bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison between simplified and refined models for deflection in continuous reinforced concrete T-beams
Authors: Maria Clara Silveira Mello e Silva  , Elisabeth Junges Laure
Published: January 2025

Verification of the Serviceability Limit State for allowable displacements is a mandatory step in the design of a reinforced concrete (RC) beam. In order to proceed this verification, simplified methods recommended by Design Codes or analytical models can be employed. In these models, the variation in flexural stiffness due to the concrete cracking is the primary factor to be considered. A T cross-section beam present greater stiffness compared to a rectangular section of equal height and area. The concentration of more area at one end of the section raises questions about whether this type of section exhibits the same behavioral response as the rectangular section when applying the models for predicting deflection as indicated by Codes. In this work, a comparative study of different simplified methods and finite element (FE) models used for calculating deflections in reinforced concrete T-beams is performed. Simplified methods employed are the one recommended by Brazilian Code ABNT NBR 6118, and the Bilinear method recommended by the fib Model Code. Two FE models are adopted, in which the material nonlinearities are considered by means of moment-curvature diagrams, these based on the simplified methods. The deflections obtained by the different models are compared for several examples of continuous RC T-beams at service, by varying the beam geometry and the reinforcing ratio. The results are analyzed for short-term deflections and long-term deflections. In the end of this work, differences between the models are pointed and recommendations regarding the use of then are drawn for this specific section type.
Computational Modeling for Evaluation of Plane Frames in Seismic Zones
Authors: Wydem Lucas Elias dos Santos  , Eduardo Nobre Lages
Published: January 2025

Seismic events, also known as earthquakes, induce dynamic effects on structures due to the abrupt movement of the ground, potentially leading these structures to collapse. These earthquakes are often associated with the movement of tectonic plates and primarily occur in regions near the edges of these plates, where interactions are more intense. However, there exists a specific category of earthquakes called induced seismic events, which are triggered by human activities such as mining, natural resource extraction, and fluid injection into the ground. There has been an increase in the occurrence of these earthquakes in some countries, raising concerns among authorities, especially in urban areas. In this context, our work aims to present a computer program for the dynamic analysis of plane frames, focusing on the structural behavior of such frames under the influence of seismic events. We consider seismic actions as stipulated in the Brazilian standard NBR 15421/23, as well as real induced earthquakes. The results obtained are essential for understanding the behavior of the analyzed structures and are necessary to ensure proper structural design, providing greater safety when these structures are subjected to this type of action.
Effect of proof loading on the fatigue life of mooring lines
Authors: Fábio José Coutinho da Silva Filho  , Michele Agra de Lemos Martins  , Evilly Raquel Henrique da Silveira  , Eduardo Nobre Lages  , Mauro Costa de Oliveira
Published: January 2025

The oil and gas production sector has experienced substantial expansion in recent decades, playing a crucial role in the global economy. To enhance productive efficiency, several extraction operations are carried out on offshore floating platforms over deep waters, which require advanced mooring system technologies to maintain their positional stability. These systems are exposed to cyclic loads throughout their operation and must be properly designed to withstand fatigue. However, recent incidents of premature failures in mooring lines have revealed a new type of fatigue failure in mooring chain links, induced by mechanisms entitled Out-of-Plane Bending (OPB) and In-Plane Bending (IPB), characterized by fatigue phenomena due to moments out of the plane of the link and in the plane of the link. The origin of these bending mechanisms is related to the manufacturing process of the moorings, during which proof loads of approximately 65% to 80% of the Minimum Breaking Load (MBL) are applied, as recommended by technical standards to extend the moorings lifetime. This process, however, causes plastic deformations that restrict sliding movement between adjacent links, resulting, along with friction, in significant bending stresses in the links. In this context, various studies have shown that parameters such as operational tension, link diameter, friction coefficient, and the level of proof loading significantly influence the incidence of fatigue damage in mooring lines. Therefore, the present study proposes to conduct a parametric analysis through finite element simulations, focusing on the variation of the proof loading level to assess its effects on parameters directly related to fatigue calculation and, consequently, the lifetime of mooring lines, such as stress concentration factors, OPB angle variation, OPB moment, among others.
Effect of repair factors on multi-level optimization of maintenance planning for corroded pipelines considering different failure modes
Authors: Luam Sena Acosta  , Álamo Ditarso Sousa Pessoa  , Savanna Cristina Medeiros D'Aguiar  , Paulo Fernando Silva Sousa  , Silvana Maria Bastos Afonso da Silva
Published: January 2025

The use of pipelines for transporting fluids is essential and has been growingsignificantly in the oil and gas industry. Although pipelines are one of the safestmethods to transport these materials, it is necessary to consider the risks of failures inthe design, as such incidents can cause considerable damage to the population, theenvironment, and the infrastructure. In this context, the aging of the pipeline networkhas been extensively studied, and corrosion is one of the main concerns regardingstructural integrity. Therefore, adequate maintenance planning is essential to ensure thesafety and cost-effectiveness of the sector, as effective pipeline integrity managementcan reduce expenses and maintain safety standards throughout the operational life of thepipeline. In this scenario, inspection and maintenance planning research has becomeincreasingly relevant; recent studies have utilized reliability analysis through MonteCarlo simulations to define optimal maintenance schedules for corroded pipelines,aiming to minimize operational costs associated with pipeline management. This paperinvestigates the influence of repair factors on the estimated total costs of inspectionschedules optimized for a given number of inspections, considering only one failuremode and the combination of these (small leak, burst, and rupture). For this, acombination of methodologies already validated and presented in previous works isused, in which a multilevel optimization is carried out by predefining an upper limit forthe maximum failure probability, which will act as a constraint on the optimizationproblem. The reliability analysis will be performed using Monte Carlo simulations,which are commonly used in the literature. Finally, preliminary results indicated that thefailure mode strongly influences the final cost, so the results considering only onefailure mode are expected to differ considerably.
Finite element method applied to plane frames
Authors: Filipe Matheus dos Santos Oliveira  , Felipe Alexander Vargas Bazán  , Marina Colins Micenas  , Paulo César de Oliveira Queiroz  , George Fernandes Azevedo
Published: January 2025

The calculation of displacements and forces in structural models is of great relevance in structural design and provides information about the behavior of the structure under different loading conditions. Due to the complexity of real problems and the demands of the production sector, the solution of a structural model becomes unfeasible without the aid of computational tools. The direct stiffness method, also known as matrix structural analysis, can be considered as a particular case of the finite element method. This article presents a computer software for structural analysis of plane frames using the direct stiffness method. The software considers the presence of hinged nodes and elastic supports in the structural model. The computational code was developed in Python language. Excel files are used as data input and output. Results include information such as nodal displacements, internal forces, and support reactions in the structure. Variations of internal forces along the frame axis, i.e. internal force diagrams, are presented in graphical manner. The influence of considering rigid or elastic supports on the results is investigated in the article.
HOOP: a Python software for homogenization of multiphase composite materials using object-oriented architecture
Authors: Rodrigo Mero Sarmento da Silva  , Carlos André Dos Santos Lima  , Leonardo Melo de Medeiros
Published: January 2025

HOOP (Homogenization Object-Oriented Programming) is a Python software package designed for efficient and flexible mean-field micromechanical analysis. Utilizing an object-oriented architecture, HOOP enables researchers to investigate mechanical and thermal phenomena within multiphase composite materials. By leveraging established libraries like NumPy, Seaborn, and Matplotlib, HOOP offers robust numerical operations, data manipulation capabilities, and compelling visualizations. The strategic integration of various Python libraries within HOOP's architecture fosters inherent flexibility and interoperability. This enables tailored workflows and seamless integration with established tools. Users can leverage alternative libraries for specific tasks, expanding capabilities beyond core functionalities. Moreover, HOOP has been rigorously tested and validated, emerging as a powerful and cost-effective alternative to commercial software for multiphase composite analysis. This makes it an invaluable tool for academic researchers and engineers alike, democratizing access to advanced micromechanical analysis capabilities.
Isogeometric Analysis of Functionally Graded Plates using High-Order Theories
Authors: Gabriel Braga Alves de Matos  , Evandro Parente Júnior
Published: January 2025

Functionally Graded Materials are composites, usually of ceramic and metal, in which the volume fraction of their constituents varies smoothly along an interest direction. These materials were initially proposed as a solution for thermal barriers development, but are currently used in different applications. The composition variation results in a gradual change in their properties, enhancing the performance of structures subjected to thermal and mechanical loads, but making structural analysis more complex. Plates, on the other hand, are three-dimensional flat structures in which the thickness is much smaller than their other two dimensions. Different theories have been proposed for structural analysis of plates. These theories can be grouped based on the considerations adopted for the behavior of transverse shear deformations. In this regard, there are the Kirchoff-Love Theory (also known as the Classical Plate Theory - CPT), which disregards the effect of these deformations, the Reissner-Mindlin Theory (also known as the First-Order Shear Deformation Theory - FSDT), which considers shear deformations constant throughout the plate thickness, and Higher-Order Shear Deformation Theories (HSDTs), which consider a nonlinear variation of shear deformations through different approaches. Among these theories, the most robust and accurate ones are evidently the HSDTs. However, it is important to clarify that they require the displacement field to have a C1 continuity, which is complex for isoparametric finite elements. Thus, Isogeometric Analysis emerges as a more viable alternative by employing high continuity elements based on Non-Uniform Rational B-Splines (NURBS) functions. Therefore, this paper presents a NURBS-based isogeometric formulation for buckling and free vibration analyses of functionally graded plates using a HSDTs. A series of tests were conducted to assess the accuracy of this formulation considering examples available in the literature with different geometries, boundary conditions, and materials. The obtained results present excellent agreement with the reference solutions for thin and thick plates.
Numerical approximation of the Womersley problem in OpenFOAM.
Authors: Beatriz Cortez Rodriguez dos Santos  , Amanda Sayuri Oizuni  , Fábio Cunha Lofrano  , Pablo Javier Blanco  , Fernando Akira Kurokawa
Published: January 2025

Replicating the pulsatile blood flow in simulations under various physiological conditions is essential for understanding hemodynamic behavior and its relationship with cardiovascular diseases, as well as for developing innovative clinical approaches. The Womersley number, which describes the relationship between pulsatile flow and mean flow in a blood vessel, directly influences vascular biomechanics. Computational Fluid Dynamics (CFD) simulation provides a detailed analysis of blood flow in three-dimensional models of vessels, allowing for precise representation of vascular geometry and the inclusion of pathological conditions such as stenoses and aneurysms. This study aims to implement the Womersley number in CFD simulations using the OpenFOAM software to model hemodynamic behavior in blood vessels. Cases will be developed to obtain Womersley velocity profiles in different vascular geometries using a periodic pressure difference. Results will be compared with literature data to ensure the accuracy and reliability of the Womersley number application.
Numerical investigation of wind loads on an industrial shed with rounded eaves with different height-width relationships
Authors: Leonardo Guimarães Teodoro Júnior  , Marco Donisete de Campos
Published: January 2025

Pressure distributions due to wind in structures are commonly estimated using computational analysis tools as an alternative to studies carried out in wind tunnel tests, thus making it possible to study the dynamics of this fluid for various boundary conditions and geometries. That way, this work discusses the behavior of the external pressure coefficients in an industrial shed with rounded eaves, taking into account the following height-to-width ratios (H/B): h/b=0.5, /b=0.75, h/b=1.0 and h/b= 1.25. In addition, the following radius-height ratios (R/H) were also investigated for this model considering the most critical case (θ=90°; H=18.75 m): R/H=2.5%, R/H=5%, R/H=7.5%, and R/H=10%. Using Ansys Workbench software, the external pressure coefficients were obtained for wind at 45° and 90°. In the height-width ratio analysis, the results indicated that the external pressure coefficients are more intense in the 90° configuration, and the behavior of these coefficients changes between the wind directions analyzed from approximately 50% of the width of the shed. For the radius-height reduction, there was a noticeable attenuation of the suctions in the roof. Therefore, the distribution of external pressures obtained using computational methods allowed us to conclude that the effects caused by the variation in the height parameter can be, in the worst of the cases analyzed, intensified or reduced by varying the rounding radius of the eaves.
Numerical investigation the influence of solid and porous parapets on wind loads on low-rise buildings.
Authors: Cesar Felipe Gonzaga de Souza  , Marco Donisete de Campos
Published: January 2025

Several studies have shown that parapets mitigate the damage and economic losses due to wind action on buildings. Therefore, in this work, a computational analysis of the influence of different parapet geometries and heights on the wind flow on the roofs of low-rise buildings has been developed using the Ansys Workbench software. Solid and porous parapets were considered, and a decrease in the external pressure coefficient was observed as the height of the parapet increased, as well as a greater efficiency of porous parapets than solid ones.
Numerical Modelling of Conductor Casing Settlement Using a Two-phase Model
Authors: Jamerson Braga de Omena  , Mávyla Sandreya Correia Tenorio  , Jennifer Mikaella Ferreira Melo  , Beatriz Ramos Barboza  , Jose Luis Gomes Marinho  , João Paulo Lima Santos  , Fabio Sawada Cutrim  , Rafael Dias
Published: January 2025

Oil exploration in subsea wells is a complex activity that involves a number of technical challenges, including installation conductor casing installation. The conductor casing plays a crucial role in the structural stability and overall performance of the well. Thus, for the conductor sttelemnt, one can highlight, among other techniques, the jetting method. Jetting is a promising technique for clay soils since seabed sediments behave like fine mud. In order to numerically model the operation, the clayay soil can be represented by a highly viscous non-Newtonian fluid. The aim of this study was therefore to carry out a numerical analysis of the conductor settlement by jetting. In order to achieve the proposed objectives, an eulerian - eulerian two phase model has been adopted. The soil phase has been modelled as a non-Newtonian fluid and computational fluid dynamics (CFD) has emerged as a powerful numerical tool for modeling and simulating problems of this nature in a attempt to bypass the issues that comes with large deformations problems other numerical methods. Ansys Fluent software was used, a CFD program based on the Finite Volume Method (FVM), which stands out for its robustness and precision when carrying out fluid dynamic simulations. The numerical analysis was carried out using the Gidaspow drag model to characterize the soil, which combines the Ergun and Wen-Yu empirical correlations. The results obtained showed that the excavation of the seabed using the jetting technique is significantly influenced by the velocity of the jet. In addition, other criteria also affect excavation, such as the type of fluid injected and the size of the drill bit.
Partially encased composite steel and concrete columns: a systematic approach to the literature
Authors: Bruna de Oliveira Souza de Mattos  , Hidelbrando Jose Farkat Diogenes
Published: January 2025

Partially encased composite columns emerge as a promising solution in structural engineering, combining the versatility of steel with the durability of concrete. This article explores their characteristics and advantages, highlighting the construction efficiency and resource savings they offer compared to traditional reinforced concrete structures. While steel provides strength and speed in construction, concrete offers protection against fire and compression. The study consisted of two stages: the systematic literature review, in which the most relevant bibliography for the objective of the article was selected, and the meta-analysis stage. The studies indicated a decrease in the initial stiffness, maximum load and ultimate strength of the columns, with an increase in eccentricity, as well as an increase in the peak axial load and final moment of resistance in high-strength concrete, especially in slender columns which present reduced peak axial load due to the increase in the slenderness index. Furthermore, partially encased columns demonstrated superior compressive strength to steel at high temperatures. Therefore, these columns represent a promising option, subject to additional considerations and specific studies.
Practical Design of Cold-Formed Steel Sections by the Direct Strength Method
Authors: Wydem Lucas Elias dos Santos  , Gilson Carvalho Filho  , Luciano Barbosa dos Santos
Published: January 2025

Cold-formed steel are among the most widely used in steel construction, being extensively employed in roofing and lightweight structures in general. Despite their popularity from a construction perspective, due to the existing manufacturing and utilization facilities, they prove to be quite complex from a design standpoint, as verifying these components involves extensive and complex calculation procedures due to the various global and local instability phenomena that may occur. Among the three design methods presented by the Brazilian standard NBR 7190, this study applies the Direct Strength Method in the development of a computational application that allows for the practical design of cold-formed steel subjected to oblique composite bending. This addresses the vast majority of calculation situations encountered in practice. The application has been tested in various design scenarios, and the results have been compared with those provided by other methods recommended by NBR 7190, showing a highly satisfactory performance.
Reliability-Based Boundary Element Models for plane linear elasticity
Authors: Evyllyn Dos Santos Vieira  , Eduardo Toledo lima junior
Published: January 2025

In Structural Engineering, one of the main objectives is to find robust solutions that ensure structural safety without sacrificing cost-effectiveness. To achieve this goal, one strategy involves considering the uncertainties inherent in projects, taking into account the variability of design parameters, rather than relying solely on characteristic values provided by semi-probabilistic approaches. This probabilistic paradigm allows for estimating the probability of failure of structural elements and systems, providing robustness to design, contributing to decision-making process, and reducing risks associated with both overly conservative and expensive projects, and economical yet unsafe projects. This study aims to implement the coupling between mechanical and reliability models to analyze the structural behavior of plates in linear regime. Mechanical models based on the Boundary Element Method (BEM) and reliability models based on Monte Carlo Simulation (MCS) and First Order Reliability Method (FORM) will be developed and validated, by using Python language. The random variables considered may include mechanical parameters such as elasticity modulus and Poisson's ratio, dimensions of structural elements, as well as applied loads. The objective is to evaluate the probability of occurrence of usual limit states in structural analysis, such as the violation of allowable displacement and stress values.
Space truss finite elements applied to actuated structures and origami  implementation and discussions
Authors: Rafael Rosas Garcia Almeida  , Humberto Breves Coda
Published: January 2025

In the various branches of engineering, dynamic analysis of structures is always a relevant topic and the training of future professionals and researchers in this area is always important. Nowadays, with the evolution of materials and topological dispositions, structural elements and structures are becoming increasingly lighter and slender, increasing the amplitude of movements in such a way that nonlinear geometric analysis is necessary. regarding actuated structures or origami mechanisms, there is a natural mobility between planes defined by the relative rotation in the creases that makes it possible to create foldable devices of great interest such as the production of retractable roofs, retractable antennas, wheels for light vehicles, biomechanical devices , among others. This work introduces the presence of actuators in spatial structures by directly controlling the initial length of truss elements (actuation). At the same time, to define origami or flat 3D structures, it is necessary to introduce the strain energy associated with the folds at the junction between flat panels (creases). To introduce this energy, vectors orthogonal to the adjacent origamic planes are defined and fictitious spring elements are introduced to oppose the change in the anglebetween the planes. Illustrative examples and discussions of future work are presented.
Surrogate Based Optimization of Functionally Graded Plates
Authors: Igor de Oliveira Lima  , Evandro Parente Junior
Published: January 2025

Functionally Graded Materials (FGM) are composites, usually made of ceramic and metal, in which the volume fraction of their constituents varies smoothly along an interest direction. These materials were initially proposed as a solution for the development of thermal barriers, but are currently used in different applications. The variation in composition results in a gradual change in their properties, improving the performance of structures subjected to thermal and mechanical loads, but making structural analysis more complex. Plates, on the other hand, are three-dimensional flat structures in which the thickness is much smaller than their other two dimensions. For projects involving functionally graded plates, both the choice of their constituents and the definition of the distribution of volume fractions are necessary. Computational methods, which simulate the behavior of these structures, and optimization techniques, which explore the design space, are used to obtain a more efficient solution. However, the computational cost of structural analyses can be a limiting factor in the optimization process, since bioinspired algorithms require the analysis of a large number of trial solutions to find the optimal design. Thus, this work addresses the use of surrogate models capable of efficiently approximating the results of numerical simulations. These models are an alternative to reduce the computational cost of the design optimization of complex structures. Surrogates have been incorporated into an optimization methodology known as Sequential Approximate Optimization (SAO), where the approximate response surface is continuously updated and improved by the insertion of new points, enhancing the model approximation. The proposed methodology will be used in the design optimization functionally graded plates considering buckling and free vibration. The results will be evaluated in terms of accuracy and efficiency based on a set of benchmarks.
Surrogate model for predicting stresses of concrete slabs subjected to real vehicle loading using multilayer perceptron neural network
Authors: Rodrigo Corrêa Pereira  , Francisco Evangelista Junior
Published: January 2025

This work proposes an innovative method that uses machine learning with computational finite element simulations to optimize the design of concrete slabs for rigid pavements subjected to moving loads of different speeds. The objective is to create a surrogate model that takes into account the uncertainties of weight, shape and speed of vehicle loading on the concrete slabs, together with the uncertainties of the pavement temperatures, to predict the displacements and stresses in the concrete slabs. Realistic finite element models consider the three-dimensionality of the multilayer problem as well as the inertial effects due to moving loading at different speeds. Based on the results of finite element analyses, machine learning techniques are used to train and validate a surrogate model. This model allows the analysis and quantification of the uncertainties of displacements and stresses in concrete slabs under different conditions of vehicle speed, vehicle load and pavement temperatures. Based on these analyses, it is possible to optimize the shape and thickness of concrete slabs to cope with the effects of uncertainties, thus ensuring adequate performance of the structure under a wide range of operating conditions. This approach allows for a more precise and efficient optimization of concrete slabs, taking into account the dynamic and stochastic variables involved in the process.
Top of cement influence on APB mitigation in high pressure and high temperature oil wells
Authors: Antonio Peroba de Oliveira Teodoro  , Catarina Nogueira de Araújo Fernandes  , Gilberto Lucas Leandro dos Santos  , Thiago Barbosa da Silva  , William Wagner Matos Lira
Published: January 2025

This work presents a study on the influence of Top of Cement (TOC) in mitigating Annular Pressure Build-Up (APB) in wells subjected to high pressure and high temperature (HPHT) conditions. Oil and gas exploration in HPHT wells poses significant engineering challenges, including an increased occurrence of APB. Under extreme circumstances, APB can compromise casing integrity, leading to oil leakage into the marine environment and jeopardizing safety and operational continuity. The objective of this study is to comprehend how TOC height influences APB behavior. Additionally, in cases where the cement top does not cover the previous casing shoe (open shoe), the study examines how fluid leak-off affects APB response. The methodology consists of four main stages: i) literature review on characterizing and modeling APB in HPHT wells; ii) implementation of a semi-analytical model proposed in the literature to calculate APB considering cement effects and formation leak-off; iii) modeling scenarios with varying TOC heights; and iv) analyzing results to observe the relationship between APB, TOC heights and casing safety factors. These results are compared with those from widely used commercial software in the industry. The results obtained with the implemented model demonstrate that positioning the TOC below the previous casing shoe effectively reduces APB. However, caution is warranted when reducing TOC height, as it is crucial for wellbore stability. Thus, this study contributes to developing a methodology for evaluating the impact of TOC height and leak-off on APB, providing guidance for future research and practical applications in the industry, and enhancing safety and operational efficiency in HPHT wells.
Use of Computational Fluid Dynamics to investigate heat exchanges in Floating Solar Plate Systems
Authors: Hícaro Raffael Dionizio Silva  , CAMILA OLIVEIRA DOS SANTOS BORGES  , NUCCIA CARLA ARRUDA DE SOUSA
Published: January 2025

This study aims to investigate the temperature gradient between floating and non-floating solar panels, with the purpose of comparing results and enhancing the efficiency of solar energy production by reducing the temperature of the solar modules. This modeling is crucial to inform future development and implementation of more effective and sustainable solar systems, as well as to pursue the implications caused by these installations.Thermal analyses between floating and non-floating solar modules were conducted using Computational Fluid Dynamics (CFD) via the Finite Volume Method to obtain the variables of interest. These finite volumes are interconnected by points called nodes. The set of all these elements and nodes is called a mesh, produced by the discretization of the geometry. All stages of this simulation were performed by entirely open-source software, from geometry and mesh generation to result visualization.The simulation revealed a significant difference between the temperatures of the floating and non-floating panels, approximately 6 K (6°C), considering only one photovoltaic module. This discrepancy tends to have a positive impact on energy production, as the temperature of the solar cell affects its electrical current. Thus, reducing the temperature of the solar cells, as observed in the floating panel, results in an improvement in energy production. However, it is important to note that the increase in temperature resulting from the installation of a photovoltaic array on a large scale may lead to an increase in water temperature.In summary, the experimental data presented by the simulation, corroborated by previous experiments, highlights the relevance of research in the field of solar energy, emphasizing the potential of innovative solutions, such as solar panel floating, to boost the efficiency and sustainability of photovoltaic energy generation. All of this supports our results and encourages us to continue investigating innovative solutions in the field, with the learning and improvement of simulations via computational methods and the perpetuation of the use of open-source tools.
Visual Analysis of Anomalous Behavior Patterns in Oil Wells Using Dimensionality Reduction with t-SNE Projection
Authors: Bruno Batista dos Santos  , Thales Miranda de Almeida Vieira
Published: January 2025

Anomaly detection in production processes, especially in the oil industry, is of paramount importance due to the complexity and criticality of these systems. Producing oil wells are subject to a series of dynamic and interdependent variables, which can be monitored using sensors installed along the well. Precise analysis of these sensor records is essential for early identification of possible anomalies, as any deviation from the normal pattern can result in serious consequences, from operational failures to environmental and safety risks. Given the multidimensionality and variability of this data, the use of machine learning techniques becomes indispensable for analyzing and classifying the well's situation. However, even for computational software, anomaly identification remains a significant challenge, given the oscillatory behavior and scale disparity of the variables analyzed throughout the well's productive life. To mitigate these challenges, dimensional reduction techniques can be implemented, as they can bring some advantages, such as reducing computational cost, noise reduction, and improving classifier accuracy. A widely used tool for dimensional reduction, especially for visualization, is Distributed Stochastic Neighbor Embedding (t-SNE), which seeks to project high-dimensional data into a low-dimensional space preserving clusters, bringing similar data together by affinity through a t-distribution. For this approach, real records of pressure and temperature sensors from oil wells are used. These sensors are located at eight distinct points in the well, totaling eight dimensions that will be reduced to a two-dimensional plane. Therefore, this study aims to identify behavior patterns in multivariate data from producing oil wells visually using the t-SNE dimensionality reduction method. It is expected that through visualization, it will be possible to identify behavior patterns before and after the occurrence of anomalies and enable the development of appropriate artificial intelligence algorithms for this anomaly detection problem.
Distortional Strength and DSM Design of Cold-Formed Steel Lipped Channel Beams under Transverse Loadings
Authors: Alexandre Landesmann  , Lucas Aguiar Pigliasco da Fonseca  , Dinar Camotim
Published: January 2025

This paper reported the results of an ongoing numerical (ABAQUS shell finite element) investigation on the distortional buckling, post-buckling and ultimate strength behaviours and DSM (Direct Strength Design) Design of cold-formed steel beams subjected to major-axis non-uniform bending due to one midspan point load (transverse applied load). The beams analysed consisted of single-span lipped channel members exhibiting (i) 15 geometries, (ii) end sections that are locally and globally pinned and may warp freely, (iii) triangular bending moment diagrams, and (iv) 8 yield stresses, selected to cover a wide distortional slenderness range. After acquiring in-depth insight into how the triangular bending moment diagram influences the beam distortional buckling and post-buckling behaviours, an extensive numerical (shell finite element) parametric study is carried out in order to gather significant distortional failure moment data concerning lipped channel beams. These failure moments are then employed to assess the merits of the available DSM beam distortional strength curves in predicting them, namely (i) the one currently codified in North America (AISI 2016) and (ii) those proposed by Martins et al. (2017). The above curves were found to be inadequate for providing safe and accurate predictions of failure moments, highlighting the need to continue developing an efficient and reliable DSM-based design approach for beams failing in distortional modes under non-uniform bending.
A positional FEM approach for free vibrations of orthotropic laminated shells
Authors: Vinícius de Barros Souza  , Humberto Breves Coda
Published: January 2025

This paper presents a positional formulation of the Finite Element Method (FEM) for free vibration analysis of laminated shells with cross-ply and angle-ply fibers. The starting point of this formulation is the use of positions and generalized vectors as degrees of freedom, i.e., three coordinates and three vector components per node in the 3D space. The formulation is more general than Reissner-Mindlin by introducing an additional parameter which allows linear deformation in the three directions, avoiding locking effects. The material layers are orthotropic according to the Saint-Venant Kirchhoff law, in which the constitutive tensor regarding the shell reference axes is obtained with a second-order tensor transformation matrix. The numerical solution uses Hammer quadrature on the shell reference surface and Gauss-Legendre to integrate along the thickness, while the free vibration problem is solved as a standard eigenvalue and eigenvector problem. Two examples are discussed. The results are compared with papers in the open literature, which demonstrates good accuracy and efficiency of the present formulation.
Evaluating Design Methods for Cellular Steel Beams Through Parametric Modelling
Authors: Lucas Alves de Aguiar  , Matheus Erpen Benincá  , Inácio Benvegnu Morsch
Published: January 2025

Under some design conditions, cellular beams can be a better structural solution than I-section beams due to their enhanced strength-to-weight ratio, allowing for more lightweight and cost-effective constructions. However, their varying cross-sections lead to additional failure mechanisms, which require further research due to the lack of specific standardized design procedures covering this topic in Brazil. This paper evaluates five different design methods, as proposed by Annex N (1998), Veríssimo et al. (2013), Fares et al. (2016) and Grilo et al. (2018). Using a parametric approach, this paper investigates the geometric variations in cellular beams with the mentioned design methods, in comparison to shell finite element models already validated in a previous work of Benincá and Morsch (2020). The results reveal that while the design methods are generally conservative for longer spans, they might underperform in terms of safety for shorter spans. The Ward (1990) method was the most effective in identifying failure modes based on Formation of Vierendeel Mechanism (FMV) and Web-Post Buckling (WPB). In contrast, the adaptation of the Veríssimo et al. (2013) method, combined with the WPB check from the Grilo et al. (2018) method, was more sensitive in evaluating the WPB failure load. Finally, the findings confirm that cellular beams offer more significant benefits when used across longer spans.
The influence of high-strength steel on the failure modes of steel-concrete composite cellular beams
Authors: Lucas Gomes Ferreira  , Felipe Piana Vendramell Ferreira  , Silvana De Nardin
Published: January 2025

The use of steel-concrete composite cellular beams expands the options in civil construction projects, as it results in greater strength capacity when compared to components acting separately, as well as greater steel savings when compared to full-span beams. In this respect, it is interesting to study the influence of high-strength steel on the failure modes and strength capacity of composite cellular beams. Therefore, this study aims to contribute to the study of composite cellular beams under positive moment, with the replacement of ordinary steel by high-strength steel, identifying the influence of this parameter on their failure modes and on the strength capacity of the composite cellular beam. In this way, using ABAQUS software, a numerical model was developed and validated using experimental results from the literature, to obtain the original behavior and then parametric analysis focused on replacing ordinary steel with high-strength steel. The study resulted in four numerically validated cellular composite beam models and three variations of each, modifying the yield strength of the steel and realizing that, as expected, the strength capacity of the beam increased considerably.
The use of normative models under combined compression and bending for verification of concrete-filled steel tubes with high strength materials
Authors: Glaubert Araujo Miranda  , Fernanda Grobério Calenzani  , Walnório Graça Ferreira
Published: January 2025

Buildings have been demanding increasingly slender pillars from projects, consequently increasing the demand for efficient and economical solutions. One of the solutions adopted is the use of high-strength concrete and steel and the optimization of sections for filled mixed tubular pillars, which has been widespread in European, American, and Asian countries; however, there is little application in Brazil's constructions. Verification of mixed pillars under flexo-compression can be done by simplified methods or analytical methods such as the method of deformation compatibility. The draft revision of ABNT NBR 8800:2023 introduces three simplified calculation models for flexo-compression verification, with limitations in its application for concrete with characteristic compression strength below 50 MPa and steel profile with yield strength below 450 MPa, as well as proposing polygonal lines to trace interaction curves. In this article, the simplified calculation models from the draft revision of ABNT NBR 8800:2023 are compared with experimental results from the literature of prototypes of circular tubular filled mixed pillar sections with concrete strength above 50 MPa and steel profile with yield strength above 450 MPa. For this purpose, a computational tool was developed in MATLAB that traces the interaction curves of the draft revision project of ABNT NBR 8800:2023. The suitability and conservatism of simplified methods were verified when using high-strength materials outside the normative range.
Application of Q4 Strain Gradient Notation Finite Element Method (SGN-FEM) in Level Set Optimization Using Radial Basis Functions
Authors: João Elias Abdalla Filho  , Leilson Joaquim Araujo
Published: January 2025

The Strain Gradient Notation Finite Element Method (SGN-FEM) employs physically interpretable polynomials in the development of finite elements, allowing for the precise identification and subsequent elimination of parasitic shear sources, which cause shear locking. The element is corrected a priori, during development, by simply removing the spurious terms from the shear strain polynomials.The Level Set Method (LVM) is an optimization technique widely employed in topology optimization to minimize the compliance of structures. This method consistently provides clear boundary and geometry information during the optimization process, giving it inherent advantages in solving boundary and geometry-related problems.While numerous studies investigate different approaches to calculate level set optimization, there are fewer studies evaluating how the finite element technique contributes to the analysis. Considering this, this paper presents the application of Q4 SGN-FEM in optimization studies using LVM to minimize the compliance of a two-dimensional linear elastic structure. The differences obtained when using the SGN-FEM model are investigated. The parametrized level set method, as defined in Wei et al. (2018), is utilized alongside SGN-FEM to conduct the study. The model is validated through comparison with other studies, demonstrating that SGN-FEM proves to be a viable alternative for conducting optimization studies using the level set method.
Dimensionality Reduction and Visualization for Structural Reliability Analysis using Artificial Neural Networks
Authors: Wellison José de Santana Gomes
Published: January 2025

Structural reliability analyses may become very computationally demanding, especially when numerical simulations are employed to represent the structural behavior, and/or these analyses are used within structural optimization procedures. To overcome this problem, surrogate models have been largely used in the last decades, helping to avoid evaluations of the demanding parts of the computational code and to reduce the overall computational demand. However, the efficiency of the surrogates is usually compromised when dealing with high dimensional problems. In fact, high dimensionality imposes some difficulties not only to surrogate models but also for some structural reliability methods available in the literature. For these reasons, the present paper proposes to investigate the application of Artificial Neural Networks to reduce the dimensionality of structural reliability problems. A proper dimensionality reduction may help visualizing and understanding the problem and may assist surrogate models and reliability methods which would otherwise lose accuracy, precision and/or efficiency when applied to high dimensional problems.
Methodology for Reliability Analysis of Reinforced Concrete Structures over time Considering Combined Corrosion
Authors: Ana Carolina Cavalcanti Moraes  , Renato de Siqueira Motta  , Silvana Maria Bastos Afonso da Silva  , Eleni Toumpanaki  , Raffaele De Risi
Published: January 2025

One of the main causes of deterioration in reinforced concrete structures (RC) is the corrosion of steel bars. Many factors, including materials, environments, and loading conditions, which often have uncertain characteristics, affect the performance of RC structures. Some uncertainties may depend on time and location, and associated reliability issues become more difficult to address. This study presents a comprehensive method for assessing the temporal reliability of reinforced concrete structures, taking into account combined effects of carbonation (general corrosion) and chloride penetration (pitting corrosion). Probabilistic models are used to capture uncertainties related to the beginning, propagation, and combined effects of corrosion on structural performance over time. The time-dependent reliability of bridge structures is evaluated using sophisticated numerical simulations in conjunction with the FORM method for reliability analysis. Both time and space variables are treated as uniformly distributed random variables within specific intervals when generating sample points. Engineers and decision-makers can assess the reliability of reinforced concrete bridges using a systematic framework that considers the complex interactions of corrosion mechanisms. This aids an informed maintenance planning and effective resource allocation to ensure long-term structural safety and durability. Finally, the suggested method is tested on a reinforced concrete bridge with corroded steel reinforcement bars. The original work is validated, and the results are compared with the crude Monte Carlo simulation (MCS) method.
Optimal Adaptive Importance Sampling for Reliability Analysis
Authors: André Jacomel Torii  , Lucas Araújo Rodrigues da Silva  , André Teófilo Beck
Published: January 2025

Reliability Analysis play a central role in Structural Safety. For this reason, several methods have been proposed and adapted to solve this problem over the years. In this work we focus on a family of sampling-based schemes called Adaptive Importance Sampling (AIS). The idea of AIS is to take an initial sampling distribution, draw a sample, evaluate the required statistical moments and then update the sampling distribution using some rule in order to make it closer to the target distribution. The procedure is then repeated iteratively until a good representation of the target distribution is obtained. In the context of Reliability Analysis, this idea can be employed to represent the optimal sampling distribution of IS and thus allow an accurate estimate of the probability of failure. There exist several variants of AIS, but all of them provide a sequence of samples obtained with a sequence of sampling distributions. If employed to evaluated statistical moments, as is the case of Reliability Analysis, it is then necessary to combine the estimates obtained at each iteration to get a final result. Generally, this is done by taking the average value among all iterations. However, in this work we reflect on better ways to combine these estimates in order to obtain the final result.