bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimisation and testing of simply‐supported WAAM beams
Authors: Weber Ben , Meng Xin , Nitawaki Masashi , Gardner Leroy
Published: September 2023

The design and performance of optimised wire and arc additively manufactured (WAAM) rectangular hollow section (RHS) beams, with varying material strengths and thicknesses along their lengths, are investigated in this study. Simply‐supported beams under three‐point bending were considered. Size optimisation of the RHS beams was carried out by fixing the nominal outer profile and varying the local thicknesses and steel grades in discrete steps to accommodate the variation of the bending moment along the member length. Two optimised beam specimens were manufactured via WAAM and tested, and were shown to have excellent load‐carrying capacities at greatly reduced self‐weights compared with the conventionally manufactured beams, indicating a considerable increase in their structural efficiency. This study confirms the feasibility of combining materials with different thicknesses and steel grades using WAAM, which provides structural engineers with further design freedom and opportunities to minimise material use.
Local buckling behaviour of high strength steel tubular beams under moment gradients
Authors: Yang Zichang , Meng Xin , Walport Fiona , Gardner Leroy
Published: September 2023

This paper presents an experimental study into the effect of moment gradients on the local buckling behaviour of hot‐rolled high strength steel square hollow section (SHS) beams. The influence of moment gradients was investigated by testing 20 beam specimens, ranging from Class 2 to Class 4 according to the cross‐section classification limits given in prEN 1993‐1‐1:2020. Both four‐ and three‐point bending loading configurations were considered with varying shear span lengths. The influence of intermediate stiffeners at the loading point was examined by employing two different loading configurations in the three‐point bending tests, achieving fully stiffened or unstiffened conditions. Local geometric imperfections were measured by means of 3D laser scanning, and the displacement and strain fields at critical regions were monitored by digital image correlation (DIC) during testing. It was shown from the tests that specimens subjected to moment gradients exhibited higher ultimate moment capacities than those subjected to uniform moments.
Parametric study for Y‐shape perfobond shear connection
Authors: Mefleh Wajdi , Kovács Nauzika
Published: September 2023

The development process of the composite structures is always an ongoing process, to gain more the benefits of the composite work between steel and concrete. This process has created a wide range of types of shear connections. Different types of perfobond shear connections have been developed to overcome the disadvantages of the conventional headed stud connections. The new types like the Y, puzzle, clothoid, etc. shape perfobond plates have been studied due to their beneficial ultimate resistance and deformation capacity. The Y‐type perfobond rib shear connection is a superior alternative to the conventional perfobond due to its improved performance characteristics, such as higher ductility and stiffness, and greater resistance against uplifting force. In this paper the focus in on Y‐shape perfobond shear connections. A finite element model for a push‐out test has been developed to analyze the influence of structural parameters on the behavior of the connection. The model was verified by the experimental test completed at the Department of Structural Engineering, in Budapest University of Technology and Economics. The FE model was developed on Atena GID software. In this paper the effect of the angle of the inclined Y parts and the geometrical dimensions of the inclined Y parts are analyzed on the resistance, degradation tendencies, deformation capacity and the stiffness of the connection, conclusions are drawn, and beneficial structural details are recommended.
Theory of Plastic Mechanism Control for Linked Column Frames
Authors: Montuori Rosario , Nastri Elide , Piluso Vincenzo , Pisapia Alessandro
Published: September 2023

The main purpose of this work is to define a design procedure for dissipative replaceable link frames (LCFs). These structural schemes are characterized by the columns connected with link elements representing the plastic zones of the structure and, consequently, they assure the maximum dissipation of seismic energy in input. The design rules, proposed in this paper, are based on the Theory of Plastic Mechanism Control (TPMC). This procedure is based on the extension of the kinematic theorem of limit analysis to the concept of the equilibrium curves of the failure mechanisms and it guarantees the achievement of the global collapse mechanism under severe seismic actions. In order to evaluate the accuracy of this procedure, a case study is presented. In particular, a LCF with four storeys and three bays is designed by means of the proposed design rules. Finally, the same steel frame is implemented in SAP2000 program, and a pushover analysis is performed to evaluate the ultimate behaviour of the modelled structure.
Geometric imperfection measurement on welded hybrid steel box‐section girders
Authors: Somodi Balázs , Wassfee Dhiaa , Kövesdi Balázs
Published: September 2023

High‐strength steel materials (steel grades of S500 ‐ S960) gaining prominence in civil engineering, especially for large‐span bridges. In the case of bridges, the application of hybrid girders combining low‐ and high‐strength steel materials is an effective and economical solution. The hybrid girders generally consist of webs comprised of low‐strength steel and flanges made of high‐strength steel. In Europe, apart from some minor practical applications and research results in Sweden, these structure types are completely new solutions in bridges, and the theoretical background of their stability design is missing from the current European standardized design provisions. To determine the theoretical background of this girder type and to develop the design theories for application purposes it is essential to execute experimental laboratory test programs. Analyzing the local buckling and plastic behavior of hybrid steel plate girders through experiments is essential to have an approopriate knowledge on the geometrical and structural imperfections of the hybrid girders. Therefore, in the present paper the measurement of geometric imperfection on 14 welded hybrid steel box‐section girders with varying geometry is presented and their results are evaluated and discussed. The flanges of the examined hybrid girders are made of S700 or S500, the web of the specimens consists of S355 steel grade. The measured imperfection values are evaluated based on the steel grade and geometric parameters such as plate width or thickness. Using the measured imperfection, a numerical model will be developed to predict the bending and shear resistance of the specimens.
Digital Twin‐Based Deterioration Prognosis of Steel Wind Turbine Towers in Modular Energy Islands
Authors: Heng Junlin , Zhang Jiaxin , Kaewunruen Sakdirat , Dong You , Baniotopoulos Charalampos
Published: September 2023

The Modular Energy Island (MEI) offers a promising solution to unlock the plentiful Aeolian source at deep‐waters. Meanwhile, high‐speed wind and strong corrosivity in the harsh marine environment, along with increasing dynamics, escalate the corrosion‐fatigue (C‐F) deterioration issue of steel wind turbine towers on MEIs notably. Thus, a better understanding of the C‐F states is of particular concern to maximize the lifetime power generation and minimize operational costs. This study aims to provide novel insights into the C‐F deterioration states of wind turbine towers by integrating the material test data, site measurement, and multi‐physics simulation based on the concept of digital twins. The DTU 10MW reference turbine has been selected as an engineering prototype. Based on the in‐situ wind‐wave data, the structural response of the steel turbine tower at critical details is predicted via multi‐physics simulations and accordingly, stress spectra are constructed. Besides, the corrosion rate is estimated from material test data and the site‐specific climate conditions. Then, a probabilistic C‐F model is established for the deterioration state of critical components in the tower by incorporating the derived stress spectra and corrosion rate. Not only does this study highlight the escalating C‐F deterioration issue in steel wind turbine towers, but it also offers a novel basis for crucial insights into the digital twin‐based operation and maintenance (O&M) of the next‐generation MEIs by integrating models and data from various sources.
Lateral‐torsional buckling experiments of built‐up section CFS beams
Authors: MA DI , RASMUSSEN KIM , ZHANG HAO
Published: September 2023

This paper investigates the lateral‐torsional buckling of built‐up cold‐formed steel beams featuring two or three component C‐ or sigma‐sections arranged to have a closed loop. Several thicknesses of each cross‐section with nominal yield stress values of 450 MPa and 550 MPa were tested to obtain lateral buckling strength data for a range of cross‐section slenderness values. Complementary reference tests were conducted on the same built‐up sections braced laterally to obtain the in‐plane section capacities, precluding the effect of lateral‐torsional buckling. Coupon tests were also conducted to determine the mechanical properties of the steel material. The test rig featured a dual‐actuator set‐up, with one actuator (applying vertical load) mounted on a trolley that was moved horizontally by the second actuator in response to the signal from a transducer measuring the lateral buckling displacement at the mid‐length of the beam, thus ensuring vertical loading throughout the experiments. The rig also featured specialized end bearings allowing free flexural rotations and warping, while restraining lateral displacements and twist rotations. The paper describes the test rig and the results of the in‐plane and lateral‐torsional buckling experiments. Particular attention is paid to the use of closed parts to enhance the torsional rigidity of the built‐up sections and thereby their lateral‐torsional buckling capacity.
Lateral torsional buckling of hot rolled channel sections – Numerical simulations and design proposal
Authors: Beyer André , Khelil Abdelouahab , Bureau Alain , Boissonnade Nicolas
Published: September 2023

This paper describes a parametric study addressing the resistance of U‐profiles (channel profiles) subject to bending and torsion to lateral torsional buckling. In case of U‐sections, the torsional moment results, in the majority of cases, from an unavoidable eccentricity of the applied load from the shear centre. The behavior and resistance of the studied members is addressed through a parametric study based on a numerical model validated with laboratory tests. This study is divided into two parts. First, U‐sections subject to bending only are studied in order to provide a method for this reference load case. In particular, the non symmetric stability behaviour of this type of section will be highlighted. Based on the numerical results an adaption of the European buckling curves is proposed. Then, the members are studied under combined bending and torsion. Existing design methods applicable to I sections are extended in order to account for the specific behaviour of U sections.
Study on the fire performance of novel G550 galvanized steel‐concrete composite slabs
Authors: Cheng Yun , Yu Xianglin , Shi Yongjiu
Published: September 2023

To reduce the construction and maintenance difficulties caused by fire proof coatings and reinforcement used in composite structures, 2 new types of steel‐concrete composite slab was proposed combining G550 galvanized steel with re‐entrant sheeting and closed profiled sheeting. 12 full‐scale standard fire tests were conducted to investigate the fire performance of G550 galvanized steel‐concrete composite slabs. Temperature rise within profiled sheeting and concrete are compared for the novel composite slabs. With the development of bearing capacity index, the fire performance of novel G550 galvanized steel‐ concrete composite slabs are analyzed under the same unified standard. Results showed that all the newly developed composite slabs could reach the design requirements for buildings up to 18 m above ground without the use of coatings and reinforcement. And the composite slabs with closed profiled sheeting can reach 120 min fire resistance when bearing capacity index is less than approximately 0.1 and are suitable for application in high‐rise buildings.
Mechanical properties of S355 butt welds at elevated temperatures
Authors: Santiago Aldina , Crescenzo Pasquale Nacchia , Craveiro Helder , Latour Massimo , Rodrigues Dulce , Leitão Carlos
Published: September 2023

The performance of welded connections in steel structures under fire depends on the mechanical properties of welds at elevated temperatures. Currently, EN 1993‐1‐2 [1] provides the following information for the design strength of welds: for butt welds, up to 700 °C, the design strength shall be taken as equal to the strength of the weaker part joined considering the reduction factors for material properties of the steel, while for butt welds above to 700 °C, and also for fillet welds, specific reduction factors for the design strength are proposed.

This paper presents the preliminarily results of an experimental investigation of specimens of butt welds realised with GMAW process under elevated temperatures. Steady‐state tensile tests, at 20 °C, 300 °C and 600 °C, were conducted on tensile coupon specimens extracted from welded steel plates. Results from these experiments have been used to evaluate the stress‐strain response, yield strength, modulus of elasticity, ultimate strength, and ultimate strain, as a function of the temperature for butt welds. Reduction factors were predicted for these mechanical properties. Some differences were achieved, especially at 600 °C, between the calculated reduction factors and those proposed by the EN 1993‐1‐2 [1]. Finally, it was also observed that the temperature has an impact on the tension fracture surface in welds.
Experimental and Numerical Study on Shear Behaviour of Bolted Inter‐Modular Connection
Authors: Rajanayagam Heshachanaa , Gunawardena Tharaka , Mendis Priyan , Poologanathan Keerthan , Gatheeshgar Perampalam , Nagaratnam Brabha , Corradi Marco
Published: September 2023

This study presents a comprehensive evaluation of the shear behaviour of bolted intermodular connections under lateral load using theoretical, experimental, and numerical approaches. Three design configurations with varying bolt sizes and hole tolerances of the proposed bolted intermodular connection were established and tested under lateral load to study their shear slip resistance. 3D finite element models in ANSYS were then developed and validated against the load‐deformation behaviour from the experiment. The validated models were then used for the comprehensive analysis of the connection components' response under lateral load. The study showed that the proposed connection has a tendency to fail by slippage even under extremely light lateral loads thereby identifying the connection as a slip‐critical connection for the serviceability design. Moreover, it was also found that the main cause of connection failure under lateral load is the combined tension and shear effect, not pure shear. This paper then presents the developed methodology for estimating the connection stiffness, such that the stiffness values can be used for the global modelling of modular buildings with connections as simplified link or spring elements. Finally, the study suggests recommendations and appropriate strategies to optimize the connection design to further enhance the strength and serviceability requirements.
Characterizing transition zone between steel‐concrete composite and reinforced concrete members
Authors: Dragan Dan , Das Rajarshi , Degee Herve
Published: September 2023

Steel profiles are often embedded in reinforced concrete (RC) members (specially columns) to achieve higher performance in a localised manner. Although the RC and steel‐concrete composite zones of such members can be respectively designed according to the Eurocodes 2 and 4, the transition zone between the steel profile and its surrounding concrete needs to be adequately designed to ensure an effective transmission of the axial force, shear and bending moments carried by the interrupted steel component. This is currently not covered by the design standards and is only partially covered by the current literature. This article proposes a design procedure for such transition zones relying on a 2‐steps approach: (1) Definition of the transverse load to be transferred from the steel part of the composite zone to the RC part, based on a reasonable distribution of the contact pressure between the profile and the surrounding concrete; and (2) Evaluation of a suitable “strut & tie” mechanism to ensure the appropriate transfer of this load and consecutive design of the transverse reinforcement. In order to evaluate the efficiency of the design approach, the transition zone between a composite and a pure RC part of a locally composite column was investigated experimentally. Four test specimens were designed and tested in order to study the influence of certain parameters, e.g. length of the assumed transfer zone, presence of one or two lateral beams at the level of the transfer zone, compression level in the column, etc.
Wire‐and‐Arc Additive Manufacturing for lattice steel structures: overview of the experimental characterization on dot‐by‐dot rods
Authors: Arrè Lidiana , Laghi Vittoria , Palermo Michele , Gasparini Giada , Trombetti Tomaso
Published: September 2023

With the advent of a new arc‐based additive manufacturing (AM) process, referred to as Wire‐and‐Arc Additive Manufacturing (WAAM), the scale of the metal printed parts increased up to several meters, thus becoming suitable for large‐scale applications in marine, aerospace and construction sectors. However, specific considerations in terms of geometrical and mechanical properties ought to be made in order to effectively use the printed outcomes for structural engineering purposes. The introduction of the novel printing strategy referred to as “dot‐by‐dot”, consisting in successive drops of molten metal, enabled the use of WAAM to realize complex lattice structures, made by continuous grids of WAAM rods. Nevertheless, their proper design requires an accurate evaluation of the influence of the non‐negligible inherent geometrical irregularities on the mechanical response of the rods. Hence, extensive experimental work is needed in order to evaluate the mechanical response of “dot‐by‐dot” WAAM rods with geometrical imperfections. The present study focuses on the mechanical characterization of dot‐by‐dot WAAM‐produced 304L stainless steel intersected rods, constituting the basic units of grid and lattice structures. The mechanical response of the specimens is assessed through tensile experimental tests conducted on two‐ways planar nodes obtained from the intersection of two rods with different angles, hereafter also refereed to as crossed rods. The experimental results are then compared with tensile tests on single rods, to quantify the influence of the intersection angle in the structural response of the lattice structures.
Performance evaluation of cold‐formed steel spot weld connections
Authors: Rajić Andrea , Lukačević Ivan , Ćurković Ivan , Žuvelek Vlaho
Published: September 2023

[Spot welding is a fast and productive technology widely used in industry to join various cold‐formed steel (CFS) elements. Depending on the type of analysis and model complexity, various definitions of spot welds in finite element (FE) models can be applied. In structures with a large number of spot welds, simple models that use a reduced number of elements should be used because detailed models have too many degrees of freedom. This study deals with the investigation of point‐based fasteners in FE analysis for spot weld connections in CFS structures. The paper summarises the experimentally determined results of the spot‐welded connections in shear for eight groups of spot‐welded connections made of sheet thicknesses 0.8, 1.0, 1.5, 2.5 and 3.0 mm. The shear performance tests show different failure modes: full button pull‐out failure mode and interfacial fracture. Based on the test results, the FE models for spot‐welded connections were calibrated. The FE models for shear connections were created in ABAQUS using the simplified method based on point‐based fasteners and explicit dynamic analysis. Experimentally and numerically obtained results were compared with analytically calculated characteristic resistances of spot welds according to European standards.
Multiaxial fatigue analysis of circumferentially butt‐welded steel connection using fiber optic‐based distributed strain sensing
Authors: Karpenko Olena , Koetsier Mathieu , Pavlović Marko
Published: September 2023

This paper presents a study on the performance of circumferentially butt‐welded steel connections under constant tensile‐tensile axial fatigue and cyclic tensile‐tensile bending tests. The study utilizes fibre‐optic based distributed strain sensing to measure the strains and stresses in the regions of the weld. The results confirm the desired pure bending of the specimen during the fatigue cycles. The suitability of fibre‐optic monitoring for fatigue testing of welds is demonstrated. In addition, the study compares the numerically predicted stresses in the welded connection using Finite Element Analysis (FEA) with experimental results, thereby substantiating the accuracy of the FEA predictions.
Renovating the Van Brienenoord Bridge Steelwork in mechanical system of bascule bridge spanning 50m.
Authors: Janssens Tom , Hesselink Bert , Montijn Jacques , de Kluijver Erik , Mooijweer Rik , Brands Mack , van der Graaf Patrick
Published: September 2023

The Van Brienenoord Bridge is a large bridge which includes three movable bascules. The two oldest bascules stem from 1965. A study into renovation and/or replacement of these bascules has been performed and replacement was deemed necessary. A new design for the mechanical driving system has been made, where the design of the western bascule served as starting point. The regulations and requirements have become more stringent since 1965, however the available space is restricted by the existing concrete structure. A steel rack and pinion design is chosen as the best option for the mechanical driving system. In the design of the steel rack, several considerations have been made with respect to the material choice. A fully welded construction was desired due to the lower weight of the construction. However, stringent requirements are made with respect to the hardness, yield strength and tensile strength in several locations of the rack. After considerable calculations and consulting suppliers/manufacturers the tooth rack will be made of 25CrMo4 as the best compromise between material properties and weldability. The pinion material is selected as 34CrNiMo6 since weldability is not an issue. The choice here has to do with the minimum required mechanical properties (even above‐normative refinement). The connection to the concrete structure consists of an eye which is rather big and bulky. This is considered to be rather conservative due to the calculations methods and leaves room for optimisation.
Size effects on the structural behaviour of wrapped composite CHS joints
Authors: Yang Jincheng , Koetsier Mathieu , Peeters Tjeu , Wolter Mees , Pavlovic Marko
Published: September 2023

Recent pilot studies have shown the superior performance of wrapped composite joints as an alternative to conventional welded joints for circular hollow sections (CHS). Considering the large dimensions of CHS joints for field application and potential size effects from testing the structure on reduced scales, geometrical size effects need to be investigated. This work presents an experimental analysis and FE results of wrapped composite joints with three different scale sizes. The size effects on the uniaxial tensile behaviour of specimens were investigated in monotonic loading. The size effects on the structural behaviour of wrapped composite joints were evaluated regarding the performance in ultimate limit states. The outcome of this research supports the structural analysis and modelling of wrapped composite joints with upscaled sizes.
Stiffening of slender plates using Wire Arc Additive Manufacturing
Authors: Tankova Trayana , Veljkovic Milan
Published: September 2023

Additive manufacturing provides the possibility for innovative structural configurations promoting optimized material use for economy and sustainability, and new functions which are not available for traditional products. This paper explores the possibility to use wire‐and‐arc directed energy deposition process for fabrication of innovative WAAM stiffener for thin plated structures. The proposed solution is demonstrated in several geometrical configurations by varying depth and thickness of stiffener, by including openings or not, in addition to adopting irregular shapes such as circular of ellipsoidal stiffeners. The performance of the WAAM stiffened panel is compared to use of thin plate stiffened by prismatic stiffener by considering the critical buckling load and resistance for three different load cases. The results from the analyses performed showed that the WAAM stiffened panels reach the same resistance as the traditionally stiffened plate but using less material.
Research and outlook of steel beam‐to‐column joints retrofitted by welding haunches
Authors: Zhao Huatian , Shi Gang
Published: September 2023

A critical issue in structural retrofitting is to enhance the moment resistance of steel beam‐to‐column joints. The authors have investigated the cyclic behaviour and design of existing welded unreinforced flange‐bolted web (WUF‐B) joints, in which welding haunches were utilised to retrofit weak panel zones. In this study, three full‐scale joint specimens were retrofitted by haunches and stiffeners after applying axial column compression load. Then, cyclic tests, numerical simulations, and finite element parametric analyses were conducted. Results indicated that the retrofitted joints exhibited increased moment resistance and satisfactory seismic performance, meeting the ductility requirement of Special Moment Frames in the AISC 341 provision. The force‐transferring mechanism was substantially changed after adding haunches, and thus, a simplified mechanical model has been established to predict the force distribution. Furthermore, parameters influencing the joint behaviour (i.e., haunch geometries and axial column load before retrofitting) were involved in parametric analyses. Based on the above experimental and numerical results, the design method has been proposed, including the recommended configurations, calculations of the moment resistance and initial rotational stiffness, and detailed seismic checking procedures. This study reports a feasible solution to retrofit weak panel zones with column compression remaining and provides an outlook on retrofitting beam‐to‐column joints in future investigations.
Comparative study regarding the seismic design of diagonal concentrically braced frames
Authors: Köber Helmuth , Marcu Ramona , Stoian Marina
Published: September 2023

The present paper analyses some possibilities to improve the provisions concerning the seismic design of diagonal braced frames according to the in charge European and Romanian seismic design code (EN 1998‐1:2004 [1], respectively P100‐1/2013 [2]). Three design variants were used for the dimensioning under seismic actions of two ten story concentrically braced frames, taking into consideration different contributions of the tensioned and compressed braces in carrying horizontal seismic forces. The considered braced frames had two spans of 6.0m and ten storey of 3.5m. One of the frames had ascendant diagonal braces (from the lateral columns to the central column) and the other had descendant diagonal bracings (from the lateral columns to the central column). Static nonlinear analyses were performed with all the designed variants of the frames. The loading and deformation states at different steps during the analyses were compared. The distribution of plastic hinges in the structure was analysed. A more favourable behaviour of the frame during static nonlinear analysis was ensured by providing reduced cross‐sections along all frame girders ends (resembling the dog‐bone detail).
Finite element study on the behaviour of free from damage connections under fire
Authors: Santos Ana Francisca , Santiago Aldina , Craveiro Helder , da Silva Luís Simões
Published: September 2023

The free from damage connection, developed during the recent RFCS FREEDAM has shown to be a promising solution to dissipate high amounts of energy due to its sliding system given by the friction damper with slotted holes, located at the lower beam flange. Additionally, this sliding mechanism proved to be also efficient in the event of exceptional loading scenarios such as impact loads or even in column loss scenarios, because it allows the dissipation of part of the action through slipping and, on the other hand, gives an extra “elastic” ductility to the connection since, up to the end of the slip, the components of the connection are designed to remain in the elastic range.

In this paper, this specific behaviour is exploited in the case of fire scenario. During fire events, axial forces can develop in the beams (initially in bending, only) due to the expansion of the steel elements and the restraint provided by the boundary conditions. For the cases where the high axial forces develop, the moment‐rotation behaviour of the connections will change due to the interaction between the axial forces (N) and bending moment (M) as well as the effects due to the increase in temperature. The the use of connections such as the free from damage connection is interesting also from this point of view since it delays the development of great axial forces due to its slipping mechanism. This analysis is carried out through FEM analysis using ABAQUS software.
Investigation of Wood‐Steel Composite Shear Walls Behavioural Parameters
Authors: Vogiatzis Tzanetis , Efthymiou Evangelos , Tsalkatidis Themistoklis
Published: September 2023

Over the last few years, hybrid steel‐timber components and systems are enjoying increasing popularity in the construction sector, particularly in the case of multistorey timber buildings where significant benefits arise due to faster and safer on‐site erection, improved structural and seismic performance combined with minimized environmental impact. Most of these studies focus on steel frames with Cross‐laminated Timber (CLT) infills and hybrid steel‐timber joints. However, it may only sometime to be possible to satisfy the maximum drift limit prescribed by building codes only with CLT shear walls and hybrid steel‐timber joints. Some promising improvements have been proposed in the literature for improving buckling stability and avoiding excess building drifts. Among these, is a new type of shear wall called the Wood‐Steel Composite Shear Wall, which has much higher stiffness and can drastically reduce the overall building drifts due to the employment of Steel Plate Shear Walls. Regarding the above considerations, this paper assesses the structural behaviour of Wood‐Steel Composite Shear Wall systems via the finite element method. In the developed Wood‐Steel Composite Shear Wal system, glue connects a thin gauge steel web plate to the boundary Laminated Strand Lumber frame. Based on previous experimental studies, finite element modelling was performed to investigate the effects of behavioural parameters on the response of the Wood‐Steel Composite Shear Wall system. It was found that the plate wall thickness has a significant effect on the initial stiffness and the peak capacity of this system, while changing that parameter may not change the failure mode of the system.
Shear Capacity of Channel Shear Connectors Applied in Composite Slabs with Profiled Steel Decking
Authors: Cardoso Hermano , Pupin Luis Augusto
Published: September 2023

This paper assesses the shear capacity and the structural behaviour of channel connectors in composite slabs. Push‐out specimens were analyzed numerically by using the finite element program ABAQUS. For the studied solution, regular openings at the lower flange in the profiled decking are considered to allow the welded channel connector to pass through. The numerical model was calibrated against experimental outputs on push‐out tests found in the literature. Then, the influence of steel decking thickness on load capacity, stiffness and ductility of channel connectors in composite slabs was also assessed. In addition, it was concluded that safe predictions of load capacity could be obtained by including reduction factors in the Canadian design approach.
On the load‐carrying behaviour of CSTC slim‐floor beams
Authors: Kroyer Robert , Vigneri Valentino , Taras Andreas
Published: September 2023

Composite steel truss and concrete (CSTC) beams are steel‐concrete composite structures mostly used as slim‐floor systems in industrial buildings. The proposed paper focuses on the load‐bearing behaviour of the so called NPS beam system as a specific type of CSTC beam. This system is made of a sinusoidal smooth steel truss welded to a steel plate, and embedded in cast‐in‐situ concrete. Unlike standard composite beams, NPS beams do not have dedicated shear connectors for transferring the longitudinal shear force from the steel part to the concrete. The shear connection between steel and concrete is enabled by the sinusoidal bar as an integrated part of the steel profile. The load‐slip behaviour of the shear connections in NPS beams was recently investigated through push‐out tests and appropriate design rules were proposed to predict their resistance. However, the longitudinal shear connection behaviour within the overall beam system is still not fully understood and requires further investigations. Furthermore, the ductility of composite slim floor systems depends strongly on their geometrical and mechanical properties. Strain‐limited analyses provide more reliable design predictions, but typically still simplify the shear connection behaviour strongly. It is therefore reasonable to conduct full‐scale experimental tests to investigate the structural behaviour at a cross‐sectional and a global level. The presented work addresses those issues through preliminary strain‐limited analyses and the description of an advanced measurement concept using fibre optical sensors for full‐scale beam tests.
Seismic performance of hybrid coupled shear walls
Authors: Morelli Francesco , Natali Agnese , Poggi Gabriele , Salvatore Walter
Published: September 2023

Hybrid Coupled Shear Walls are an innovative seismic‐resistant system that aims at merging the advantages of the classical Coupled Shear Walls with the dissipative capacity and easy‐to‐repair characteristics of steel elements. They are constituted by a reinforced concrete wall connected to two side steel columns by dissipative steel links. Depending on the stiffness/strength of the links, it is possible to obtain different distributions of the seismic forces between the wall and the columns. As resulting from previous research activity on this topic, the seismic behavior of this structural system can be strongly influenced by the higher modes, especially for mid/high‐rise buildings, making classical pushover analyses unable to catch the correct behavior. In this regard, the paper presents the comparison between the results of Incremental Dynamic Analyses and of different Pushover Analyses, giving indications about a more reliable procedure for the assessment of the seismic performance through suitable pushover analysis.
Influence of reinforced concrete slab on the cyclic response of bolted shear links
Authors: Chesoan Adriana , Stratan Aurel , Ciutina Adrian
Published: September 2023

High seismic hazard zones are found all over the world, arising concerns about life and economic loss in the event of major earthquakes. Thus, structural engineers must find ways to increase seismic safety without attracting excessive costs. This can be done by implementing the concepts of removable dissipative members and re‐centering capability in a dual structure, obtained by combining steel eccentrically braced frames with removable bolted links with moment resisting frames. Shear bolted links are intended to provide the energy dissipation capacity and to be easily replaceable, while the more flexible moment resisting frames provide re‐centering capability. One of the critiques of bolted shear links is related to the interaction between the dissipative element and the reinforced concrete slab. Using continuous slab over links, besides replacing the damaged link, reinforced concrete slab needs also repair following a major seismic event. Thus, recent research investigates the behavior of flush end‐plate shear links, experimentally quantifying their strength, stiffness, and ductility, with and without reinforced concrete slab. It is established if repairing the concrete slab after link damage is needed for further acceptable seismic performance.
Evaluation of Seismic Performance of Offshore Wind Turbine Foundations with Slip Joints by Large Shaking Table Tests
Authors: Soya Yoko , Matsuki Satoshi , Yamasawa Tetsuya , Arai Nanae , Fujii Ayumi , Suzuki Yoshitaka , Sako Yuji
Published: September 2023

In Europe, a monopile is the most commonly used foundation type for offshore wind turbines. Existing connections between the monopile (MP) and transition piece (TP) are generally bolts or grout, but another new method is the slip joint. In this method, the joints between the MP and TP are conically shaped and are simply joined together, which is expected to improve workability and reduce maintenance and management costs. In order to apply this structure in Japan, it is necessary to verify its seismic resistance. This paper reports the results of shaking table tests using a scaled specimen to verify the structural safety of the structure against earthquakes.
Machine learning models for the ultimate strength of steel beams – influence of bending moment diagram
Authors: Couto Carlos , Real Paulo Vila
Published: September 2023

Artificial intelligence models using machine learning techniques are widely used in engineering to predict the mechanical behavior of structural members. Different machine learning (ML) algorithms such as artificial neural networks, random forests, and support vector regression were used to develop and train models in this study to predict the ultimate strength of steel beams, in particular that include the influence of the bending moment diagram on its lateral‐torsional buckling resistance. An extensive dataset was constructed using finite element analysis to obtain the ultimate strength of simply supported beams. A comparative study of different hyperparameters was carried out. The results show that the ML models outperform state‐of‐the‐art analytical models and that are able to capture the influence of bending moment diagrams. The limits of application of these ML models are explored, providing an overview of their potential use in designing real structures.
Wrapped Composite Joints for Circular Hollow Section Structures
Authors: Pavlovic Marko , Veljkovic Milan , Segeren Maxim
Published: September 2023

An innovative bonding joining technology for truss/lattice circular hollow section (CHS) supporting structures is being developed as replacement for welded joints. Wrapped Composite Joint uses bonding instead of welding to transfer the joint forces and bending moments between the chord and brace CHS members through a dedicated fibre reinforced polymer composite wrap. It is aimed to replace all welds in different types of joints such as X, K, KK and splice joints in fatigue and/or corrosion dominated designs of truss/lattice structures such as offshore wind jackets and floaters, fish farms, truss bridges, etc. Composite material is known for good fatigue performance from aerospace industry and wind turbine blades. Number of joint experiments showed superior fatigue performance of the wrapped composite joints compared to welded CHS joints. This new concept allows for huge reduction of thickness of CHS members resulting in significant truss/lattice structure weight reduction and increase of fatigue lifetime. This paper presents state of development and outlook of the wrapped composite joint technology in terms of design, production and joint performance for ultimate limit state, fatigue and influence of the environment. Framework of prediction methods and design principles based on ongoing experimental and numerical research will be presented. The scope includes material, interface, and joint level experiments from small to full scale (100‐600 mm member diameter) and finite element modeling of complex steel‐composite bonded joints. Advantage of using state‐of‐the‐art monitoring techniques such as Digital Image Correlation, Fibre Optics Strain Measurement and 3D scanning is highlighted
Experimental investigation of the service shear strength of the welded clip‐angle connector in a CFS beam‐to‐column connection
Authors: Madheswaran Ranjithkumar , Mallepogu Nagaraju , Madhavan Mahendrakumar
Published: September 2023

The present research endeavours to experimentally evaluate the service shear strength of the cold‐formed steel (CFS) welded clip‐angle connector in a CFS beam‐to‐column connection. A total of 30 laboratory tests were conducted on the 27 configurations of the clip‐angle by varying its thickness, width, and depth. The governing design failure modes observed in the welded clip‐angle are (i) Local buckling and (ii) Distortional buckling. The existing traditional elastic design approach for the service limit state design of CFS connector was found to be highly conservative for most of the welded clip‐angle specimens. Hence a new design approach is developed for the welded clip‐angle configuration and the corresponding design shear equation is suggested. A comparative study was conducted between the present welded clip‐angle configuration and existing screwed configuration. The design recommendations were suggested for the efficient design of the connection for the welded clip‐angle configuration. The relevant design factors for the suggested shear equations of welded clip‐angle were evaluated from the reliability analysis.
Structural behaviour of Cold‐Formed Steel back‐to‐back welded sections subjected to longitudinal shear
Authors: Naik Bishal , Madhavan Mahendrakumar
Published: September 2023

The current study focuses on understanding the behaviour of flare v‐groove welds on back‐to‐back connected Cold‐Formed Steel welded sections (G300) subjected to longitudinal shear. A novel welding technique called Cold Metal Transfer (CMT) welding was used for fabrication with copper‐coated steel welding wire as a filler metal (ER70S‐6). This mode of welding has the advantage of controlled material deposition compared to the spray or globular mode of welding. Lap shear tests were carried out on unlipped channels including thickness of the weld, and length of the weld. The weld geometry was observed under an optical microscope after polishing and chemical etching of the weld cross‐section, as American Iron and Steel Institute (AISI) design standard provides no specification on thickness of flare v‐groove welds for CMT welding process. In general, the lap shear specimens failed in plate tearing failure mode and brittle fracture of weld at the weld contours. Additionally, the appropriateness of AISI's shear design strength equations for flare v‐groove welds was verified and preliminary design guidelines are provided addressing the lacunae in AISI design standard.
Cyclic pushout tests on high‐performance concrete‐filled steel tube columns for seismic applications
Authors: Schurgacz Przemyslaw , Winkler Rebekka , Knobloch Markus
Published: September 2023

Concrete‐filled double steel tube columns (CFDST) made from high‐performance materials represent an advanced type of prefabricated composite components with excellent fire performance, enabling a slender design under high loading compared to traditional concrete‐filled steel tubes (CFST). CFST have been proven to be a viable solution under seismic loading, as they can achieve improved load‐carrying capacities (improved stiffness, strength, ductility, and energy dissipation capabilities) compared to conventional concrete columns. However, there is currently a lack of experimental and numerical investigations on CFDST.

This paper presents experimental results on five load‐reversal pushout tests on high‐strength CFDST columns. The objective was to investigate the bond behavior between steel and concrete, as well as the accompanying adhesion, micro‐, and macro‐locking effects under cyclic loading in order to better assess the seismic performance of such structures. The results showed a continuous decrease for the interface carrying capacity as well as for the overall bond stress behavior for each new loading cycle. However, macro‐locking represents the dominant mechanism for composite strength and is strongly influenced by the geometric shape of the high‐strength steel tubes. Even in post‐interface carrying capacity range, significantly higher bond stress states were reached.
Novel Aspects about “Lifetime” in Upconversion Luminescence
Authors: Han Yingdong , Zhang Xingxing , Huang Ling
Published: September 2023

Recent progress on the temporal response (TR) of lanthanide‐doped upconversion luminescence (UCL) has enriched the means of UCL regulation, promoted advanced designs for customized applications such as biological diagnosis, high‐capacity optical coding, and dynamic optical anti‐counterfeiting, and pushed us to reacquaint the dynamic responses of sensitizer/activator ions in UCL systems. In particular, the lifetime of UCL should be revisited after discovery of novel experimental phenomena and luminescence mechanisms, i. e., it should be understood as the collective TR (in the decay edge) of all the involved ions rather than the reciprocal of the radiative rate of an individual ion. In this Concept, we retraced the latest understanding of the dynamics in UCL with special attention to the relationship between excitation and emission, means of TR regulation, and discussed existing challenges. It is expected to provide some fundamental insights to deepened understanding, further regulation, and frontier applications of TR features of UCL.
B−N Co‐Doped Biphenylene as a Metal‐Free Cathode Catalyst for Li−O2 Batteries: a Computational Study
Authors: Guo Cong , Zhang Xinxin , Wang Yu , Li Yafei
Published: September 2023

Lithium‐oxygen batteries (LOBs) meet the growing demand for long‐distance transportation over electric vehicles but face challenges because of the lack of high‐performance cathode catalysts. Herein, using density functional theory calculations, we report a unique graphene allotrope, biphenylene, of which the doping structures exhibit great potential as metal‐free catalysts for LOBs. Our modeling results demonstrate that the biphenylene nanosheets retain metallic properties after B doping, N doping, or B−N co‐doping. Compared with the pristine biphenylene, the catalytic activity of the doped biphenylene is greatly improved due to charge redistributions. Notably, the overpotentials of the B−N co‐doped biphenylene are as low as 0.19 and 0.18 V for the discharge and charge processes, respectively. Based on the electronic structure and bonding analysis, we identify two factors, i. e., Li−O bond strength and *Li2O2 adsorption energy, that can influence the Li−O2 electrochemical reactions. This study not only proposes a promising cathode catalyst but also provides insights into optimizing cathode catalysts for LOBs.