EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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15 resultados
Resultados da Pesquisa
Item Automatic detection of corrosion in large-scale industrial buildings based on artificial intelligence and unmanned aerial vehicles.(2023) Lemos, Rafael; Cabral, Rafael; Ribeiro, Diogo; Santos, Ricardo; Alves, Vinicius Nicchio; Dias, AndréIn recent years, Artificial Intelligence (AI) provided essential tools to enhance the productivity of activities related to civil engineering, particularly in design, construction, and maintenance. In this framework, the present work proposes a novel AI computer vision methodology for automatically identifying the corrosion phenomenon on roofing systems of large-scale industrial buildings. The proposed method can be incorporated into computational packages for easier integration by the industry to enhance the inspection activities’ performance. For this purpose, a dedicated image database with more than 8k high-resolution aerial images was developed for supervised training. An Unmanned Aerial Vehicle (UAV) was used to acquire remote georeferenced images safely and efficiently. The corrosion anomalies were manually annotated using a segmentation strategy summing up 18,381 instances. These anomalies were identified through instance segmentation using the Mask based Region-Convolution Neural Network (Mask R-CNN) framework adjusted to the created dataset. Some adjustments were performed to enhance the performance of the classification model, particularly defining an adequate input image size, data augmentation strategy, Intersection over a Union (IoU) threshold during training, and type of backbone network. The inferences show promising results, with correct detections even under complex backgrounds, poor illumination conditions, and instances of significantly reduced dimensions. Furthermore, in scenarios without a roofing system, the model proved reliable, not producing any false positive occurrences. The best model achieved metrics’ values equal to 65.1% for the bounding box detection Average Precision (AP) and 59.2% for the mask AP, considering an IoU of 50%. Regarding classification metrics, the precision and recall were equal to 85.8% and 84.0%, respectively. The developed methodology proved to be extremely valuable for guiding infrastructure managers in taking physically informed decisions based on the real assets condition.Item Numerical and theoretical investigation of bolted sleeve connections with rectangular hollow sections.(2023) Oliveira, Matheus Miranda de; Amparo, Lucas Roquete; Tanus, Lucas da Silva; Monteiro, Isabella Estevão; Alves, Vinicius Nicchio; Sarmanho, Arlene Maria CunhaThis article presents a theoretical and numerical study of bolted sleeve connections with rectangular hollow sections (RHS) under axial tension and compression. The geometric form of a hollow section provides resistance for high axial loads, torsion and combines effects, spreading its utilization in truss systems. In this context, the sleeve connections proposed explore these characteristics of RHS and offer an attractive aesthetic appearance for the continuity of elements. The bolted sleeve connection with RHS is formed by two outer tubes connected by an inner tube and staggered bolts. Herein, a parametric study was developed for identification of the failure modes in the connection. Finite element models with different geometric parameters and number of bolts were created in commercial software. The width, depth and thickness of RHS tubes and diameter of bolts were variated. In the theoretical/numerical/ parametric results, the yielding gross section failure, the fracture through the effective net area failure and the bearing failure were observed. These failure modes occurred in both outer and inner tubes. The load results were compared to determine the resistance capacity of sleeve connections. The theoretical formulations were evaluated for representation of the ultimate load of the failure modes.Item Design of sleeve connections with cross-bolted on circular hollow sections under axial tension.(2022) Amparo, Lucas Roquete; Oliveira, Matheus Miranda de; Sarmanho, Arlene Maria Cunha; Xavier, Ellen Martins; Alves, Vinicius NicchioThis present paper evaluates the behavior and resistance capacity of cross-bolted sleeve connections with circular hollow sections (CHS) under axial tension. This connection allows harmony in the continuity of the tubes. The cross-bolted sleeve connection with CHS comprises outer tubes connected by an inner tube and cross bolts at 90◦. Therefore, an experimental, numerical, and parametric study was conducted to identify the connection’s possible failure modes. The experimental tests were developed with cross bolts at 90◦, which enable the identification of fracture through the effective net area, bearing failure, and bolt bending. Finite element (FE) numerical models were developed and validated by Ansys software to provide a parametric study. Thus, such a parametric study was carried out using the verified FE models. The failure modes were evaluated considering the effects of geometric properties concerning their type and location; a relative slenderness limit for the design of connections was proposed, directing the occurrence of a failure in the outer tube. Normative prescriptions do not foresee the design of the sleeve. Therefore, new formulation methods for estimating the strength were proposed, allowing the design of these connections.Item Simulation of the dynamic behavior of a centenary metallic bridge under metro traffic actions based on advanced interaction models.(2021) Ribeiro, Diogo; Costa, Bruno J. Afonso; Cruz, Luís; Oliveira, Matheus Miranda de; Alves, Vinicius Nicchio; Montenegro, Pedro Aires; Calçada, RuiThe present work focuses on the evaluation of the dynamic behavior of a centenary steel arch bridge, located in Portugal, under light railway tra±c loads. This works aims to assess the dynamic behavior of the bridge subjected to an alternative type of railway vehicle, more speci ̄cally, a typical underground vehicle that is currently in service in the Lisbon Metro. The dynamic response of the system has been evaluated using two distinct methodologies, namely a moving loads model and a vehicle–bridge interaction model. To achieve this goal, ̄nite element (FE) models from both the bridge and the vehicle have been developed and a comprehensive study has been carried to evaluate the in°uence of distinct factors in the dynamic response of the bridge–train system, namely the methodology used to assess the dynamic response, the location of the response reference point in the deck, the train speed and the vehicle con ̄guration (single or double vehicle). Moreover, both the tra±c safety, passenger comfort and pedestrian comfort have also been evaluated using normative criteria based on acceleration responses. The results shown that the normative limits related to tra±c safety and passenger comfort were never exceeded in any condition analyzed in the study. However, the pedestrian comfort was jeopardized when the train speed exceeded 20 km/h.Item Effect of chord length on CHS-RHS T-joints with slender sections.(2021) Pereira, Daniel José Rocha; Guerra, Messias Júnio Lopes; Sarmanho, Arlene Maria Cunha; Silva Neto, João Batista da; Nunes, Gabriel Vieira; Alves, Vinicius NicchioThe chord length is an essential geometric property that must be defined in the analysis of isolated joints composed of hollow steel sections, as well as the boundary conditions of the test. The analysis of these parameters’ effect on the behavior of joints has been addressed by other studies, mostly with joints between circular hollow sec- tions with compact or semi-compact cross-sections. Recent research about tubular joints has addressed cases with slender sections, where the design of joints containing these sections is still in development. In this context, this study aimed to evaluate the effect of the chord length in the behavior of T-joints between circular hollow section braces and slender rectangular hollow section chords through experimental tests and a numerical study considering the application of axial compression at the braces. The joint behavior was examined through the load-strain and load-deformation curves and the von Mises stress distribution, which allowed the failure mode's determination and the joint resistance value. Chord face failure was observed in the prototypes. It was concluded that a minimum chord length of 0.6m would be the adequate value for the study of the T-joints containing the geometric properties used in this study, which would be equivalent to a chord length five times higher than the width of the cross- section (5b0).Item Bearing failure in bolted sleeve connections with circular hollow sections under compression.(2020) Oliveira, Matheus Miranda de; Amparo, Lucas Roquete; Sarmanho, Arlene Maria Cunha; Pereira, Daniel José Rocha; Alves, Vinicius NicchioThis article analyzes sleeve connections between circular hollow sections. This type of connection is composed of two tubes connected by bolts to an inner tube with a smaller diameter, and explores the efficiency, aesthetics and resistance of hollow sections subjected to tension and compression. In previous researches, sleeve connec- tions with aligned and crossed bolt dispositions and under axial tension were studied. Herein, the behavior of sleeve connections with aligned bolts and under compression was analyzed. A model to represent the connection using the finite element method was developed, which allowed a numerical analysis with geometric property varia- tions. In the numerical/parametric results, bearing failure was observed in all cases, either in the outer or inner tube. Limiting the number of bolts to 6 and considering that connections have a lower outer thickness than the inner tube, a formulation was proposed to determine the ultimate bearing capacity of sleeve connections under com- pression and with bearing failure.Item Model-based damage identification of railway bridges using genetic algorithms.(2020) Alves, Vinicius Nicchio; Oliveira, Matheus Miranda de; Ribeiro, Diogo; Calçada, Rui; Cury, Alexandre AbrahãoThe assessment of structural integrity via numerical model updating has been drawing attention in several areas of engineering over the last years. Basically, it consists in an optimization process based on the minimization of the residuals between measured and estimated numerical re- sponses. In such methodologies, several factors influence the success of both localization and quantification of structural damage, such as: the damage features used in the formulation of the objective function, the optimization algorithm and the adopted updating parameters. Many ex- isting studies using these methods are applied to simple structural systems, e.g., beams, frames and trusses. However, few studies applied to large and complex structures are found in the lit- erature. In this context, this work proposes to assess the performance of a genetic algorithm- based approach applied to two case studies. The first case refers to a two-dimensional model of a hypothetical railway bridge, where the efficiency and robustness of five different indicators are assessed considering three damage scenarios. In the second case, a real railway bridge is con- sidered. The results obtained show that the proposed approach is able to detect, locate and quantify multiple damage with several updating parameters and few target responses.Item Behavior and design formulation of steel CHS with sleeve connections.(2021) Amparo, Lucas Roquete; Oliveira, Matheus Miranda de; Sarmanho, Arlene Maria Cunha; Xavier, Ellen Martins; Alves, Vinicius NicchioStructures with tubular profiles gain space in civil construction due to their excellent response under tension, compression, and torsion. They are widely used in structural trusses, especially in large lengths. The profiles have a limited size due to the manufacturing and transport process. Therefore, there is a need to use some mechanism to perform the joint of profiles and obtain the desired length. This work aims to develop a new type of bar splice in circular hollow section (CHS) connection called sleeve connection, composed of two tubes connected with another smaller diameter tube with bolts arranged in a line (staggered bolts). This research presents an experimental, numerical, and parametric study of sleeve connection in CHS under centric axial tension. A numerical model was developed using the finite element method (FEM) considering sleeve connection with staggered bolts. From the numerical results, it was possible to analyze the connection behavior and failure modes: yielding gross cross-section, fracture through the effective net area, bolt shear failure, bearing failure of the plate, and bolt bending failure. This way, formulations were proposed to predict the sleeve connections' behavior with staggered bolts as a function of the failure modes.Item Experimental and numerical assessment of CHS-RHS T-joints with chords subjected to axial tensile forces.(2021) Silva Neto, João Batista da; Nunes, Gabriel Vieira; Sarmanho, Arlene Maria Cunha; Pereira, Daniel José Rocha; Guerra, Messias Júnio Lopes; Alves, Vinicius NicchioHollow steel sections are widely used in the construction industry due to their mechanical properties. Joints used in these structures are the subject of research because of their singular and critical behavior. Joints containing chords with more slender cross-sections and axially loaded are still a challenge for design, especially in joints with circular hollow sections (CHS) in the braces and rectangular hollow sections (RHS) in the chords. In this context, this work aimed to study joints formed by a combination of CHS braces subjected to compression loads and RHS chords axially loaded with tension, welded as T-joints. Experimental tests, a numerical model using finite elements, and a parametric analysis were developed. A new equation for the chord stress function was proposed, including joints containing chords with semi-compact sections in tension. The joint resistance values obtained through the numerical models were compared with the equations from ISO 14346:2013 and with the proposed equation. It was observed that, for the numerical models with geometric properties inside the normative validity ranges of ISO 14346:2013, the mean rate of analytical by numerical joint resistance results was equal to 68%, using either the normative or the proposed equation. In the same way, for models outside the current validity ranges, either the proposed equation or the modified equation from ISO 14346:2013 could be used to design CHS-RHS T-joints with the geometric and material properties analyzed.Item Bearing failure in bolted sleeve connections with circular hollow sections under compression.(2020) Oliveira, Matheus Miranda de; Amparo, Lucas Roquete; Sarmanho, Arlene Maria Cunha; Pereira, Daniel José Rocha; Alves, Vinicius NicchioThis article analyzes sleeve connections between circular hollow sections. This type of connection is composed of two tubes connected by bolts to an inner tube with a smaller diameter, and explores the efficiency, aesthetics and resistance of hollow sections subjected to tension and compression. In previous researches, sleeve connections with aligned and crossed bolt dispositions and under axial tension were studied. Herein, the behavior of sleeve connections with aligned bolts and under compression was analyzed. A model to represent the connection using the finite element method was developed, which allowed a numerical analysis with geometric property variations. In the numerical/parametric results, bearing failure was observed in all cases, either in the outer or inner tube. Limiting the number of bolts to 6 and considering that connections have a lower outer thickness than the inner tube, a formulation was proposed to determine the ultimate bearing capacity of sleeve connections under compression and with bearing failure.