Mestrado em Geotecnia, Estruturas e Construção Civil (EECA)
URI Permanente para esta coleção
Navegar
Submissões Recentes
Item Estudo de parâmetros físico-químicos da solução do poro de argamassas com adições minerais e sua contribuição para a durabilidade(Universidade Federal de Goiás, 2023-08-09) Santos, Aloísio Fernando Silva; Oliveira, Andrielli Morais de; http://lattes.cnpq.br/9590390602101344; Matos, Oswaldo Cascudo; http://lattes.cnpq.br/3336749062812376; Matos, Oswaldo Cascudo; Faria, Tulio Honório de; Ferreira, Rondinele Alberto dos Reis; Cascudo, Helena Carasek; Oliveira, Andrielli Morais deRecent studies have shown that the durability of reinforced concrete is related to its chemical ability to maintain an alkaline environment through the porous solution. In the absence of aggressive agents, the passivation film on the steel bars remains stable. However, in the presence of chlorides or under the effect of carbonation, this protection can be interrupted and the corrosion process initiated. Therefore, it is crucial to have knowledge of the internal chemical composition of the pores in cementitious materials to mitigate these effects, especially the chemical knowledge of the free water present in these materials. The chemical analysis of the electrolytic solution present in the pores has been studied for decades. However, there are few studies that focus on cementitious materials subjected to combinations of aggressive agents and the use of mineral additions. Thus, this work aims to analyze and obtain physicochemical parameters of the pore solution in mortars with silica fume and metakaolin using different methods of extracting the internal free water, namely: pressure application extraction, ex situ leaching, in situ leaching, and equilibrium water extraction when subjected to chloride attack or accelerated carbonation, as well as both situations combined. The use of mineral additions was considered with the objective of generating different chemical parameters related to the aqueous solution in the pores since they chemically modify the entire composition and also modify the microstructure of mortars. They are widely used supplementary materials of great relevance in civil construction. pH analysis, electrical conductivity, ionic strength, dissolved solids, redox potential, and ionic chemical analysis were performed. To better understand the formation and changes in the chemical composition of the pore solution, microstructural implications were also studied in terms of thermogravimetry, FTIR, XRD, SEM, surface electrical resistivity, specific surface area, and pore volume. The different analytical techniques used to analyze the ionic composition of the pore solution were considered similar and reliable. It was observed that mineral additions contributed to the reduction of the ionic charge in the solution, while carbonation and chloride attack caused significant changes in the ions present. When these mechanisms occur in combination, the order in which they occur influences the formation of products and the quality of the pore solution. Finally, it is important to emphasize that the methods of extracting the pore solution can be used in different situations, but each one has its own limitations and requires precautions during the test. It is essential to consider these restrictions and adopt appropriate measures to ensure the reliability of the obtained results.Item Avaliação do potencial mitigador da sílica ativa e do metacaulim frente à formação de etringita tardia – DEF em concretos(Universidade Federal de Goiás, 2022-11-25) Oliveira, Solanda de; Hasparyk, Nicole Pagan; http://lattes.cnpq.br/4932240949129648; Oliveira, Andrielli Morais de; http://lattes.cnpq.br/9590390602101344; Oliveira, Andrielli Morais de; Kuperman, Selmo Chapira; Bonsembiante, Francieli Tiecher; Hasparyk, Nicole Pagan; Matos, Oswaldo CascudoDelayed ettringite formation, or DEF, is an internal expansive reaction of hardened concrete that occurs due to the chemical reactions of sulfate ions from Portland cement under high temperatures. The phenomenon begins when, at the first hours of hydration, the temperature enhances levels above 60-65ºC due to the heat of hydration of Portland cement in massive structures with high binder content or in cases of concrete submitted to heat-curing process, being one of the causes of concrete expansion and cracking. Thus, DEF can damage concrete structures over time, impairing its durability and safety. This research presents the use of mineral admixtures, specifically silica fume (SF) and metakaolin (MTC), in different rates as partial replacement of Portland cement (Brazilian Type CP V – high early strength), to mitigate the expansion and damage caused by DEF. The behavior of these pozzolans was evaluated throughout mortars and concrete with and without mineral admixtures. Besides, the DEF occurrence in lab was stepped up by a controlled heat curing process. So, the mechanical and microstructural properties could be assessed to qualify damages in concrete. An overview of degradation caused by DEF, assessed both by the test results and the damage rating index (DRI), could be provided. As a result, the reference mortar (without any mineral admixture) presented, by far, the highest expansions, up to 0.90% at 450 days. In the other hand, the mortars with mineral admixtures presented expansion values less than 0.04% at 450 days. Regarding the expansion of concrete, the reference one (REF) presented expansion of 1% at the age of 365 days. The SA8 concrete (with 8% of silica fume) had expansion around 0.30% and the others - SA12, MCT12 and MTC14 concrete - presented expansion values less than 0.04% at the age of 350 days. The type and content of mineral admixtures led to a great difference in the mixture behavior, with the performance improved by using high contents of metakaolin and silica fume. Nonetheless, it is important to note that the modulus of elasticity decreased about 15% in MTC12 concrete versus 70% of REF concrete. In the case of compressive strength, DEF promoted reductions about 10% for MTC concrete and about 44% for REF concrete. The tensile strength reduced up to 40% for REF and SA8 concrete, while the MTC concrete reached levels far below than that. The deterioration indexes varied from 300 to 700 for the studied concrete of this research, standing greater for REF concrete and for SA8 one. As conclusion, it could be seen that, even though silica fume and metakaolin reduced the damages, they were not able to mitigate entirely DEF, what indicates that they were not enough to contain its occurrence and development over time.Item Estudo reológico de pastas e concretos de cimento portland: avaliação da eficiência de aditivos químicos e do teor de sílica ativa(Universidade Federal de Goiás, 2023-03-07) Santos, Jéssica Rodrigues dos; Matos, Oswaldo Cascudo; http://lattes.cnpq.br/3336749062812376; Oliveira, Andrielli Morais de; http://lattes.cnpq.br/9590390602101344; Oliveira, Andrielli Morais de; Matos, Oswaldo Cascudo; Cascudo, Helena Carasek; Santos, Karyne Ferreira dosStudies of rheology and optimization of Portland cement mixtures can play an important and prominent role in the correlation with performance, mechanical behavior, high durability and service life in the hardened state of concrete. The present work encompasses stages of rheological characterization of Portland cement pastes, with the aim of evaluating the intervention of chemical admixture and silica fume contents (8%, 10% and 12%) in two water/binder ratios (0.40 and 0.55). Additionally, these variables were also analyzed in concrete, measuring the rheometric parameters, basic mechanical behavior properties (compressive strength and modulus of elasticity) and water absorption. In addition, the chemical admixtures were characterized physic-chemically and the validation of a technical instruction for conducting rheology tests on pastes was proposed. As a result, the superplasticizer type admixtures and those with higher solids content exhibited better behavior in the viscosity properties and shear rate of the pastes. The 8% silica fume content was more interesting in terms of mechanical behavior and water absorption. The paste results were coherent with the results obtained from the concretes.Item Estudo das técnicas de tomografia ultrassônica e radar de penetração com contribuição em metodologia de inspeção de obras de concreto(Universidade Federal de Goiás, 2022-12-21) Leonel, Antônio Carlos Assis; Matos, Oswaldo Cascudo; http://lattes.cnpq.br/3336749062812376; Oliveira, Andrielli Morais de; http://lattes.cnpq.br/9590390602101344; Oliveira, Andrielli Morais de; Cascudo, Helena Carasek; Vieira, Janine Domingos; Matos, Oswaldo CascudoPeriodic inspection programs are essential for planning preventive and corrective maintenance in a timely manner, making financial contributions and hiring technical and engineering staff, and avoiding structure collapses, huge monetary losses and social disturbances. Allied to these needs for maintenance actions, modern non-destructive testing methods are important tools for monitoring the integrity of these structures, offering quantitative and qualitative parameters that help the inspector's analysis. Given this context, this work proposes to evaluate the applicability of non-destructive tests for detecting damage in concrete structures, mainly ultrasonic tomography and GPR radar tests and, based on quali-quantitative parameters, propose the improvement of a methodology pre-existing infrastructure dedicated to large Brazilian infrastructure works such as dams, hydroelectric plants and wind farms, considering their degree of deterioration. The proposed experimental program foresees the laboratory production and molding of two structural concretes used in infrastructure works, with strength classes C25 and C45, under two curing conditions: air and humid. In these concretes, the basic characterization of the constituent materials and physical and mechanical characterization were carried out with the use of tests of compressive strength, modulus ofelasticity, water absorption by immersion and voids index and non-destructive tests (rebound hammer, ultrasonic wave velocity and surface electrical resistivity and volumetric) from 1 to 28 days. The potential use of ultrasonic tomography and GPR radar tests was also verified to identify bars and tubes inside blocks, analysis of defects generated in plates and cracking in slabs. As a result, it was possible to obtain good correlations between destructive and non- destructive tests, with coefficients of determination R 2 , mostly above 0.9. The smallest correlations obtained (on the order of 0.7 to 0.79) refer to the results of electrical resistivity of concrete submitted to dry curing in air. Regarding the verification of defects and damages in the C25 and C45 concretes, the GPR radar proved to be efficient to locate reinforcement and defects of greater magnitude. The use of ultrasonic tomography, on the other hand, proved to be useful to analyze different homogeneities, detect internal voids in small and medium-sized concrete structures, in addition to being able to act in the detection of reinforcement. However, none of the techniques could be able to accurately identify concrete cold joints. Thus, each situation in which these cutting-edge techniques are used must be precisely analyzed, depending on the test conditions and the expected results, since on many occasions it is up to the operator to interpret what is presented to him by the images generated by the radar and tomography. Finally, a proposal has been presented to change the GDE UNB methodology, with the recommendation of inserting some non-destructive tests, as well as the addition of new weighting and intensity factors to be considered, in order to compose a methodology focused on the damage analysis adapted to the situations of large infrastructure works.Item Estudo de ensaios e parâmetros de transporte de cloretos no concreto para aplicação em modelos preditivos de vida útil(Universidade Federal de Goiás, 2022-03-31) Fagundes, Rayane Campos Lopes; Matos, Oswaldo Cascudo; http://lattes.cnpq.br/3336749062812376; Oliveira, Andrielli Morais de; http://lattes.cnpq.br/9590390602101344; Oliveira, Andrielli Morais de; Faria, Tulio Honorio de; Cascudo, Helena Carasek; Matos, Oswaldo CascudoIn a contemporary engineering context, a performance approach and the design of more durable, sustainable and efficient structures are required. Corrosion of reinforcement is one of the main mechanisms of degradation of reinforced concrete structures, especially in the marine environment, and can lead to its collapse if there is no intervention. To meet this approach, predictive models have been developed, with the objective of predicting the useful life of structures, considering different degradation mechanisms; among them, the corrosion of the reinforcements. Thus, the objective of this work is to study different parameters of chloride transport in concrete with three water/cement – w/c ratios (0.40; 0.55 and 0.70) for application in prediction models of service life. For that, four different test methodologies were used to evaluate the transport of chlorides, over four months. Two migration tests were then considered – NT Build 492: 1999 (in non-steady state); LMDC test (steady state) – and a nonsteady state diffusion test: NT Build 443: 1995, carried out in two different ways, according to the standard (exclusive diffusion mechanism, with the concrete continuously submerged) and by means of weekly cycles of wetting and drying (hybrid mechanism, containing capillary absorption in the convection layer and diffusion in the deeper saturated layers). The results of the experimental program, as expected, showed a tendency for the coefficients to increase with increasing w/c ratio and a decrease in these parameters with increasing maturity of the cement matrix (age effect). Despite having different principles, the coefficients obtained by different methods showed good correlations: with the results of the NT Build 492 and NT Build 443 standards being close to each other and about 10 to 16 times greater than the effective coefficient (steady state) obtained by the LMDC test. The application of prediction models indicated the importance of a more assertive definition of the input parameters of these models, especially the diffusion coefficient used. Among the methods studied, the use of the effective diffusion coefficient (LMDC test) as an input parameter resulted in service lives more in line with reality. Among the models applied, Life-365 stood out for considering different influential factors and getting closer to reality. Regardless of the model applied or the coefficient considered as an input parameter, the w/c ratio strongly influenced the calculated service life: it reduced, on average, 40% of concrete with w/c ratio 0.40 for concrete with w/c ratio c 0.55, reduced by 50% when the w/c ratio increased from 0.55 to 0.70 and 70% from 0.40 to 0.70.Item Avaliação da resistência à força cortante de lajes alveolares protendidas em piso misto de altura reduzida por meio de modelagem computacional(Universidade Federal de Goiás, 2021-07-01) Souza, Jefferson Rosa de; Araújo, Daniel de Lima; http://lattes.cnpq.br/8801080897723883; Araújo, Daniel de Lima; Almeida, Sylvia Regina Mesquita de; Nardin, Silvana deTo be a competitive solution as a structural system, since both elements are industrialized, reaching efficiency from a structural and constructive point of view. In a conventional composite floor system, the slabs are supported on the top flange of the steel profile and the composite action between the materials is guaranteed by mechanical connection. In a shallow composite floor system (slim floor), the slabs are supported on the bottom flange of the steel profile, which is incorporated into the height of the slab. In this case, the composite action can be guaranteed by mechanisms of adhesion between the materials, by means of concrete pins, reinforcement bars passed in the web of the steel profile or shear connectors. Slim floor system presents various advantages with respect to the conventional composite floor, such as greater protection of the metal profiles against fire and, especially, a reduction of the beam and slab set height. However, during the design phase, the shear strength of hollow core slabs on flexible supports needs particular attention and caution. In this context, this study aims at investigating the mechanical behavior of slim floors, focusing on the shear strength of hollow core slabs supported on steel profiles, through computational modeling via the Finite Element Method. To calibrate the computational models, test results on physical models available in the literature have been used. Numerical simulations of isolated hollow core slabs supported on rigid support and slim floor systems were compared with experimental test results, and analytical models for prediction of the resistant shear force. The computational models well-reproduced the tests of slim floor systems with hollow core slabs. A parametric analysis was carried out to evaluate the influence of the core filling of the slabs and the variation of flexural stiffness of the steel profile. The results of the parametric analysis indicate that the shear strength is marginally affected by the filling of the cores. In the case of the use of slabs with oblong-shaped openings, the filling can reduce the shear strength of the slab. The influence of support flexibility on the shear strength of the slab was well represented by an analytical model available in the literature, providing better strength prediction than the model recommended in technical bulletins published by fib (International Federation for Structural Concrete).Item Modelo discreto para avaliação dos esforços e momentos máximos de silos de armazenamento em condição de carga/descarga: uma análise exploratória(Universidade Federal de Goiás, 2022-11-29) Pereira, Henrique de Oliveira; Silva, Frederico Martins Alves da; http://lattes.cnpq.br/9929132527197884; Silva, Frederico Martins Alves da; Soares, Renata Machado; Almeida, Ariovaldo Fernandes deBrazil is one of the largest grain producers in the world, with an annual production of 255 tons of grains, making the demand for storage of these grains high. The type of structure most used for storage are metallic cylindrical silos, being slender shell structures, which have a great capacity to resist axial loads and lateral pressures that are submitted by grain storage. This study aims to analyze the behavior of orthotropic and longitudinally stiffened silos subjected to static and dynamic actions. For mathematical modeling of the orthotropic silo, the nonlinear Sanders- Koiter theory is used and the grain pressures under the silo walls are defined according to the Janssen model. Discretized equations of motion for the cantilever-free silo are obtained by applying Hamilton’s Principle and the Rayleigh-Ritz method. First, the results obtained for the maximum displacements and natural frequency by the analytical model are compared with those determined from a numerical analysis via finite elements. This first step, in addition to validating the proposed analytical formulation, allows determining the number of degrees of freedom necessary to obtain a reliable analytical model for the other parametric analyzes of this work. Then, the increase of the internal forces and moments that arise in the silo during the grain charging/discharging process for different geometries, physical properties and distance between the longitudinal stiffeners are evaluated. From the results found in this work, we propose factors to increase the static effects for an orthotropic, cantilever-free and longitudinally stiffened silo, in order to simplify the initial design phases without disregarding the importance of the dynamic effects that arise due to the grain charging/discharging process.Item Estudo do precondicionamento para o ensaio de carbonatação acelerada do concreto(Universidade Federal de Goiás, 2019-12-18) Jungblut, Mônica Engel; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Cascudo, Helena Carasek; http://lattes.cnpq.br/3023241186996790; Cacudo, Helena Carasek; Possan, Edna; Oliveira, Andrielli Morais deDurability indicators are indispensable parameters for assessing and predicting the durability of the element and structure as a whole and must be easily quantifiable by laboratory testing. However, in Brazil there is not yet a standard to standardize the accelerated carbonation test and, therefore, the tests are performed based on international standards or literature data. The accelerated carbonation test is used to obtain the durability indicator for carbonation. One of the important steps for the accelerated carbonation test is preconditioning, which must occur after curing and prior to the onset of accelerated carbonation and aims to achieve an appropriate degree of saturation of the specimen so that the carbonation reactions can occur accelerated form. Due to the lack of standardization and the variety of methodologies found in the literature to perform this step, it was proposed to study the influence of different preconditioning methods on the carbonation results with a view to proposing a methodology. For this, four types of concrete were molded: three of them being without mineral addition, with water/binder of 0,40; 0,55 and 0,70; and onde concrete with replacement of 10% by weight of cement with metakaolin with 0,55 water/binder. The concretes were preconditioned by four different methods, following the recommendations of the ISO 1920-12 (2015), NF EN 13295 (2004), XP P 18-458 (2008) e RILEM TC 116-PDC (1999). Subsequently, the accelerated carbonation test was performed with 3% of CO2, 22°C and 65% of relative humidity. The results showed that the preconditioning type had a significant influence on the carbonation depths, and for the methods of ISO 1920-12 (2015) and NF EN 13295 (2004) the measured depths were smaller, while for the methods according to XP P 18-458 (2008) and RILEM TC 116- PDC (1999) were higher, considering the same type of concrete. In addition, it was observed that concretes with lower carbonation depths presented higher surface humidity at the beginning of the test, and this humidity was reduced at the end of the test, indicating that, for these concretes, the balance between internal humidity and ambient humidity had not yet been established during preconditioning ; this had a significant influence on the carbonation depth results. Thus, the simplest preconditioning method with the least influence of internal humidity in the accelerated carbonation test was XP P 18-458 (2008).Item Envoltória de resistência do Concreto Compactado com Rolo (CCR), incluindo o efeito escala(Universidade Federal de Goiás, 2010-08-31) Junqueira, Pedro João Barbosa; Cascudo, Oswaldo; http://lattes.cnpq.br/3336749062812376; Vargas, Carlos Alberto Lauro; http://lattes.cnpq.br/3816106720170772; Vargas, Carlos Alberto Lauro; Cascudo, Oswaldo; Bittencourt, Túlio NogueiraThe dam construction tecnology with roller compacted concrete has undergone noticeable improvements in the areas of concrete technology and enforcement procedure. One can cite the enrichment of roller compacted concrete dam face and the whole sequence leading to obtaining such enrichment, in a short-term enforcement, by the least cost and with the guarantee of the security needed, as one of those remarkable improvements. This work, however, tries to contribute with the theme of the properties of concrete and incorporates basic issues of materials science to set a failure criterion to the results of combined loadings tests performed in RCC specimens of varied sizes, made with the same dosage of Junqueira et al. (2008). The goal is to predict the real strength of the roller compacted concrete dam. Therefore, tests of diametral compression, uniaxial compression, triaxial compression and direct shear tests were performed in RCC specimens of different sizes. The results of such tests were presented using tables and graphs which showed a fall of resistance with increasing the size of the specimen tested face of such loadings. Finally, the data from all trials of this work and of Junqueira et al. (2008) were gathered and studied, so as to increase the precision of the strength envelope of Hoek and Brown set.Item Provas de carga estáticas em estacas metálicas tubulares de ponta aberta em um solo tropical(Universidade Federal de Goiás, 2019-06-13) Nascimento, Breno Breseghelo do; Angelim, Renato Resende; http://lattes.cnpq.br/9831984428217477; Sales, Maurício Martines; http://lattes.cnpq.br/2033708685029423; Sales, Maurício Martines; Santos, Eder Carlos Guedes dos; Albuquerque, Paulo José Rocha deOpen-ended steel pipe piles are oftenly employed on piled foundations around the world, especially in offshore construction, due to ease of driving, less vibration imposed to the ground and the possibility of using large pile diameters. However, the behavior of this type of pile in tropical soils is not well known, because of lack of studies. Specific phenomenona that occurs on those piles, like plugging, aggravates this scenario. In this study, static load tests were done on steel pipe piles installed in a lateritic soil profile located in the region of Goiânia-GO, aiming at observing their behavior. The piles were installed in an experimental area at EECA-UFG. The area was characterized by means of granulometric analyses, an SPT borehole, and dynamic cone penetrometer PANDA profiles. Five piles installed by jacking were load tested, with varying diameter, installation date, and the tip configuration, open or closed. The soil column height inside the piles and the applied load were measured during jacking. Each pile was load tested in compression with buried lengths of approximately 1,80 m and 3,50 m and, after that, tested in tension. The soil profile at the experimental area was classified as a loose lateritic silty sand, of red color and having low penetration resistance in most of the depth of the profile. All piles were became fully plugged with about 1,00 m of jacked length, continuing that way in the rest of jacking and during load test. The load measured during jacking served as a reasonable prediction for the ultimate load capacity during static load testing and the load x settlement curves for all piles were practically linear until close to failure. Comparing different piles, the closed-ended pile showed less load capacity than the open-ended pile, the higher diameter pile showed greater load capacity than the lesser one and the load capacity of piles of the same dimensions but installed at different dates were different due to changes in soil water content. By applying different load capacity formulas, it was found that the methods have better prediction capacity for longer piles, that the Aoki-Velloso (1975) method have better performance than the Décourt-Quaresma (1978, 1996) method and that the international methods had good and similar performance.Item Soil stabilization with lime for reservoir shoreline erosion control(Universidade Federal de Goiás, 2019-06-27) Vilhena, Ricardo Moreira; Angelim, Renato Resende; http://lattes.cnpq.br/9831984428217477; Mascarenha, Márcia Maria dos Anjos; http://lattes.cnpq.br/5184066802578105; Mascarenha, Márcia Maria dos Anjos; Rezende, Lilian Ribeiro de; Carvalho, José Camapum deO autor não apresentou resumo em outra língua.Item Utilização de solo laterítico, fosfogesso e bentonita em barreiras hidráulicas: uma análise hidromecânica e ambiental(Universidade Federal de Goiás, 2019-02-01) Borges, Yago Isaias da Silva; Mascarenha, Márcia Maria dos Anjos; http://lattes.cnpq.br/5184066802578105; Mascarenha, Márcia Maria dos Anjos; Sales, Maurício Martines; Boscov, Maria Eugênia GimenezThe objective of this study is to evaluate the technical viability of using a sandy lateritic soil chemically stabilized as a liner material, regarding hydromechanical and environmental features. For the chemical stabilization, dehydrated phosphogypsum and sodic bentonite were added to the soil, such six samples were obtained: Soil (S), soil + 10% phosphogypsum (SP), soil + 10% phosphogypsum + 3% bentonite (SPB3), soil + 10% phosphogypsum + 6% bentonite (SPB6), soil + 3% bentonite (SB3) and soil + 6% bentonite (SB6). Since x-ray diffractions tests showed that phosphogypsum shouldn’t be subjected to temperatures above 70˚C, the moisture values of all samples containing this material were determined in this temperature. However, the moisture values obtained in this temperature were corrected, since the soil moisture was determined at 110 ˚C and bentonite’s one at 130 ˚C. It was done through mathematical correlations, obtained comparing samples of this materials in different temperatures. For the hydromechanical tests, specimens were compacted in miniature, in accordance to the Brazilian MCT methodology, in Proctor standard energy. The compaction curves presented similar apparent dry weight values, but the stabilized samples presented higher values of optimum water content than soil. The hydraulic conductivity tests were carried out using the same cylinders used in compaction, with variable hydraulic head and gradient of 10m∕m. Phosphogypsum did not modify the coefficient of hydraulic conductivity of samples, while for the 3% of bentonite addition, these values decreased approximately one order of magnitude. Samples containing 6% of bentonite presented coefficients lower than 1x10-9 m ∕s, therefore, acceptable values for liners. In unconfined compression tests, the samples containing phosphogypsum presented lower strength, while those containing bentonite had an increasing in these values, but all them presented results higher than 200 kPa. The compatibility with contaminants was analyzed through chemical percolation tests, similar to hydraulic conductivity tests, but substituting water with solutions of HNO3, NaOH, NaCl and ethanol. The results showed that the solution of NaOH decreased the coefficients of hydraulic conductivity of samples. On the other hand, the HNO3 increased the coefficients of samples containing bentonite, such all samples presented values higher than 1x10-9 m ∕s. No significant changes were observed for solutions of NaCl and ethanol. The risk of environmental contamination due to the use of phosphogypsum was investigated through chemical analysis of solubilized extracts obtained from samples containing this by-product, taking into account the parameters prescribed by the Brazilian resolution CONAMA 396, for groundwaters. The results obtained indicated excess of iron (attributed to soil) and manganese (attributed to phosphogypsum), but further analysis was recommended for that a precise risk diagnosis was delineated.Item Monitoramento de pavimento composto por revestimento delgado e base melhorada com cimento(Universidade Federal de Goiás, 2019-08-29) Santos, Hebert Oliveira; Rezende, Lilian Ribeiro de; http://lattes.cnpq.br/9258692609398794; Rezende, Lilian Ribeiro de; Silva, João Paulo Souza; Branco, Verônica Teixeira Franco CasteloAlthough the highway system is the most important for Brazilian development, the pavements’ quality is low, with more than 50% of the built road networks presenting problems; one of the responsible for this situation is the design method currently used, that presents limitations. It is necessary to develop researches that allow the implementation of a method that among other factors that takes into account the deformation stresses of the pavement. In this context, this study aims to present the preliminary results of one of the monitored test track in the state of Goiás, GO-230, incorporating mechanistic analysis to contribute to the database of materials, technologies and performance of an asphalt pavement executed with double surface treatment (TSD). For this, laboratory tests were performed with the materials used for the track pavement construction, aiming the characterization, mechanical, and resilient behavior of the components of each layer, The gravel with cement mix behavior in three different grades was also evaluated. TSD grain sizing was checked with theoretical and empirical methods complemented by the calculation of the PUC coefficient. The conditions under the pavement was built, the functional conditions, micro, macrotexture, apparent defects, and the structural behavior were investigated after six months of the traffic opening. The actual traffic was determined, the stresses and deformations developed by the pavement structure were analyzed and the resilient modules obtained by the back-analysis process was obtained by the BAKFAA and BackMedina softwares. Swelling suppression and high mechanical gain were observed with the addition of cement in the gravel. It was found that the Brazilian requirements for TSD execution are generic, differing from the sizing methods and allowing the emulsion to be oversized. Execution control showed failures in the construction process while monitoring shows many apparent pathologies. The stress-strain analysis predicted high deformations in the subbase and subgrade that decreased while the base stiffness was increased. The back-analyzed modules presented higher values than those measured in the laboratory by the two softwares used, and BackMedina offers a more accurate adjustment to the deflection curves. Studies of this work, both in the field and in the laboratory, have shown that the project life of 10 years is unlikely to be achieved.Item Influência de não linearidades física e geométrica no comportamento de placas retangulares(Universidade Federal de Goiás, 2022-06-28) Aguiar, Daniella Maria Oliveira; Soares, Renata Machado; http://lattes.cnpq.br/1938664529309726; Soares, Renata Machado; Carvalho, Eulher Chaves; Silva, Frederico Martins Alves daThis work studies the influence of physical and geometric nonlinearities on the behavior of simply supported rectangular plates made of hyperelastic, isotropic, homogeneous, and incompressible material. In static analysis, geometrical nonlinearity is accounted for using two different theories to comparison - Novozhilov nonlinear theory and von Kármán nonlinear theory. The plate is under pressure loading that is described in two ways: distributed radial force (dead load) and displacement-dependent pressure (follower load or actual pressure). First the displacement field expansions are considered with three and twelve degrees of freedom, and then the Karhunen-Loève Method is applied to obtain a reduced order model. The pressuredisplacement responses are compared with those of other papers to validate the formulations. And, again using the pressure-displacement responses, the differences depending on the characteristics of the formulation employed are discussed and the solution obtained by the reduced order model is compared with the solution of the original system. In the dynamic analysis, the geometrical nonlinearity is described through von Kármán nonlinear theory, dead load pressure is applied, and the displacement field expansions are derived from the KarhunenLoève Method. The transverse frequency-displacement responses around various initial static configurations are examined. In both static and dynamic analyses, the physical nonlinearity is accounted for by the hyperelastic Neo-Hookean constitutive law, and the equations of motion are derived using Hamilton's Principle, the Rayleigh-Ritz method, and the local model method (MML). The Newton-Raphson method, adapted due to the MML, is used to solve the equations of motion. It is observed that the use of the reduced model gives satisfactory results and that the influence of nonlinearities, both physical and geometrical, are predominant when the plate is subjected to high amplitude displacements.Item Estudo dos mecanismos de transferência de tensões de cisalhamento em concreto reforçado com fibras de aço: análise do intertravamento de agregados(Universidade Federal de Goiás, 2017-06-30) Lobo, Fausto Arantes; Araújo, Daniel de Lima; http://lattes.cnpq.br/8801080897723883; Araújo, Daniel de Lima; Pituba, José Julio de Cerqueira; Bittencourt, Túlio NogueiraIt was performed an experimental analysis in order to evaluate the contribution of the steel fibers and the aggregate size in the shear strength of the concrete. This paper describes tests to evaluate the shear strength and a test method for evaluation of shear stress transfer by aggregates interlock. In the experimental development, it was used concrete with a mean strength of 60 MPa, with 9.50 mm and 12.50 mm coarse aggregate, varying the volume of steel fibers in 0%, 0.5% and 1.5%. The results showed that the methodology developed to evaluate the direct shear test with two planes worked well until the maximum force for all the models. The direct shear testing results for pre-cracked (push-off test) attested that the fibers contribute to the effect of the aggregates interlock by reducing the crack opening and the sliding of the interface for a given shear stress. Moreover, the aggregate size contributes to the increasing of the interface roughness and consequently in the increasing of shear stress transfer. In addition, it was proposed the modification in one of the empirical models used to evaluate the interlocking aggregate phenomenon in the concrete by considering the experimental value of shear strength concrete. This modified empirical model demonstrated good correlation with the shear stress versus dilatancy that was obtained experimentally.Item Ligação viga-pilar em fase de montagem para estruturas de concreto pré-moldado: análise via modelagem computacional(Universidade Federal de Goiás, 2016-07-05) Silva, Erlucivânia Bueno da; Araújo, Daniel de Lima; http://lattes.cnpq.br/8801080897723883; Araújo, Daniel de Lima; Soares, Renata Machado; Oliveira Júnior, Luiz Álvaro deThe connection is one of the most important phases in the precast structures project, being responsible for connecting the elements and enabling the efforts transference, directly interfering on the global stability of the structure. The real connection behavior can be studied by using physical experiments or by computer modelling. Both must be confronted with analytical models in order to obtain models that can be employed in the project connections. The computer modelling is a practical and economical way to investigate the structures behavior due to the programs sophistication based on the Finite Element and of Contour Method, and thanks to the increasing processing of computers performance. This study aims to analyze, by computer modelling, using the program DIANA® 9.6., the behavior of a beam-column connection composed by a steel corbel, formed by welded steel sheets “U” shaped, inserted in the column, and a steel hanger, inserted in the beam, formed by welded steel sheets in the shape of rectangular and hollow profile section. This connection has been studied experimentally by Prado (2014). The computer results of the validated three-dimensional model are compared with experimental ones and with the calculating models. In the final part, new proposals with modifications in the union form between the elements are presented in order to improve the mechanical performance. It was observed that the ultimate strength in proposals I and II, were respectively, 5,19% and 17,17% greater than the one in in the computer model M-VIIc.Item Análise do conforto ambiental em salas de aula da Universidade Federal de Goiás(Universidade Federal de Goiás, 2010-09-24) Ochoa, Juliana Herlemann; Araújo, Daniel de Lima; http://lattes.cnpq.br/8801080897723883; Brandstetter, Maria Carolina Gomes de Oliveira; Sattler, Miguel Aloysio; Morais, Ludmila Rodrigues deProvide users good physical conditions in educational institutions is essential for the proper development of teaching and learning. This work deals with the verification in-loco of the environmental comfort of classrooms in two buildings with different architectural and construction techniques, that are part of the structure of the Federal University of Goiás. So the research aimed at exploring these buildings in order to identify the peculiarities of its thermal, acoustic and light performance which are being influenced by the technologies adopted and the physical conformation of the same. The technical data collected were analyzed by type of comfort. In lighting comfort, measurements were carried out near the solstices and equinoxes and the data collected were analyzed by means of ambient illuminance, uniformity coefficient and contribution of artificial light. The thermal comfort data collected were temperature and relative humidity for a period of approximately 11 months, which were assessed using the concept of comfort zone, degree-hours analysis and absolute maximum and minimum values. The acoustic measurements collected the sound pressure levels and occurred over a day of daily activities in both buildings. It was noted that there is an influence of the architectural elements of environmental comfort in buildings. Among other factors, one that can be highlighted is that despite having similar solar orientation, which is a comfort condition, the results of the environmental performance of each of the buildings were quite different. Parallel to these technical assessments were also done a periodic application of questionnaires to the users of the classroom, one per season, which sought to characterize the perception of these in relation to each of the types of comfort. Finally, a correlation was established between the technical data collected and perceptive. In most of cases, the opinions expressed by users were not consistent with the results evaluated by measurement techniques, thus demonstrating a difference between the comfort zone adopted and the actual user satisfaction of the buildings.Item Análise do comportamento de sistemas dinâmicos com absorsores de vibração não-lineares sintonizados(Universidade Federal de Goiás, 2022-05-13) Marques Filho, Marcello Gomes; Nuñez del Prado, Zenón José Guzmán; http://lattes.cnpq.br/7703344458057759; Nuñez del Prado, Zenón José Guzmán; Avila, Suzana Moreira; Soares, Renata MachadoSlender and flexible structures, such as buildings or long span bridges, have become more susceptible to dynamic loads effects and an increment of their oscillation amplitudes can be noticed. Hence, the effect of large-amplitude vibrations and the consideration of nonlinearities become a relevant factor on the analysis, and, in a lot of cases, an intervention is necessary, by using vibration control mechanisms. First, in this work, the performance of a nonlinear tuned mass damper is evaluated when applied to a nonlinear Duffing equation considering nonlinear stiffness parameters with both softening and hardening behavior for the main system and the damper. For this, damped and undamped Duffing nonlinear oscillators are studied when subjected to a harmonic load or free vibration and attached to a nonlinear damper. First, the optimal linear control parameters were obtained by using Den Hartog’s criteria and these parameters are used to evaluate its performance on the nonlinear vibration regime. Then, the performance of a nonlinear tuned mass damper is evaluated when applied to a simply supported nonlinear 2D Euler-Bernoulli beam, subjected to a harmonic load or an aerodynamic follower load. For this case, the optimization process is also performed. A parametrical analysis is performance to evaluate the quality of the nonlinear tuned mass damper on the resonance curves, basin of attraction, time responses, phase planes and Poincaré sections for both the discrete and the continuous systems.Item Avaliação da durabilidade dos concretos fornecidos por centrais dosadoras(Universidade Federal de Goiás, 2018-09-28) Paula, Marcelo Cândido de; Matos, Oswaldo Cascudo; http://lattes.cnpq.br/3336749062812376; Matos, Oswaldo Cascudo; Oliveira, Andrielli Morais de; Santos, Sergio Botassi dosThis research aimed to evaluate the mechanical behavior and durability of concrete supplied by premixed concrete batching plants with the strength classes most used by the main construction companies in the region of Goiânia/GO (C25, C30, C35, C40 and C45, being conventional pumped concrete with maximum dimension characteristic of coarse aggregate of 19 mm and consistency class S50, slump 50 ≤ to < 100 mm). The durability parameters used were obtained through accelerated and natural carbonation, chloride migration, total absorption, capillary absorption, water permeability, electrical resistivity and ultrasound tests. In terms of mechanical properties, compressive strength and modulus of elasticity were the studied parameters. Finally, the impact on the durability of the concrete produced by the increase in the water/binder ratio was evaluated, considering the environment in which the structural element is inserted, as well as the effect of different constituent materials present in each concrete (in this context of durability). Based on the results obtained, it was found that a significant part of the concrete does not comply with the maximum water/cement ratio recommendations of ABNT NBR 6118: 2014, and its values are, in many cases, much higher. This causes an important drop in the performance regarding the carbonation of concrete, which will certainly result in a reduction in the useful life of the concrete structure and in non-compliance with the current minimum VUP requirements of 50 years for the structural system (according to ABNT NBR 15575: 2013). As for chlorides, there is an important influence of the water/binder ratio, but the effects resulting from the type of cement used were very significant in the results. In this regard, an important contribution of mineral additions in reducing the transport of chlorides in concrete was found.Item Estabilidade de treliça abatida de material hiperelástico(Universidade Federal de Goiás, 2021-08-27) Santos, Antônio Adryel Lima dos; Soares, Renata Machado; http://lattes.cnpq.br/1938664529309726; Albuquerque, Arthur Alax de Araujo; Del Prad, Zenon José Guzman Nunez; Soares, Renata MachadoThe study of the stability of truss slaughtered hyperelastic material is part of the research line of nonlinear dynamic stability of structural elements. In this work, an analytical solution is initially used, where the equations that govern the structural system of a flat truss of two bars, hyperelastic, symmetrical and asymmetric, are obtained from the variation of the system's energy functional, using the Euler-Lagrange equations. The incompressible hyperelastic material is described by the neo-Hookean constitutive model, also considering geometric nonlinearity in the study. The Finite Element Method (FES) is used through the ABAQUS® finite element commercial program to perform static and dynamic analyses to verify the influence of bending efforts on the behavior of the trusses studied. Thus, the main stresses, buckling load and the balance paths of the external forces and axial loads on the bars are obtained in static analysis. From dynamic analysis, frequency-load, frequency displacement, phase planes and responses in time under forced vibration are obtained. The results obtained allow us to conclude that the presence of bending efforts led to higher values for the natural frequency and limit load of the structure.