Abstract:This study aims to develop a final design for the Northwest Slope of the Cuajone Mine (Peru) by calculating the factor of safety (FS) using finite element methods, proposing that this method enables a more accurate assessment of slope stability. The methodology included geological and geotechnical characterization of the slope through field mapping, sample analysis, and laboratory testing. A three-dimensional model was created using Phase2 software to simulate the interaction between slope geometry and operational conditions, conducting a stability analysis under different loads and disturbances. The results indicate that the finite element method detailedly evaluated the safety factor and the inter-ramp angle (IRA). In the southern zone (section A-A'), it was determined that an IRA of 43° generates an FS of 1.1. In the northern zone (section B-B'), an IRA of 38° is recommended to achieve an FS of 1.57. These findings are essential for ensuring operational safety and efficiency at the mine, as an inadequate slope design could compromise infrastructure integrity and worker safety. Advanced methods, such as finite element analysis and considering factors like IRA and disturbance factors, allow for a precise slope stability assessment and effective stabilization measures to manage risks and develop specific reinforcement solutions according to the slope's geotechnical configuration.

Resumen: El objetivo de este estudio es desarrollar un diseño final para el Talud Noroeste de la Mina Cuajone (Perú) utilizando el cálculo del factor de seguridad (FS) mediante métodos de elementos finitos, planteando que este método permite una evaluación más precisa de la estabilidad del talud. La metodología incluyo la caracterización geológica y geotécnica del talud mediante mapeo de campo, análisis de muestras y pruebas de laboratorio. Se creo un modelo tridimensional usando el software Phase2 para simular la interacción entre la geometría del talud y las condiciones operativas, realizando un análisis de estabilidad bajo diferentes cargas y perturbaciones. Los resultados indican que el método de elementos finitos proporciono una evaluación detallada del factor de seguridad y del ángulo interrampa (IRA). En la zona sur (sección A-A'), se determina que un IRA de 43° genera un FS de 1.1. En la zona norte (sección B-B'), se recomienda un IRA de 38° para lograr un FS de 1.57. Los hallazgos son fundamentales para garantizar la seguridad y eficiencia operativa en la mina, ya que un diseño de talud inadecuado podría comprometer la integridad de la infraestructura y la seguridad de los trabajadores. La aplicación de métodos avanzados como el análisis de elementos finitos y la consideración de factores como el IRA y el factor de perturbación permite una evaluación precisa de la estabilidad del talud y la implementación de medidas de estabilización efectivas para gestionar los riesgos y desarrollar soluciones de refuerzo específicas según la configuración geotécnica del talud.

Abstract The paper addresses the stability analysis of a circular tunnel face driven by a pressurized shield by means of the limit analysis kinematic approach implemented in the context of the Mohr-Coulomb strength condition. Emphasis is given to the assessment of the effects of seismic loading on the value of face support pressure that is required to prevent failure. The approach relies upon the pseudo-static method to model the destabilizing effects induced by the inertial forces associated with the passage of seismic waves in the ground. Rigorous limit analysis solutions for the limit face supporting pressure are derived from the analytical implementation of 3D and 2D failure mechanisms specifically devised for dealing with such a stability analysis problem. Indeed, original analytical expressions are provided and allow the evaluation of the pressure stabilizing the tunnel face. The accuracy of the approach predictions is assessed by comparison with available experimental and analytical results as well as with 2D finite element solutions. The influence of some relevant problem parameters in the context of tunnel face stability analysis is finally investigated, thus providing some preliminary guidelines for practical use in tunnel engineering.

Resumo A corrosão em estruturas de concreto armado tem se tornado uma preocupação crescente, principalmente devido aos fatores relacionados às mudanças climáticas, como o aumento dos níveis de dióxido de carbono, mudanças de temperatura e precipitação. A fim de aplicar essas mudanças a estrutura, avaliações regionais são essenciais devido aos impactos ambientais variados. Este estudo examina a corrosão no Brasil, utilizando os níveis urbanos de CO2, utilizando a NBR 6118 (2023) para prever a despassivação, as fissuras iniciais e a falha devido a deslocamentos excessivos (Estados Limites de Serviço). Os resultados indicam uma probabilidade de despassivação de 50% em 13 anos para um cobrimento de 2,5 cm no pior cenário. Além disso, a probabilidade de falha por deslocamento excessivo sofre uma influência significativamente do diâmetro das armaduras, com um aumento de 311% ao longo de 45 anos ao usar um diâmetro de 5 mm em vez de 10 mm. Embora preliminar, este estudo também serve como um alerta para as construções futura e existentes, destacando a necessidade de pesquisas contínuas.

Abstract Corrosion in reinforced concrete structures has become a growing concern, primarily due to climate change-related factors such as the rise of carbon dioxide levels, temperature fluctuations, and altered precipitation patterns. To address this, regional assessments are vital due to varying environmental impacts. This study examines corrosion in Brazil, focusing on urban CO2 levels, employing NBR 6118 (2023) to predict depassivation, initial cracks, and failure due to excessive displacement (Serviceability Limit State). Results indicate a 50% depassivation probability within 13 years for a 2.5 cm concrete cover in the worst-case scenario. Additionally, the diameter of reinforcements greatly influences failure probability for excessive displacement, with a 311% increase over 45 years using a 5 mm diameter instead of 10 mm. These findings underscore the urgency of adapting construction practices to consider accelerated carbonation rates in urban environments and the need for ongoing research to refine predictive models and update construction standards accordingly.

Abstract This article focuses on numerical thermos-structural behavior evaluation of composite steel and concrete beams under fire conditions. Several models of composite beams are analyzed, changing the following parameters: steel beam, span length, load level, slab thickness, concrete and steel strength. The numerical models, validated by experimental results of other authors, were developed using the finite element method on software ANSYS and the language APDL. It was observed that the structural load level is the main parameter that affects the structural behavior of composite steel and concrete beams under fire conditions.

Abstract This paper presents analysis and discussion of an urban vertical excavation, with the soil nailing technique, in fine-grained soils with high plasticity. The excavation was numerically evaluated using finite element analysis (FEA) using a 3D finite element model (FEM). Several field and laboratory soil investigations were conducted, interpreted and used in the FEA. The FEM model was calibrated using instrumentation and monitoring results during the soil nailing construction. Analyses were conducted focusing in horizontal displacements, nail pullout strength, nail tensile load, soil stress state, and tensile load at the nail head. The results showed that the behavior of the soil nailing retaining wall in fine-grained soils differs significantly from what is typically reported in the literature for non-cohesive soils. The high apparent cohesion of the fine-grained soil resulted in good performance, with reduced horizontal displacements on the face and lower tensile loads in the nails and at their head.

ABSTRACT This study explores the fastening behavior of punctured double-double (DD) laminates, a superior alternative to traditional quadaxial laminates (QUAD) due to improved structural efficiency and lower maintenance. However, the effect of various cutout shapes and sizes on DD laminates’ fastening performance is still unexplored. This research examines optimal ply orientations, rotation angles, and fastening loads for DD laminates with circular, elliptical, and combined-shape cutouts to assess their impact on stability. A hybrid optimization method using an artificial neural network (ANN) and genetic algorithm (GA) is developed to predict maximum buckling loads, avoiding time-intensive finite element analysis (FEA). The ANN models, with R2 values of 0.994 to 0.999, show excellent performance. The best model for circular cutouts achieved R2 is 0.999 with a mean absolute error of 0.0059. Results indicate that elliptical and combined-shape cutouts significantly influence ply angles and buckling loads. Combined-shape cutouts offer superior stability as size increases, with buckling load improvements of 15% over circular cutouts. This study highlights the potential of ANN-GA techniques for optimizing DD laminate designs and improving structural performance.

Abstract The objective of this research is to present practical solutions for improving structural performance of thin-walled conic polygonal monopoles. The analysis encompasses computational simulations, analytical evaluation, and structural verification of reinforcements for openings and longitudinal folded stiffeners of flat walls. A benchmarked solution is derived from a design involving a 20-sided cold-formed steel polygonal section employed to support telecommunication antennas at a height of 40 meters. The structural verification is performed under the influence of wind loads, with particular attention to the commonly reported basic gust wind speed in Brazil. The conducted analysis encompasses: (i) wind-induced static equivalent dynamic behavior, (ii) parametric elastic buckling analysis, (iii) non-linear finite element analysis of reinforced openings, and (iv) direct strength method (DSM) performance evaluation of stiffened polygonal cross-sections. The importance of combining tailored numerical tools such as the finite strip and finite element methods, as well as wind-induced behavior, is demonstrated through the structural analysis results. In essence, the study's findings reveal the previously overlooked local-distortional buckling interaction in current design guidelines. Moreover, the research demonstrates that incorporating reinforcements and longitudinal stiffeners significantly enhances the flexural capacity of slender structures. Notably, the adoption of a single 4-fold (trapezoid) stiffener shape, per polygonal wall, emerges as a promising effective solution for enhancing the overall flexural capacity. Further full scale experimental structural tests and computational fluid dynamics should be considered for advanced structural analysis and improved design.

Abstract A numerical investigation is performed in this work to evaluate the influence of controlled spoilers on pressure mitigation over low-rise building roofs. Considering that low-rise buildings are susceptible to severe damages caused by wind action, spoilers are utilized along the roof windward edges to reduce the aerodynamic load, which are controlled using PID control techniques. Numerical simulations are carried out using a semi-implicit Characteristic-based Split algorithm, where linear tetrahedral finite elements are employed for spatial discretization in a standard Galerkin procedure. Turbulence modeling is performed using Large Eddy Simulation and the flow fundamental equations are written considering isothermal and incompressible conditions in arbitrary Lagrangian-Eulerian kinematical description to consider the spoiler angular motion. Two and three-dimensional simulations are carried out using a low-rise building model, where the influence of controlled roof spoilers is evaluated. Wind tunnel predictions are utilized to validate the numerical formulation proposed here.

Abstract This work is concerned with the simulation of pavement behavior using the Finite Element Method (FEM) with the goal of predicting the appearance of cracks during its useful life. The developed method can help maintenance planning towards providing users with safety and comfort. The effects of both traffic loads and temperature variations are considered. Artificial Intelligence (AI) tools are adopted to reduce the time necessary for the interpretation of simulation results for the development of an efficient pavement management system. The developed rigid pavement management system uses the Artificial Neural Networks (ANN) technique for the prediction of both pavement response to fatigue accumulation and the behavior of the modeled pavement with a high degree of precision. The networks showed 4.5% and 3.6% square errors for positive and negative temperature gradients and 95% and 97% data correlation, respectively. The SR stress ratio obtained by the developed ABAQUS model is 0.614 and the value provided by the pavement management system is 0.648. The developed methodology was applied to a section of highway BR-101/NE, between the states of Paraiba PR and Pernambuco PE, in Brazil. Comparing the results with the limits provided by National Cooperative Highway Research Program (NCHRP) for traffic in the study, this pavement would require maintenance every six months. The maximum values of tensile stress due to bending were obtained by combining the positive temperature gradient with the traffic axis load at the edge during the summer months (December to March) due to the higher thermal gradient values.

Resumo Este trabalho foca-se na simulação do comportamento de pavimentos utilizando o Método de Elementos Finitos (MEF) com o objetivo de prever o aparecimento das fissuras durante sua vida útil. O método desenvolvido pode ajudar no planejamento da manutenção no sentido de proporcionar segurança e conforto aos usuários. São considerados os efeitos das cargas de tráfego e das variações de temperatura. Ferramentas de inteligência artificial (IA) são adotadas para reduzir o tempo necessário para a interpretação dos resultados das simulações para o desenvolvimento de um sistema eficiente de gestão de pavimentos. O sistema de gerenciamento de pavimentos rígidos desenvolvido utiliza a técnica de Redes Neurais Artificiais (RNA) para a previsão da resposta do pavimento ao acumulo de fadiga e do comportamento do pavimento modelado com alto grau de precisão. As redes apresentaram erros quadrados de 4.5% e 3.6% para gradientes de temperatura positivos e negativos e correlação de dados de 95% e 97%, respectivamente. O índice de tensão SR obtido pelo modelo desenvolvido em ABAQUS é 0.614 e o valor fornecido pelo sistema de gerenciamento de pavimentos é 0.648. A metodologia desenvolvida foi aplicada a um trecho da rodovia BR-101/NE, entre os estados da Paraíba PR e Pernambuco PE, no Brasil. Comparando os resultados com os limites previstos pelo Programa Cooperativo Nacional de Pesquisa Rodoviária (NCHRP) para o tráfego do trecho de estudo, este pavimento necessitaria de manutenção semestral. Os valores máximos de tensão de tração por flexão foram obtidos combinando o gradiente positivo de temperatura com a carga do eixo de tráfego na borda durante os meses de verão (dezembro a março) devido aos maiores valores de gradiente térmico.

Abstract Aircraft operators often modify aircraft configurations, install new equipment, and alter airframes to accommodate this equipment, leading to operations in flight envelopes different from original design profile. These modifications necessitate airframe structural assessments, which typically require comprehensive aircraft design data, often unavailable to operators. This study aims to develop and validate a practical method for finite element analysis (FEA) of aircraft structures in the absence of this detailed design data. Focusing on a case study involving structural analysis of an aircraft wing, this study presents assumptions and idealizations used to develop 2.5D finite element (FE) model of the wing. Fidelity of this model is established by comparing FE analysis results with experimental data. Key validation metrics include reaction forces, load distribution at wing-fuselage attachments, and deformation at reference points on the wing under design load. Comparison between FE analysis and experimental results is carried out to substantiates accuracy of these geometric simplifications and idealizations of load-carrying behaviour of structural members. Therefore, practicality of these idealizations in absence of design data is demonstrated. This study offers a novel approach for structural assessments of aircraft without relying on proprietary design data. The validated method enhances capability of aircraft operators to perform effective structural analyses, thereby extending service life of aircraft with continued airworthiness

Resumen Los operadores de aeronaves a menudo modifican las configuraciones de las aeronaves, instalan nuevos equipos y modifican las estructuras de los aviones para acomodar estos equipos, lo que lleva a operaciones en envolventes de vuelo diferentes al perfil de diseño original. Estas modificaciones requieren evaluaciones estructurales de la estructura del avión, que normalmente requieren datos completos de diseño de la aeronave, que a menudo no están disponibles para los operadores. Este estudio tiene como objetivo desarrollar y validar un método práctico para el análisis de elementos finitos (FEA) de estructuras de aeronaves en ausencia de estos datos de diseño detallados. Centrándose en un estudio de caso que involucra el análisis estructural del ala de un avión, este estudio presenta suposiciones e idealizaciones utilizadas para desarrollar un modelo de elementos finitos (FE) 2.5D del ala. La fidelidad de este modelo se establece comparando los resultados del análisis FE con datos experimentales. Las métricas clave de validación incluyen fuerzas de reacción, distribución de carga en las uniones ala-fuselaje y deformación en puntos de referencia en el ala bajo carga de diseño. Se lleva a cabo una comparación entre el análisis EF y los resultados experimentales para corroborar la precisión de estas simplificaciones geométricas e idealizaciones del comportamiento de carga de los miembros estructurales. Por lo tanto, se demuestra la practicidad de estas idealizaciones en ausencia de datos de diseño. Este estudio ofrece un enfoque novedoso para evaluaciones estructurales de aeronaves sin depender de datos de diseño patentados. El método validado mejora la capacidad de los operadores de aeronaves para realizar análisis estructurales efectivos, extendiendo así la vida útil de las aeronaves con aeronavegabilidad continua.

Abstract Cross-laminated timber (CLT) is a product used in the form of panels that presents as a challenge the simultaneous consideration of the orthogonal arrangement of lamellae with the orthotropic behaviour of wood. In order to evaluate the mechanical behaviour of CLT panels in bending, it is possible to resort to plate theories, numerical and simplified methods. Within this context, this paper proposed to analyse the normal and shear stresses, as well the vertical displacements in a given CLT panel through three plate theories, three simplified methods, Finite Element Method and a proposed analytical method. For the study, a five-layered CLT panel with lamellae thickness of 20 mm, at first, with sides of 3 m. Afterward, parametric variations of the ratio between spans were also stipulated. The structural analysis permitted to obtain the stresses and the vertical displacements for the aforementioned panel. The parametric variations carried out made it possible to verify the sensitivity of the proposed panel in terms of stresses and vertical displacements against variations in the ratio between the panel’s plan dimensions.

Resumo Amadeira lamelada colada cruzada (MLCC) é um produto empregado na forma de painéis que apresenta como desafio a consideração conjunta da disposição ortogonal de lamelas com o comportamento ortotrópico da madeira. Para avaliar o comportamento mecânico de painéis de MLCC, em flexão simples, é possível recorrer a teorias de placas, métodos numéricos e simplificados. Dentro desse contexto, este trabalho se propôs a analisar as tensões, normais e de cisalhamento, bem como os deslocamentos verticais em um dado painel de MLCC por meio de três teorias de placas, três métodos simplificados, método dos elementos finitos e um método analítico proposto. Para o estudo, foi considerado um painel de MLCC com cinco camadas de 20 mm de espessura, inicialmente quadrado com lados de 3 m, sendo, posteriormente, realizadas análises paramétricas da razão entre as dimensões em planta. Com as análises estruturais, foi possível a obtenção das tensões, bem como os deslocamentos verticais do referido painel. As análises paramétricas realizadas permitiram averiguar a sensibilidade do painel de MLCC proposto, em termos de tensões e deslocamentos verticais, frente às variações da razão entre as dimensões em planta do painel.

Abstract Glued laminated timber (glulam) beams manufactured with glued steel bars can achieve improvements in their mechanical performance and the effects of the arrangement of steel bars in the cross-section are of technological interest. This study aimed to evaluate the mechanical behavior of beams with symmetric reinforcements (compression and tension zones) and beams with asymmetric reinforcements (compression zone), under loading imposed at the serviceability limit state. To achieve this goal, glulam beams with reinforcement ratios ranging from 0.5% to 4% were simulated using the finite element method. When compared to the nonreinforced beams it was found for the deflections that the asymmetric reinforcements provided reductions of up to 31.5% and the cases with symmetric reinforcements were more efficient, with deflection reductions of up to 45%. In comparison to the symmetric arrangement of the bars, the asymmetric distribution provided a reduction of up to 10.5% in the normal stress of the glulam beam compression zone. The asymmetrically arranged reinforcement effectively contributed to increasing the stiffness of the beam and was more efficient in reducing normal stresses in the compressive zone, thus preventing the initial yielding of the wood.

Resumo As vigas de madeira lamelada colada (MLC) fabricadas com barras de aço coladas podem alcançar melhorias no seu desempenho mecânico e os efeitos da disposição das barras de aço na seção transversal são de interesse tecnológico. Esta pesquisa objetivou a avaliação do comportamento mecânico de vigas com reforços simétricos (zonas de compressão e de tração) e vigas com reforços assimétricos (zona de compressão), sob condições de carregamento impostas ao estado limite de serviço. Portanto, vigas de MLC com taxas de reforço variando de 0,5% a 4% foram simuladas pelo método dos elementos finitos. Em relação às vigas sem reforços, as flechas das vigas reforçadas assimetricamente resultaram até 31,5% menores e, as vigas com reforços simétricos foram mais eficientes, cuja redução das flechas foi de até 45%. Comparativamente ao arranjo simétrico das barras, a distribuição assimétrica proporcionou uma redução de até 10,5% na tensão normal da zona de compressão da MLC. A armadura disposta de forma assimétrica contribuiu efetivamente para o aumento da rigidez da viga e foi mais eficiente na redução das tensões normais na zona compressiva, evitando com isso o escoamento inicial da madeira.

Abstract Columns are important structural elements in a building and can be reinforced to increase their capacity. Reinforcement by bonding Fiber Reinforced Polymers (FRP) is attractive because it is easy to apply and does not modify the section. This material has been used in columns for its confinement effect. However, the confinement of columns in non-circular sections is not as efficient as in circular ones. Non-circular geometries behave differently because part of the concrete is not confined. This research aims to study the behavior of rectangular concrete columns reinforced with carbon fiber mats. The aim is to evaluate the performance of rectangular columns with a section side ratio of 2 and to determine the efficiency of the reinforcement. Two groups of columns were tested, one without reinforcement and the other reinforced with a layer of mat. Numerical models were designed with the Finite Element Method (FEM) using Abaqus. The numerical model made it possible to analyze the distribution of stresses in the pillars. Experimental results of maximum force were compared with analytical predictions. The results obtained indicate the efficiency of the reinforcement by improving ductility and increasing load capacity by 30%.

Resumo Pilares são elementos estruturais de grande importância numa edificação e que durante sua vida útil podem ser submetidos a um processo de reforço para aumento da sua capacidade. O reforço com Polímeros Reforçados com Fibras (PRF) é atraente pela facilidade de aplicação e não modificação da seção. O material vem sendo utilizado em pilares pelo efeito de confinamento. Entretanto, em pilares com seções não circulares, o efeito do confinamento não é eficiente como em circulares. Em geometrias de seções não circulares, parte do concreto não fica devidamente confinado. A pesquisa busca estudar o comportamento do reforço de pilares de concreto retangulares pelo confinamento com manta de fibras de carbono. O objetivo é avaliar o desempenho e a eficiência do reforço em pilares retangulares não armados, com altura de 800 mm e relação entre os lados igual a 2. Foram ensaiados dois grupos de pilares, um sem reforço e outro reforçado. Foram idealizados modelos numéricos com o Método dos Elementos Finitos utilizando-se o Abaqus. O modelo numérico permitiu analisar a distribuição das tensões nos pilares. Os resultados experimentais de força máxima foram comparados com previsões analíticas. Os resultados obtidos indicam eficiência do reforço por meio de melhoria na ductilidade e aumento da capacidade de carga em 30%.

South Africa has two main platinum reef deposits, namely the Merensky reef and the UG2 reef. These reefs are currently mined using traditional drilling and blasting methods. Mechanized cutting could potentially enable continuous mining, which would offer significant advantages. This would require thorough understanding of the cutability of the rock. To explore this, a linear cutting machine was developed to conduct laboratory scale cutting tests. This work describes the development and commissioning of the cutting machine using sandstone, as well as subsequent characterization tests on UG2 reef samples. UG2 reef has large variability in strength on a millimeter scale. This introduces uncertainty in the test results due to added variance from one cut to the next for the same UG2 reef sample. Another problem is the variability in rock properties of the UG2 reef, when testing samples from different mines. The cutting tests led to fine fragmentation, which is known to be a significant problem for cleaning operations in underground stopes and warrants further research. A finite element method simulation of the rock cutting was conducted using ANSYS LS-DYNA and the continuous surface cap model to simulate rock cutting in the UG2 reef. It was found that it is possible to use LS-DYNA with the continuous surface cap model to model rock cutting of UG2 reef and get acceptable results, but the user must calibrate the model parameters using the experimental results. Therefore, the model is only fit for one set of cutting parameters and further work is required to generalize results.

Replacing traditional stirrups with high-strength rectangular spiral stirrups can improve the seismic performance of reinforced concrete columns. In order to study the seismic performance of high-strength spiral stirrup confined concrete columns, a validated finite element (FE) method was proposed to establish the FE model of reinforced concrete columns. Combined with the measured data of two existing specimens, parameter analysis was conducted on 19 specimens. The axial compression ratio, shear span ratio, stirrup spacing, and stirrup diameter were variable parameters. Based on a reliable model, internal stress analysis was conducted, and the influence of different variables on the seismic performance of reinforced concrete columns was revealed. The FE results suggest that, when the axial compression ratio is not greater than 0.6, the requirement of ductility greater than 3 in the Chinese Standard GB 50011-2010 can be met. The recommended shear span ratio for optimal ductility was around 4.5. The reinforcement ratio of high-strength spiral stirrups ranges from 1.0% to 2.2%. After completing the simulation of nearly 100 specimens (only calculating the ductility coefficient), a matching relationship between the axial compression ratio limit and the shear span ratio was proposed.