bluuebunny/crossref_metadata_2025 huggingface dataset:
Wisdom of the inner crowd benefits both face and voice matching
Authors: Kramer Robin S. S. , Flanagan Emily , Jones Alex L. , Gous Georgina
Published: September 2023

Identification often involves determining whether two face photographs or voice samples originated from the same person. Here, we investigated the wisdom of the (outer) crowd (averaging two individuals' responses to the same trial) and inner crowd (averaging the same individual's responses to the same trial after completing the test twice) as routes to increased performance. Participants completed the same face (Experiment 1) or voice matching test (Experiment 2) twice with no delay. In addition, we reanalysed previously collected data where these tests were completed with a one‐week interval between sessions. For both tests, whether with or without a delay, inner crowds outperformed participants' individual test responses and were equivalent to outer crowds of two participants. Taken together, we demonstrate the use of inner crowds as a robust method of improvement during identification. In contexts where outer crowds are not feasible, agencies should consider inner crowds as a promising alternative.
Lightweight Triboelectric Nanogenerators Based on Hollow Stellate Cellulose Films Derived from Juncus effusus L. Aerenchyma
Authors: Chen Qi , Li Wenjian , Yan Feng , Maniar Dina , van Dijken Jur , Rudolf Petra , Pei Yutao , Loos Katja
Published: September 2023

This study reports a facile delignification and natural drying process for synthesizing cellulose films using the unique surface roughness, porosity, and lightness of the hollow stellate cellulose (HSC) united aerenchyma of the wetland weed Juncus effusus L. By controlling the grafted amino/fluorine‐bearing group content of various silane coupling agents, this work successfully manipulates the triboelectric polarities of HSC films after silanization. Subsequently, a layer of Ag nanowire electrodes is coated on one side of the silanized HSC friction layers, resulting in flexible, lightweight, semi‐transparent HSC‐based triboelectric nanogenerators (HSC‐TENGs) featuring both macro‐scale surface roughness and micro‐nano inner pores. These all‐in‐one HSC‐TENGs achieve the highest output voltage of 4.86 V, which is 28 times that of TENGs employing two pristine HSC films as triboelectric layers (PHSC‐TENG). Finally, the HSC‐TENG with the optimum output power is applied as a wearable self‐powered sensor for gait analysis, demonstrating stable and sustainable performances in distinguishing different body motions such as walking, running, jumping, and calf raising. This study not only proposes a new cellulose‐based TENG for future in‐depth body locomotion analysis but also paves the way for converting differently structured aerenchyma from abundant problematic aquatic or wetland weeds into promising structural templates in multifunctional cellulose‐based applications.
Fast Nitrogen Dioxide Sensing with Ultralow‐Power Nanotube Gas Sensors
Authors: Jung Seoho , Roman Cosmin , Hierold Christofer
Published: September 2023

The study reports fast, ultralow‐power operation of carbon nanotube‐based nitrogen dioxide (NO2) sensors enabled by nanotube self‐heating and transient sensing. The self‐heating effect in the nanotube channel significantly accelerates the desorption of gas molecules, reducing the sensor recovery time to a minute. As gas molecules re‐adsorb on the nanotube after cooling, the initial rate of the sensor transient is used to determine NO2concentration within a few minutes. To accelerate and optimize the operation of the sensor, the study considered temperature profiles along the self‐heated carbon nanotube, their effect on different sensing regions, and a physical model‐based fit. As a result, the nanotube‐based NO2sensor demonstrates recovery and readout times below 5 min and an extrapolated limit of detection below 10 ppb. The peak power consumption of this operation mode is below 6 µW. The combination of fast readout, fast recovery, low limit of detection, and ultralow power consumption demonstrated in this work shows strong promise of carbon nanotube‐based NO2sensors in mobile or Internet‐of‐Things (IoT) applications.
Oxidative Cleavage of C−C Bonds in Non‐aromatic Oxygenates with Molecular Oxygen for Synthesis of Carboxylic Acids
Authors: Nakagawa Yoshinao , Yabushita Mizuho , Tomishige Keiichi
Published: September 2023

Oxidative carbon‐carbon cleavage reactions of non‐aromatic oxygenates such as vicinal diols are reviewed. In comparison with aromatic oxygenates where the benzyl positions are easily oxidized, non‐aromatic alcohols are difficult to be oxidized. The use of excess base in combination with metal catalysts is a typical approach, and the oxidations of 1,2‐cyclohexanediol and dihydroxylated derivatives of oleic acid have been reported with good yields of (di)carboxylate. Oxidation under acidic conditions typically uses vanadium as a key component of catalyst. Vanadium alone is active in oxidation of hydroxyketones and not effective in oxidation of saturated alcohols and polyols. Oxidation of sugars to formic acid is catalyzed by vanadium. For the oxidation of vicinal diols, the combination of platinum and vanadium is effective. There are some recently‐discovered systems for carbon‐carbon dissociation reactions of 1,2‐difunctionalized compounds, such as 2‐methoxycyclohexanone oxidation to adipic acid with polyoxometalate catalysts. On the other hand, the progress of research in the oxidation of cyclohexanone to adipic acid, which is an important industrial process, is less rapid, and we commented on the situation.
Cobaloxime‐Integrated Covalent Organic Frameworks for Photocatalytic Hydrogen Evolution Coupled with Alcohol Oxidation
Authors: Wang Shihuai , Wu Tai , Wu Shuyang , Guo Jingjing , He Ting , Wu Yinglong , Yuan Wei , Zhang Zhengyang , Hua Yong , Zhao Yanli
Published: September 2023

We report an azide‐functionalized cobaloxime proton‐reduction catalyst covalently tethered into the Wurster‐type covalent organic frameworks (COFs). The cobaloxime‐modified COF photocatalysts exhibit enhanced photocatalytic activity for hydrogen evolution reaction (HER) in alcohol‐containing solution with no presence of a typical sacrificial agent. The best performing cobaloxime‐modified COF hybrid catalyzes hydrogen production with an average HER rate up to 38 μmol h−1 in ethanol/phosphate buffer solution under 4 h illumination. Ultrafast transient optical spectroscopy characterizations and charge carrier analysis reveal that the alcohol contents functioning as hole scavengers could be oxidized by the photogenerated holes of COFs to form aldehydes and protons. The consumption of the photogenerated holes thus suppresses exciton recombination of COFs and improves the ratio of free electrons that were effectively utilized to drive catalytic reaction for HER. This work demonstrates a great potential of COF‐catalyzed HER using alcohol solvents as hole scavengers and provides an example toward realizing the accessibility to the scope of reaction conditions and a greener route for energy conversion.
Functionalized amino Al‐MOF as a novel fluorescence chemosensor for determination of Pb2+ in aqueous solution
Authors: Abu‐Melha Sraa
Published: September 2023

Lead is an environmental pollutant that has been present for a long time and has harmful effects on human health. The essential task of protecting public health requires sensitivity and selectivity in monitoring and removing Pb2+ from the environment. NH2‐Al‐MOF was utilized to create a chemical sensor that can quickly detect Pb2+ ions. By combining the Al–metal–organic framework (MOF) with 2‐Acetyl‐4‐methylpyridine, the 2A4MP=N‐Al‐MOF sensor was developed. The NH2‐Al‐MOF and 2A4MP=N‐Al‐MOF sensor were characterized by X‐ray photoelectron spectroscopy (XPS), Brunner–Emmet–Teller (BET), X‐ray diffractometer (XRD), Fourier transform infrared (FT‐IR), and scanning electron microscopy (SEM). Characterization results indicate that 2‐Acetyl‐4‐methylpyridine was effectively incorporated into the Al‐based MOF, and the 2A4MP=N‐Al‐MOF sensor's pore structure is primarily made up of mesopores. To determine the optimal conditions for detecting Pb2+ ions using the 2A4MP=N‐Al‐MOF sensor via fluorescence measurement, several experimental studies have been carried out. A steady spectroscopic signal can be achieved with a sensor that has a response time of below 30 seconds. According to ICH guidelines, the suggested methods underwent validation for LOD, LOQ, linearity, and precision. The results show that the 2A4MP=N‐Al‐MOF chemosensor has a high sensitivity and selectivity toward the Pb2+ analyte, with a detection limit of 0.171 ppm and a linear range of 0.0–2.0 ppm. The 2A4MP=N‐Al‐MOF chemosensor also exhibited good reproducibility, with a relative standard deviation of less than 3%. As a result, the Pb2+ ions were sensitively and selectively identified in various environmental water samples using the 2A4MP=N‐Al‐MOF sensor.
Determining the structure and stability of essential oil‐sunflower wax and beeswax oleogels
Authors: Çokay Hatice , Öğütcü Mustafa
Published: September 2023

In this study, essential oil oleogels were produced using eucalyptus, lavender, lemon peel and tea tree oils with sunflower and beeswax. The physicochemical, thermal, textural, and structural features of the oleogels were determined. For the essential oils used, an addition level of less than 15% of beeswax (BW) was insufficient to form stable oleogels, whereas an addition level of 10% of sunflower wax (SW) was sufficient to form stable oleogels. The acid and peroxide values of the gels were higher than those of the oils. All of the oleogels exhibited peaks around 3.70 and 4.10, indicating the presence of β' polymorphic forms. The hardness and stickiness values of the oleogels were influenced by the type and level of wax addition, as well as the viscosity of the oil used. Based on the thermal analysis results, the oleogels based on beeswax exhibited lower melting properties compared to those based on sunflower wax. The thermogravimetric data indicated that the polymeric matrices formed by the waxes, which depended on the type and level of wax addition, affected the vaporization of the volatiles. In conclusion, oleogels represent a green and sustainable approach for reducing the loss of volatile or bioactive compounds from various essential oils, which are widely used in the food, cosmetics, and pharmaceutical industries.
Unlocking generosity: Turning volunteers into donors
Authors: Fellman Ann
Published: September 2023

It's widely held industry knowledge that volunteers are much more likely to donate to the organization they support than those who don't volunteer their time. Nonprofit organizations may be missing out on an important opportunity to convert volunteers into donors. This article examines the best practices to turn acts of service into enduring acts of generosity year‐round.
Determination of cefuroxime in breast milk by LC–MS/MS using SALLME technique
Authors: Kul Aykut , Sagirli Olcay
Published: September 2023

The World Health Organization recommends that infants be exclusively breastfed for the first 6 months. Antibiotics are among the most commonly prescribed drugs for pregnant and lactating women. The vast majority of drugs pass into breast milk, which may create a risk for the infant. In cases where drug exposure may pose a risk, breastfeeding should be discontinued. Therefore, the mother's drug use should be decided by considering the most accurate and recent data. Cefuroxime is a second‐generation cephalosporin antibiotic with a broad spectrum of activity against Gram‐negative and ‐positive microorganisms. In this study, we aimed to develop the LC–MS/MS method using salt‐assisted liquid–liquid micro‐extraction (SALLME) for the determination of cefuroxime in breast milk. The method was validated according to the European Medicines Agency (EMA) guidelines. Cefuroxime and the internal standard cefixime were extracted from plasma by a SALLME technique. The results obtained from the entire validation study are at an acceptable level according to the EMA criteria. The calibration curve of cefuroxime was between 25 and 1000 ng/ml, with correlation coefficients of >0.99. The lower limit of quantitation was 25 ng/ml for cefuroxime. Furthermore, the developed method was applied for the determination of cefuroxime in real patient breast milk.
Performance of the 32 mm Myval transcatheter heart valve for treatment of aortic stenosis in patients with extremely large aortic annuli in real‐world scenario: First global, multicenter experience
Authors: Holzamer Andreas , Bedogni Francesco , van Wyk Pieter , Barwad Parag , Protasiewicz Marcin , Ielasi Alfonso , Nombela‐Franco Luis , Seidler Tim , Hilker Michael
Published: September 2023

Background

Extremely large aortic valve anatomy is one of the remaining limitations leading to exclusion of patients for transcatheter aortic valve replacement (TAVR).

Aims

The newly approved Myval 32 mm device is designed for use in aortic annulus areas up to 840 mm2. Here we want to share the initial worldwide experience with the device.

Methods and Results

Retrospective data were collected from 10 patients with aortic stenosis and very large annular anatomy (mean area 765.5 mm2), who underwent implantation with 32 mm Myval transcatheter heart valve at eight centers. Valve Academic Research Consortium‐2 device success was achieved in all cases. Mild paravalvular leak was observed in three patients and two patients required new pacemaker implantation. One patient experienced retroperitoneal hemorrhage caused by the contralateral 6 F sheath and required surgical revision. No device‐related complications, stroke, or death from any cause occurred within the 30‐day follow‐up period. In a studied cohort of 2219 consecutive TAVR‐screened patients from a central European site, only 0.27% of patients showed larger anatomy than covered by the 32 mm Myval device by instructions for use without off‐label use of overexpansion. This rate was significantly higher for the 34 mm Evolut Pro (1.8%) and 29 mm Sapien 3 (2.1%) devices.

Conclusions

The Myval 32 mm prosthesis showed promising initial results in a cohort of patients who previously had to be excluded from TAVR. It is desirable that all future TAVR systems accommodate larger anatomy to allow optimal treatment of all patients.
Why the Perfectly Symmetric Cobalt‐Pentapyridyl Loses the H2 Production Challenge: Theoretical Insight into Reaction Mechanism and Reduction Free Energies
Authors: Kiser Ayas , Gurdal Yeliz
Published: September 2023

Researchers have extensively investigated photo‐catalytic water reduction utilizing Cobalt‐based catalysts with polypyridyl ligands. While catalysts exhibiting distorted polypyridyl ligand demonstrate higher H2 production yields, those with ideal octahedral coordination display poor performance. This outcome suggests the crucial role of ligand framework in catalytic activity, yet reasons behind the disparity in H2 production rates for catalysts with octahedral geometries remain unclear. We theoretically examined the water reduction mechanism of Co‐based poly‐pyridyl catalyst, CoPy5, having perfect octahedral coordination. We clarified the effect of octahedral coordination by utilizing each intermediate step of ECEC mechanism. We determined spin states, solvent response, electronic structures, and reduction free energies. CoPy5 with perfect octahedral coordination, alongside its distorted counterparts, exhibit similar spin states as the reaction progresses through each intermediate step. However, the first reduction free energy obtained for the CoPy5 is slightly higher than that of its distorted counterparts. Following the second protonation, resulting H2 molecule experiences limited diffusion from the Co center due to the compact structure of the CoPy5, which blocks the Co center for the next H2 production cycle. Catalysts having distorted octahedral geometries facilitate fast removal of H2 into the solvent. Thus, the reaction center becomes immediately available for subsequent H2 production.
Development of a preloadable, temperature‐stable, geopolymer‐based gap compensation material
Authors: Morgenstern Hendrik , Kunde Carsten , Raupach Michael
Published: September 2023

Consequences of climate change are becoming increasingly clear and while resources are dwindling, extreme climatic situations become more frequent. This leads to higher temperatures and thermal stress on the one hand and to the construction of more wind power plants and respectively an increasing demand for gap compensation materials on the other hand. These materials are commonly made of epoxy resins, which perform well under certain circumstances, but have some disadvantages such as heat instability, high costs, high resource claim, and hazards for the environment and health. This paper presents the latest results from the development of a low‐viscosity, high‐temperature stable geopolymer for gap compensation. In several newly developed test rigs, experiments were carried out to investigate injectability, flow behavior, mechanical properties, high‐temperature stability, and the possibility to induce preload. Through inorganic additives, the geopolymer expands or, if expansion is constrained, preloads itself during the hardening. This is essential to retain or enhance the preload of connection bolts and ensure force transmission as any volume reduction would create a new (smaller) gap.
Experimental investigation on stress state and deformation in bolts through tightening of perfect flange connections
Authors: Schierl Christopher , Stang Andre , Ghafoori Elyas , Schaumann Peter
Published: September 2023

The fatigue loads of bolts in ring flange connections are significantly influenced by the pressure body between the compressed flanges, which in turn depends on two main scattering parameters ‐ geometric flange imperfections and the preload level. Depending on the tightening method and geometric boundary conditions, shear and bending stresses occur in addition to the axial stress in the bolt during prestressing of the connection. This multiaxial stress condition leads to different plastic deformations in the threads and thereby influence the performance respective the maximum achievable preload of tightening methods. In accordance with the objective, the authors identify the stress state in HV‐bolts during installation for different tightening procedures through experimental testing. Based on a comparison of the strain measurements with the 3D scan of the bolt geometry, this study evaluate to what extent the initial imperfections corresponds to bolt bending. Derived from the scope of a joint national research project, this contribution point out that the yield controlled tightening ensure prestresses close to the individual yield strength of the bolt within a narrow scatter.
Strength Evaluation of Pipe‐Rack Connection Using Extended End Plate
Authors: Kang Seong‐Hun , Woo Jong‐Hun , Shin Kyung‐Jae , Lee Woo‐Geun , Park Hwa‐In
Published: September 2023

Pipe‐rack structure is generally designed as a steel structure, but size of each column and beam is small because vertical loads on the structure is relatively low. In addition, due to the surrounding environment, the end plate joint is mainly used as on‐site bolting rather than welding. In this paper, seismic performance evaluation of pipe‐rack structures was conducted for three types of extended type end plate connection using the panel zone reinforcement and end plate thickness as variables. Connection of the pipe‐rack structure which is commonly used is the type of panel zone yielding occurred before other members, and its ductility and energy dissipation capacity was calculated 24.2% and 19.5% higher than the type of reinforcing panel zone by plates. As a result of the test, it is judged that yielding of the panel zone in a steel structure such as a pipe‐rack structure can be beneficial in the seismic loads.
Experiments on Welded High Strength Steel S700 K‐joints
Authors: Alshawwa Omar , Mela Kristo , Ahola Antti , Björk Timo
Published: September 2023

High strength steel (HSS) hollow sections are widely available for structural applications nowadays. A typical structure employing HSS hollow sections is a truss with welded joints. The behavior and design of HSS welded tubular joints still includes some open issues, and so‐called K‐joints require more experiment‐based research. This research addresses the effect of specific parameters (chord preloading and the gap size) on the behavior of welded HSS K‐joints made from cold‐formed hollow sections. These parameters have been selected based on their limited conducted research. In the experiments the degree of chord tension preloading and gap size were varied to obtain a broad scope for the study. This study of the aforementioned parameters was conducted on 6 welded HSS K‐joints of grade S700. The study is entirely based on experiments targeting the effect of each parameter in a comparative manner. The tested joints were fabricated with full strength butt and fillet welds and were designed to target one type of failure in K‐joints to occur which is chord face failure. Subsequently, the load‐displacement behavior of the tested joints is reported. The experimental results are compared with the expected behavior according to the most recent version of the second generation Eurocode. The level of agreement between the tests and current guidelines is compared and analyzed. Accordingly, this research contributes to the ongoing discussion on behavior and resistance of welded HSS hollow section joints.
Simulation of Welding Residual Stresses in Large Structures – First Results of Thermal Analyses
Authors: Gkatzogiannis Stefanos , Gantes Charis
Published: September 2023

Simulation of welding residual stresses and distortions has been applied mostly for small‐scale components, smaller than those applied in civil engineering structures, due to the high requirements in computational capacities. In the present study, work hypotheses, which can reduce the computational load of welding simulations for an accepted sacrifice in accuracy, are discussed. A series of thermal analyses is carried out, in order to check the validity of the proposed modelling approaches, which refer to the application of simple weld heat source models and hybrid shell‐solid element models. Application of local‐global models is also discussed. The present study aims to work as a first step towards the establishment of an engineering approach for the simulation of welds in civil engineering structures with sufficient accuracy and reduced requirements for computational capacity.
New analytical approach for predicting the plastic shear resistance of the panel zone in steel joints
Authors: Corman Adrien , Jaspart Jean‐Pierre , Demonceau Jean‐François
Published: September 2023

This paper presents a new analytical approach for predicting the plastic resistance of the sheared panel zone in steel beam‐to‐column joints. This approach has been developed within the framework of a larger research project dedicated to the prediction of the full non‐linear behaviour up to failure of the sheared panel zone. It is suggested as an alternative to the current European and North American design approaches, which are proved to be unsafe in many cases. This is demonstrated in this paper through comparisons with a non‐exhaustive sample of experimental results carefully selected from the scientific literature. In contrast, the new proposed expression, which more faithfully depicts the physical phenomena governing the resistance of the panel zone, provides safe estimates for all the investigated cases.
Innovative hollow section column‐splice connections resorting to laser cutting
Authors: Das Rajarshi , Kanyilmaz Alper , Couchaux Mael , Degee Herve
Published: September 2023

Circular Hollow Section (CHS) columns are highly encouraged in the modern industry due to their good resistance against high compression, tension and flexure in all directions, combined with their exceptional aesthetics. However, conventional end plate‐bolted column‐splice connections tend to limit the full potential of the CHS by focusing most of the damages in the bolts and sometimes discourage architects with a poor aesthetic. An innovative “passing‐through” concept (using laser cutting technology) have therefore been proposed in the EU‐RFCS project LASTTS to develop efficient column‐splice connections. Three different configurations have been presented in this article: (1) CS‐1: CHS columns connected using passing‐through steel plates, bolts and steel cover plates outside the tube diameter; (2) CS‐2: CHS columns connected using passing‐through steel plates, bolts and steel cover plates inside the tube diameter; (3) CS‐3: CHS columns connected using passing‐through steel plates, bolts and steel end plates inside the tube diameter. Nonlinear parametric studies have been conducted based on finite element models, calibrated from a previous experimental campaign, to understand the influence of each parameter and subsequently characterize the analytical assumptions to calculate their ultimate resistance under different loads. Additionally, they are compared among each other to note their advantages/disadvantages in terms of strength, stiffness and industrial application.
Experimental study of the cyclic behavior of steel tube in concrete‐filled steel tube members
Authors: Wang Shiye , Wang Wei , Lignos Dimitrios G.
Published: September 2023

A concrete‐filled steel tube (CFST) specimen was tested under uniaxial loading to acquire the nonlinear monotonic and cyclic response of the steel tube in CFST members including inelastic cyclic local buckling. The failure mode, hysteretic response, envelope curves, strength, and stiffness degradation of the CFST specimen were comprehensively studied. The observed failure modes of the CFST specimen were local buckling and ductile fracture of the steel tube due to ultra‐low‐cycle fatigue. The effective stress‐strain curve of the steel tube exhibited negative stiffness due to local buckling. The compressive resistance of the CFST specimen decreased significantly when local buckling progressed at the steel tube. The tensile unloading stiffness slightly decreased relative to the elastic stiffness of the CFST specimen; conversely the compressive unloading stiffness experienced severe deterioration upon increased cyclic loading. The tensile stiffness decreased gradually during the whole loading process, while the post‐capping stiffness remained stable.
Major‐axis buckling of pin‐ended stainless steel equal‐leg angle section members: FE modelling and design
Authors: Behzadi‐Sofiani Behnam , Wadee M. Ahmer , Gardner Leroy
Published: September 2023

The behaviour and design of cylindrically‐pinned stainless steel equal‐leg angle section members under compression and compression combined with strong‐axis bending are investigated herein. Numerical models are developed by means of shell finite element modelling formulated within ABAQUS and validated against experimental data. A numerical parametric study is then presented considering both hot‐rolled and cold‐formed stainless steel equal‐leg angle section columns alongside beam‐columns with a wide range of cross‐section and member geometries. Finally, new design proposals for pin‐ended stainless steel equal‐leg angle section members under compression and compression plus major‐axis bending are developed and verified against the results of physical experiments and numerical simulations. The proposed design rules are shown to offer substantially more accurate and consistent resistance predictions compared to existing codified design rules.
Life‐Cycle‐Assessment of a wildlife bridge: influence of the structural design on the carbon emissions
Authors: de Paula Filho José Humberto , Zanon Riccardo , Glorieux Antoine
Published: September 2023

In 2020, 37% of the global share of CO2eq. emissions were attributed to the construction sector. More recently, awareness has been raised on embodied carbon, where emissions from materials and products must be urgently addressed to ensure sustainable constructions. To assess the environmental impacts of a project, a Life‐Cycle‐Assessment (LCA) can be applied: it is a science‐based standardized methodology for quantifying the environmental impacts. It can be used to measure and provide insights to reduce the embodied carbon of constructions over their life.

The present publication details the LCA of a wildlife bridge built in France. In addition to the original bridge structure, other structural systems are considered including different materials such as steel and reinforced concrete. The boundary of the LCA is a cradle‐to‐cradle analysis. The life cycle inventory (LCI) is composed of environmental product declarations (EPD) according to EN 15804.

The influence of the structural design on the bridge's global warming potential (GWP) emissions and the influence of LCA assumptions (for example, EOL scenarios) are analyzed. This publication aims to support a holistic approach for bridge LCA and help identify the opportunities that can result from implementing sustainable construction strategies.
Influence of eccentric load introduction during launching with rockers using an elastomeric bearing
Authors: Thomas Nadine , Mensinger Martin , Ndogmo Joseph
Published: September 2023

During launching, the superstructure acts as a continuous beam supported by different launching bearings on the piers. Just before reaching the next pier, a part of the superstructure temporarily behaves as a long cantilever. As a result, a large bending moment and reaction force at the last bearing occur. The interaction of the internal forces results in a biaxial stress state in the cross‐section. This load case is usually determining for the buckling check and the structural design of the webs. Additionally, the webs of the superstructure and the launching bearing often fail to share the same center lines. This eccentricity can be caused by misalignments of the launching bearings, the necessary air gap to the lateral guide as well as the different thicknesses of the panels along the superstructure. These eccentricities are not considered in the buckling check according to EN 1993‐1‐5 [1]. It is often discussed how these eccentricities affect the buckling behaviour and whether they must be considered in the buckling check. In the case of launching bearings like a rocker system which includes an elastomeric bearing between the superstructure and the launching beam, the reaction forces of the nonlinear material behaviour are additionally discussed. In [2] the effects on the buckling resistance in dependence of load eccentricity for some parameters for the different types of launching bearings are presented. [3] shows the comparison of the buckling resistance with investigations from [4] and [5] with the buckling check according to [1]. A comprehensive summary and the new proposal for considering an eccentric load application and clamping effects in the buckling zone can be read in [6]. This paper shows first investigations of the influence of the elastomeric bearing and the problem of the reaction of the nonlinear material behaviour and its definition in the numerical model. The results have shown that load eccentricities in combination with elastomeric bearings have no impact on the buckling behaviour.
Investigating the impact of thermal stresses on blistering effects in sandwich panels
Authors: Kühn Annalena , Haugwitz Christoph , Hinrichs Jan , Kupnik Mario , Lange Jörg
Published: September 2023

Lightweight steel constructions made of sandwich panels are an economical solution for wall and roof claddings, especially in industrial construction. The panels consist of two thin sheets of steel and a core with thermal insulating properties. In the mounted state and at high temperatures on the outer face of the panel, damage to the components may occur due to blister formation. In a current research project, the influence of defects in sandwich panels with a PIR‐foam core is examined. This article presents the results of experimental tests regarding the influence of various parameters, such as face temperature, production defects and design of the longitudinal joint on blistering in sandwich wall panels with a PIR‐core. The aim is to identify the necessary conditions for the occurrence of blisters. Using an optical strain measuring method (Digital Image Correlation), the temperature‐induced deformations and strains in the covering nose of sandwich wall panels with hidden fastening are measured and will be analyzed with regard to blistering. First results reveal a significant dependence on the geometry and design of the covering nose.
Monotonic and cyclic behaviour of 6082‐T6 aluminium alloy
Authors: Georgantzia Evangelia , Kashani Mohammad M
Published: September 2023

Over the last few decades, the application of 6000 series aluminium alloys as structural material has been increased owing to their favourable properties. Many research studies on the monotonic behaviour have been reported, whilst the studies investigating the cyclic behaviour are quite limited. To address this gap, an experimental campaign is currently underway to investigate the nonlinear stress‐strain behaviour of 6000 series aluminium alloys. This paper presents and discusses preliminary experimental results on the stress‐strain behaviour of 6082‐T6 aluminium alloy under monotonic and cyclic loading. Particularly, tensile, and variable amplitude cyclic coupon tests are executed to determine the mechanical properties of 6082‐T6 aluminium alloy. The obtained failure modes as well as the monotonic and hysteretic curves are presented and discussed. It was found that at increased strain demands the examined aluminium alloy exhibited hardening behaviour without material degradation demonstrating its potential for structural application in earthquake prone areas. The experimental curves are also utilised to assess the accuracy of existing theoretical models for monotonic and cyclic envelope curves. Finally, the need for a constitutive model capable of predicting the hysteretic behaviour of 6,000 series aluminium alloys is highlighted.
Investigations on the fatigue behaviour of welded cover plates with extended weld seams
Authors: Roth Jakob , Dürr André , Mensinger Martin , Rausch Niclas
Published: September 2023

Nowadays the necessity to design lightweight structures and reducing the use of resources is more important than ever. Normally, cover plates are used as a local strengthening for an optimised load bearing in all kind of steel structures like steel bridges. Under cyclic loading, this notch detail exhibits a worse fatigue behaviour due to the geometrically induced notch factor at the end of the cover plate. By using extended weld seams the stress concentration of this detail can be reduced by a continuous and smooth transition between the ground and the cover plate and thus the fatigue strength can be improved. By using different post weld treatment methods, the fatigue strength could be raised further. Unfortunately, there are almost no experimental results in literature dealing with extended weld seams for any notch detail, even when this type of detail is already used for different construction machines.

Within this paper systematic experimental research on possible influencing factors for extended weld seams will be presented.
Interaction Formulae for N‐My and N‐Mz and their Accuracy in Hollow Sections
Authors: Ludwig Christian
Published: September 2023

In those cases where architectural requirements are a priority, hollow sections are the preferred solution. Considering cross‐sectional classes 1 and 2, plastic cross‐sectional design is a possibility that is preferable for both economic and ecological reasons. In technical standards and the literature, a wide variety of interaction formulae can be found. However, in most cases, information about their accuracy is not provided. In this article, the accuracy of the different interaction formulae for two frequently used combinations of internal forces and moments (N‐My and N‐Mz) is determined. Comprehensive parametric studies show that the interaction formulae for hollow sections given in EN 1993‐1‐1 exhibit some non‐conservative results. In addition to the comparison of the different accuracy levels, simplified interaction formulae will be introduced here allowing conservative plastic design of hollow sections.
Determination of actual material properties in existing structures using small specimens
Authors: van Es Sjors , Braendstrup Cécilia , Slot Henk , Seinen Jeroen , Dekker Richard
Published: September 2023

During reassessment of an existing steel structure, the designer is often confronted with the fact that the current design loads exceed the loads considered in the original design. Furthermore, fatigue damage may exist that needs to be accounted for in the assessment of the future design life. A possible approach in such a case is to use the actual values of fy and fu, because these commonly exceed the nominal values by a considerable margin. For a fatigue assessment by means of a crack growth analysis, fracture toughness properties are required which are usually not well documented, especially for older structures. To obtain specimens to determine the material properties by standardized material tests, a sizable quantity of material needs to be removed from the structure at the critical location where the design loads exceed the resistance, which is undesirable.

This paper presents material testing methods using small specimens, for which only a small quantity of material is needed. The material is extracted by drilling a M39 bolt hole, which has a limited influence on the static resistance of the structure. Furthermore, a high fatigue detail category can be attained by applying a preloaded bolt. Tensile tests are performed on the removed material which give equivalent results to the current standardized tests. Fracture toughness tests are also performed, again with similar results as commonly used standardized tests. Validation of the test methods is shown through comparison with standardized tests.
Behaviour, finite element modelling and design of high strength steel homogeneous and hybrid welded I‐section beams
Authors: Zhu Yufei , Yun Xiang , Gardner Leroy
Published: September 2023

The behaviour and design of homogeneous and hybrid high strength steel (HSS) beams are addressed in the present study. Six in‐plane three‐point bending tests on three different welded I‐sections were first conducted. Following the experimental investigation, a finite element (FE) modelling programme was performed, which included a validation study confirming the accuracy of the developed FE models in replicating the flexural behaviour of HSS welded I‐section beams, and a parametric study generating additional FE data on HSS welded I‐section beams over a broader range of cross‐sectional slendernesses, steel grades and loading configurations. Then, the suitability of the current Eurocode 3 cross‐section slenderness limits for HSS homogeneous and hybrid welded I‐sections in bending were evaluated. It is shown that the current Eurocode Class 2 and Class 3 slenderness limits are suitable for the classification of the outstand flange (in compression) and internal web (in bending) elements of both HSS homogeneous and hybrid welded I‐sections subjected to major axis bending, while stricter Class 1 slenderness limits are considered necessary to achieve sufficient rotation capacity for plastic design. The findings indicate that plastic design can be used for HSS structures, provided the proposed stricter Class 1 slenderness limits are employed. Further work is underway to develop advanced design approaches using second‐order inelastic analysis with strain limits for HSS welded I‐section members.
Fatigue resistance of austenitic stainless steel bolts under tension
Authors: Stranghöner Natalie , Ehrhardt Lukas
Published: September 2023

The design of bolts made of carbon steel and stainless steel under fatigue loading is carried out according to EN 1993‐1‐9. However, the current regulations of the fatigue resistance of stainless steel bolts are based on investigations carried out for bolts made of carbon steel although the material properties of stainless steel are clearly different in terms of nonlinearity and strain hardening. Herewith, the question arises whether the design rules for carbon steel bolts are applicable to stainless steel bolts as the actual fatigue behaviour is almost unknown.

In order to close this gap of knowledge, experimental investigations into the fatigue behaviour of partially threaded bolts according to EN ISO 4014 made of austenitic stainless steel were carried out under tension with constant amplitude loading with either a constant stress ratio R or with a constant mean stress σm. The tests were statistically evaluated and S‐N curves could be determined.

The fatigue tests showed that a fatigue resistance of FAT class 50 according to EN 1993‐1‐9 can be achieved. Herewith, so far, it can be shown that a design according to FAT class 50 might be on the safe side for partially threaded bolts made of austenitic stainless steel.
HIGH TEMPERATURE PUSH‐OUT TESTS ON DEMOUNTABLE SHEAR CONNECTORS OF STEEL‐CONCRETE COMPOSITE BEAMS
Authors: Mansilla Roberto , Espinós Ana , Payá‐Faforteza Ignacio , Odenbreit Christoph , Romero Manuel L.
Published: September 2023

There is no denying that there is a growing need for reusable systems in the construction industry. This is not only a by‐product of the increasing demand of materials, but also a necessity to reduce greenhouse gas emissions associated to the manufacturing process of construction components. Reusable systems aim to solidify the transition from a linear economy model to a circular economy model, where the lifecycle of materials is extended overtime. However, there are several factors that might hinder the reusability of structural components, ranging from regular use over a time period to accidental situations, such as earthquakes and fires.

This experimental study focuses its efforts on the analysis of demountable shear connectors for composite structural systems under the influence of high temperatures that resemble a situation of fire. The main idea behind this experimental campaign is to combine a standard push‐out test, where a specimen composed by a HEB‐260 steel profile with reinforced concrete slabs connected to its flanges via high strength bolts is subjected to a vertical force by utilizing a hydraulic jack with a simultaneous thermal action.

The tests reproduce a previous experimental campaign performed at the University of Luxembourg (cylinder and coupler systems), but subjected to 4 different temperatures (20, 300, 500 and 600 °C). The loss of strength of the connectors with the temperature, the failure mode and the reusability after a situation of fire are discussed in the present study.
Study on headed shear studs influencing the interfacial bond behaviour in CFST columns
Authors: Debnath Partha Pratim , Chen Junbo , Varma Amit H. , Chan Tak‐Ming
Published: September 2023

The performance of concrete‐filled steel tubular (CFST) columns with headed shear studs under push‐out loading has been investigated. The primary objective of the research programme was to investigate the bond behaviour between the steel tube and the infill concrete core of the square CFST column. A numerical investigation has been carried out using the commercially available finite element software. For the simulated numerical models, they have been initially validated with existing experimental results. The validations were made in terms of failure modes, bond strength‐slip curves and the initial stiffness. The validated models were further used to carryout parametric studies. The parameters studied include, vertical spacing of shear studs, horizontal spacing of shear studs, and CFST cross‐section slenderness. From the investigation, it is observed that with reduced vertical spacing of studs, the bond strength increases significantly. Specimens having horizontal spacing of studs as width/4 has more bond strength than specimen with horizontal spacing of width/2 and 0. For specimens with reduced vertical and horizontal spacing of studs though leads to higher bond stress, but also drops suddenly due to loss of contact between the stud and concrete. Therefore, 70% of the peak stress value may be considered as the achieved bond stress, as this stress value sustains for higher slip values. Lastly, as the column cross‐section slenderness reduces, there is a trend in increase in interfacial bond strength.
Resilience Assessment of a two‐storey Steel Structure equipped with Innovative Connections
Authors: Elettore Elena , Freddi Fabio , Latour Massimo , Piluso Vincenzo , Rizzano Gianvittorio
Published: September 2023

In the last few decades, increasing research efforts have been devoted to the definition of innovative seismic resilient design strategies with the aim of reducing direct and indirect losses. Among others, the use of Friction Devices (FDs) for Beam‐to‐Column joints (BCJs) has emerged as an effective solution to ensure the damage‐free behaviour of steel Moment Resisting Frames (MRFs). Additionally, more recent research studies have revealed the benefits of replacing traditional full‐strength Column Bases (CBs) with innovative CBs promoting the residual drift reduction of steel MRFs. Additionally, several research studies developed and investigated structures that could be easily repaired after an extreme event, promoting a functional recovery of the structures and able to reinstate the original seismic performance in a short time. However, experimental research on suitable structural repair techniques is still marginal and the lack of confidence in the performance of repaired structures are relevant issues contributing to the high demolition rates. In this direction, an experimental campaign has been performed on a large‐scale steel structure equipped with BCJs with FDs and innovative CBs. Several pseudo‐dynamic tests have been performed and at the end of each test, the structure have been repaired by simply loosening the bolts of the FDs. Results demonstrated the effectiveness of repairing methodology.
Different fatigue design stress methods for common constructional details in cylindrical shells under axial loading – Influence of the r/t‐ratio and the shell thickness
Authors: Ecker Alexander , Unterweger Harald
Published: September 2023

Cylindrical shells are frequently used in industrial constructions, for example in pipes, towers and masts and are often subjected to fatigue loading. Two common welded constructional details were studied: i) detail 1, the wall thickness transition with a circumferential butt weld and ii) detail 2, the welded ring stiffener. Both details are loaded with axial stresses due to N and/or M. In the new Eurocode prEN 1993‐1‐9:2021 three different fatigue design stress methods are provided in general. For these two constructional details, beside the modified nominal stress method, the hot spot stresses and effective notch stresses are determined with Finite‐Element‐Analyses, with variation of geometric parameters, like shell thickness t, radius‐over‐thickness‐ratio, t2/t1‐ratio at the thickness transition and thickness ts of the ring stiffener. Stress concentration factors for the different fatigue design stress methods are presented and the influence of the geometric parameters are investigated. Especially the difference between a plate with an infinite radius‐over‐thickness‐ratio and the pipe with a finite radius‐over‐thickness‐ratio is shown. Also, the influence of the shell thickness is investigated. For comparison of the three different methods the utilization factors of the hotspot stress method and the effective notch stress method are compared with those of the modified nominal stress method. A recommendation is given, which design stress method is appropriate for the two studied details, depending on the geometric parameters.