bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Eurocode‐compliant Design Approach for Cold‐Formed Steel Sections
Authors: Ungermann Dieter , Lemański Tim , Brune Bettina 
Published: September 2022

AbstractA new, Eurocode‐compliant design approach based on the Direct Strength Method (DSM) combined with EN 1993‐1‐3 was developed for the design of thin‐walled cold‐formed steel sections. The new design approach transfers cross‐sectional resistance according to DSM, based on numerical elastic buckling analyses on the gross cross‐section, into the global stability check according to EN 1993‐1‐3. Experimental investigations on various perforated and unperforated cold‐formed sections in compression and bending serve to verify the new design approach. In addition, a numerical model was developed, it was calibrated on the test results and used for further parametric analyses on the load‐carrying capacity of cold‐formed sections.
Energy‐based Equations for Local and Anti‐symmetric Distortional Modes of Lipped Channel Columns
Authors: de Salles Guilherme , Taissum Daniel , Batista Eduardo 
Published: September 2022

AbstractThis paper presents an energy‐based approach to obtain the critical length and stress of local (L) and anti‐symmetric distortional (D2) modes of simply supported lipped channel columns. For each mode, deformed shapes are assumed and the Rayleigh Quotient Method is applied to obtain analytical expressions for the buckling stress. The shape functions adopted for local buckling ensure compatibility of rotation and bending moments at wall junctions and at the stiffener's free end. For the D2 mode, equilibrium of bending and twisting moments are considered leading to an analytical derivation of the mode's warping stress distribution. While for L mode it is not feasible to obtain a closed expression for the critical length (but a simple length testing procedure is sufficient), for D2 mode an expression dependent on geometrical properties is derived. The developed equations for L and D2 modes are validated against CUFSM's pure local modes and GBTul's pure D2 mode (mode 6 in GBTul convention) respectively. For sections with flange‐to‐web width ratio, bf/bw, ranging from 0.2 to 1.0 and lip‐to‐web width ratio, bs/bw, from 0.1 to 0.4 the average ratios obtained for critical stresses (σcr,reference/σcr,proposed) are 1.014±0.019 and 1.011 ± 0.014 for L and D2 modes respectively.
New Test Bed for Corroded Large Size Bolted Connections Under Fatigue and Pretension
Authors: Betz Kai Stephan , Schaumann Peter , Kulikowski Jan 
Published: September 2022

AbstractIn this paper, a newly developed test method to evaluate the influence of corrosion on pretension and fatigue of bolted connections is presented, suitable from size M36 to M72. A first preliminary series of M30 property class 10.9 bolts were tested to validate the individual test setup steps and to detect challenges and improvement. Pretension load tests, static load tests and fatigue load tests were performed while monitoring stresses on a small number of bolts. The method presented is used to compare different coatings for bolts, like Hot‐dip galvanized coatings and zinc flake coatings, as well as nano‐coatings. To create a realistic approach on offshore corrosion and loading conditions, the bolts will be preloaded in a clamping device resembling the ring flange of an offshore wind tower segment. In a next step, the bolts are corroded in a climate chamber, using the salt spray test or condensation test. Following the corrosion process, the bolts are tested for fatigue without loosening the nut and damaging the thread. Before corrosion and after the fatigue test, 3D surface scans are made to document the corrosion process and to create numerical models of the corroded surface. The method presented offers a new way to evaluate fatigue, pretension and corrosion effects, which is validated on bolts M30 property class 10.9. In close future, the test method is used for larger series of corroded M36 property class 10.9 bolts, having different coating systems applied.
Strengthening of Steel Beam by Inclined Stiffeners
Authors: Vild Martin , Bajer Miroslav , Barnat Jan , Holomek Josef 
Published: September 2022

AbstractThere are several ways how to increase the bending resistance of a beam. The simplest method is to increase the cross‐section size. But this method may not be the most efficient or feasible, especially in the case of an existing building in need of strengthening. In this paper, the method of strengthening a beam by welded inclined stiffeners is investigated. The beam is susceptible to lateral‐torsional buckling. A sensitivity study is prepared for the beam length and cross‐section size, boundary conditions, and the number and position of stiffeners. A validated numerical model using Component‐based Finite Element Method is used. The model combines shell elements for analyzed member and bar elements for related members. The joints are included in the model. Bolts and welds are simulated by special nonlinear elements with resistance based on codes. Validation and verification of the model is presented. It is based on the experiment performed at AdMaS center at Brno University of Technology of a beam with semi‐rigid joints loaded by three‐point bending. The model is verified by comparing critical buckling load and buckling resistances of columns and beams with clear boundary conditions. The results are also compared to those by another general finite element software, ANSYS and ABAQUS.
Numerical Investigation of Doubler Plate Reinforced Tubular T‐joints under Chord Compression Loads
Authors: Pamplona Gil , Vellasco Pedro , Tenchini André , Lima Luciano , Rodrigues Monique 
Published: September 2022

AbstractTubular profiles present geometric properties that enable a better structural behaviour in comparison with other cross‐sections when subjected to torsion. In regards to the joints between its elements, there are a few parameters that govern the design of the T‐joint resistance and change its failure mode. This paper presents a numerical investigation of square hollow sections (SHS) T‐joints with doubler plate reinforcement on the upper chord face under axial compression. The geometrical parameters are the slenderness chord, brace to chord width ratio, and reinforcement plate thickness combined with a certain level of axial compression on the chord. A numerical model has been developed compared with experimental tests. In addition, a parametric study was performed based in order to evaluate the parameters that influence the structural behaviour of reinforced T‐joint. Concerning outcomes, the increase of reinforcement plate thickness was responsible for the improvement of the joint capacity. In opposite to recommended by actual codes, the compression applied on the chord reduced the joint resistance mainly for those slender chord wall. Comparing with formulation from both code and other works, it was possible to conclude that there is an unsafe level from the actual codes.
Imperfections for the LTB‐design of Members with I‐sections
Authors: Stroetmann Richard , Fominow Sergei 
Published: September 2022

AbstractFor the stability assessment of members and structures according to EN 1993‐1‐1 the equivalent member method, the geometrical nonlinear calculation with equivalent geometrical imperfections or the GMNIA analysis with geometrical imperfections and residual stresses can be used alternatively. The second possibility requires a corresponding model for the cross‐section resistance. For the verification of lateral torsional buckling, bow imperfections e0 out of plane are defined, which lead in combination with the given loading in plane and the geometrical non‐linear analysis to bending Mz and torsion of the members. The amplitudes of the imperfections are highly dependent on the nature of the approach (e.g., scaling of the buckling shape, assumption of bow imperfections) and the resistance model for the members. Within the framework of the scientific work supervised by the TU Dresden and the TU Darmstadt [1], extensive parameter studies were carried out to calibrate imperfections for lateral torsional buckling based on the GMNIA. After determining the nature of imperfections and the design models for section resistance, this paper presents results of these parameter studies and shows the calibration of imperfections for a standardisation proposal based on EN1993‐1‐1. The evaluation of the data in combination with the necessary simplifications for the design practice leads to appropriate definitions of imperfection values e0,LT and the necessary differentiations.
Out‐of‐plane Stability Design by GMNIA – Equivalent Imperfections and Strain Limits
Authors: Quan Chunyan , Walport Fiona , Kucukler Merih , Gardner Leroy 
Published: September 2022

AbstractAn accurate and consistent approach to the out‐of‐plane stability design of steel beams and structures utilising geometrically and materially nonlinear analysis with imperfections (GMNIA) and strain limits is proposed. The method is implemented using computationally efficient beam elements, with the ultimate structural resistance defined either by (i) the ultimate load factor or (ii) the load factor at which a strain limit, determined on the basis of the continuous strength method (CSM), is attained, whichever occurs first. In the present paper, the scope of this method is extended from the in‐plane design of steel structures and structural components to scenarios in which out‐of‐plane stability effects, with a focus on lateral‐torsional buckling (LTB), govern. First, two shapes and corresponding amplitudes of equivalent imperfections, which consider the combined influence of both geometric imperfections and residual stresses, for the out‐of‐stability design of steel and stainless steel members by GMNIA are established. The existing CSM strain limits for in‐plane design are then extended to allow for the influence of shear, torsion and warping, to enable their general applicability to three‐dimensional buckling problems. It is shown that employing the proposed design method together with the proposed equivalent imperfections generally provides more accurate and consistent ultimate strength predictions than traditional Eurocode design calculations and also streamlines the design process by eliminating the need for cross‐section classification and individual member design checks.
Revision of EN 1993‐1‐1 – Design Rules for Member Buckling
Authors: Bureau Alain , Snijder Bert , Knobloch Markus , Kuhlmann Ulrike , Gardner Leroy , Taras Andreas , da Silva Luis 
Published: September 2022

AbstractIn the framework of the revision of Eurocode 3 Part 1‐1, several amendments have been proposed and accepted in order to improve the rules for the resistance to member buckling. For clarification, a flow‐chart connecting the global analysis (1st or 2nd order), the imperfections and the type of verification has been implemented for ease of use. Since the publication of the standard in 2005, many research projects have been carried out across Europe on this topic and their results have contributed to provide appropriate answers to problems identified in practice. Therefore, the revised code provides new design rules for stability. Important works of calibration have been performed in these different projects to derive appropriate values of the partial factor on the resistance side.For example, a new formulation for lateral torsional buckling has been introduced for the calculation of the reduction factor. The consequence is a reduction of the discrepancy between the results obtained by these new methods and those from experimental or numerical tests. In order to extend the scope of Eurocode 3 Part 1‐1, additional methods have been implemented in an annex to cover the stability of members with mono‐symmetric cross‐section under compression axial force, biaxial bending, with or without torsion. The format of the resistance criteria remains similar to the format of the current interaction formulae so that the designers can easily identify the evolution of the rules. This paper presents in a systematic way the new implementations in prEN 1993‐1‐1.
Structural Stability Verification for Steel Beam‐columns in Fire ‐ a Consistent Approach with Ambient Temperature Rules
Authors: Schaper Lukas , Knobloch Markus 
Published: September 2022

AbstractSteel structures are characterized by a slender design, which makes stability verifications particularly important. While the design methods for steel members at ambient temperatures have been continuously developed and revised for the second generation of Eurocode 3, the method for elevated temperatures in prEN 1993‐1‐2 is still based on the corresponding rules of ENV 1993‐1‐1 of 1992. This leads to a divergence of methodology for ambient and elevated temperatures and to unnecessarily complex design methods for the engineering practice. Therefore, a harmonization of design models for ambient temperature and fire design is desirable.This paper presents a theoretical and numerical study on the stability behaviour of steel members at elevated temperatures. The structural fire behaviour of steel beams, columns and beam‐columns, i.e. flexural buckling under pure compression, lateral torsional buckling under major axis bending and spatial buckling of members under combined bending and axial compression has been investigated. Based on results available in the literature as well as an extensive numerical parametric study, reduction factors and interaction factors were determined. The new reduction and interaction factors were used to develop a design model for the member stability verification in fire that follows the format of FprEN 1993‐1‐1. Thus, engineering practice is provided with a harmonized verification method for steel members in bending and compression for ambient temperature and fire design.
Application of Machine Learning to Predict the Mechanical Properties of High Strength Steel at Elevated Temperature
Authors: Shaheen Mohamed , Presswood Rebecca , Afshan Sheida 
Published: September 2022

AbstractHigh strength steels are increasingly used in several areas of construction offering structural solutions with a high strength‐to‐weight ratio. Safe fire design of these structures relies heavily on accurate predictions of mechanical properties of the material with temperature. This paper presents the results obtained using Machine Learning (ML) algorithms to predict the mechanical properties, including ultimate tensile strength, yield strength and elastic modulus, of high strength steel plate material. The mechanical properties collected from the literature experimental tests show a high degree of scatter, implying that they are influenced significantly by various factors such as the testing method, manufacturing process and chemical composition. However, the current methods for predicting the mechanical properties of high strength steels at elevated temperatures by using ‘reduction factors’ adopted by the structural design codes do not consider these effects and may lead to inaccurate predictions. These deficiencies are overcome by using a ML‐based prediction method, where the effects of the chemical composition on these reduction factors are considered. Deep Neural Networks is trained to predict the mechanical properties with temperatures. The ML‐based method together with the obtained results are presented where it is shown that the trained algorithm gives an excellent correlation coefficient with very small error value.
Direct Design of Stainless Steel Frames: Recommendations and Case Studies
Authors: Arrayago Itsaso , Rasmussen Kim J.R. , Zhang Hao , Real Esther 
Published: September 2022

AbstractAcknowledging the potential of system‐based design approaches, most international design standards for steel structures include preliminary versions of such alternative design methods. The Direct Design Method (DDM) is one of these approaches, which allows designing steel structures directly using advanced numerical analyses without requiring further member checks. This paper presents the DDM design (and verification) procedure and summarizes the key aspects of the advanced finite element model necessary for the determination of the system strength, with an emphasis on cold‐formed stainless steel portal frames. Through the design of two frames, the DDM design procedure is illustrated and the resulting cross‐sections are compared with those derived using the traditional two‐step design approach in the Eurocode and ASCE design frameworks. The results demonstrate that the DDM verification process is simpler and more direct, and that lighter structures are obtained when designing using the DDM for strength considerations. Finally, this paper also highlights that allowing larger deformations in the ultimate limit state design for the DDM does not have additional negative effects on the serviceability requirements if compared to the traditional two‐step design approach.
Numerical Modelling for Resistance of Welds in Steel Structures from High‐Strength Steel
Authors: Ghimire Abhishek , Wald František 
Published: September 2022

AbstractThis paper presents the overview of the numerical design model of welds in structural steels using finite element shell element. Many researches are emerging in the field of advanced modelling of welds in steel connections by using finite element analysis in order to represent accurate geometry and stiffness of welds. There are several weld modelling techniques used for the computation of structural hot spot stresses in fatigue; oblique shell elements, rigid links and increased thickness techniques. The article intends to eliminate the gaps in knowledge about the numerical modelling of welds using shell elements to compute the direct resistance of the welds in structural steels.This paper focuses on the study of numerical design calculation for the resistance of the welds in steel structures from high‐strength steels. Inclined shell elements are used to represent geometry and the stiffness of the welds during modelling of transverse fillet welds in double lapped joint. Several design standards, and guidelines are widely used to check the resistance of the welds. To verify and validate the results of finite element models, analytical and experiment results from literature are used in the undermatching welding conditions. Based on numerical design calculations, a general approach of inclined shell element is recommended to represent the welds for computation of the direct resistance of the welds in steel structures.
Large Scale Buckling Tests of Bar Bundle Columns
Authors: Röß Rudolf , Schäfers Michael , Mensinger Martin , Ameri Shaghayegh , Zehfuß Jochen 
Published: September 2022

AbstractBar bundle columns are a new type of composite column. For this purpose, a bundle of high‐strength reinforcing bars with a yield strength of 670 N/mm2 is set in a steel tube and then grouted with mortar.Due to the lower cross‐sectional thickness of the threaded bars, no strength reduction due to material thickness effects is required compared to a solid core cross‐section. The bundling of the steel bars results in a high steel content in relation to the total cross‐section; as a result, the novel composite column achieves load‐bearing capacities that are usually typical for columns with significantly larger cross‐sectional dimensions. In addition, bar bundle columns exhibit better heating behavior compared to composite columns with solid cross sections, as the bars only touch at certain points. As part of the AiF research project IGF‐ 20352 N, 10 buckling tests with lengths between 3.5 m and 8 m were carried out. Cross sections with 1, 3, 7 and 19 bars as core were investigated. The experimental setup, the measurement technique and the results are shown here.
Influence of Longitudinal Stiffeners on the Local Stresses in Crane Runway Girders ‐ Experimental and Numerical Investigations
Authors: Kettler Markus , Unterweger Harald 
Published: September 2022

AbstractCrane runway girders with slender webs are often strengthened by additional longitudinal stiffeners to avoid local plate buckling of the web. It is expected that this leads to an increase of local vertical bending stresses near the top edge of the web due to eccentric wheel loads. These local stresses have a significant impact on the fatigue design of the flange‐to‐web connections and the required girder dimensions. However, the current design model in EN 1993‐6 for crane supporting structures does not consider this effect. In order to study this behaviour in detail, laboratory tests and numerical finite element calculations are carried out on crane runway girders with longitudinal stiffeners at different positions of the web. It is verified that the local stresses increase with decreasing distance of the stiffeners from the top edge of the web plate. Based on these results and a modified proposal from literature, the design model in EN 1993‐6 is extended to also cover additional stiffeners. Finally, the model is validated through a comparison with tests and numerical calculations.
Nonlinear Thermal Buckling Analysis of Thin‐walled Structures: Solid‐shell Discretization, Continuation Method and Reduction Technique
Authors: Liguori Francesco S. , Magisano Domenico , Leonetti Leonardo , Madeo Antonio , Garcea Giovanni 
Published: September 2022

AbstractThis work presents an accurate and efficient numerical tool for geometrically nonlinear thermoelastic analyses of thin‐walled structures. The structure is discretized by an isogeometric solid‐shell model with an accurate approximation of geometry and kinematics avoiding the parameterization of finite rotations. An efficient modeling of thermal strains, temperature‐dependent materials and general temperature profiles based on a numerical pre‐integration through the shell thickness is proposed. Then, a generalized path‐following method is developed for solving the discrete equations with the temperature amplifier as additional unknown, in order to trace the temperature‐displacement nonlinear curve also in case of limit points and unstable paths. A consistent definition of the tangent operators and a mixed integration point strategy give a robust and efficient analysis. Finally, a reduction technique is derived for a quick estimate of the nonlinear thermal buckling point. The reduced model consists of the initial path tangent, the first linearized buckling modes and their second order corrections. Numerical applications are given.
A New Displacement‐based Design Procedure for the Retrofitting of RC Buildings with Steel Braces
Authors: Moreira Rodrigo Falcão , Castro José Miguel , Varum Humberto 
Published: September 2022

AbstractThis paper proposes a new displacement‐based methodology for the design of concentric steel‐brace retrofitting systems for RC framed buildings. It relies on deformation control for different levels of seismic intensity and explicitly considers the interaction between both structural systems. When dealing with the seismic assessment and strengthening of existing RC buildings, practitioners are likely to resort to the q‐factor approach, due to its simplicity and popularity for the design of new structures. However, in non‐seismically designed RC structures, the uncertainties associated to the nonlinear behaviour are relevant, making it therefore very difficult to define a direct correlation between the real internal forces that develop in structural members during the seismic excitation, and those experienced by an equivalent indefinitely elastic structure. Consequently, several authors have argued that the force‐based seismic assessment and retrofitting of existing RC structures will not yield, in general, satisfactory results. The design methodology proposed herein thus addresses this limitation, offering a solution which is intuitive and fit to be used in practical applications, while providing retrofitted structures with adequate and more predictable seismic performance.