bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatigue behavior of girder with flange thickness transitions and cope holes ‐ tests and simulations
Authors: Röscher Stefanie , Knobloch Markus , Derler Christoph , Langwieser Martin , Unterweger Harald
Published: September 2023

The fatigue behavior of steel girders with flange thickness transition and cope hole has been experimentally analyzed with two large‐scale cyclic tests. Special attention is paid to the arising and interacting local effects. The fatigue tests have been conducted in a four‐point bending setup. Both girders have shown fatigue‐induced failure at the flange butt welds at the thickness transition. The experimental results are presented in terms of fatigue life, differentiating the initiation and propagation life, as well as observed crack position and shape. Moreover, an advanced fatigue life prediction using the Two‐Stage‐Model is applied to the tested girders. The Two‐Stage‐Model applies the Strain‐Life and the Crack Propagation Approach to assess the total fatigue life. Thereby, the number of cycles as well as the crack shape show a good agreement with the experimental results and proves the applicability of the Two‐Stage Model for an advanced fatigue assessment.
Prediction of prestress level in steel structures strengthened by bonded Fe‐SMA strips
Authors: Li Lingzhen , Wang Sizhe , Chatzi Eleni , Motavalli Masoud , Ghafoori Elyas
Published: September 2023

Previous studies have demonstrated a great potential of prestressed strengthening of steel structures employing iron‐based shape memory alloys (Fe‐SMAs). A bonded Fe‐SMA strengthening solution has been proposed with partial activation, in which the prestrained Fe‐SMA strip is fully bonded onto the steel structure, and the middle region of the Fe‐SMA strip is heated to generate prestress. The two ends remain unheated and transfer the prestress to the parent structure. In this study, a column model and a beam model are developed to analyze the prestress level in the steel structures strengthened by bonded Fe‐SMA. The predicted strains in the parent structure are in excellent agreement with the experimental measurement from the literature.
Experimental tests of a modular composite frame corner for integral abutment bridges with sheet‐piling foundations
Authors: Rittich Nils , Wolters Kevin , Nonn Jonas , Feldmann Markus , Ivanov Stoyan , Tibolt Mike
Published: September 2023

With the increasing need to replace ageing bridge infrastructure, new concepts for sustainable constructions are needed. Ways to achieve this include material choice, concept design and the consideration of life‐cycle‐costs. Within the scope of FOSTA research project P1521, a concept will be derived for a modular frame corner for bridge spans up to 45 m. The load transfer of horizontal and vertical forces, as well as the bending moment of the frame corner, are analyzed in experimental tests and subsequent numerical studies.

To determine the bending resistance, load paths and critical details of the connection, the node is split into an upper and lower part, connecting the main girder and the sheet‐piles respectively to the abutment. Composite dowels with high fatigue resistance are used to transfer both forces and moments through a newly designed shear connection. This article looks at the results of 4 static tests from the upper‐part series as well as numerical studies.

The results of both experimental as well as numerical models shows a high load bearing capacity of the connection with the composite dowels contributing positively to the constraining of the main girder. The concept shows promising results for future application.
Experimental investigations on composite columns: round hollow sections with embedded solid core section made of high‐strength steel
Authors: Nonn Jonas , Janiak Till , Wolters Kevin , Rittich Nils , Feldmann Markus
Published: September 2023

Due to price developments, steel composite columns have lost significant market shares to prefabricated reinforced concrete columns in recent years. Using high‐strength steel (HSS) in composite columns may offer a way of reviving the market for these kinds of columns. There are different ways of using HSS for composite columns, however, many are associated with the use of welds. Welding of HSS can lead to cold and hot cracks, while also causing high residual stresses which can lead to a decrease of the load bearing capacity. Hollow section composite columns with embedded solid core cross‐sections and using HSS may offer a way to solve this problem.

Round hollow sections with embedded solid core as a composite column have so far only been investigated for steel grades up to S460. Within the scope of German FOSTA research project P1501, a concept for a test setup is derived to investigate hollow sections with embedded solid core as a composite column made of HSS. The experimental results will be used as the basis for further numerical studies, which will be discussed within the scope of this paper. Based on these models, parametric studies will be conducted in the future to validate design concepts.
Experimental Investigations on load‐bearing Capacity and characteristic Preload of Lockstud Systems
Authors: Meyer Melanie Hagemann née , Schwarz Mathias , Glienke Ralf , Schwerdt Daniela , Henkel Knuth‐Michael
Published: September 2023

The joining technology Lockstud System combines the advantages of a bolt thread for making a tapped thread joint and the advantages of a lockbolt. On the tapped thread joining side, the bolt has a metric ISO thread. On the assembly side, the bolt has a grooved geometry like lockbolts of type A, B and C. This article publishes results on the mechanical‐technological properties, the assembly process with the initial preload, the preload losses due to embedding under long period of time and the load‐bearing capacity subjected to static and fatigue normal stress for Lockstud systems of nominal diameters M12, M16 and M20 (strength grade 10.9) compared to conventional bolt assemblies and lockbolt systems.
New fire resistance design approach for concrete‐filled cold‐formed steel (CF‐CFS) built‐up composite column
Authors: Rahnavard Rohola , Craveiro Hélder D. , Simões Rui
Published: September 2023

Prior research investigated the fire resistance prediction of the concrete‐filled cold‐formed steel (CF‐CFS) built‐up columns when subjected to axial compression and high temperatures. However, a complex heat transfer analysis is needed to calculate the temperature development of the steel and concrete components of the composite cross‐section to predict the fire resistance of a composite column, as provided in EN1994‐1‐2. In order to estimate equivalent temperatures for the steel and concrete used in CF‐CFS built‐up column sections, this research provides a series of empirical formulae. A two‐dimensional heat transfer analysis calibrates a finite element model to estimate temperature across the CF‐CFS built‐up column sections. The concrete infill was simplified by separating into an inner and outer core. The empirical formulas' accuracy was assessed by comparing them with 2D heat transfer analysis results. Finally, the fire resistance of a CF‐CFS column was obtained using numerical simulation and compared with the analytical prediction following EN 1994‐1‐2 incorporated with the current empirical formulation. The results showed a high accuracy of the empirical formulation to determine the equivalent temperatures of the steel and concrete core components.
Buckling resistance of angle bracing members with one‐leg bolted end connections
Authors: Antonodimitraki Sofia , Bezas Marios‐Zois , Demonceau Jean‐ François , Vayas Ioannis , Maesschalck Jan , Anwaar Muhammad‐Omer , Jaspart Jean‐Pierre
Published: September 2023

Steel angle members are widely used for the construction of lattice towers, mainly because of easy assembly on site and compact transport. Bracing members, especially, are connected directly or through gusset plates to the adjacent members with one or more bolts on one leg only. This type of connection provides some rotational restraint at the ends of the bracing, but also induces eccentricities. This paper presents the European normative framework covering the design against buckling of angle bracing members in lattice towers and identifies the differences between the different design rules available in existing normative documents. These differences are quantified through worked examples and the normative design procedures are evaluated against experimental results from the literature. The influence on the buckling resistance of various parameters, such as the support conditions and the steel grade, covering members made of both conventional mild steel as well as high strength (S460) steel, is also studied and quantified. Finally, useful conclusions are drawn about the accuracy of the available design rules.
Development of an automated quality assurance approach for welded joints
Authors: Dänekas Christian , Schaumann Peter , Ghafoori Elyas , Heikebrügge Steffen , Heide Klaas Maximilian , Breidenstein Bernd
Published: September 2023

A more economical and resource‐saving construction of offshore wind energy converters is necessary in order to achieve climate policy objectives. Automated quality assurance of welded joints offers a great potential to enable less conservative manufacturing of the support structures. The main objective of this study is to find a correlation between the parameters that describe the weld geometry and the fatigue life. Butt welded specimens were scanned with a laser line sensor. The weld seam parameters including notch radius and flank angle were evaluated and the stress concentration factors in the notch were determined considering the microstructural support effect. A series of constant amplitude fatigue tests was conducted in order to evaluate S‐N‐curves according to nominal stress approach and notch stress approach. The fatigue results show a good correlation between notch stresses and fatigue life, demonstrating the great potential of the quality assurance approach for evaluating the weld seam geometries.
Orthotropic composite slabs for road bridges
Authors: Stroetmann Richard , Wisnewski Joachim , Mansperger Tobias
Published: September 2023

Large increases in traffic loads led to extensive fatigue damages to existing orthotropic steel deck slabs of road bridges. Reinforced concrete bridges and conventional composite bridges are less susceptible to fatigue but considerably heavier. The ortho‐composite slab is a lightweight and robust alternative construction method, which retains the advantages of the previously mentioned construction methods, but eliminates their disadvantages. Within the framework of the AiF‐FOSTA research project P1265 [1], the construction of the bridge deck was developed using dowel strips as composite elements with high load‐bearing capacity and fatigue resistance. The principle of area composite with loading of the dowel strips in longitudinal and transverse direction was used. Extensive experimental and structural mechanics studies were conducted, particularly investigating the load‐bearing capacity and fatigue strength of the ortho‐composite slab under local load application. The following article describes the load‐bearing structure of the ortho‐composite slab and the motivation for the research project P1265. It gives an overview of the experimental investigations carried out. Finally, the article presents pilot projects that were carried out to apply the construction method. In further articles on Eurosteel, the experimental investigations and structural‐mechanical calculations are described in more detail (see [2] and [3]).
Fatigue strength of the joint of steel cantilevers in composite bridges
Authors: Erlemann Raphael , Kraus Josef Karl , Geissler Karsten
Published: September 2023

Box girders with steel cantilevers underneath the deck are frequently used in the design of composite steel bridges. Hereby, the welded joints between the main girder and the transverse system have to endure fatigue loads. Current design specifications for this joint, e.g., a tapering in thickness of the top flanges at the same position of a transition radius, are complex to manufacture and provide a higher fatigue resistance than necessary. This article addresses the optimization of this structural detail, which is realized hundreds of times per structure. Several laboratory tests and numerical simulations were carried out regarding the load‐bearing behavior and the fatigue safety of the cantilevers as double‐T‐sections and as box girders. Additionally, 60 fatigue tests were conducted on small‐scale specimen to classify the resulting simplified design variants in detail categories of the nominal stress concept. As a result, two design recommendations are proposed for the joint at the intersecting top flanges. Moreover, the effect of an unplanned axial misalignment on the fatigue strength of the joint at the bottom flange is quantified.
Partially sleeved joints between hollow sections using self‐drilling screws.
Authors: López‐Colina Carlos , García Ismael , Serrano Miguel A. , Picallo Diego G. , Vigón Paula
Published: September 2023

The present piece of research studies partial sleeve joints between similar rectangular tubes, involving bolts under shear as joining means. These are connections between two rectangular hollow sections that can be fitted one in another just by adequately cutting some faces and then bolting. For these elements, the use of self‐drilling screws is evaluated here. These connections could be removable and reusable in some cases, providing more sustainability. They also present semi‐rigid behaviour, which leads to weight saving structures and makes them ideal in many situations for structures like greenhouses or other light portal frames.

The structural joints following this typology can be planned as beam‐column, ridge, or even column‐base plate joints. This paper is focused on the initial experimental results of the first two cases under bending moments, comparing them with some simplified analytical assumptions for the strength and the stiffness. These calculations are based on eccentric bolted connections with in‐plane moments but considering some particularities of these joints and joining means (self‐drilling screws).
Life‐Cycle‐Assessment of purlin systems: the influence of the low carbon high strength steels in CO2eq. emissions
Authors: de Paula Filho José Humberto , Guimarães Leonardo , Guth Jérôme , Marioni Luca
Published: September 2023

Due to the decarbonization of the energy sector, embodied carbon has been recognized as the dominant climate impact driver. In response, countries are currently accelerating their efforts to comply with climate change commitments and regulations, pressure grows for the construction sector to reduce its impact rapidly.

In the present paper, the life cycle assessments (LCA) of purlin roof systems, used as secondary structural elements on single‐story industrial buildings, are compared. Three structural materials are considered: metallic‐coated structural steel, reinforced concrete, and structural timber. In addition, different steel grades are compared to highlight the environmental benefits of using high‐strength steels (HSS) allowing weight‐optimized design.

The LCA focuses on the product stage (modules A1‐A3), transport (module A4), end‐of‐life (module C), and the benefits and loads beyond the system boundary (module D). The life cycle inventory (LCI) is composed of construction environmental product declarations (EPD) published according to EN 15804. All the LCA evaluations are performed using the commercial software One Click LCA following the recommendations of EN 15978.
Investigations on the historical Széchenyi chain bridge
Authors: Kövesdi Balázs , Kollár Dénes , Szabó Bence , Dunai László
Published: September 2023

The Széchenyi chain bridge is an almost 170‐year‐old historical structure located in the downtown of Budapest, which has been reconstructed between 2020‐2022. The chain system of the bridge is more than 100 years old, and the rotational capacity of the pins is questionable due to corrosion and friction. This phenomenon significantly influences the static behavior of the chain elements and the entire suspending system. Therefore, connected to the renewal process, the Budapest University of Technology and Economics, Department of Structural Engineering investigated the rotational capacity of the pins of the chain elements, and the corrosion grade of the chain bars. To investigate these two issues, three on‐site measurements are executed: (i) loading test to measure the bending moments in the chains and checking the rotation of the pins, (ii) one‐year‐long monitoring system operating during the renewal process and checking the internal force distribution of the structure during the reconstruction phases, and (iii) corrosion measurements on the chain bars. The paper introduces the measurement results, the main conclusions, and their practical application possibilities in the renewal process.
Load carrying capacity of star‐battened angle members made of S460 steel in compression
Authors: Bezas Marios‐Zois , Antonodimitraki Sofia , Beyer Andre , Anwaar Muhammad‐Omer , Maesschalck Jan , Jaspart Jean‐Pierre , Demonceau Jean‐François
Published: September 2023

Lattice towers are extensively built in Europe and worldwide to serve power transmission purposes. Their members mainly consist of single angle profiles, while built‐up sections, such as star‐battened ones, are usually preferred for the strengthening of individual members or in case of very high compression loads. Recent upwards developments of the power grid requests also lead to the need to use high strength steels (HSS) for the design and construction of higher and heavier loaded steel lattice transmission towers. Within the present paper, investigations conducted on the bearing capacity of a star‐battened member made of two S460 L250×250×28 angles are presented, even if the conclusions may be extended to any angle size and steel grade.

Firstly, a critical review of the current European normative documents (EN 50341, EN1993‐1‐3, prEN1993‐3) is made and the buckling resistance of the above‐mentioned member is evaluated. Secondly, the results of an experimental compression test performed on the studied member are presented; these results are complemented by a full non‐linear finite element numerical simulation. All the obtained results are finally compared and discussed.
Numerical studies on the torsional behavior of octagonal concrete‐filled linked double steel tubes
Authors: Sulthana Mashudha
Published: September 2023

The concrete confinement is improved in octagonal concrete‐filled double steel tubular (OCFLDST) columns by linking the steel tubes with steel plates and thereby it enhances ductility. It has the potential to improve the torsional resistance in concrete‐filled steel tubular cross‐sections. This paper investigates the torsional behavior of OCFLDST through analytical and numerical investigations. The numerical model for OCFLDST is developed in ABAQUS and validated using test data available in the literature for axial loading conditions. The validated model is then subjected to pure torsion to study the torsional behavior of OCFLDST. In comparison with bare steel tubes, concrete filling of linked steel tubes has increased the torsional resistance by 33%. Further, parametric studies are conducted to understand the influence of various parameters like yield strength and thickness of the outer steel tube, compressive strength of concrete, the thickness of the linking plates, and axial load ratio. The numerical results are compared with the proposed expression for finding the torsional capacity based on St. Venant's torsion theory. The proposed capacity prediction is in good agreement with the numerical results.
Experimental evaluation of the load‐bearing capacity of steel‐reinforced CFST stub columns under a fire scenario
Authors: Medall David , Ibáñez Carmen , Espinós Ana , Romero Manuel L.
Published: September 2023

Composite construction is becoming increasingly used across the world, since it enables to exploit the benefits of steel and concrete working together, leading to cost‐effective solutions. Recent technological developments have facilitated the introduction of new typologies, which combined with the use of high performance materials allow for significant load‐bearing capacities with reduced cross‐sectional dimensions. One of these innovative composite sections are the so‐called steel‐reinforced concrete‐filled steel tubular (SR‐CFST) columns, where an open steel profile is embedded into a CFST section. Apart from the broadly recognized benefits of these typologies at room temperature, they show an enhanced fire performance due to the inherent fire protection offered by the surrounding concrete to the inner steel profile, which delays its loss of mechanical capacity at elevated temperatures. However, the experimental evidence on the fire behaviour of SR‐CFST columns is still scarce, being much needed for the development of specific design provisions that consider the use of the inner steel profile in CFST columns.

In this paper, a new testing program on the thermo‐mechanical behaviour of SR‐CFST columns is presented to extend the available experimental database. A cylindrical electric furnace attached to a loading rig equipped with a 5000 kN hydraulic jack is used. In total six SR‐CFST stub columns are tested, three circular and three square sections, combining high strength steel and concrete.
Plate and stiffener buckling in transversely loaded steel panels
Authors: Kleppe Svein‐Rune , Aalberg Arne
Published: September 2023

Stiffened plates may be loaded by axial forces in two directions, i.e., along and transverse to the stiffeners, by in‐plane shear force, and by out‐of‐plane loads as from traffic or water pressure. Special care must be taken for buckling effects caused by the compressive in‐plane forces.

The buckling behaviour of plates stiffened with four trapezoidal stiffeners was investigated for the case of compressive axial force directed transverse to the stiffener direction. The width and length of the stiffened plate and the ratio between the plate‐ and stiffener stiffnesses were varied. The investigation aimed to determine criteria to ensure that the dominating buckling mode was either buckling of the plate between the stiffeners, or a predictable buckling pattern of the stiffeners. For this, two formulas are presented, giving the necessary plate‐to‐stiffener stiffness ratio or the maximum length of the panel. Furthermore, capacity approaches for the axial resistance for transverse axial loading are studied, applying the Effective Width Method (EWM) and the Reduced Stress Method (RSM). Comparisons with nonlinear FE‐simulations show that the predictions range from 45% to 99% of the FE‐results.
Revision of the standard EN 1993‐1‐11 and background information
Authors: Friedrich Heinz , Misiek Thomas , Pedro José Oliveira , Ruff Daniel C.
Published: September 2023

Within the framework of the development of the second generation of Eurocode 3, Part 1‐11, related to the design of steel tension components, was completely revised.

This paper introduces the main developments in the prEN 1993‐1‐11:2023 regarding the basis of design for the three groups of tension components: A ‐ Rods, B ‐ Ropes, and C ‐ Parallel strand or wire systems. For each of the three groups, complete information on the “Material”, “Ultimate limit state” (including fatigue) and “Serviceability limit state” requirements are provided. Improved formulas for the design of saddles and clamps are presented, including new saddle solutions for group C. Reference is made to the new group D ‐ Parallel wire tension components for suspended structures, included in new Annex C. Annex A “Product requirements for tension components” was completely revised to reflect modern testing requirements. Informative Annex B has been also updated with new figures that reflect the state of the art in tension elements and terminations.
Statistical evaluation of the influence of manufacturing tolerances on the flexural cyclic behavior of I‐shaped hot rolled steel beams
Authors: Eshaghi Cyrus , Mohabeddine Anis , de Barros Rui Carneiro , Romão Xavier , Castro José Miguel
Published: September 2023

This paper investigates the influence of manufacturing tolerances on the cyclic behavior of steel beams with European I‐shaped profiles. It also explores the applicability of machine learning methods in predicting this behavior. Previous research has focused on nominal sections, overlooking the effects of dimensional tolerances specified in the EN10034 standard. Through advanced finite element modeling, the study evaluates the influence of geometrical variability on the strength and deformation capacity of steel beams under cyclic flexural loading. A parametric study with Latin Hypercube sampling generated two thousand samples of various profiles and lengths, revealing that dimensional tolerances can lead to variation in overstrength ratio or reduced ductility. Finally, the paper assesses the accuracy of several machine learning models in predicting moment and rotation capacity, including nonlinear and linear regression analysis, neural network, decision tree, and random forest.
The effect of temperature actions on single‐sided fillet welds in small‐sized box girders of bridges
Authors: Ltaief Malik , Mensinger Martin
Published: September 2023

The use of small‐sized box girders has shown to bring numerous benefits in the design of bridges with short to medium spans. Therefore, it has become an established construction method in Germany. However, the beams are not accessible for inspection due to their small size, requiring the girder to be welded airtight. The limited accessibility also has consequences on the manufacturing process. Two of the four longitudinal fillet welds can only be executed from outside resulting in single‐sided fillet welds. As a result of the airtight construction, temperature actions lead to fluctuation of the internal pressure of the box. The single‐sided fillet welds are consequently subjected to unscheduled bending stress, which has an unclear impact on the weld. Subject of the research project, presented in this paper, is the influence of this unscheduled load case on the load‐bearing capacity of the girder. To quantify the temperature which leads to changes of the internal pressure, numerical studies based on meteorological data are performed. The load‐bearing behavior of single‐sided fillet welds is investigated in experiments. It can be shown that the load‐bearing capacity is underestimated by simplified calculation methods.
Design and analysis of steel‐concrete hybrid coupled walls with hinged base and corner components
Authors: Scozzese Fabrizio , Ceccolini Nicola , Zona Alessandro , Dall'Asta Andrea , Leoni Graziano , Degeé Hervé
Published: September 2023

The seismic performance of hybrid coupled walls (HCWs) made of a single reinforced concrete (RC) wall connected to two steel side columns by means of steel links is studied in this article. Steel links are designed as dissipative elements while the RC wall and the steel side columns should remain elastic. Given that previous studies highlighted the difficulties in avoiding damage at the base of the RC wall due to the concentration of bending moment, the scheme with fixed base is modified in this study with the adoption of a hinged connection and vertical steel elements called corner components. A ductile design methodology is proposed and applied to the design of case studies with different building heights (three and six stories) and different base conditions (fixed base and hinged base with corner components). Moreover, the influence of uniform and variable distributions of links along the building height is assessed. Results of pushover analyses are presented to validate the design methodology and provide insight into the structural response of the proposed solution, showing the benefits of a hinged base with corner components.
Shear connector design using data analytics approaches
Authors: Koh Hyeyoung , Blum Hannah B.
Published: September 2023

The field of structural engineering can be augmented with advanced data analysis techniques. Structural engineering applications consist of datasets which may include experimental or/and computational data, and can be used to derive design provisions based on the measured data. Cluster analysis is a data exploration technique that involves identifying groups in a dataset and providing relationships between input parameters, which could supplement existing engineering intuition and knowledge. As a test case, this paper reanalyzes the existing test data for shear connectors using a cluster analysis. A database of push‐out tests was established from the literature, which was then sorted into subsets using two methods: (1) manual grouping based on engineering judgment and (2) Gaussian mixture models that detect clusters based on relationships between parameters in the data. The recommended data groupings based on the two methods were compared. Reliability analyses were conducted on each data subset to determine the recommended resistance factors. The results were compared to the resistance factors prescribed in the AISC 360‐22 Specification, which now permits a performance‐based alternative for the shear connector design.
Testing of a Novel Induction Heat Treated Steel Brace with Enhanced Buckling Behaviour
Authors: Jamshiyas Shadiya , Skalomenos Konstantinos
Published: September 2023

Steel braces are widely used to stabilize steel structures forming horizontal or vertical truss structures; however, their relatively poor buckling behaviour is often lead to overdesigned structures. Induction Heat (IH) treatment technology is a novel contactless material transformation process to effectively strengthen local areas of steel sections. Utilizing IH to increase the strength of the middle length of steel brace sections, buckling behaviour can be improved. The present study experimentally investigates the compression behaviour of the novel braces fabricated by IH‐treated circular hollow steel sections. A Digital Image Correlation (DIC) system is used to measure the experimental deformation quantities, such as axial displacements, out‐of‐plane deformations, and strain distributions along the brace length. Four specimens were tested with two set of different slenderness ratios (λ). Each set includes one conventional steel brace (CSB) and one IH‐treated steel brace (IHSB) with a stronger section at its mid‐length. The specimens were subjected to a monotonic displacement‐controlled loading history until reaching an axial compressive strain of 2.5%. It was found that buckling load can increase up to 20% in IHSBs. IH treatment was also beneficial in improving the post‐buckling behaviour of the brace. The compression strength was found to be more than double in IHSBs than in CSBs at a ductility level of 5 (ductility is defined as the ratio of the target axial displacement to the yielding axial displacement). Moreover, out‐of‐plane displacements were reduced by 28% for the IHSBs at an axial strain of 1% showing a more evenly distribution of strain demands along the brace length.
Further development of detail categories for bolt‐assemblies subjected to normal stress in steel constructions
Authors: Glienke Ralf , Schwarz Mathias , Meyer Melanie Hagemann née , Seidel Marc , Dörre Maik
Published: September 2023

The fatigue strength of bolts is determined not only by the geometric design but also by production‐related influences such as rolled before heat treatment, rolled after heat treatment or even hot‐dip galvanising. For the bolts of steel constructions considered in this paper, these production‐related influencing factors are considered very differently in the evaluation of the fatigue resistance, depending on the used respective standards. This is for example done according to the still valid version of EN 1993‐1‐9 in the unified form of detail category 50, taking into account the size effect, but independent of the other influencing factors mentioned before. This is not least due to the very limited available experimental database and test documentation. The authors address this topic in this paper, especially for large‐size bolts used in large quantities in wind turbines. This article presents an evaluation of results from 22 fatigue test series (n = 411 tests) on 3 different high‐strength bolt assembly systems with varying manufacturing conditions. The data base is covering a diameter range between M12 and M72 and focusses on test series with high mean stress in a representative order of magnitude for practical application of the bolts. For their further evaluation, the findings described in the technical literature are considered in relation to the different tested manufacturing conditions. The additional comparison of the test results with the current design codes serves to a better classification of the results. The authors give a proposal for the adjustment of detail categories of bolt assemblies subjected to normal stress.
A comparative experimental study on blind‐bolted beam connections to square steel tubular columns filled with polyurethane foam or concrete
Authors: Skalomenos Konstantinos , Gunes Sahin , Taleb Farzad , Theofanous Marios
Published: September 2023

In the last two decades blind‐bolted connections have been developed to allow bolting of open section beams (e.g, I‐beam) to steel hollow section (SHS) columns where access from all sides of the column is not possible. Filling the tubular column with concrete in the vicinity of the beam‐to‐column connection has been shown to improve the anchoring mechanism of the blind‐bolted connection thereby increasing the strength and stiffness of the connection and reducing the column face deformation, however it adversely affects the joint ductility. This study introduces polyurethane foam filled steel tubular columns in combination with a new anchoring arrangement employing hollo‐bolts to develop a novel connection between the SHS columns and open section beams that provides a better combination of stiffness, strength and ductility. To investigate the behaviour of the proposed arrangement, monotonic pull‐out tests of blind bolted T‐stub connections anchored to foam‐filled steel tubular (FFT) and concrete‐filled steel tubular (CFT) columns using holloBolts were conducted. Benchmark tests on unfilled SHS columns were also conducted for comparison. The FFT in conjunction with the proposed anchoring mechanism was shown to provide a good stiffness as the CFT columns, and almost similar ductility to that of the unfilled steel tube blind‐bolted connection. Hence it is concluded that employing foam instead of concrete as an infill leads to favourable combination of strength and ductility, thus rendering FFT an attractive light alternative to CFT sections when ductility of the joint is an important design consideration.
Seismic performance assessment of self‐centering hybrid coupled walls: an 8‐story case study structure
Authors: Farahi Mojtaba , Freddi Fabio , Latour Massimo
Published: September 2023

In response to the demand for resilient structures, a variety of innovative structural solutions have been recently introduced to reduce residual deformations and expedite the repair of structures subjected to earthquakes. This paper discusses the seismic performance of a self‐centering lateral load‐resisting system developed with the intent of diminishing earthquake‐induced damage and residual deformations. The proposed solution is composed of a reinforced concrete (RC) shear wall coupled to two steel side columns with coupling beams featuring a friction‐damped self‐centering mechanism. The intended system is referred as Self‐Centering Hybrid Coupled Wall (SC‐HCW). The applied self‐centering mechanism is aimed at reducing earthquake‐induced residual deformations. Limited residual deformations facilitate the repair of SC‐HWs after severe earthquakes, which improves the seismic resilience of the structure. The seismic performance of a SC‐HCW is examined and compared with that of a conventional hybrid coupled wall (HCW). Nonlinear static and Incremental Dynamic Analyses (IDAs) are conducted on these archetypes. The outcomes elaborate the efficiency of the SC‐HCW in minimizing earthquake‐induced residual deformations.
Innovative bio‐based steel envelope systems
Authors: Izabel David , Renaux Thibault , Gelders Tommy , Eizaguirre‐Iribar Arritokieta , Lange Jörg , Pradhan Eric Man , Gervásio Helena , Soares José Hector , Martins Claudio , Spagni Daniel , Brutin Alexis , Chi André , Huet Valérie , Palisson Anna , Olano‐Azkhune Xabier , Prudor Valérie
Published: September 2023

The INCSEB project is aimed at developing 5 ultra‐low carbon envelope systems made in steel and that incorporate innovative use of wood fiber insulation. The systems under development are: 3 sandwich panels (cladding, pitch & flat roofing), 2 claddings (double skin & façade with plank). INCSEB includes tests to study various behaviors: mechanical, fire, thermal calculation, acoustic insulation, air/water/vapor permeability. Interpretation and classification reports will be done for each type of test. 2 full scale prototypes will allow to estimate the durability in real life conditions. LCA indicators and comparison of carbon footprint (GWP) to conventional systems based on a real office building will be provided. An economic study of the projected price of the 5 systems compared to existing conventional systems is also planned. Besides, as far as the production of innovative panels is concerned, it appears that they can be integrated in current production lines. Finally, actions to facilitate the dissemination of results and industrial application will be organized: drafts of design and installation guides, publications, submission of 3 amendments to relevant EN standardization committees, workshop, BIM objects. Lastly, the manufacturers plan to apply for patents protection.
A comparative study on steel‐concrete composite columns for use in RC Tall Buildings in Seismic Areas
Authors: Mert Hazal , Celik Oguz C.
Published: September 2023

Usable/rentable floor areas are crucial for the building owners in reinforced concrete (RC) tall buildings. To address this issue, concrete‐encased (CE) or concrete‐filled (CF) composite columns are proposed as alternative vertical load carrying elements by providing the required strength and ductility, but with smaller dimensions. Comparing the performance of columns with different configurations can be done using moment (M)‐axial load (N) interaction curves. This paper summarizes the approaches proposed by Eurocode 4 and AISC 360‐16 for both types of composite columns, presenting simplified and true curves for a specific class of sections. Two case studies involving hybrid RC tall buildings in Istanbul, which utilized composite columns, are presented along with a comparison with steel‐concrete composite and RC solutions. Numerical results indicate that employing steel‐concrete composite columns resulted in approximately 24% reduction in total cross‐sectional areas for one of the case studies, leading to increased usable/rentable areas. Additionally, concrete‐encased and concrete‐filled composite columns exhibited similar performance in terms of axial load‐moment capacities. The impact of longitudinal rebar ratios is also investigated, revealing that the AISC 360‐16 approach yields smaller bending moments and compression capacities compared to Eurocode 4 due to the significant strength reduction factor considered in calculating the concrete contribution in composite sections.
Application of machine learning approaches for modelling crack growth rates
Authors: Ben Seghier Mohamed El Amine , Plevris Vagelis
Published: September 2023

The scientific community has widely accepted the use of machine learning techniques to tackle complex engineering problems. Among the most intriguing problems is finding the correlation between alloy steel properties and cyclic fatigue and crack growth rate. Employing machine‐learning models can provide more robust and accurate predictive models to address such challenges. This paper presents the application of four machine learning models, namely decision trees (DT), random forest (RF), adoptive boosting (AdaBoost), and gradient boosting regression tree (GBRT) to predict the crack growth rate of steel/alloys. The study utilizes a large database gathered from literature to construct the predictive models and compares the results using various statistical metrics and graphical representation. The study's findings demonstrate the effectiveness and suitability of machine learning techniques to handle complex databases related to fatigue problems.
Numerical Fatigue Strength curve for the C1 Wedge Connection
Authors: Mohabeddine Anis , Malschaert David , Creusen Koen , Winkes Jasper , Veljkovic Milan
Published: September 2023

This paper presents an investigation on the fatigue life prediction of the C1 Wedge Connection based on advanced finite element analysis. Recently developed, this connection links tubular sections of wind turbine towers using small horizontally placed bolts to slide two wedges, which pull the fork‐shaped upper flange and shaft‐shaped lower flange of the tower together. The fork‐shaped upper flange is manufactured using electron beam welding. A 3D finite element model is developed in ABAQUS software to simulate the behavior of the connection. A sequential thermal‐mechanical analysis is performed to simulate the electron beam welding process and estimate the residual stresses and distortions. The crack initiation at the lower flange, where the largest stress range is observed, governs the fatigue resistance of the connection. Fatigue crack initiation is assessed using the strain‐based local approach and code‐based methods such as the EN1993:1‐9 and DNV‐RP C2003. A comparison of the predictions from these methods is presented.
I‐Twin. Computational twin connectors for I‐profiles. Towards unforeseen interoperability of digital tools
Authors: Posada Hector , Chacón Rolando , Ramonell Carlos
Published: September 2023

Standard BIM data‐exchange format requirements are permeating Building Construction. This is due to the increasing digital communication between Stakeholders of complex projects. All steps of development (conception, design, procurement, construction and operation) are pushing towards integration of data schemas. Desirably, knowledge and value generated by one stakeholder may then be leveraged by other stakeholders. 3D models, simulations, measurements, logbooks, schedules, as‐built conditions and other information constructs are on the verge of interoperable communication. Structural Analysis must play a significant role within those more digitized data exchanges. This paper presents recent developments of frameworks, connectors and tools for the integration of structural I‐shaped beam entities into Digital Twins. The information construct I‐Twin encompasses information loads for geometries (IFC‐Based), sensors (IoT) and simulations (FEM).
Fatigue verification of orthotropic bridge decks with the hot‐spot method – Background to TS 1993‐1‐901
Authors: Maljaars Johan , Pijpers Richard , Veljkovic Milan , van Dooren Frank
Published: September 2023

The design of orthotropic bridge decks (OBD) is driven by fatigue. The Eurocode on fatigue of steel structures – prEN 1993‐1‐9:2023 – provides fatigue resistance (S‐N) curves for relevant details in OBD. These curves are to be used with the far field (nominal) stress. However, due to the complex geometry and loading of OBD, the nominal stress is not well defined for many details. In addition, cracks have been found in practice in OBD at locations for which S‐N curves are not provided. In order to overcome these issues, experimental and numerical studies are carried out on the use of local stresses (hot‐spot stresses where possible) for the fatigue design of OBD. The different stress extraction method also implies the use of different S‐N curves. A large number of fatigue tests carried out in the past have been re‐evaluated to determine the hot‐spot stress S‐N curves. Additional fatigue tests have been carried out for details lacking data. The study has resulted in a guideline to design OBD for fatigue with the hot‐spot stress method. This guideline, TS 1993‐1‐901:2023, will be published as a Technical Specification (TS) to the standard prEN 1993‐1‐9:2023.

This paper provides a short background to the newly created TS. It demonstrates the derivation of S‐N curves based on available tests for a number of details. It highlights fatigue relevant details that are missing in prEN 1993‐1‐9:2023 and that are added to TS 1993‐1‐901. It explains how to evaluate cracks starting from the root of the weld, for which the hot‐spot stress method is traditionally not applicable. Finally, the paper demonstrates how the method can be applied in the fatigue design, including the application of the load in finite element models.
Calibration of ductile and shear damage models for carbon and stainless steel shear studs
Authors: Presswood Rebecca , Shaheen Mohamed , Afshan Sheida
Published: September 2023

Steel‐concrete composite beams are commonly used in bridge construction. The corrosion of the supporting steel beams and the shear connectors are however known as a major cause of premature deterioration of composite bridges. Stainless steel beams and shear connectors offer a viable alternative solution to the steel corrosion problem in composite bridges located in harsh environmental conditions. This paper presents experimental and numerical investigations of the tensile and shear behaviour of stainless steel welded shear connectors. The results of tensile coupon and double shear tests on stainless steel and carbon steel shear connectors to characterise the tensile and shear response are reported. Numerical modelling is carried out using the ABAQUS finite element software to develop calibrated ductile damage and shear damage fracture models for stainless steel shear connectors. The development and validation of the numerical models together with the calibration of the fracture models are presented and comparisons are made with those of carbon steel shear connectors.
Digital‐Image‐Correlation for Simulating Cyclic Local Buckling in Steel Beams
Authors: Ozden Selimcan , de Castro e Sousa Albano , Lignos Dimitrios
Published: September 2023

Nonlinear continuum finite element (CFE) analyses rely on accurate multiaxial constitutive law formulations along with reliable imperfection patterns for simulating nonlinear geometric instabilities in steel members under mechanical loading. Validations of these models usually rely on conventional measurements of macroscopic parameters (e.g., displacement and strain field). It is common to use global deformation characteristics (e.g., deduced moment versus chord rotation) for model validation purposes of steel members exhibiting inelastic cyclic local buckling. The reason is that measurements from conventional strain gauge readings are not deemed to be reliable well before the onset of local buckling. This is potentially problematic when the accurate prediction of local strain demands is essential. This paper discusses the experimental results from a steel beam instrumented with a digital image correlation (DIC) system and how optical measurements acquired from DIC can be used to benchmark a CFE model representation of this beam. It is shown that while different CFE model types simulate accurately the moment rotation relationship of the steel beam, local strain demand predictions could vary considerably between model types. The results suggest that DIC measurements can inform the selection of proper imperfection patterns to be used in CFE models for the reliable estimation of inelastic strain demands.