
Carlos CoutoUniversity of Aveiro | UA · Department of Civil Engineering
Carlos Couto
Ph.D
Research towards safer and more economical steel structures by developing design methods and machine learning models
About
83
Publications
13,990
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
747
Citations
Publications
Publications (83)
This paper presents a comprehensive review of the developments leading to the proposal of European fire design rules for steel beams with thin-walled I-sections. Thin-walled beams are favoured in steel construction due to their structural efficiency, however they are prone to buckle when subjected to in-plane loads, phenomenon which requires a thor...
Trusses and bracing systems are usually constructed from monosymmetric and built-up cross-sections, which under compression stresses may buckle in torsional or flexural-torsional modes. In fire, this phenomenon is utterly important as failure in bracing systems or trusses may cause the collapse of buildings and result in loss of lives or severe eco...
The focus of this work, in the context of the AlticeLabs@UA 1 project-SAFER-Fire, was to develop a machine learning model capable of detecting a fire in its early stages while being lightweight enough to be used in a low-power device, such as a single-board computer. Different algorithms were analyzed, and YOLO (You Only Look Once) was elected the...
Complex temperature fields may develop inside structural steel elements in fire, severely affecting the local and global response of the structure. However, simplified yet well-accepted design procedures allow for uniform temperature distributions in the steel elements. The second generation of Eurocodes provides advanced models for localised fires...
A parametric investigation of several unbraced steel frames with regular and irregular geometry subjected to elevated temperatures is carried out in this study to determine the most accurate procedure and buckling lengths to be considered during the structural design under a fire situation. In such conditions, the stiffness and strength of steel de...
To study the importance of post-earthquake fire events, 500 reinforced concrete (RC) frames were designed without seismic considerations. These consist in three-bays frames with a variation in the number of floors from two to six (100 frames each). Numerical analyses were performed in SAFIR to investigate the influence of different types of damage,...
To gain a deeper understanding of post-earthquake fire behaviour, 100 reinforced concrete (RC) frames representative of a building stock designed without considering seismic loading were modelled using the software SAFIR. A total of 4400 numerical analyses were performed to investigate the impact of different assumptions, such as the type of damage...
Structural fire safety is crucial for building design and construction. Fires in buildings can affect strength and stability of structures and cause devastating consequences on human life and property.
Lightweight steel framing (LSF) walls are commonly used in modern buildings due to their high strength-to-weight ratio and readiness for installation. However, empty cavities within these walls can pose a fire risk if not properly addressed. In order to ensure the fire resistance and performance of LSF walls with empty cavities, various modelling t...
Artificial intelligence models using machine learning techniques are widely used in engineering to predict the mechanical behavior of structural members. Different machine learning (ML) algorithms such as artificial neural networks, random forests, and support vector regression were used to develop and train models in this study to predict the ulti...
17 The local buckling behaviour of hot-rolled and welded I-sections under simple load cases at elevated 18 temperatures is investigated numerically through extensive numerical analysis. Advanced shell Finite 19 Element (F.E.) models are firstly developed and validated against existing experimental data for I-20 sections under fire conditions and th...
The definition of the resistance and the associated failure time of unprotected steel members in fire is crucial to the safety of steel structures. For this purpose, design standards allow for prescriptive approaches that rely on nominal fire curves that do not represent the physics of a real fire, for instance, a localised fire. Indeed, the therma...
In thin-walled steel members, the complexity of the interaction between the buckling of the plates and the buckling of the member, combined with the reduction of steel properties with increasing temperature, hinders the development of simple accurate analytical models. As a result, analytical design methods tend to be overly conservative for simple...
Steel portal frames are common structures used in practice. Owing to their optimization, members with tapered geometry and slender sections are prevalent. Since local buckling is a possible mode of failure, an additional complexity arises that requires the use of shell finite elements to assess the ultimate capacity of these structures. On the othe...
Due to the interaction between local and global instability modes at elevated temperatures, predicting the capacity of thin-walled columns in the fire situation is a complex endeavor. This work investigates the application of machine learning techniques to assess the resistance of slender steel columns with I-shaped cross-sections at elevated tempe...
The design of steel structures using elements with non‐uniform geometry is common in practice, both for aesthetic reasons and material optimization. Tapered beams are one of such examples which are widely used. This work is focused on the development of artificial neural networks to predict the critical moment of tapered beams subject to bending mo...
The General Method of EN 1993‐1‐1 covers the safety verification of non‐prismatic members, as the variable geometry precludes the use of the standard verification clauses. However, no specific guidelines are provided in the fire part of the Eurocode 3 (EN 1993‐1‐2) regarding its implementation at elevated temperatures, apart from adopting the reduc...
Artificial intelligence based models, namely using machine learning techniques, have been widely used in different engineering fields, providing accurate, easy‐to‐apply and fast assessment tools to predict the mechanical behaviour. These models not only can be used to increase the inference about the mechanical phenomena of a certain problem but al...
The validation of numerical models, for the behaviour of structures in case of fire, is crucial for the development of precise and safe design rules for members at elevated temperatures and for the application of advanced calculation methods, on part or complete building structures under fire. Recently, a new constitutive law model for stainless st...
Most design standards require the calculation of the elastic critical bending moment for the design and verification of steel beams. Formulae exists for uniform beams with double or mono-symmetric cross-sections but, for tapered beams, simple design formulae are yet to be developed because of the complexity associated with the non-uniform geometry...
Earthquakes can cause several catastrophic events and the consequences of fires in urban areas can be even worse than the consequences of the earthquake itself. Several numerical models were developed with SAFIR-software that models the behaviour of structures subject to fire for reinforced concrete (RC) frames to study their post-earthquake fire b...
The present investigation describes the final piece of a three-part numerical parametric study on the validation and calibration of the General Method (GM) for the fire design of web-tapered steel members.
The GM covers the safety verification of non-prismatic members, as the variable geometry precludes the use of the standard verification clauses....
It is known that the loading type significantly influences the resistance of steel I-beams to lateral torsional buckling (LTB), which led to the development of Eurocode 3 design rules accounting for the beneficial effect of non-uniform bending in laterally unrestrained beams. New calculation formulae for stainless steel beams under fire conditions...
For thin-walled beams in fire, the development of simple analytical models is hindered by the complexity of the interaction between local and lateral-torsional buckling combined with the temperature reduction of steel properties, resulting in overly conservative fire design rules. This paper investigates the application of machine learning models t...
The accuracy of different fire design methodologies for hollow cross-sections subject to compression and major-axis bending is studied and compared in this paper. For that purpose, a numerical model based on shell finite elements is developed and validated against existing experimental results available in the literature. Comprehensive numerical pa...
The present investigation describes a numerical and parametric study on the validation of the General Method (GM) for the fire design of web-tapered steel beams using GMNIA.
The GM covers the safety check of structural elements with complex support conditions and/or of non-prismatic members, as the non-uniform geometry prevents the use of the stand...
Os modelos de inteligência artificial, nomeadamente com recurso a técnicas de machine learning, têm sido amplamente utilizados nas diversas áreas da engenharia, fornecendo ferramentas para previsão do comportamento mecânico muito eficientes e de rápida aplicação. Estes modelos permitem não só compreender e explorar melhor os fenómenos envolvidos co...
The present investigation describes a numerical and parametric study on the validation of the General Method (GM) for the fire design of web-tapered steel beams using GMNIA. The GM (clause 6.3.4 of EN 1993-1-1) covers the safety check of structural elements with complex support conditions and/or of non-prismatic members. However, the fire part of t...
This work applies finite element (FE) modeling and machine learning (ML) techniques to investigate the resistance of slender steel columns at elevated temperatures. First, a numerical study is performed with the FE software SAFIR to evaluate the columns' response for a range of cross-sections and boundary conditions. The FE model is used to generat...
This paper describes the influence of the imperfections in the critical temperature assessment of steel members at elevated temperatures. An extensive numerical investigation using shell FE models is performed in the scope of this work to calculate the critical temperature of steel members for particular combinations of geometric and material imper...
The purpose of this paper is to validate the General Method for the stability check of unrestrained I-section web-tapered columns in fire situation. The General Method (clause 6.3.4 of EN 1993-1-1) covers the safety check of structural elements with complex support conditions and/or of non-prismatic members. However, the fire part of the Eurocode 3...
Post-earthquake fires may appear after a large earthquake and its effects on urban areas can be even worse that the effects of the earthquake itself. The aim of the present work is to define a methodology to evaluate the consequences of the damage introduced by the seismic events on the fire resistance of reinforced concrete frames. It was performe...
Large earthquakes may cause a chain of events, and one of which can be fire after an earthquake. The effects of fire after earthquake on urban areas can be even worse than the effects of the earthquake itself. Buildings are not adequately designed for fire after an earthquake since most standards ignore that possibility. The aim of the work is to e...
The lateral-torsional buckling of steel beams with welded slender I-shaped sections, or Class 4 sections according to Eurocode 3 classification, is investigated in this paper. While the response of non-Class 4 section beams has been extensively studied in the literature, welded slender section beams have received less attention to date.
Finite elem...
In this paper, a numerical investigation is carried out for determining the influence of imperfections on the lateral-torsional buckling of welded I-shaped slender section beams. The buckling resistance of unrestrained beams is calculated with nonlinear shell-element based FE analysis, including material and geometrical imperfections. The sensitivi...
The General Method (GM) covers the safety check of structural elements with complex support conditions and/or of non‐prismatic members. However, it's not widely validated at normal temperature and is inexistent in fire part of the Standard EN 1993‐1‐2. With that in mind, this investigation aims at proposing and validating the GM to perform the safe...
Purpose
The purpose of this paper is to assess whether the adaptation to fire of current proposals/design methodologies at normal temperature is capable of producing accurate predictions of resistance for the out-of-plane stability of tapered beams.
Design/methodology/approach
The adaptation of these methodologies to fire has been done by accounti...
In this work, an appraisal of the influence of the residual stresses and geometric imperfections is carried out for thin-walled I-shaped sections covering both hot-rolled and welded profiles based on a numerical study using the Finite Element Method. The Eurocode 3 design provisions for local buckling are presented and evaluated in comparison to th...
Os sismos podem provocar uma cadeia de eventos, sendo que um deles pode ser a ocorrência de um incêndio. Os efeitos do incêndio após um sismo em áreas urbanas podem ser mais severos que os efeitos diretos do próprio sismo [1]. Os edifícios podem não estar adequadamente dimensionados para a ação de incêndio após um sismo visto que a maioria dos regu...
In this paper, the effect of non-uniform bending on the lateral torsional buckling (LTB) of steel beams with slender cross-sections subjected to elevated temperatures is numerically investigated. Local buckling is the main failure mode for slender sections whereas the lateral torsional buckling is one of the principal failure modes for beams, thus...
The generalised slenderness concept has been gaining popularity recently. One of the methods that is based on this concept is the General Method, which was introduced in Part 1-1 of Eurocode 3 to enable the assessment of the out-of-plane stability of steel members that fall outside the scope of the buckling resistance of uniform members formulae. H...
This paper describes a numerical investigation on the critical temperatures of members with Class 4 cross‐sections according to Eurocode 3 design. For such sections, the norm suggests the use of a default critical temperature of 350 °C irrespective of the load level conditions if no other calculation is made. On that regard, the authors have previo...
O presente artigo descreve uma investigação numérica dos fenómenos de encurvadura lateral (LTB) em vigas de aço de secção transversal esbelta sujeitas a momento fletor não uniforme a elevadas temperaturas. Constituindo-se a encurvadura local como o fenómeno de colapso predominante em secções esbeltas e a encurvadura lateral como um dos principais r...
The fire design of a steel frame is defined according to Part 1.2 of Eurocode 3 (EN 1993-1-2). It is based on security check to standard ISO 834 fire, where the structure must resist to fire during time set by regulation. For a natural fire, the structural resistance is ensured in the way that the collapse does not occur during the fire, including...
The behaviour of laterally restrained steel beam-columns with slender cross-sections (Class 4) where local buckling occurs under fire situation is numerically investigated. Although recommendations are given in Eurocode to address the local buckling for the case of fire, few studies address its influence at elevated temperatures, and more particula...
The use of beams with corrugated webs (WCB) has been increasing considerably during the last years due to the high load-carrying capacity in relation to the material usage. The major asset of this structural solution lies in taking advantage of the increase of rigidity provided by the web corrugation leading to better resistance against local buckl...
Part 1-1 of Eurocode 3 presents the General Method to assess the out-of-plane stability of steel members, for cases that fall outside the scope of the interaction formulae. However , there is still a lot of uncertainty regarding the safety and accuracy of this method, particularly when dealing with non-uniform members. In this paper, a comparison b...
The structural design is divided in two different parts: the global behaviour analysis, which means the determination of internal forces and the displacements; and the elements and joints design, considering the non-linear global and local effects analysis, the elastic-plastic material behaviour and the global and local imperfections. In this paper...
Resumo. A Parte 1-1 do Eurocódigo 3 apresenta o Método Geral que permite a verificação de elementos à encurvadura para casos não abrangidos pelas fórmulas de interação. Neste artigo é estudada uma proposta de adaptação do Método Geral para situação de incêndio, desenvolvida pelos autores e implementada num programa informático, validando-a e compar...
O Eurocódigo não clarifica se a análise por elementos é suficiente para um incêndio natural, desta forma, este trabalho tem como objetivo verificar se a análise por elementos é suficiente para um incêndio natural utilizando o conceito de comprimentos de encurvadura na verificação das colunas. Assim, foram analisados três pórticos não contraventados...
Neste trabalho apresenta-se um estudo numérico sobre as temperaturas críticas de secções transversais de Classe 4. Recorrendo ao programa de elementos finitos SAFIR, efetuou-se um estudo paramétrico considerando diferentes geometrias das secções, tipo de aço e graus de utilização. Com base nos resultados obtidos, são propostas temperaturas críticas...
The present paper addresses the study of laterally unrestrained steel beams with slender cross-sections for the case of fire with special focus on the influence of loading. A numerical investigation of several beams submitted to triangular and bi-triangular end-moment distribution and uniformly distributed loads is carried out at elevated temperatu...
p>According to the Eurocode 3 Part 1-2 (EN1993-1-2) (CEN 2005b), it is possible for structural engineers to consider physical based thermal actions and to do performance based design instead of using prescriptive rules based on nominal fire curves. However, some uncertainties remain in the use of such approaches. This study focus on the clarificati...
There is currently no specific rules in Part 1-2 of Eurocode 3 for the stability verification of non-uniform members under fire conditions. For normal temperature, Part 1-1 of the same code provides a General Method to check the stability against lateral and lateral-torsional buckling for these type of members, though it requires some extensive cal...
This paper approaches the lateral-torsional buckling design of steel beams composed of slender cross-sections. The current rules found in Eurocode 3 and a proposal based on a consistent derivation of the Ayrton-Perry formulation developed for compact and semi-compact cross-sections (cross-sections of Class 1, 2 and 3) is applied to beams with slend...
This paper deals with the verification of the mechanical resistance of web-tapered beam-columns in case of fire, since no specific guidance is given in the Eurocode 3 Part 1-2 (EN 1993-1-2), on how to verify the capacity of these elements although they are commonly used in steel construction. Studies on this subject are very limited with few tests...
Neste trabalho efetuou-se um estudo numérico alargado para avaliar o comportamento de vigas metálicas com secções esbeltas em situação de incêndio. A influência da encurvadura local na resistência à encurvadura lateral de vigas com secções de Classe 3 e Classe 4 é analisada e os resultados obtidos são comparados com a curva de encurvadura lateral p...
A Parte 1.2 do Eurocódigo 3 preconiza, para elementos com secção transversal de Classe 4, a utilização de uma temperatura crítica por defeito de 350ºC, se nenhum cálculo for efetuado para a sua determinação, tendo em conta os esforços efetivamente instalados. Esta temperatura crítica pode ser demasiado conservadora pelo que é recomendável que se fa...
O Eurocódigo 3 apresenta na sua parte 1-1 um procedimento denominado Método Geral, que visa a verificação da resistência à encurvadura em elementos estruturais não uniformes. A sua aplicação apresenta alguns constrangimentos justificando-se a criação de ferramentas de cálculo que automatizem este processo. Neste artigo apresenta-se o programa de cá...
In this work, the mechanical resistance of slender cross-sections exposed to fire where local buckling has a predominant role in the ultimate strength is investigated. A numerical study is performed by using a finite element analysis software for evaluating the existing design methods preconized in Part 1.2 of the Eurocode 3 cross-sectional resista...
A simple calculation method to evaluate the cross-sectional resistance of class 4 cross-sections in fire conditions is currently available in the EN version of the Eurocode 3 part 1-2 and part 1-5. However, numerous finite elements analysis in the scope of a numerical parametric study to know the cross-sectional resistance of class 4 cross-sections...
The present paper deals with the study of the lateral torsional buckling of steel beams with class 4 cross-sections in case of fire. More precisely, a finite element method FEM numerical study of beams submitted to uniform bending moment at elevated temperatures is performed considering different class 4 cross-sections and the results are then comp...
Com base num estudo numérico das componentes (placas) individuais das secções transversais verificou-se que, de acordo com as recomendações do Eurocódigo 3, a utilização das expressões à temperatura normal para ter em conta a encurvadura local no cálculo em situação de incêndio, não traduz o comportamento destes elementos a altas temperaturas. Nest...
The present paper deals with the study of the lateral torsional buckling of steel beams with welded class 4 cross-sections in case of fire. A numerical study of several beams with different class 4 cross-sections submitted to uniform bending moment at elevated temperatures has been performed using the finite element method. The results are compared...
In this study the software CLoad is presented and a buckling analysis of a braced and unbraced frame exposed to fire is done. The software CLoad allows for the buckling analysis based on the matrix structural analysis of a frame taking into account the effect of the temperature in the reduction of the steel properties at elevated temperatures. With...
At normal temperature, the ultimate load bearing capacity of a steel portal frame, where buckling can occur, usually depends of the non-linear geometric and material effects. To perform an analysis that includes all of these non-linear effects is prohibitive for a day basis use. Accordingly, the Eurocode 3 proposes alternate and approximate methodo...
No presente trabalho estuda-se a verificação da segurança de colunas de pórticos metálicos em situação de incêndio. Em particular, analisa-se a forma como o comprimento de encurvadura das colunas evolui em situação de incêndio no caso de pórticos contraventados e não contraventados, efectuando-se uma comparação entre os valores obtidos e os valores...
This paper aims at evaluating the validity of using in fire situation the same procedures used at normal temperature for checking the stability of unbraced steel frames. A comparison is made between simple and advanced calculation models. Based on a parametric study a procedure is proposed for evaluating the buckling lengths of columns in unbraced...