G. Hajdú

58556373200

Publications - 17

Shear buckling behaviour of beams with partial-depth stiffeners at the support

G. Hajdú Hartmut Pasternak

Publication Name: Thin Walled Structures

Publication Date: 2025-02-01

Volume: 207

Issue: Unknown

Page Range: Unknown

Description:

This paper presents the findings from experimental tests and numerical simulations on plate girders with various end post configurations. While EN 1993-1-5:2024 provides design rules for both rigid and non-rigid end posts, it does not address the shear resistance of partially stiffened webs. The use of partial-depth stiffeners faces risks due to the lack of thorough investigation into their mechanical behaviour. To explore this issue, small numbered experimental tests and large numbered parametric studies on beams with different web slenderness were conducted using advanced numerical simulations. The results indicated that the shear buckling capacity of girders is lower than the design recommendation when the web stiffener height is <50 % of the web height. For girders with full-height stiffeners, EN 1993-1-5:2024 yields safe results. The accuracy of the EN 1993-1-5:2024 design rule for partially stiffened beams was also evaluated and new and shear buckling design curves were proposed for girders with partial-depth stiffeners.

Open Access: Yes

DOI: 10.1016/j.tws.2024.112622

Shear buckling performance of welded I-girders with partially stiffened web at the support

G. Hajdú Hartmut Pasternak

Publication Name: Bauingenieur

Publication Date: 2025-01-01

Volume: 100

Issue: 1-2

Page Range: 21-32

Description:

This paper presents findings from tests and numerical simulations conducted on plate girders with varying end post configurations. Although EN 1993–1–5:2024 provides design guidelines for both rigid and non-rigid end posts, it does not cover the shear resistance of webs that are only partially stiffened. Partial-depth stiffeners pose potential risks due to the limited research into their mechanical behaviour. To investigate this issue, tests and parametric studies were per-formed on beams with differing web slenderness using advanced numerical simulations. EN 1993–1–5:2024 provides reliable estimates for fully stiffened beams, while new shear buckling curves have been proposed for partially stiffened beams.

Open Access: Yes

DOI: 10.37544/0005-6650-2025-01-02-55

Machine learning models for the elastic-critical buckling moment of sinusoidal corrugated web beam

Andreas Müller Nurullah Bektaş G. Hajdú

Publication Name: Results in Engineering

Publication Date: 2024-09-01

Volume: 23

Issue: Unknown

Page Range: Unknown

Description:

The torsional stiffness of I-beams with sinusoidal corrugated web is higher than that of flat web beams and the accuracy of the available hand-calculation methods to determine the elastic critical lateral-torsional buckling moment depends on the geometrical parameters of the beam and the web corrugation. This study proposes different machine learning models to determine the elastic lateral-torsional buckling moments of corrugated web beams. Various machine-learning algorithms such as Decision Tree, Random Forests, Gradient Boosting, Support Vector Regression, Catboost, and Deep Neural Network were employed to develop and train for predicting the elastic-critical lateral-torsional buckling moments of I-beams with corrugated web. An extensive dataset with 2250 pieces was constructed using linear buckling analyses on full-shell finite element models to determine the elastic-critical buckling moment of simply supported beams with sinusoidal web corrugation. Based on the statistical parameters of the predicted and test data, the accuracy and safety assessment of the different machine learning models are examined. The accuracy of the available hand-calculation methods is also investigated. The results of the parametric study showed that the overall performance of the different machine learning models is promising, although, not all are directly suited for the described problem.

Open Access: Yes

DOI: 10.1016/j.rineng.2024.102371

Out-of-plane behaviour of imperfect beam-column with sinusoidally corrugated web

G. Hajdú Imre Cserpes

Publication Name: Journal of Constructional Steel Research

Publication Date: 2024-05-01

Volume: 216

Issue: Unknown

Page Range: Unknown

Description:

This paper presents an analytical formula for the second-order normal stresses in flanges of the imperfect I beam-columns with sinusoidal web corrugation. To deduce the analytical expression, the beam is separated into three parts. The flanges are modelled as thin-walled beam-columns and the corrugated web is modelled as a thin equivalent orthotropic plate with uniform thickness. The indispensable elastic critical loads are derived from the total potential strain energy of the imperfect beam-column using an energy method. To assess the accuracy of the proposed analytical formula, full shell finite element models were created in Abaqus software. The result of the benchmark example showed that the derived expression is accurate and applicable for geometrically nonlinear analysis of beam-columns with sinusoidal web corrugation. Based on the proposed analytical expression, the Ayrton-Perry type solutions for corrugated web columns and beams are also presented in this paper.

Open Access: Yes

DOI: 10.1016/j.jcsr.2024.108615

Lateral-torsional buckling behaviour of I-beams with sinusoidally corrugated web

G. Hajdú Imre Cserpes Hartmut Pasternak

Publication Name: Bauingenieur

Publication Date: 2024-01-01

Volume: 99

Issue: 3

Page Range: 69-77

Description:

AB ST R AC T This paper presents a new approach to calculate the elastic lateral-torsional buckling moment of I-beams with sinusoidally corrugated webs. The appropriate hand calculation methods to determine the elastic critical moment of corrugated web beams have so far been based on the modification of the warping constant of the cross-section. Instead of modifying the warping constant, the corrugated web is modelled as a thin, equivalent orthotropic plate with uniform thickness. With the usage of the elastic critical moment the inelastic lateral-torsional buckling resistance of sinusoidally corrugated I-beam is determined according to the current Eurocode 1993–1–1:2005.

Open Access: Yes

DOI: 10.37544/0005-6650-2024-03-29

Assessing the Performance of Machine Learning Algorithms in Predicting Buckling Moments of Corrugated Web Beams

Andreas Müller Nurullah Bektaş G. Hajdú

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 121-127

Description:

I-beams with corrugated webs have higher torsional stiffness than that of flat web beams. Furthermore, the geometrical dimensions of the beam and the web corrugation heavily influence the precision of the currently used traditional pen-andpaper methods for determining the elastic lateral-torsional buckling moment. This study aims to suggest several machine learning models with the intention of predicting the elastic lateral-torsional buckling moment of corrugated web beams. Multiple machine learning models, including Random Forests, Gradient Boosting, Categorical Boosting, and Deep Neural Networks, were deployed to develop and train models to predict the elastic critical lateral-torsional buckling moments of Ibeams with corrugated web. The database used for training the different models was compiled through linear bifurcation analyses conducted on shell finite element models. The study evaluates the precision of the various machine learning models by examining their performance against statistical parameters derived from both predicted and test data. The findings from the parametric evaluation highlight the surprisingly high performance and accuracy of the machine learning models.

Open Access: Yes

DOI: 10.3233/ATDE240535

Lateral-torsional buckling assessment of I-beams with sinusoidally corrugated web

G. Hajdú Ferenc Papp Hartmut Pasternak

Publication Name: Journal of Constructional Steel Research

Publication Date: 2023-08-01

Volume: 207

Issue: Unknown

Page Range: Unknown

Description:

This paper assesses the elastic and inelastic lateral-torsional buckling resistance of I-beams with sinusoidal corrugated web through an extended 22 degrees of freedom thin-walled beam-column finite element method. The appropriate hand calculation methods to determine the elastic critical moment of corrugated web beams are based on the modification of the warping constant of the cross-section. Instead of modifying the warping constant, the corrugated web is modelled as a thin, equivalent orthotropic plate with uniform thickness. An approximate expression is also derived from the total potential strain energy of the beam using the Ritz method. The result of the parametric study showed that the developed finite element is accurate and applicable for linear buckling analysis of beams with sinusoidal web corrugation. With the results of the linear buckling analysis the plastic resistance of the corrugated web beam can also be determined. Based on advanced finite element simulations' results the parametric study showed that the standard-based imperfection factor leads to conservative results to predict the inelastic lateral-torsional buckling resistance of sinusoidally corrugated beams, so a more precise but still safe imperfection factor is proposed for sinusoidally corrugated web beams.

Open Access: Yes

DOI: 10.1016/j.jcsr.2023.107916

Structural Optimization of a Steel Truss for Sustainability in Parametric Environment – a Case Study

J. Szép Kitti Karolyfi G. Hajdú Kira Rodaeva

Publication Name: Chemical Engineering Transactions

Publication Date: 2023-01-01

Volume: 107

Issue: Unknown

Page Range: 13-18

Description:

Although designing a structure is an iterative process by nature, a very limited number of iterations can be done with the traditional methods to reach the near-optimal solution. However, with the development of information technologies, the usage of parametric design in the construction industry has expanded. This paper aims to show the potential benefits of implementing parametric design and optimization techniques in the early structural design process. For this purpose, a simple parametric model of a steel frame with a truss roof system was created and then optimized for minimum mass and a given floor area. The case study demonstrated that the application of parametric design can reduce the Global Warming Potential of the structure by 7.6 % by optimizing the geometry and the cross-sections, leading to a more sustainable solution.

Open Access: Yes

DOI: 10.3303/CET23107003

On the accuracy of general method adapted in EN 1993-1-1

G. Hajdú Ferenc Papp

Publication Name: Journal of Constructional Steel Research

Publication Date: 2022-08-01

Volume: 195

Issue: Unknown

Page Range: Unknown

Description:

In this paper, a safety assessment of the General Method (GM) in Eurocode 1993–1-1:2005 is carried out. The GM covers the stability verification of steel structures subjected to compression and/or bending even in cases where the structures have irregular shape, complex load and support conditions. Several research papers dealt with the accuracy of the GM, but within the method, all of them used the Ayrton–Perry formula type standard reduction factors calibrated for the fundamental (flexural and lateral-torsional) buckling modes. These studies compared the results of the GM to the results of the geometrically and materially nonlinear analysis with imperfections (GMNIA) applying characteristic numerical models. In this paper, firstly the exact imperfection factors of fundamental buckling modes are calculated with GMNIA, after that these factors are used within the GM. This way the effect of the inaccuracy of the standard calibrations is excluded, and the real accuracy of the GM will be reflected in the results. This study covers the fundamental case of coupled flexural and lateral-torsional buckling modes in case of hot-rolled IPE and H-type cross-sections.

Open Access: Yes

DOI: 10.1016/j.jcsr.2022.107354

Out-of-plane buckling resistance of members with monosymmetric I-section according to prEN 1993–1–1:2020

A. Rubert G. Hajdú

Publication Name: Bauingenieur

Publication Date: 2022-01-01

Volume: 97

Issue: 6

Page Range: 173-185

Description:

In this paper, the stability resistance of beam-columns with monosymmetric I-section are examined according to prEN 1993–1–1:2020 standard. The buckling behaviour of the members with monosymmetric I-section is different from doubly symmetric cross-section because the eccentricity between the shear centre and centre of gravity causes additional second-order bending moments and second-order bimoment from compression. This paper aims to show a comparison between the results of the Interaction Method, General Method and the Overall Imperfection Method. To investigate the accuracy of the above-mentioned design methods several geometrically and materially nonlinear analyses with imperfections (also known as GMNIA) were carried out by the authors. The parametric study showed that the different methods have similar safety level in the investigated cases.

Open Access: Yes

DOI: 10.37544/0005-6650-2022-06-33

Eigenshape based imperfection method for beam-columns with mono-symmetric I-sections

A. Rubert G. Hajdú

Publication Name: Stahlbau

Publication Date: 2021-08-01

Volume: 90

Issue: 8

Page Range: 600-613

Description:

Eigenshape based imperfection method for beam-columns with mono-symmetric I-sections. This paper shows for the first time the application of the Overall Imperfection Method (OIM) for columns, beams and beam-columns with mono-symmetric I cross-section. The buckling failure mode of compressed members with mono-symmetric I-section is torsional-flexural like. The second-order effect from the rotation around the longitudinal shear axis during the loss of stability is taken into account when the amplitude of the initial imperfection is calculated for the compressed members. For beams, the buckling behaviour is also different from doubly symmetric cross-section because the shear centre and the centre of gravity of the cross-section do not meet at the same position. This paper shows the extension and the usability of the OIM for steel structures with mono-symmetric I-section. The automatic determination of the equivalent amplitudes for columns, beams and beam-columns are presented for the first time. The practicality of the proposed method is demonstrated for single and multi-span members with three examples.

Open Access: Yes

DOI: 10.1002/stab.202100017

Validation of the Overall Stability Design Methods (OSDM) for tapered members

G. Hajdú Ferenc Papp J. Szalai

Publication Name: Sdss 2019 International Colloquium on Stability and Ductility of Steel Structures

Publication Date: 2019-01-01

Volume: Unknown

Issue: Unknown

Page Range: Unknown

Description:

Two new stability design methods are demonstrated and validated: the Overall Strength Reduction Method (OSRM) and the Overall Imperfection Method (OIM). Both methods are based on the linear buckling analysis (LBA) of global structural models and use the standard reduction curves. The OSRM is formulated in the classic way using generalized slenderness and reduction factors while the OIM uses equivalent amplitude for the buckling mode based geometrical imperfection. These new design methods cover all types of buckling modes, which can be calculated by LBA of structural models composed of tapered members with arbitrary support conditions and subjected to any complex loading. This paper clarifies the mechanical interpretation and proper calculation of all the components of the two methods in case of tapered members with arbitrary support conditions. The validation is performed on GMNIA results for several different buckling situations of tapered members proving the accuracy of the OSDM.

Open Access: Yes

DOI: DOI not available

Validation of the overall stability design methods (OSDM) for tapered members

G. Hajdú Ferenc Papp J. Szalai

Publication Name: Stability and Ductility of Steel Structures Proceedings of the International Colloquia on Stability and Ductility of Steel Structures 2019

Publication Date: 2019-01-01

Volume: Unknown

Issue: Unknown

Page Range: 1111-1119

Description:

Two new stability design methods are demonstrated and validated: the Overall Strength Reduction Method (OSRM) and the Overall Imperfection Method (OIM). Both methods are based on the linear buckling analysis (LBA) of global structural models and use the standard reduction curves. The OSRM is formulated in the classic way using generalized slenderness and reduction factors while the OIM uses equivalent amplitude for the buckling mode based geometrical imperfection. These new design methods cover all types of buckling modes, which can be calculated by LBA of structural models composed of tapered members with arbitrary support conditions and subjected to any complex loading. This paper clarifies the mechanical interpretation and proper calculation of all the components of the two methods in case of tapered members with arbitrary support conditions. The validation is performed on GMNIA results for several different buckling situations of tapered members proving the accuracy of the OSDM.

Open Access: Yes

DOI: DOI not available

Safety Assessment of Different Stability Design Rules for Beam-columns

G. Hajdú Ferenc Papp

Publication Name: Structures

Publication Date: 2018-06-01

Volume: 14

Issue: Unknown

Page Range: 376-388

Description:

In EC3-EN 1993-1-1, there are three different methods to check the global stability resistance of steel columns, beams, and beam-columns. The design formulas are based on buckling curves, which are available for purely compressed or purely bended members with uniform cross-sections. Beam-columns are subjected to compressive force and the bending moment can be designed using the so-called interaction formula where the interaction factors may be alternatively determined. Over the past few years, many research groups have worked on correcting and improving the accuracy of the available design methods for steel members. The aim of this paper is to compare the accuracy of the different revised methods for steel beam-columns. In order to investigate the accuracy of the above-mentioned design methods, numerous geometrically and materially nonlinear analyses with imperfections (also known as GMNIA) were executed by previous research projects. The results of the semi-probabilistic safety assessments may help the designer choose the most reasonable method for their design works.

Open Access: Yes

DOI: 10.1016/j.istruc.2018.05.002

Overall imperfection method for flexure and compression steel beam-columns

A. Rubert G. Hajdú Ferenc Papp

Publication Name: Stahlbau

Publication Date: 2017-06-01

Volume: 86

Issue: 6

Page Range: 483-496

Description:

Overall imperfection method for flexure and compression steel beam-columns. The principles and applications of the overall (global) imperfection method (OIM) for beam-columns are presented in this paper. The buckling resistance of a beam-column member is determined by the resistance of its critical cross-section taking into account second-order effect of the eigenform equivalent initial imperfection. The maximum amplitude of this initial imperfection, in the shape of elastic buckling mode, is determined from fundamental cases, which are simply fork supported members with uniform cross-section under uniformly distributed normal force or bending moment. The standardized buckling resistance of the fundamental cases is based on theoretical and empirical background. The proposed global imperfection method is adequate for computer-aided design method using advanced elastic beam-column finite element method including the warping behavior of the cross section. The accuracy of the presented method is illustrated step-by-step with numerical examples.

Open Access: Yes

DOI: 10.1002/stab.201710471

Overall imperfection method for beam-columns

G. Hajdú Ferenc Papp

Publication Name: Advances and Trends in Engineering Sciences and Technologies II Proceedings of the 2nd International Conference on Engineering Sciences and Technologies Esat 2016

Publication Date: 2017-01-01

Volume: Unknown

Issue: Unknown

Page Range: 87-92

Description:

The principles and applications of the overall imperfection method for beamcolumns are presented in this paper. The buckling resistance of a beam-column member is determined by the resistance of its critical cross-section taking into account the second-order effect. The maximum amplitude of the initial imperfection, in the shape of elastic buckling mode, is determined from fundamental cases. Fundamental case: simply-supported member with uniform cross-section subjected to uniformly distributed forces. The standardized buck-ling resistance of this reference member is based on theoretical and empirical background. The proposed overall imperfection method is adequate for computer-aided design procedures which contains an advanced elastic beam-column finite element method. The accuracy of the overall imperfection method is shown by a parametric study.

Open Access: Yes

DOI: DOI not available

Shear Buckling Resistance of I-Beams with Partially Stiffened Webs

G. Hajdú Hartmut Pasternak

Publication Name: Advances in Transdisciplinary Engineering

Publication Date: 2024-01-01

Volume: 59

Issue: Unknown

Page Range: 358-365

Description:

This paper presents the results of laboratory tests and numerical analysis for plate girders with partial height end stiffeners. Design rules for rigid end posts and non-rigid end posts are given in EN 1993-1-5:2006 but the shear resistance of partially stiffened webs is not mentioned. The use of non-tightly fitted stiffeners is hazardous due to insufficient investigations of the real behaviour. To discover this problem parametric studies on beams with different web slenderness are examined with the usage of advanced numerical simulations. The accuracy of the EN 1993-1-5:2006 standard design rule for partially stiffened beams is also examined. The results of the numerical simulations shows that the shear buckling capacity of girders is lower than the design recommendation where the height of the web stiffener is b5% of the web height. For girders with full height stiffeners the EN 1993-1-5:2006 standard leads conservative results.

Open Access: Yes

DOI: 10.3233/ATDE240567