reduction in the reaction of the support close to the acute angle, with an increasing trend towards the obtuse angle, presenting itself higher in the support closer to the obtuse angle. When the behavior of the bending moment was analyzed, it was also possible to observe a change in its behavior with the introduction of skews. In general, the Mx and My moment, in module, became larger close to the obtuse angle. Finally, the percentages and variations observed for the slab model were much higher than those observed in the grid models.Master Thesis Avaliação da influência das curvaturas e das transversinas na distribuição do momento fletor devido à carga móvel em pontes curvas de concreto armado(2019-06-17) Ribeiro, Valberllan Albuquerque; Silva Filho, José Neres da; ; ; Barros, Rodrigo; ; Luchi, Lorenzo Augusto Ruschi e;The structural analysis of bridges with curved longitudinal geometry presents greater complexity when compared to with straight bridges. This fact is due to a series of consequences caused by the interaction between the bending moment and the torsion moment. This makes torsion requests considerable, where they can condition the dimensioning and stability of the structure, as well as causing the increased distortion of the cross section of the element, generating transverse and longitudinal stresses that cannot be neglected. In view of this, the main objective of this research is to carry out a parametric study on the Influence of curvatures and the insertion of support transversal (diaphragm) in bridges with curved longitudinal trajectory in the horizontal plane, in the distribution of bending moment in the spars. Thus, for the analysis of the behavior of bridges, numerical models using the Finite Element Method (FEM) using the software CsiBridge v20 will be used, as well as validated by the V-Load analytical method. The analysis of the results showed that the inclusion of the support transversal (diaphragm) made the bending moment distribution more balanced for most of the analyzed models. The curvature effect significantly altered the distribution of the BMDF in the beams along the cross section of curved bridges, showing a trend of progression of these factors as it approaches the girder most external to the curve. Such behavior is attributed to the coupled effects of the bending moment and torsion moment in the curved girders. In addition, the curvature induces a complex state of tensions, since these structures are subjected to twist combined with bending and shearing. In addition, regarding the influence of the TI's associated to the effect of the monolithic systems, there is a tendency of equivalence in the load distribution of the bridges as the quantity of TIs is increased for both precast and in situ molded construction methods. Finally, with respect to the V-Load Method, although it has been used in the past for open-section curved bridges, results of very discrepant bending moment distribution are presented when compared with the MEF results.Master Thesis Análise do comportamento estrutural de blocos de concreto armado sobre estacas como fundação para aerogerador onshore(2018-06-18) Araújo, Kaique Yuri Márcio; Barros, Rodrigo; Nascimento Neto, Joel Araújo do; ; ; ; Silva Filho, José Neres da; ; Bezerra, Leonardo Melo;The growth of the wind energy industry in Brazil has demanded projects of big size foundations, which in most cases are pile caps. These structural elements spend close to 300 cubic meters of concrete and 20 tons of steel in its construction. In this context, a deepest structural analysis about this kind of wind turbine foundations should contribute to improvement of projects in this sector, that are of great relevance for the development of the Brazilian energy matrix. In that way, this work proposes to analyze the structural behavior of reinforced concrete pile caps, as onshore wind turbine foundations, using numerical models. In order to do, eight finite elements models were constructed, with the aid of the ANSYS V17 and SAP2000 V17 softwares. It was adopted as variables: the finite element type used for modeling the pile cap and piles (solid or shell); the soil representation (spring or semi-infinite space); and, the consideration or not of the soil under the pile cap base. All the materials constitutive models were considered as with linear elastic behavior. The interest results were: pile´s reaction; division of loading between soil and piles; pile cap´s displacement; radial normal stress and bending moments in the pile cap; and, the increase of vertical stresses in the soil. The models designed in solid elements and plate elements demonstrated good compatibility between the found values. In some models, the numerical analysis showed results against the structural safety of the foundation when the soil under the pile cap is not considered.Master Thesis Comportamento de radiers estaqueados assentes em solos arenosos(2018-04-06) Bittencourt, Eduardo de Castro; Freitas Neto, Osvaldo de; ; ; Santos Junior, Olavo Francisco dos; ; Cunha, Renato;It is observed in the last decades, the search of the optimization of pile foundations from the analysis of the benefit that the contact of the pile cap or raft with the ground can confer to increase the load capacity and stiffness. Contribution that is not inserted in the design of the foundation system by the traditional methodology of pile group. Thus, in the present dissertation an analysis of the behavior of a foundation conceived by the pile group methodology was carried out, in light of the piled raft, through numerical modeling. The study work is from Instituto Cérebro, located in the Central Campus of the Federal University of Rio Grande do Norte (UFRN), Natal-RN. Theoretical and experimental studies, highlighting pioneering and more recent searchs on the theme of this work, were used as subsidies to present the state of the art of foundations in piled raft. The study foundation consists of bored piles of the continuous flight auger, composed of lengths of 15, 17 and 20 m and diameters of 250, 400 and 500 mm. For the analysis of the behavior of this foundation, the numerical program PLAXIS 3D Foundation, based on the Finite Element Method (FEM). To verify if the program was handled correctly, the verification of the software was done through comparative analysis of cases previously studied by other researchers. The program input data and back-analysis of soil geotechnical parameters were subsidized by Standard Penetration Test (SPT), carried out in the field according to the procedures recommended by NBR 6484/2001 and static load tests (PCE), carried out according in NBR 12131/2006. The local subsoil, which was modeled assuming its elastic behavior perfectly plastic, is formed by layers of fine and medium sand, little compact silt, until reaching the impenetrable. The water level was not detected in any of the 13 boring performed. It was observed in the results obtained that the interaction of the pile cap with the soil increased the load capacity and stiffness of the system. The pile cap presented up to 21% contribution in receiving the efforts applied in the foundation. In addition, it has been observed that the load capacity of the piled raft foundation system is not confined to the algebraic sum of the isolated resistances of the pile cap and pile(s). Considering these results, it can be concluded that the methodology of foundation in piled raft is configured as a positive foundation technique for the city of Natal for medium-sized buildings.Master Thesis Modelagem computacional para avaliação do efeito do não preenchimento das juntas verticais na resistência da alvenaria estrutural(2017-03-03) Ferreira, Anderson Albino; Maciel, Daniel Nelson; Diógenes, Hidelbrando José Farkat; ; http://lattes.cnpq.br/6693686167483212; ; http://lattes.cnpq.br/4343155598427033; ; http://lattes.cnpq.br/3518076578408970; Nascimento Neto, Joel Araújo do; ; http://lattes.cnpq.br/2747505817148030; Silva, Andrea Brasiliano; ; http://lattes.cnpq.br/7960530718632221Masonry is a composite material, consisting basically of units and mortar joints (vertical and horizontal), and may also be associated with other materials, such as steel and grout. In Brazil, from the 1980s, structural masonry consolidated itself as a highly productive, rational and economical construction system due to characteristics as: simplification of execution techniques, less diversity of materials employed, reduction of labor and speed execution. In structural masonry, one of the execution possibilities that can be explored is the non-filling of vertical joints, also called dry joints. The adoption of this practice generates certain advantages as the reduction in the execution time of the construction, the reduction of the consumption of materials and the minimization of the cracking caused by the intrinsic deformations, such as retraction and thermal deformations. However, despite be employed to some years in country, the implications of its use often has been not properly considered in the projects, this is due to the fact that there is few research that deals with this subject. Moreover, the existing researches sometimes present results that diverge from each other, mainly with respect to the resistance to compression and shear. In this work, numerical simulations of small walls of ceramic and concrete units, with and without vertical joints, tested with the requirements of NBR 15812-2 (ABNT, 2010), NBR 15961-2 (ABNT, 2011) and NBR 14321 (ABNT, 1999). The purpose of this work was to evaluate the influence of non-filling of vertical joints on the compressive strength and shear strength of the masonry. For the numerical analyzes, the Finite Element Method was used from DIANA® software. According to the numerical results obtained in the models in compression, and the comparison between these and the experimental results, it was possible to conclude that the absence of the vertical joints did not influence the compressive strength of the masonry. However, from the results obtained in the shear models, it was concluded that it was not possible to quantitatively evaluate the influence of the vertical joints on the shear strength of the masonry.Master Thesis Análise do comportamento da barragem engenheiro Armando Ribeiro Gonçalves - Açu/RN - durante sua construção, primeiro enchimento e operação do reservatório(2017-03-30) Souza, Andriele Nascimento de; Santos Júnior, Olavo Francisco dos; Freitas Neto, Osvaldo de; ; http://lattes.cnpq.br/6335708403185496; ; http://lattes.cnpq.br/1573496204231636; ; http://lattes.cnpq.br/7616510880468035; Bezerra, Raimundo Leidimar; ; http://lattes.cnpq.br/1046305389288490; Saramago, Robson Palhas; ; http://lattes.cnpq.br/8692478241704161The Açu Dam is an important geotechnical built in Rio Grande do Norte and in Northeast Brazilian, especially because of its size and complexity. In addition to its size and importance, it has gained prominence in the national and international literature because of the collapse in upstream slope in the end of construction period. This paper aimed to analyze its behavior in stages of dam construction, first filling and operation of the reservoir. In each step, were analyzed: the stress-strain behavior, the flow and the pore-pressure variation, and the slope stability. These analyses were performed with the software Sigma/W, Seep/W and Slope/W, which are components in a suite of geotechnical products called GeoStudio, produced by Geo-Slope International Ltd. The results were compared with the instrumentation dates available in Rocha (2003). In the comparative analysis of vertical displacements, the largest difference between modeling results and instrumentation data was 8.9 cm, in the T7 extensometer, at the end of the first filling. In the stability analysis, the lowest safety factor was 1.3 for the upstream slope in the reservoir operation phase, but the media of the safety factors obtained by the methods based on limit equilibrium was 2.4. For a downstream slope, this factor was equal to 1.6 in all stages. These results confirm the dam stable condition. In pore-pressure analysis, the pneumatic piezometers presented greater divergences between modeling and instrumentation than those of the Casagrande type. The most significant difference was 46% (23 kPa), in the PZP1 piezometer, at the first filling of the reservoir. However, considering the differences obtained by other authors who also studied the water flow in this dam, we conclude that the results of the present analysis are satisfactory and that the adopted parameters are adequate to characterize the soils modeled.Master Thesis Modelagem numérica de estruturas de contenção atirantadas em areia(Universidade Federal do Rio Grande do Norte, 2012-07-02) Gurgel, John Glennedy Bezerra; Costa, Yuri Daniel Jatobá; ; http://lattes.cnpq.br/6737841388506901; ; http://lattes.cnpq.br/7862991490186910; Santos Júnior, Olavo Francisco dos; ; http://lattes.cnpq.br/1573496204231636; Albuquerque, Paulo José Rocha de; ; http://lattes.cnpq.br/0419076401765262; Soares, Wilson Cartaxo; ; http://lattes.cnpq.br/3832097394733852A numerical study on the behavior of tied-back retaining walls in sand, using the finite element method (FEM) is presented. The analyses were performed using the software Plaxis 2D, and were focused on the development of horizontal displacements, horizontal stresses, shear forces and bending moments in the structure during the construction process. Emphasis was placed on the evaluation of wall embedment, tie-back horizontal spacing, wall thickness, and free anchor length on wall behavior. A representative soil profile of a specific region at the City of Natal, Brazil, was used in the numerical analyses. New facilities built on this region often include retaining structures of the same type studied herein. Soil behavior was modeled using the Mohr-Coulomb constitutive model, whereas the structural elements were modeled using the linear elastic model. Shear strength parameters of the soil layers were obtained from direct shear test results conducted with samples collected at the studied site. Deformation parameters were obtained from empirical correlations from SPT test results carried out on the studied site. The results of the numerical analyses revealed that the effect of wall embedment on the investigated parameters is virtually negligible. Conversely, the tie-back horizontal spacing plays an important role on the investigated parameters. The results also demonstrated that the wall thickness significantly affects the wall horizontal displacements, and the shear forces and bending moments within the retaining structure. However, wall thickness was not found to influence horizontal stresses in the structure