Ferenc Papp

6701625168

Publications - 24

Axial strength of back to back cold formed steel short channel sections with unstiffened and stiffened web holes

Ardalan B. Hussein Ferenc Papp

Publication Name: Scientific Reports

Publication Date: 2025-12-01

Volume: 15

Issue: 1

Page Range: Unknown

Description:

The increasing adoption of back-to-back built-up cold-formed steel (CFS) channel columns in construction is attributed to their lightweight nature, versatility in shape fabrication, ease of transportation, cost efficiency, and enhanced load-bearing capacity. Additionally, the incorporation of web openings facilitates the integration of electrical, plumbing, and heating systems. These built-up sections are widely utilized in wall studs, truss elements, and floor joists, with intermediate screw fasteners strategically positioned at regular intervals to prevent the independent buckling of channels. Based on 18 experimental tests, this study demonstrates an excellent correlation between finite element analysis and the experimental results, confirming the accuracy of geometrically and materially nonlinear finite element modeling in predicting the axial buckling strength of built-up short columns. Furthermore, the design standards of the American Iron and Steel Institute and Australian/New Zealand Standards were found to underestimate the axial load capacity by approximately 12.5%. The primary objective of this research is to investigate the influence of various hole configurations, both with and without stiffeners, on the axial performance of built-up short CFS channel columns. A total of 180 finite element models were developed, examining four different unstiffened and edge-stiffened hole configurations, validated against experimental results from plain webs. The findings reveal that web holes and edge stiffeners significantly impact axial load-bearing capacity, while the specific shape of the openings has a negligible effect. Specifically, introducing a hole at the centroid of each web results in an approximate 8.5% reduction in axial load capacity in the absence of edge stiffening. However, the incorporation of stiffeners around the perforations mitigates this reduction and enhances both structural efficiency and load-bearing capacity. These results highlight the critical role of edge stiffening in optimizing the structural performance of perforated built-up CFS columns.

Open Access: Yes

DOI: 10.1038/s41598-025-15992-9

New Buckling Curve for a Compressed Member with Cold-Formed Channel Cross-Section

B. Vaszilievits-Sömjén Ferenc Papp

Publication Name: Buildings

Publication Date: 2024-10-01

Volume: 14

Issue: 10

Page Range: Unknown

Description:

The verification of a column made from a lipped cold-formed channel section, subjected to pure axial compression relative to the gross cross-section, often results in a combined verification of bending and compression due to the appearance of a shift of the centroid of its effective cross-section. Following Eurocode 3 rules, this requires the determination of two distinct effective cross-sections and various interaction factors. This paper, based on an analytic approach, offers a modification to the actual buckling curve, based on Ayrton–Perry formulation, to include the second-order effects raised by the eventual shift of the effective centroid due to local buckling of the compressed web plate. This eliminates the need to use an interaction formula. The modified buckling curve is verified based on a GMNIA analysis performed on a numerical parametric model, which was previously validated by laboratory tests. In addition, the results are compared with strength results provided by appropriate Eurocode 3 formulas and AISI Direct Strength Method for global-local interaction and with classic experimental results.

Open Access: Yes

DOI: 10.3390/buildings14103258

Elasto-plastic analysis and optimal design of composite integral abutment bridge extended with limited residual plastic deformation

J. Szép M. Movahedi Rad Sarah Khaleel Ibrahim Dániel Harrach Daniel Gosztola Ferenc Papp

Publication Name: Scientific Reports

Publication Date: 2023-12-01

Volume: 13

Issue: 1

Page Range: Unknown

Description:

Due to the growing significance of structural theories concerning the composite structure analysed and designed plastically, this paper introduces a new optimisation method for controlling the plastic behaviour of a full-scale composite integral abutment bridge by employing complementary strain energy of residual forces that existed within the reinforcing rebars. Composite bridges are structures made of components such as steel and concrete, which are frequent and cost-effective building methods. Thus, various objective functions were used in this work when applying optimum elasto-plastic analysing and designing the composite integrated bridge structure that was tested experimentally in the laboratory. In contrast, the plastic deformations were constrained by restricting the complementary strain energy of the residual internal forces aiming to find the maximum applied load and the minimum number of steel bars used to reinforce the concrete column part of the structure. The numerical model employed in this paper was validated and calibrated using experimental results, which were considered inside ABAQUS to produce the validated numerical model, using concrete damage plasticity (CDP) constitutive model and concrete data from laboratory testing to solve the nonlinear programming code provided by the authors. This paper presents a novel optimization method using complementary strain energy to control the plastic behaviour of a full-scale composite integral abutment bridge, with the original contribution being the incorporation of residual forces within reinforcing rebars to limit plastic deformations. Following that, a parametric investigation of the various optimisation problems revealed how models performed variously under different complementary strain energy values, which influenced the general behaviour of the structure as it transitioned from elastic to elasto-plastic to plastic; also results showed how the complementary strain energy value is connected with the amount of damaged accrued in both concrete and steel.

Open Access: Yes

DOI: 10.1038/s41598-023-32787-y

State-of-the-Art: Integrating Fastener Technology and Design Guidelines for Enhanced Performance of Cold-Formed Steel Sections

Ardalan B. Hussein Ferenc Papp

Publication Name: Buildings

Publication Date: 2023-09-01

Volume: 13

Issue: 9

Page Range: Unknown

Description:

Cold-formed steel (CFS) elements have gained significant attention in the field of structural engineering due to their numerous advantages, including high strength-to-weight ratio, cost-effectiveness, and ease of assembly and prefabrication. This review paper presents a comprehensive state-of-the-art analysis of the design and analysis of CFS structures, with a specific focus on columns and beams. The primary objectives and aims of this review paper are to provide a detailed assessment of the factors influencing the behavior and performance of CFS elements, including partial composite action, fastener spacing, bolt arrangement, web aperture, stiffeners, and connection spacing, to propose and present various formulas and methodologies that accurately estimate critical buckling loads, strength, and moment resistance for CFS members, and to emphasize the significance of proper screw and bolt placement in preventing premature failure and enhancing the overall load-carrying capacity of CFS structures. Additionally, the impact of temperature on the mechanical properties and performance of CFS members is discussed. The review paper proposes different formulas and methodologies to accurately estimate critical buckling loads, strength, and moment resistance for CFS members. Moreover, the paper highlights the importance of proper screw and bolt placement to prevent early failure and improve the overall load-carrying capacity of CFS structures. The discussion also emphasizes the need for revisions in existing standards and codes to provide more practical guidelines for designers and engineers. Overall, this state-of-the-art review paper provides valuable insights and recommendations for researchers and practitioners involved in the design and analysis of CFS elements.

Open Access: Yes

DOI: 10.3390/buildings13092338

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

The overall imperfection method for fire design situation

Samer Nemer Ferenc Papp J. Szalai

Publication Name: Engineering Structures

Publication Date: 2023-05-15

Volume: 283

Issue: Unknown

Page Range: Unknown

Description:

In this paper the Overall Imperfection Method, which is a well validated method for the assessment of the global stability resistance of thin-walled steel structural members with any load and supporting conditions, is used for fire design situation. The method uses equivalent initial geometrical imperfection in the shape of relevant elastic global buckling mode. The assessment of the global stability resistance is performed by geometrically nonlinear analysis and by checking of cross-sectional resistance using reduced elastic moduli in the analysis and reduced design strength for the cross-section checking. The validation of the method is carried out through the analysis of more thousands different structural members with hot-rolled I cross-sections. The reference values for the safety study are calculated by geometrically and materially nonlinear analysis with imperfections.

Open Access: Yes

DOI: 10.1016/j.engstruct.2023.115884

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

Influence of imperfections in the buckling resistance of steel beam-columns under fire

Samer Nemer Ferenc Papp

Publication Name: Pollack Periodica

Publication Date: 2021-08-01

Volume: 16

Issue: 2

Page Range: 1-6

Description:

This paper presents an investigation on the influence of structural imperfections on the ultimate load capacity of steel welded beam-columns with class 4 cross-section under elevated temperatures. This is done by considering different amplitudes for the global and local (plate) imperfections, and different residual stresses distributions available in the literature. To this purpose, a geometrically and materially non-linear finite element model using Abaqus software has been used to determine the buckling resistance of a steel welded beam-column at elevated temperatures, using the material properties of EN1993-1-2. The imperfection sensitivity of beam-columns is reported: the influences of the amplitudes of the geometric imperfection and the patterns of the residual stress on the load capacity are compared.

Open Access: Yes

DOI: 10.1556/606.2021.00303

Numerical investigation on flexural buckling behavior of hot-rolled steel columns at elevated temperatures

Samer Nemer Ferenc Papp

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2021-07-13

Volume: 65

Issue: 3

Page Range: 918-927

Description:

In this paper, a numerical investigation on the global buckling capacity of the axially compressed steel columns with hot-rolled I cross-section at elevated temperatures is presented. Geometrically and materially non-linear finite element model and the ABAQUS software were used to determine the buckling resistance. The numerical ABAQUS model was validated using experimental results available in the literature, and then the validated numerical model was used to generate a database of load-carrying capacity. The parametric study covered three different cross-section classes (class 1, 2 and 3), ten different non-dimensional slenderness ̄λ = 0.5, 0.6, 0.7, 0.9, 1.1, 1.3, 1.5, 1.7, 1.9, 2.0), three different temperatures (400°C, 500°C, 600°C), and two stress-strain constitutive relations including (the nonlinear material model adopted in the European guidance for structural fire design EN1993-1-2, and a Bilinear material model), with and without residual stress. The influence of the model parameters on the load capacity of steel columns at elevated temperatures was evaluated. The results of the parametric study were compared with the results of the simplified calculation model presented in EN1993-1-2.

Open Access: Yes

DOI: 10.3311/PPci.17799

Investigation of the effect of formwork shape on packing density of aggregates

Kitti Karolyfi Dániel Harrach Ferenc Papp

Publication Name: Pollack Periodica

Publication Date: 2020-12-31

Volume: 15

Issue: 3

Page Range: 125-134

Description:

Packing density of aggregate influences greatly the properties of concrete. Maximization of packing density increases the flowing ability and segregation resistance of the fresh concrete and the compressive strength of the hardened concrete. The determination of maximum density is difficult experimentally; therefore several models have been developed for that purpose. However, these models do not take the size of the formwork into account. In this study, 20 different formwork shapes were examined with defined aggregate fractions. Results show that increasing the formwork size increases the packing density of aggregate, and the growth depends on the formwork size and compaction method.

Open Access: Yes

DOI: 10.1556/606.2020.15.3.12

A new assessment methodology for fair-faced concrete surfaces based on digital image processing

Andras Horvath Kitti Karolyfi Ferenc Papp

Publication Name: Proceedings of the 2020 Session of the 13th Fib International Phd Symposium in Civil Engineering

Publication Date: 2020-01-01

Volume: Unknown

Issue: Unknown

Page Range: 288-295

Description:

Fair-faced concrete elements have become even more popular in architecture because of their pure aesthetics and favourable material properties. The europian standards and guidelines are usually specifying four classes regarding to the surface quality. However, the strandard assessment methodologies are based only on manual methods and they are very subjective in some cases. In order to increase the efficiency and accuary of the evaluation a new methodology is proposed using digital image processing. In this paper the basis of the evaluation method made by using the Python 3.6 software is presented by focusing on the surface void ratio which is one of the most common surface defects of fair-faced concrete structures.

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: 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

The correspondences between formwork geometry and concrete composition in the case of fair-faced concrete elements

Kitti Karolyfi Ferenc Papp

Publication Name: Pollack Periodica

Publication Date: 2018-08-01

Volume: 13

Issue: 2

Page Range: 43-54

Description:

Modern architecture is unimaginable without fair-faced concrete. However, there is no generally accepted method for design the suitable concrete composition to get the required surface quality. This paper presents the effect of saturation degree on fair-faced concrete surfaces and raises additional research areas with regard to the formwork geometry and packing density of aggregate. This study is the first part of a wider research that aims to work out a method for determination of the adequate saturation degree of cement paste depending on the geometrical proportions of the formwork to reach the highest surface quality.

Open Access: Yes

DOI: 10.1556/606.2018.13.2.5

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

Evaluation of fair-faced concrete surfaces using digital image processing

Kitti Karolyfi Ferenc Papp

Publication Name: Proceedings of the 12th Fib International Phd Symposium in Civil Engineering

Publication Date: 2018-01-01

Volume: Unknown

Issue: Unknown

Page Range: 1003-1010

Description:

In modern architecture concrete is increasingly used as a design feature as well as for its mechanical properties. Therefore, today's concrete architecture is characterized by various forms, textures and high surface quality. The exact determination of the surface quality requirements is crucial for being able to substantiate any deficiencies of the completed surface if necessary. According to the German, Austrian and Hungarian standards there are four concrete classes distinguished based on several aspects, such as porosity, discoloration, texture, etc. However, the standardized assessment methodologies for fair-faced concrete surfaces are mainly based on manual methods and several aspects can be evaluated only subjectively. The goal of the present study is to propose an objective method for the evaluation of the surface void ratio using photogrammetry and digital image processing techniques. The goal of the whole research is to develop an effective assessment method - taking all aspects into account - with which the overall evaluation and classification of the surfaces can be done automatically from one sampling. This method will lead to a quantitative, objective and therefore more reliable evaluation of the surface-quality of fair-faced concrete elements.

Open Access: Yes

DOI: DOI not available

Evaluation of fair-faced concrete surfaces using digital image processing

Kitti Karolyfi Ferenc Papp

Publication Name: Fib Symposium

Publication Date: 2018-01-01

Volume: Unknown

Issue: Unknown

Page Range: 1003-1010

Description:

In modem architecture concrete is increasingly used as a design feature as well as for its mechanical properties. Therefore, today’s concrete architecture is characterized by various forms, textures and high surface quality. The exact determination of the surface quality requirements is crucial for being able to substantiate any deficiencies of the completed surface if necessary. According to the German, Austrian and Hungarian standards there are four concrete classes distinguished based on several aspects, such as porosity, discoloration, texture, etc. However, the standardized assessment methodologies for fair-faced concrete surfaces are mainly based on manual methods and several aspects can be evaluated only sub-jectively. The goal of the present study is to propose an objective method for the evaluation of the surface void ratio using photogrammetry and digital image processing techniques. The goal of the whole research is to develop an effective assessment method - taking all aspects into account - with which the overall evaluation and classification of the surfaces can be done automatically from one sampling. This method will lead to a quantitative, objective and therefore more reliable evaluation of the surface-quality of fair-faced concrete elements.

Open Access: Yes

DOI: DOI not available

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

Buckling assessment of steel members through overall imperfection method

Ferenc Papp

Publication Name: Engineering Structures

Publication Date: 2016-01-01

Volume: 106

Issue: Unknown

Page Range: 124-136

Description:

This paper presents a proposal for an overall imperfection method utilizing Linear Buckling Analysis (LBA) and developed equivalent initial imperfection for the assessment of the out-of-plane buckling resistance of steel members. The equivalent initial imperfection for the flexural buckling assessment of columns subjected to compressive force has been specified in the Eurocode 3. In this paper this formula is reorganized in order to establish a suitable computer-aided procedure, and then the equivalent initial imperfection for the fundamental cases of lateral torsional buckling and coupled buckling are defined. (Fundamental case: simply-supported member with uniform cross-section subjected to uniformly distributed forces; the buckling resistance of this reference member has been defined by a standardized design equation based on theoretical and empirical background). The amplitude for the equivalent initial imperfection in the shape of the buckling mode is expressed with second-order normal stresses, on one hand calculated with the equivalent amplitude specified in the relevant standard (e.g. Eurocode 3), and on the other hand calculated with the initial imperfection in the shape of the buckling mode with arbitrary amplitude. The design formula derived for the fundamental case is generalized by the equivalent member concept. The stability assessment is carried out verifying the cross-section resistance of the designed member using second-order elastic analysis with the derived equivalent initial imperfection. The proposed overall imperfection method is adequate for computer-aided design methodology which is based on advanced elastic beam-column finite element method. The accuracy and practicality of the proposed method are illustrated for regular, irregular, single and multi-span members.

Open Access: Yes

DOI: 10.1016/j.engstruct.2015.10.021

Spatial stability analysis and global stability checks according to DIN EN 1993-1-1

A. Rubert Ferenc Papp J. Szalai

Publication Name: Bauingenieur

Publication Date: 2015-10-01

Volume: 90

Issue: October

Page Range: 469-477

Description:

This paper presents the spatial stability analysis and global stability checks according to the "General Method" of DIN EN 1993-1-1/clause 6.3.4 for complete steel structures of thin walled open sections. This is a software based design procedure for evaluating the global eigen-solutions (eigenvalue acrop and eigen- shape) using integrated stability analysis and standard check. It is compared to the classical method using different calculation models as well as suitable software for stress analysis and the global spatial stability analysis and check. For the numerical analysis (as it is the crucial point of the method) the 14 DOF beam-column finite element of ConSteel is used. The two examples demonstrate the very safe and uneconomic restrictions of the German NA of clause 6.3.4. According the author's experiences and [16] it is not recommended to use them.

Open Access: Yes

DOI: DOI not available

On design method of lateral-torsional buckling of beams: State of the art and a new proposal for a general type design method

Bettina Badari Ferenc Papp

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2015-01-01

Volume: 59

Issue: 2

Page Range: 179-192

Description:

After introducing the Eurocode standards several theses have been published on the now much-discussed phenomenon of lateral-torsional buckling of steel structural elements under pure bending. According that, researchers are working on the development of such new design methods which can solve the problems of the design formulae given by the EN 1993-1-1. This paper gives a detailed review on the proposals for novel hand calculation procedures for the prediction of LT buckling resistance of beams. Nowadays, the application of structural design softwares in practical engineering becomes more common and widespread. Recognizing this growing interest, the main objective of our research work is the development of a novel, computer-aided design method. In this paper the details of a general type stability design procedure for the determination of the LT buckling resistance of members under pure bending are introduced. Here, the theoretical basis of the proposed method is clarified, the calculation procedure is detailed and some results for the evaluation of the appropriateness of the method is also presented. Based on the evaluations it can be stated that the new, general type design method is properly accurate and has several advantages on the stability check of beams under bending.

Open Access: Yes

DOI: 10.3311/PPci.7837

A new assessment methodology for fair-faced concrete surfaces based on digital image processing

Andras Horvath Kitti Karolyfi Ferenc Papp

Publication Name: Fib Symposium

Publication Date: 2020-01-01

Volume: Unknown

Issue: Unknown

Page Range: 288-295

Description:

Fair-faced concrete elements have become even more popular in architecture because of their pure aesthetics and favourable material properties. The europian standards and guidelines are usually specifying four classes regarding to the surface quality. However, the strandard assessment methodologies are based only on manual methods and they are very subjective in some cases. In order to increase the efficiency and accuary of the evaluation a new methodology is proposed using digital image processing. In this paper the basis of the evaluation method made by using the Python 3.6 software is presented by focusing on the surface void ratio which is one of the most common surface defects of fair-faced concrete structures.

Open Access: Yes

DOI: DOI not available

Structural behavior of built-up I-shaped cold-formed steel beams with edge-stiffened holes, unstiffened holes, plain webs, and batten reinforcement

Ardalan B. Hussein Ferenc Papp

Publication Name: Results in Engineering

Publication Date: 2025-12-01

Volume: 28

Issue: Unknown

Page Range: Unknown

Description:

Perforated cold-formed steel (PCFS) back-to-back channel beams are increasingly gaining popularity in the building sector due to their numerous advantages and economic benefits. Notably, their lightweight nature allows for easier handling and installation, while the holes in PCFS beams facilitate the accommodation of utilities such as electrical and plumbing installations. In this study, a geometrically and materially nonlinear finite element model (FEM) was developed and validated using experimental data from existing literature. The validation results indicated a strong correlation, with the ratios of FEM and Direct Strength Method (DSM) predictions to experimental outcomes being 1.007 and 0.945, respectively. This demonstrates a significant agreement among experimental data, FEM analysis, and moment capacity estimations based on American Iron and Steel Institute (AISI) Standards, although AISI predictions were found to underestimate moment capacities by approximately 5.5 %. Following model validation, an extensive parametric study involving 192 FEM simulations was conducted to evaluate the influence of hole size, hole geometry, edge stiffeners, and batten reinforcements on the moment-carrying capacity of built-up I-shaped CFS beams. The findings indicate that, in comparison with beams having plain webs, the presence of web openings leads to a reduction in moment capacity of approximately 10 %, 9 %, 9 %, and 6 % for circular, slotted, square, and rectangular holes, respectively. Furthermore, the results demonstrate that the inclusion of stiffeners around web openings, together with batten reinforcement, markedly improves the structural performance of PCFS built-up beams. In particular, the maximum enhancement in moment capacity of beams with batten reinforcement and edge-stiffened holes, relative to those with unstiffened holes, is about 9 %, 10 %, 13 %, and 14 % for circular, rectangular, square, and slotted holes, respectively. Overall, the findings offer valuable insights into the structural behavior of perforated built-up CFS beams and emphasize the effectiveness of web hole stiffening and batten reinforcement strategies in mitigating strength reductions caused by web perforations.

Open Access: Yes

DOI: 10.1016/j.rineng.2025.107545