Resumen en Inglés:

Abstract This study presents a modal analysis of a jacket-type substructure supporting a 15 MW offshore wind turbine, aiming to assess the influence of geotechnical soil variability on the foundation’s dynamic response. Three representative soil profiles from the Brazilian coast were considered, incorporating different stiffness and stratification conditions. According to offshore engineering guidelines, the soil-pile interaction was modeled using manually inserted nonlinear springs along the pile shaft, based on P-Y, T-Z, and Q-Z curves. These curves were generated using the geotechnical software PILELAT and PILEAXL and integrated into a three-dimensional finite element model developed in ANSYS. The structural model included tubular elements and concentrated masses representing the rotor-nacelle assembly. Two boundary conditions were analyzed: a conventional model with distributed springs along the depth and a simplified model with fixed supports at the jacket base. The modal results indicated that all configurations operate outside the critical resonance bands associated with rotational excitation frequencies, classifying the system as semi-rigid. Even in low-stiffness soils, the jacket system demonstrated satisfactory dynamic performance, provided proper geotechnical characterization is carried out. The findings highlight the importance of integrated modeling between foundation and structure and contribute to the safe and efficient implementation of offshore turbines in Brazilian waters, enhancing the technical feasibility of exploiting the country’s offshore wind energy potential.

Resumen en Inglés:

Abstract Lattice structures have a wide range of applications in real structures. For example, concrete buildings can be modeled as flat or spatial frames, while lattice or ribbed slabs can be modeled as grids. Computer programs frequently used for the design of buildings in Brazil allow the design to be carried out in spatial gantry and grid. Also, some include the possibility of applying calculated support settlements or manually introducing an elastic spring to simulate the behavior of the foundation. However, it is not possible to insert geotechnical data together with the structure for the geotechnical evaluation of soil deformation in an integrated way to obtain an analysis of the interaction between the stresses in the structure and the soil deformations, as well as to take into account the overlapping of stresses applied in the soil mass to evaluate settlements. In this context, classical solutions to analyze these domains together have been proposed with the use of the Finite Element Method (FEM) and by the coupling between the Boundary Element Method (SEM) and FEM. Despite being robust, these techniques are not yet commonly used in calculation offices, due to the high computational cost. In this sense, alternative formulations with lower computational cost, such as the one proposed herein, can be a viable alternative for the analysis of the effects of soil-structure interaction in conventional structures without significantly impairing computational performance. Thus, to approximate the computational analysis to the real behavior of structures, this article proposes an efficient and low-cost computational matrix analysis solution for the integration between structural and geotechnical models, considering the soil-structure interaction. Thus, the integrated model considers the compatibility between the forces calculated in the structure and the settlement prediction, carried out, considering the soil deformation caused by the global contribution of stresses, in such a way as to consider in the analysis of the soil, both the tensions arising from the support itself and those transmitted by the other foundation elements. The proposed alternative formulation was verified for isolated structural analyses, geotechnical isolates and finally considering the coupled form with equilibrium in the deformed condition of the soil, paying attention to the robustness of the implementation.

Resumen en Inglés:

Abstract This article aims to investigate the residual structural behavior, strength and Direct Strength Method (DSM) design of cold-formed steel (CFS) columns that fail in distortional modes after exposure to elevated temperatures from fire (post-fire conditions). It specifically examines the influence of temperature-dependent material properties of cold-formed steel on the residual strength of fixed-end lipped-channel (LC) columns after exposure to seven temperatures (T=20-300-400-500-600-700-800 ºC) and subsequent cooling, as reported in literature. Residual failure load data for the columns, obtained through ANSYS shell finite element analysis (SFEA), are employed to evaluate the impact of temperature-dependent steel constitutive models on the predictive accuracy of existing DSM distortional strength curves. The findings demonstrate that the current DSM distortional design curve for room temperature effectively addresses distortional failures in post-fire scenarios.

Resumen en Inglés:

Abstract Proper management and inspection are essential to ensure the safety and structural integrity of bridges. In this research, bridge management systems implemented around the world have been studied with a focus on their inspection methods. Based on the results, the authors propose a methodology that integrates the most relevant aspects of many existing approaches, targeting a Brazilian context. It covers six types of inspections, including three levels of depth and an emergency inspection. The aim is to obtain a methodology that can be adapted to the specificities and local conditions of Brazilian bridges. The three levels of inspection depth allow for a comprehensive analysis, from a basic to a detailed assessment, ensuring an accurate understanding of the condition of the bridges.

Resumen en Inglés:

Abstract The combination of RHS columns, I-beams, and welding offers an aesthetically pleasing appearance while providing excellent load transfer capabilities, expanding their potential use in multi-story buildings. Existing standards, such as NBR 16239 (2013), ISO 14346 (2013), and prEN 1993-1-8 (2021), provide limited design guidelines for welded connections. The validity of the design equations depends on geometric and non-dimensional parameters. Herein, this article presents an experimental study of I-beams welded to rectangular hollow sections (RHS) with the column connection under monotonic in-plane bending moments, with column face plastification. Six prototypes with geometrical and non-dimensional characteristics within and outside the validity ranges of established design standards are investigated. The behavior, failure mode, strength, and stiffness of the connection are evaluated and discussed. The geometric and material properties, the experimental setup and methodology, and the instrumentation details are described. In the experimental results, the failure mode characterized by column face plastification is observed. The deformed shape, beam displacement, column and I-beam strain, and moment-rotation curves are presented. The experimental moment resistance results were compared with the design equation predictions and the suitability of the equation for prototypes outside its current validity range are assessed.

Resumen en Inglés:

Abstract This study presents the hydraulic and structural design of a mini-hydroelectric power plant implemented in the USOIGUA irrigation district, located in the municipalities of Campoalegre and Hobo (Huila, Colombia). The system was conceived to supply electricity to a household in a non-interconnected rural zone, leveraging an available flow rate between 0.87 and 1.24 m3/s and a net head of 18 m. These conditions were found suitable for a Michell-Banki turbine, which was built using low-cost, locally available manufacturing methods. To ensure proper turbine operation, the project required the design and construction of a civil infrastructure capable of conveying water from an upstream intake while maintaining pressure at the injector. A reinforced structural frame was also developed to support the turbine, transmission, and generator, designed to resist both static and dynamic loads and to provide environmental protection. The resulting system was dimensioned for a flow rate of 0.24 m3/s, aiming to generate approximately 20 kW of electrical power. The project demonstrates the integration of accessible construction practices with renewable energy technologies and offers a replicable model for rural electrification in similar geographic contexts.

Resumen en Inglés:

Abstract The state of Ceará in Brazil is designing a hub with the capacity to produce at least 500,000 tons of green hydrogen per year and export to Europe (Port of Rotterdam, Netherlands) on a shipping route from the Industrial and Port Complex of Pecém to the Port of Rotterdam, in the Netherlands. A Memorandum of Understanding (MoU) has been signed by 43 companies from different countries and the Ceará government (i.e., green hydrogen hub) to implement projects in this hub. Thus, this article aims to map technological routes for green hydrogen production for the generation of energy from fuel cells, resulting in a technological roadmap as the main outcome. Of all the 43 companies that signed the memorandum for the Green Hydrogen Hub in Ceará, only 27.90% work with fuel cells, and 31 companies have publications that have hydrogen projects. This shows the incipience in the studies and works regarding this subject. However, a state of Ceará-led clean-hydrogen hub could have a sizeable and lasting impact on the region. Based on the estimated potential, the economic, environmental, and social benefits in 2050 could be substantial, fundamentally shaping the long-term vision of the Industrial and Port Complex of Pecém (CIPP) hydrogen hub.

Resumen en Inglés:

Abstract This study investigated the feasibility of recovering carbonaceous material from fine coal waste through the bench flotation process. The goal was to find an alternative for the disposal of these waste materials in tailings dams, which cause negative environmental impacts. The possibility of recovering carbonaceous material from fine coal waste through bench flotation was demonstrated. Tested were several combinations of reagents, the collectors Diesel, kerosene and Lilaflot, with concentrations ranging from 1000 to 6000g/t, and the frothers pine oil and MIBC, ranging from 100 to 600 g/t. The target of 40% mass recovery and ash content below 35% was achieved by three tested combinations, being the better result Diesel+MIBC, with concentrations of 6000 g/t + 400 g/t, and mass recovery of 42.2% and ash content of 33.5%. The desliming stage significantly contributed to improving the mass and carbonic recoveries, but it did not significantly improve the ash content results. The study showed potential to reduce the environmental impacts of the coal industry by decreasing the volume of waste disposed in tailings dams and minimizing the exposure of chemical elements that could lead to Acid Mine Drainage (AMD). Additionally, the recovery of carbonaceous material can produce a valuable product for use as fuel or in other applications.

Resumen en Inglés:

Abstract The total number of electronic voting machines produced in Brazil was 1,489,115 units between the years of 1996 and 2023 (14,598.99985 tons). The objective of this study was to conduct a detailed characterization of the physicochemical composition of obsolete electronic voting machines (EVM), focusing on determining the Gold (Au) and Silver (Ag) content in Printed Circuit Boards (PCB). The methodology involved both physical and chemical treatments. The physical treatment included a comminution stage using knife mills, followed by particle size classification through manual agitation using sieves with openings of 16, 32, and 60 mesh. In the chemical treatment, metal detection was carried out using a variety of analytical techniques, including Sensor-Based Sorting (SBS), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Fluorescence (EDXRF), X-ray Fluorescence (XRF), and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Four electronic voting machine (EVM) printed circuit boards (PCBs) were used in this study, with Au contents ranging from 0.02646 to 0.0768 g and Ag contents ranging from 0.087 to 0.54 g. It was observed that, in the fraction without granulometric classification, both higher and lower detections were obtained compared to the fractions subjected to the classification stage. The PCBs were similar when compared to other circuit boards, making them suitable for commercialization and logistics with other electronic equipment. Between 1996 and 2023, the economic potential derived from the characterization data for Au and Ag in the four granulometric fractions was USD 29,352,755.25 and USD 2,126,456.22, respectively, for PCBs without granulometric classification.

Resumen en Inglés:

Abstract The main objective of this field investigation was to study the influence of different plant species and the use of geotextiles on soil erosion reduction in sand mining pit recoveries. A field experiment with 24 plots was installed in a freshly excavated pit, arranged in 3 blocks with 8 treatment combinations. Four different types of plantings ('type of vegetation') and two types of soil covering ('bare or with geotextile' - jute) were used. The plant species selected for the experiment were the legume Arachis repens, a mix of four locally occurring species (including two grasses) and the grass Chrysopogon zizanioides, all introduced as plantlets. Additionally, as a control, a group of plots was left initially bare. The experiment was monitored for 07 months (Nov/20 to Jun/21) with the following measurements or observations taken in each plot: (a) the mass of eroded soil, (b) the collected runoff water volume, (c) plant survival over time. Arachis repens showed the best control of soil erosion and the highest survival rate, followed by a mix of local plants. The plants only had effect on soil erosion when ‘vegetation cover’ was higher than 25%; below this, all treatments showed the same erosion behavior, including the control plots with no initial plants. Somehow surprisingly, use of geotextile did not reduce soil erosion.

Resumen en Inglés:

Abstract This article analyzes the application of the Global Industry Standard for Tailings Management (GISTM) in tailings disposal facilities located in the southeastern region of the state of Pará. The objective was to verify compliance with GISTM for the tailings disposal system, consisting of a dam and exhausted pit disposal. To assess compliance with the Global Standard, the technical records of the tailings dam and a pit where the tailings are also deposited were used to enable the application of the International Council on Mining and Metals (ICMM) Compliance Protocols. Although GISTM assessed the system, it also assessed the structures in isolation. The research showed that the dam was more compliant with the Standard, as it had a higher level of technical information than the pit. This result is correlated with the fact that the dam complies with the National Dam Safety Policy (PNSB), while the pit does not. The adoption of GISTM represents a significant legacy for the developer in question, and directly impacts its reputation, sustainability and operational safety. The benefits of implementing the Standard will be: improved safety and disaster prevention; strengthened governance and transparency; respect for human rights and community involvement; sustainability and environmental protection, as well as significant gains in reputation, facilitating access to international markets. All these factors corroborate that implementing the Standard is a competitive and strategic differentiator for mining companies seeking to operate in a safer and more sustainable way.

Resumen en Inglés:

Abstract The decommissioning of mining operations presents multidimensional complexities and potential environmental, socioeconomic, and reputational liabilities. Conventional risk assessment methodologies in this context often lack integrated approaches and adequate parameterization for comparability between different scenarios. This article proposes the development and application of the Closure Risk Index (CRI), an innovative methodology that integrates concepts adapted from Failure Mode and Effects Analysis (FMEA), Probable Maximum Precipitation (PMP), and Human Development Index (HDI). The methodological systematization included: identification of potential failure modes; parameterized risk characterization; adaptation of PMP principles to estimate maximum potential impacts; incorporation of HDI concepts for normalization of risk indicators; and matrix integration for calculating the CRI as a weighted average of normalized indicators. The application of the model in a case study at the Córrego do Meio Mining Group demonstrated its effectiveness in hierarchizing risks and comparing alternative scenarios, revealing that critical risks were associated with water contamination and social-community impacts. Analysis of risk matrices demonstrated the general reduction of risk levels after implementing control measures. The CRI model proved to be a robust and transparent tool for strategic planning of mine closure, allowing prioritization of mitigating measures and optimization of resource allocation. Its applicability transcends the case study, constituting a significant methodological contribution to sustainability in the mineral sector.