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This research evaluates the geometric non-linear behavior of structures often used in transmission lines (TLs) and verifies the influence of different wire lengths, average wind speeds, and unevenness between adjacent towers, using the IEC 60826 standard. Different finite element numerical models were developed considering the isolated tower and also the complete system (tower, wires, and insulator chains). The analyses revealed that a simplified model can be employed for cases of adjacent, equal-length spans, but for cases with different lengths, the effect of geometric nonlinearities (GNLs) can become expressive and influence the type of analysis to be performed. Furthermore, it was found that increasing the average wind speed may imply an increase in the longitudinal unbalance. Finally, it was concluded that the unevenness between spans should be considered when calculating the loads to be applied to the structure, even if the simplified model is used. Based on the outcomes and considering wind speeds between 30 and 40 m/s and adjacent tower unevenness between 0 and 10%, this work establishes practical design criteria to be used by designers in the design of suspension structures of TLs located in the State of Minas Gerais, Brazil. The methodology presented in this paper can be extrapolated to other regions of the country, paying attention to the fact that the recommendations proposed here are valid only for self-supporting towers. [ABSTRACT FROM AUTHOR]

The flow of water in mining waste may cause serious environmental impacts associated with acid-rock drainage. In relatively dry climates, dry soil covers have been considered as feasible alternatives to minimise such effects. The objective of this paper is to evaluate the influence of the hydrological cycle and soil type on the performance of dry cover systems, considering the tropical conditions found in Brazil's central-west region. Numerical analyzes of four different cover systems composed of tropical soils were performed using the Finite Element Method. Among the proposed arrangements, three use a soil that presents a bimodal soil-water characteristic curve and the fourth system employs a unimodal soil. The thicknesses of intermediate materials were varied and different representative precipitation parameters were considered for a period of one year. The results obtained were compared in terms of the internal flow and the capacity of the cover to store water. The results indicate that bimodal soils may not be ideal materials and require specific compaction conditions to reduce the volume of macropores. Unimodal tropical soils presented adequate response as store-and-release materials. The use of an intermediate layer acting as a capillary barrier did not offer significant improvement to the cover systems evaluated. [ABSTRACT FROM AUTHOR]

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Purpose: This paper analyzes the effect that is generated in the dynamic response of a Commonwealth Advisory Aeronautical Council building for different types of power spectra. This article also compares synthetic wind method (SWM) results with wind tunnel tests and other numerical approaches. Design/methodology/approach: One of the main methodologies developed in Brazil, the SWM, is employed to determine the dynamic wind loads. The Davenport, Lumley and Panowski, Harris, von Karman and Kaimal model are used in SWM to generate the resonant harmonics. Lateral pressures are calculated by the wind speed deflection profile for 30, 35, 40 and 45 m/s. The structure is processed in Autodesk Robot Structural Analysis with numerical analysis in FEM by the Hilber–Hughes–Taylor method. To corroborate the synthetic wind with experimental results, displacement curves are developed for wind tunnel experimental results, Davenport method, Eurocode and NBR 6123, together with the SWM. Findings: Results show that for 30 m/s, the lowest convergence of the power spectra models was presented and that the greatest difference found was below 10%. In addition, it was shown that Eurocode 1-4 can lead to oversizing, while NBR 6123 can lead to undersizing, compared with the experimental results. Finally, results by the Davenport method, wind tunnel test and synthetic wind showed good accuracy. Originality/value: By carrying out this comparative analysis, this work presents an important contribution in the field of calculating the dynamic response of tall buildings. Studies with these comparisons to corroborate the SWM had not yet been carried out. [ABSTRACT FROM AUTHOR]

Most of the time, geotechnical engineering interventions require solutions that necessarily aim for better use of the available space. Many slope stabilization techniques were developed following that assumption, and one of the most applied procedures in Brazil is the soil nailing reinforcement. These engineering techniques are constantly improving. Consequently, a continuous study of the design and behavior of soil nails is important. The technique of vertical nails reinforcement in soil nailing is recent in the Brazilian scenario. Nowadays, some constructors started to use them near the slope face when stabilizing huge excavations. This paper aims to verify the vertical nails' efficiency in reducing horizontal displacements. We present three numerical modeling analyses using the finite elements method (FEM). The proposed model is a soil nailing of approximately 18m high in a homogeneous subsoil in São Paulo city. Comparing situations with and without vertical nails, as if an inclined face (slope), the results showed that adding those nails could reduce horizontal displacements. [ABSTRACT FROM AUTHOR]

One of the concerns about the use of passive Infrared Thermography (IRT) for structural health monitoring (SHM) is the determination of a favorable period to conduct the inspections. This paper investigates the use of numerical simulations to find appropriate periods for IRT-based detection of subsurface damages in concrete bridge slabs under passive heating along a 1 year of time span. A model was built using the Finite Element Method (FEM) and calibrated using the results of a set of thermographic field inspections on a concrete slab sample. The results showed that the numerical simulation properly reproduced the experimental thermographic measurements of the concrete structure under passive heating, allowing the analysis to be extended for a longer testing period. The long-term FEM results demonstrated that the months of spring and summer are the most suitable for passive IRT inspections in this study, with around 17% more detections compared to the autumn and winter periods in Brazil. By enhancing the possibility of using FEM beyond the design stage, we demonstrate that this computation tool can provide support to long-term SHM. [ABSTRACT FROM AUTHOR]

This paper is fruit of an active interaction between several universities/academics and the University of Brasília. It has focus on the design of retaining walls. This design is increasingly present in engineering projects for urban areas, given their continuous development. In the Federal District of Brazil, many retaining walls are built in order to optimize space. These excavations need retaining works in order to maintain the terrain in place and to avoid any collapse. The aim of this paper is to tentatively assess the behavior of retaining structures made of "pile curtain" by using existing commercial finite element (F.E.) and "winkler spring" type softwares. The case study is characterized by a 13m deep excavation founded in the well-known porous clay of Brasilia. The excavation's instrumentation provided displacements along depth, used to evaluate the structure's behavior. In terms of the approach by using a winkler type software, the best technique to evaluate the subgrade reaction coefficient (modulus) was an empirical equation presented by Bowles (1988). For the numerical predictions with finite element method, the Hardening Soil model tended to show a slight better result when compared to the traditional Mohr Coulomb model. It is concluded that simple techniques, and experience of the engineer, are sometimes fundamental to better simulate such types of structure founded on complex unsaturated tropical soils. [ABSTRACT FROM AUTHOR]

Most of the time, geotechnical engineering interventions require solutions that necessarily aim for better use of the available space. Many slope stabilization techniques were developed following that assumption, and one of the most applied procedures in Brazil is the soil nailing reinforcement. These engineering techniques are constantly improving. Consequently, a continuous study of the design and behavior of soil nails is important. The technique of vertical nails reinforcement in soil nailing is recent in the Brazilian scenario. Nowadays, some constructors started to use them near the slope face when stabilizing huge excavations. This paper aims to verify the vertical nails' efficiency in reducing horizontal displacements. We present three numerical modeling analyses using the finite elements method (FEM). The proposed model is a soil nailing of approximately 18m high in a homogeneous subsoil in São Paulo city. Comparing situations with and without vertical nails, as if an inclined face (slope), the results showed that adding those nails could reduce horizontal displacements. [ABSTRACT FROM AUTHOR]

• Thermal stresses produced on TCABR tokamak during baking analyzed for the first time. • Maximum equivalent stress on vacuum vessel below limit calculated by ASME BPVC. • Stress on other components below ASME limit, but above material yield strength. • Stress on vacuum vessel below ASME limit, despite high rigidity support structure. TCABR is a small-sized tokamak located at the University of São Paulo, in Brazil. It is planned to undergo an extensive upgrade, which includes a baking system. However, this tokamak wasn't designed considering baking as a possible wall conditioning technique. This paper analyzes whether a baking system with ohmic heating could in principle be installed on TCABR, considering the thermal stresses that it might produce on the vacuum vessel. An analytical steady-state heat transfer model was used to estimate the heat fluxes required to reach a target temperature of 200 °C. Thermal and structural transient finite element method models were developed using ANSYS Workbench®. The temperature distribution was used to calculate the thermal stresses, also considering the effects of gravity and vacuum pressure. The stresses produced in the vacuum vessel by baking were below the limit defined by the ASME stress code, but the graphite tiles' support rails reached stress values above their material's yield strength. The resulting temperature distribution was not uniform, with some regions far from the 200 °C target. A redesign of the baking system will be required to reach a more uniform temperature field and avoid stresses above yield strength for some components. [ABSTRACT FROM AUTHOR]

This paper analyzes the sea surface height dataset from the TOPEX, Jason-1, and Jason-2 satellites of a 19-yr time series in order to extract the tide harmonic constituents for the region limited by latitude 5°N-35°S and longitude 55°-20°W. The harmonic analysis results implemented here were compared with the tidal constituents estimated by three classical tidal models [i.e., TOPEX/Poseidon Global Inverse Solution 7.2 (TPXO7.2), Global Ocean Tide 4.7 (GOT4.7), and Finite Element Solution 2102 (FES2102)] and also with those extracted from in situ measurements. The Courtier criterion was used to define the tide regimes and regionally they are classified as semidiurnal between the latitude range from approximately 5°N to 22°S, semidiurnal with diurnal inequality from 22° to about 29°S, and mixed southward of latitude 22°S. The comparison results among all tide approaches were done by analyzing the root-sum-square misfit (RSSmisfit) value. Generally, the RSSmisfit difference values are not higher than 12 cm among them in deep-water regions. On the other hand, in shallow water, all models have presented quite similar performance, and the RSSmisfit values have presented higher variance than the previous region, as expected. The major discrepancy results were particularly noted for two tide gauges located in the latitude range from 5°N to 2°S. The latter was investigated and conclusions have mainly pointed to the influence of the mouth of the Amazon River and the considerable distance between tide measurements and the satellite reference point, which make it quite hard to compare those results. In summary, the results have showed that all models presently generate quite reliable results for deep water; however, further study should done in order to improve them in shallow-water regions too. [ABSTRACT FROM AUTHOR]

In the present study, we investigate the subsidence phenomenon affecting some neighborhoods located to the west of the city of Maceió, State of Alagoas (northeastern Brazil), which is due to the underground solution mining of halite (NaCl) from 1977 to 2019. The first symptoms of this phenomenon, such as surface cracks, ground depressions, small earthquakes, etc., began to be noticed only in 2018. So far, it has already caused enormous damage to the local population, resulting in the creation of true "ghost" neighborhoods. In this study, we have integrated surface displacement determined from satellite images using the persistent scatterer interferometry and the small baseline subset (SBAS) InSAR techniques for the period of 2016–2020, and 2D numerical modelling based on the finite element method. The results showed a wide surface subsidence (2.6 km2) with maximum vertical displacements of − 100 cm and maximum subsidence rate of − 22 cm/year. Variations in the mechanical properties of geological faults significantly affect surface subsidence pattern. We speculate that the reactivation of fractures may be an important mechanism leading to the formation/propagation of numerous cracks at the surface. Finally, the study may provide a better understanding about settlement dynamics in salt dissolution fields. [ABSTRACT FROM AUTHOR]

Installation of a mobile jack-up rigs with spudcan foundations are sometimes challenge due to uncertain offshore environments. Prediction of penetration resistance during installation is often necessary to avoid hazards such as punch-through failure. When the field monitored data deviates with these predictions, engineers have to decide how severe this deviation is based on their experience. This paper provides a method that can quantify the installation risk by a set of percentile curves of penetration resistance against depth. The percentile curves can be quantified through combining a random large deformation finite element method with Monte-Carlo simulation. The spatial variability in seabed soils can be considered and the penetration resistance curves through the random soils can be obtained. This model was verified by a spudcan installation penetration into deeper seabed. Finally, four field cases in North-East Brazil and Gulf of Mexico are investigated. Results show that the installation risk during spudcan installation can be estimated by comparing the measured preloading and penetration depth values with the percentile curves, which indicates the proposed method is capable to help decision making during spudcan installation. • This paper provides a set of percentile curves to quantify the installation risk of spudcan foundation in random soils. • The percentile curves are quantified through combining RLDFE method with Monte-Carlo simulation. • Four field cases are investigated and the results indicate the proposed method can help decision making of the engineer. [ABSTRACT FROM AUTHOR]

This paper discusses the occurrences caused during the commissioning of the ground electrode of the Porto Velho Converter Station, located at the North region of Brazil, and the methodology used to analyze and mitigate the problem. The converter station is composed of a group of agents and linked with two major power plants – Santo Antonio and Jirau, several 500 kV and 230 kV transmission lines and nearby substations. The main issue caused by an electrode at long distances is the DC current at transformers neutrals caused by ground potential difference between locations. The predicted current at the transformers neutrals are unacceptable, which main effect is the core saturation, resulting in audible noise, vibrations and excessive heating in the equipment. Due to the multi-agent nature of the station, the use of current blocking devices at third party assets are not an option. The paper will describe the investigation of alternatives, resulting in a site selection for a new electrode. We will emphasize the importance of a proper geologic survey and soil model, not only for the site selection but also for predict the ground potential rise, an effect which could extend for several kilometers. [ABSTRACT FROM AUTHOR]

The Armando Ribeiro Gonçalves Dam, popularly known as The Açu Dam, is an important geotechnical construction in Rio Grande do Norte state, Northeastern of Brazil. The monitoring and analysis of strains in earth dams is essential to understanding the safety conditions of these structures. The present study aimed at analyzing vertical strains at the Açu Dam using data from instruments installed in the body of the dam, and numerical modeling, in order to compare the results. The study was conducted in the construction stages of the embankment of the dam, first filling and reservoir operation. Numerical analyses were conducted with Sigma/W software, which uses the finite elements method to analyze stress and strains. The results of modeling were compared to instrumentation data reported in Rocha(Barragem Engenheiro Armando Ribeiro Gonçalves: histórico e avaliação do comportamento atual, Universidade Federal do Rio Grande do Norte, Natal, 2003). Analyzing the results of the instrumentation, it was found that the largest settlement measured was 39.71 cm, corresponding to 0.63% of the total height of the dam, and that the settlement occurred mainly in the construction period and upstream. Comparing the results between modeling and instrumentation, a good agreement is observed, especially during the construction period, mainly for the extensometers located downstream, with relative errors between 0.53% and 5.89%. It is concluded that the modeling performed and the parameters of the soils used corresponded well to the reality of the Açu dam, resulting in a satisfactory stress–strain analysis. [ABSTRACT FROM AUTHOR]

The paper highlights the features of constructing a model of a wet semi-autogenous grinding mill based on the discrete element method and computational fluid dynamics. The model was built using Rocky DEM (v. 4.4.2, ESSS, Brazil) and Ansys Fluent (v. 2020 R2, Ansys, Inc., United States) software. A list of assumptions and boundary conditions necessary for modeling the process of wet semi-autogenous grinding by the finite element method is presented. The created model makes it possible to determine the energy-coarseness ratios of the semi-autogenous grinding (SAG) process under given conditions. To create the model in Rocky DEM the following models were used: The Linear Spring Rolling Limit rolling model, the Hysteretic Linear Spring model of the normal interaction forces and the Linear Spring Coulomb Limit for tangential forces. When constructing multiphase in Ansys Fluent, the Euler model was used with the primary phase in the form of a pulp with a given viscosity and density, and secondary phases in the form of air, crushing bodies and ore particles. The resistance of the solid phase to air and water was described by the Schiller–Naumann model, and viscosity by the realizable k-epsilon model with a dispersed multiphase turbulence model. The results of the work methods for material interaction coefficients determination were developed. A method for calculating the efficiency of the semi-autogenous grinding process based on the results of numerical simulation by the discrete element method is proposed. [ABSTRACT FROM AUTHOR]

Theropod dinosaurs were relatively scarce in the Late Cretaceous ecosystems of southeast Brazil. Instead, hypercarnivorous crocodyliforms known as baurusuchids were abundant and probably occupied the ecological role of apex predators. Baurusuchids exhibited a series of morphological adaptations hypothesized to be associated with this ecological role, but quantitative biomechanical analyses of their morphology have so far been lacking. Here, we employ a biomechanical modelling approach, applying finite element analysis (FEA) to models of the skull and mandibles of a baurusuchid specimen. This allows us to characterize the craniomandibular apparatus of baurusuchids, as well as to compare the functional morphology of the group with that of other archosaurian carnivores, such as theropods and crocodylians. Our results support the ecological role of baurusuchids as specialized apex predators in the continental Late Cretaceous ecosystems of South America. With a relatively weak bite force (~600 N), the predation strategies of baurusuchids likely relied on other morphological specializations, such as ziphodont dentition and strong cervical musculature. Comparative assessments of the stress distribution and magnitude of scaled models of other predators (the theropod Allosaurus fragilis and the living crocodylian Alligator mississippiensis) consistently show different responses to loadings under the same functional scenarios, suggesting distinct predatory behaviors for these animals. The unique selective pressures in the arid to semi‐arid Late Cretaceous ecosystems of southeast Brazil, which were dominated by crocodyliforms, possibly drove the emergence and evolution of the biomechanical features seen in baurusuchids, which are distinct from those previously reported for other predatory taxa. [ABSTRACT FROM AUTHOR]