bluuebunny/crossref_metadata_2025 huggingface dataset:
Selective Killing of Cancer Cells by Nonplanar Aromatic Hydrocarbon‐Induced DNA Damage
Authors: Zhou Yan , Gan Fuwei , Zhang Yuanliang , He Xiaozhen , Shen Chengshuo , Qiu Huibin , Liu Peifeng
Published: September 2019

A large number of current chemotherapeutic agents prevent the growth of tumors by inhibiting DNA synthesis of cancer cells. It has been found recently that many planar polycyclic aromatic hydrocarbons (PAHs) derivatives, previously known as carcinogenic, display anticancer activity through DNA cross‐linking. However, the practical use of these PAHs is substantially limited by their low therapeutic efficiency and selectivity toward most tumors. Herein, the anticancer property of a nonplanar PAH named [4]helicenium, which exhibits highly selective cytotoxicity toward liver, lung cancer, and leukemia cells compared with normal cells, is reported. Moreover, [4]helicenium effectively inhibits tumor growth in liver cancer‐bearing mice and shows little side effects in normal mice. RNA sequencing and confirmatory results demonstrate that [4]helicenium induces more DNA damage in tumor cells than in normal cells, resulting in tumor cell cycle arrest and apoptosis increment. This study reveals an unexpected role and molecular mechanism for PAHs in selectively killing tumor cells and provides an effective strategy for precision cancer therapies.
Biaxial Strain‐Mediated Room Temperature Ferromagnetism of ReS2 Web Buckles
Authors: Ren Hongtao , Xiang Gang , Lu Jiating , Zhang Xi , Zhang Lei
Published: September 2019

Buckling‐driven delamination of thin films on rigid substrates is frequently observed, which leads to deterioration or failure of the film‐based devices. However, it is observed for the first‐time that web buckles could enhance room‐temperature ferromagnetism in PAD‐grown ReS2 thin films. Here, room‐temperature ferromagnetic ReS2 thin films with web buckles are prepared by polymer‐assisted deposition (PAD) for the first time. The morphology and crystalline structure of the samples are characterized using optical, electron, atomic force microscopes and X‐ray photoelectron spectrometry. The relationship between the web buckle–induced strain and ferromagnetic properties is further explored by combing calculations based on density functional theory and experimental techniques including Raman spectroscopy, fluorescence spectroscopy, and superconducting quantum interference device (SQUID) magnetometry. The results reveal that the biaxial strain has a robust tuning effect on the room‐temperature ferromagnetism of ReS2 samples, suggesting that strain engineering could have significant applications in low‐dimensional spintronic devices.
The animal cachexia score (ACASCO)
Authors: Betancourt Angelica , Busquets Sílvia , Ponce Marta , Toledo Míriam , Guàrdia‐Olmos Joan , Peró‐Cebollero Maribel , López‐Soriano Francisco J. , Argilés Josep M.
Published: September 2019

Background

None of the published studies involving cancer cachexia experimental models have included a measure of the severity of the syndrome like the scoring system previously developed for human subjects. The aim of the present investigation was to define and validate a cachexia score usable in both rat and mouse tumor models.

Methods

In order to achieve this goal, we included in the study one rat model (Yoshida AH‐130ascites hepatoma) and two mouse models (Lewis lung carcinoma and Colon26 carcinoma). The Animal cachexia score (ACASCO) includes five components: (a) body and muscle weight loss, (b) inflammation and metabolic disturbances, (c) physical performance, (d) anorexia, and (e) quality of life measured using discomfort symptoms and behavioral tests.

Results

Using the ACASCO values, three cut‐off values were estimated by applying hierarchical cluster analysis. Four groups were originally described, one exactly below the observed mean, a second exactly over the mean, and two other groups adjusted to every cue (inferior and superior). The three cut‐off values were estimated through maximization of the classification function. This was accomplished by using a similarity matrix based on the metric properties of the variables and assuming multinormal distribution. The results show that the four groups were: no cachexia, mild cachexia, moderate cachexia and advanced cachexia.

Conclusions

The results obtained allow us to conclude that the score could be very useful as an endpoint in pre‐clinical studies involving therapeutic strategies for cancer cachexia. The potential usefulness of ACASCO relates to the primary endpoint in pre‐clinical cancer cachexia drug evaluations.
A Sodiophilic Interphase‐Mediated, Dendrite‐Free Anode with Ultrahigh Specific Capacity for Sodium‐Metal Batteries
Authors: Ye Lei , Liao Meng , Zhao Tiancheng , Sun Hao , Zhao Yang , Sun Xuemei , Wang Bingjie , Peng Huisheng
Published: September 2019

Despite efforts to stabilize sodium metal anodes and prevent dendrite formation, achieving long cycle life with high areal capacities remains difficult owing to a combination of complex failure modes that involve retardant uneven sodium nucleation and subsequent dendrite formation. Now, a sodiophilic interphase based on oxygen‐functionalized carbon nanotube networks is presented, which concurrently facilitates a homogeneous sodium nucleation and a dendrite‐free, lateral growth behavior upon recurring sodium plating/stripping processes. This sodiophilic interphase renders sodium anodes with an ultrahigh capacity of 1078 mAh g−1 (areal capacity of 10 mAh cm−2), approaching the theoretical capacity of 1166 mAh g−1 of pure sodium, as well as a long cycle life up to 3000 cycles. Implementation of this anode allows for the construction of a sodium–air battery with largely enhanced cycling performance owing to the oxygen functionalization‐mediated, dendrite‐free sodium morphology.
Theoretical and experimental investigations of complexation with BF3.Et2O effects on electronic structures, energies and photophysical properties of Anil and tetraphenyl (hydroxyl) imidazol
Authors: Chaabene Marwa , Agren Soumaya , Allouche Abdul‐Rahman , Lahcinie Mohamed , Ben Chaâbane Rafik , Baouab Mohamed Hassen V.
Published: September 2019

The novel compounds (E)‐2‐(((4‐hydroxyphenyl)imino)methyl)phenol, Tetraphenyl (hydroxyl) imidazole and their corresponding Boron difluoride complexes were synthesized and characterized by spectroscopic techniques. Density functional theory calculations at B3LYP‐D3/6–311++G (d, p) level of theory were performed for the geometric parameters. The MEP surface studies were used to understand the behavior of molecules in terms of charge transfer and to determine how these molecules interact. We used the GIAO and the B3LYP‐D3 with a 6–311++ G (d, p) basis set to simulate the (1H‐NMR and 19F‐NMR) and the IR spectra, respectively. The corresponding calculated results are in good agreement with the experimental data. The stability of the molecule arising from hyperconjugation interaction and charge delocalization were analyzed using NBO analysis. FMOs revealed the occurrence of charge transfer within the molecule. The complexation using BF3.Et2O was also found to have remarkable effects on the electrochemical properties of the studied molecules, where (b) and (d) present lower chemical stability, higher reactivity and higher polarizability than (a) and (c), respectively. Moreover, the energy gap of (a) and (c) decreased after complexation using BF3.Et2O, indicating the reliability of the electrochemical evaluation of LUMO and HOMO energy levels. These values are the factors explaining the possible charge transfer interaction within the molecule. The absorption and emission spectra of the model compound were also simulated and compared to experimental observations in the DMF solvent. The results of DFT calculations supported the structural and spectroscopic data and confirmed the structure modification of frontier molecular orbitals for BF2 complexes as well as tunable potentials and energy levels.
Falcaria vulgaris leaf aqueous extract mediated synthesis of iron nanoparticles and their therapeutic potentials under in vitro and in vivo condition
Authors: Zangeneh Mohammad Mahdi , Zangeneh Akram , Pirabbasi Elham , Moradi Rohallah , Almasi Maryam
Published: September 2019

In recent years, researchers have used bionanotechnology techniques as cost‐effective and eco‐friendly routes to fabricate nanoparticles. The present study confirms the ability of aqueous extract of Falcaria vulgaris for the biosynthesis of iron nanoparticles (FeNPs@F. vulgaris). Also, in this study, we showed the antioxidant, cytotoxicity, cutaneous wound healing, antibacterial, and antifungal activities of these nanoparticles. FeNPs@F. vulgaris were characterized by UV, FT‐IR, XRD, FE‐SEM, and TEM analysis. According to the XRD analysis, 25.3 nm was measured for the crystal size of nanoparticles. FE‐SEM and TEM images exhibited a uniform spherical morphology and average diameters of 25 nm for the biosynthesized nanoparticles. FTIR results offered protein and polysaccharides in F. vulgaris were the sources of reducing power, reducing iron ions to FeNPs@F. vulgaris. In vivo design, FeNPs@F. vulgaris ointment remarkably reduced (p ≤ 0.01) the wound area, total cells, neutrophil, and lymphocyte and substantially increased (p ≤ 0.01) the wound contracture, vessel, hydroxyl proline, hexosamine, hexuronic acid, fibrocyte, and fibrocytes/fibroblast rate compared to other groups in rats. Also, FeNPs@F. vulgaris indicated potential antioxidant activity against DPPH, antifungal potentials against Candida glabrata, Candida albicans, Candida krusei, and Candida guilliermondii, antibacterial properties against Gram‐positive bacteria (Streptococcus pneumonia, Staphylococcus aureus, and Bacillus subtilis) and Gram‐negative bacteria (Salmonella typhimurium, Pseudomonas aeruginosa, and Escherichia coli O157:H7) without any cytotoxicity effect against human umbilical vein endothelial cells. Finally, the results showed the useful antioxidant, non‐cytotoxic, cutaneous wound healing, antifungal, and antibacterial effects of FeNPs@F. vulgaris.
Multicenter Prospective Study of the Efficacy and Safety of Combined Immunosuppressive Therapy With High‐Dose Glucocorticoid, Tacrolimus, and Cyclophosphamide in Interstitial Lung Diseases Accompanied by Anti–Melanoma Differentiation–Associated Gene 5–Positive Dermatomyositis
Authors: Tsuji Hideaki , Nakashima Ran , Hosono Yuji , Imura Yoshitaka , Yagita Masato , Yoshifuji Hajime , Hirata Shintaro , Nojima Takaki , Sugiyama Eiji , Hatta Kazuhiro , Taguchi Yoshio , Katayama Masaki , Tanizawa Kiminobu , Handa Tomohiro , Uozumi Ryuji , Akizuki Shuji , Murakami Kosaku , Hashimoto Motomu , Tanaka Masao , Ohmura Koichiro , Mimori Tsuneyo
Published: September 2019

Objective

Interstitial lung disease (ILD) accompanied by anti–melanoma differentiation–associated gene 5 (anti–MDA‐5)–positive dermatomyositis (DM) is often rapidly progressive and associated with poor prognosis. Because there is no established treatment, we undertook this study to prospectively evaluate the efficacy and safety of a combined immunosuppressive regimen for anti–MDA‐5–positive DM patients with ILD.

Methods

Adult Japanese patients with new‐onset anti–MDA‐5–positive DM with ILD (n = 29) were enrolled at multiple study centers from 2014 to 2017. They were treated with a regimen of high‐dose glucocorticoids (GCs), tacrolimus, and intravenous cyclophosphamide (IV CYC). Plasmapheresis was used if a patient's condition worsened after the regimen started. The primary end point was 6‐month survival, which was compared between this group of patients and a historical control group (n = 15) consisting of anti–MDA‐5–positive DM patients with ILD who received step‐up treatment (high‐dose GC and stepwise addition of immunosuppressant). Secondary end points were 12‐month survival rate, adverse events, and changes in laboratory data.

Results

The combined immunosuppressive regimen group showed significantly higher 6‐month survival rates than the step‐up treatment group (89% versus 33%; P < 0.0001). Over a period of 52 weeks, improvements in anti–MDA‐5 titers, serum ferritin levels, vital capacity, and chest high‐resolution computed tomography scores were observed. The combined immunosuppressive regimen group received IV CYC nearly 20 days earlier with shorter intervals and tended to receive plasmapheresis more often than patients undergoing step‐up treatment. Cytomegalovirus reactivation was frequently observed over 52 weeks.

Conclusion

A combined immunosuppressive regimen is effective for anti–MDA‐5–positive DM patients with ILD. Plasmapheresis can be used for additional effect in intractable disease. Patients should be carefully monitored for opportunistic infections during treatment.
Rheological characteristics and genotype correlation of cassava root for very high gravity ethanol production: The influence of cassava varieties and harvest times
Authors: Sakdaronnarong Chularat , Sraphet Supajit , Srisawad Nattaya , Chantasod Rattana , Jonglertjunya Woranart , Triwitayakorn Kanokporn
Published: September 2019

In very high gravity (VHG) ethanol fermentation, the rheological properties of native cassava significantly influence heat and mass transfer, mixing energy, and, thus, the yield of all steps. This study investigated the effect of cassava varieties and their harvest times on starch liquefaction, saccharification, and fermentation. The genotype correlation of the starch properties was revealed for the most suitable cassava varieties. First, the starch content, amylose content, total reducing sugar from liquefaction and saccharification, pasting properties, and ethanol yields of six cassava varieties (Huay Bong 60, Hanatee, Kasetsart 50, Pirun 1, Pirun 2, and Rayong 11) at 6‐, 9‐, 12‐, and 15‐month harvest times were evaluated. The amylose content increased significantly from the 6th to the 12th month but slightly decreased at the 15th month. It was observed that the starch content contributed to a more substantial influence on the change in peak viscosity than on the amylose content. Ethanol fermentation using Saccharomyces cerevisiae TISTR5606 showed that the Rayong 11 variety at the 15‐month harvest time provided the highest ethanol concentration of 104.7 ± 4.1 g L−1 and an ethanol yield of 0.4 ± 0.1 g ethanol g−1 reducing sugar, which corresponded to 74.5% of the theoretical yield.
Early‐Life Exposure to Pulsed LTE Radiofrequency Fields Causes Persistent Changes in Activity and Behavior in C57BL/6 J Mice
Authors: Broom Kerry A. , Findlay Richard , Addison Darren S. , Goiceanu Cristian , Sienkiewicz Zenon
Published: September 2019

Despite much research, gaps remain in knowledge about the potential health effects of exposure to radiofrequency (RF) fields. This study investigated the effects of early‐life exposure to pulsed long term evolution (LTE) 1,846 MHz downlink signals on innate mouse behavior. Animals were exposed for 30 min/day, 5 days/week at a whole‐body average specific energy absorption rate (SAR) of 0.5 or 1 W/kg from late pregnancy (gestation day 13.5) to weaning (postnatal day 21). A behavioral tracking system measured locomotor, drinking, and feeding behavior in the home cage from 12 to 28 weeks of age. The exposure caused significant effects on both appetitive behaviors and activity of offspring that depended on the SAR. Compared with sham‐exposed controls, exposure at 0.5 W/kg significantly decreased drinking frequency (P ≤ 0.000) and significantly decreased distance moved (P ≤ 0.001). In contrast, exposure at 1 W/kg significantly increased drinking frequency (P ≤ 0.001) and significantly increased moving duration (P ≤ 0.005). In the absence of other plausible explanations, it is concluded that repeated exposure to low‐level RF fields in early life may have a persistent and long‐term effect on adult behavior. Bioelectromagnetics. 2019;40:498–511. © 2019 The Authors. Bioelectromagnetics Published by Wiley Periodicals, Inc.
Self‐Assembly of Proteinaceous Shells around Positively Charged Gold Nanomaterials Enhances Colloidal Stability in High‐Ionic‐Strength Buffers
Authors: Sasaki Eita , Dragoman Ryan M. , Mantri Shiksha , Dirin Dmitry N. , Kovalenko Maksym V. , Hilvert Donald
Published: September 2019

The enzyme lumazine synthase (LS) has been engineered to self‐assemble into hollow‐shell structures that encapsulate unnatural cargo proteins through complementary electrostatic interactions. Herein, we show that a negatively supercharged LS variant can also form organic–inorganic hybrids with gold nanomaterials. Simple mixing of LS pentamers with positively charged gold nanocrystals in aqueous buffer spontaneously affords protein‐shelled gold cores. The procedure works well with differently sized and shaped gold nanocrystals, and the resulting shelled complexes exhibit dramatically enhanced colloidal stability over a wide range of pH (4.0–10.0) and at high ionic strength (up to 1 m NaCl). They are even stable over days upon dilution in buffer. Self‐assembly of engineered LS shells in this way offers an easy and attractive alternative to commonly used ligand‐exchange methods for stabilizing inorganic nanomaterials.
Pelvic splenosis—A rare cause of pelvic mass
Authors: Degheili Jad A. , Abou Heidar Nassib F.
Published: September 2019

Splenosis is a medical condition that seldom occurs after splenic tissue spillage via trauma or surgery. Ectopic spleen tissues can be found almost anywhere within the body. Albeit benign, it is often misdiagnosed as a tumor. Surgery is not indicated unless symptomatic. The imaging of choice for pelvic splenosis, although conventional, is a sulfur colloid nuclear scintigraphy.
The Sundsvall Bridge, Sweden
Authors: Thomsen Kjeld , Skov Pedersen Helge
Published: September 2019

Sundsvall is located approximately 400 km north of Stockholm on the Eastern coast of Sweden as neighbour to the Bothnian Bay. The Sundsvall Bridge presently under construction will cross the Sundsvall Fjord and is a missing link in the north south motorway E4 from Stockholm along the Bothnian Bay. The Sundsvall Bridge has a total length of approx. 1.4 km between the concrete abutments. It is designed as a continuous girder bridge with a modern closed box girder cross section. A special feature for the Sundsvall Bridge is a very complex geometry, due to the curved alignment – horizontally as well as vertically. Further a varying width and a varying height of the bridge girder together with a one‐sided slope contributes to the complexity.
Prefabricated Composite Flooring Systems with Normal and Lightweight Concretes
Authors: Ahmed I.M. , Tsavdaridis K.D.
Published: September 2019

The use of lightweight concrete in structural applications for the sustainable design of composite slabs require the revision of today's flooring systems and the development of more efficient shear connectors. This paper studies a novel prefabricated and shallow steel‐concrete composite flooring system which is consisted of two main structural components: two C‐channel steel beams and a partially encased concrete floor. The concrete floor, which is in the form of T‐ribbed slab sections, was constructed using three types of concrete (reinforced normal concrete, reinforced lightweight aggregate concrete, and reinforced ultra‐lightweight aggregate concrete), and the steel edge beams which partially encase the floor slab and provide clear and straight finish edges. This paper includes the work of 2 full‐scale push‐out tests aimed at investigating the longitudinal shear behaviour of the new shear connection system (made of shear studs and steel dowels) when the normal concrete is replaced by lightweight and ultra‐lightweight concrete.
Fatigue of composite constructions with composite dowels
Authors: Christou Georgios , Classen Martin , Wolters Kevin , Broschart Yannick
Published: September 2019

Composite dowels are being applied increasingly over the past years. Especially in the field of small and medium span bridges, composite dowels offer many advantages in comparison to other shear connectors. In contrast to headed studs, where initial steel cracks already occur after a few load cycles, composite dowels have a better resistance against dynamic loading and thus an increased lifetime. The bearing capacity of composite dowels is mainly characterized by the compression of the multiaxial stressed concrete in front of the composite dowel, where shear forces are transferred between steel and concrete. Here, the multiaxial compressive stress leads to increasing strains, that accumulate over the load cycles and lead to a cyclic growth of relative displacements in the composite connection. These relative displacements subsist of two strain‐components, the elastic and the plastic strains. The plastic strain remains constant in the connection, even after release of external loading. These permanent displacements are called inelastic slip. Due to this inelastic slip the characteristics of the static dowel curve might change significantly over the lifetime of the composite structure. The initially rigid connection between steel and concrete degrades over the lifetime and rearrangements of internal forces between the composite partners occur, which may impact the fatigue behaviour of the construction. The degradation of the composite connection can be considered by a cyclic dowel curve, which may be developed from the static dowel curve by introducing the inelastic slip. In this paper, results of cyclic shear tests are presented, in which the inelastic slip between steel and concrete and the relative slip of the steel dowel to the steel web are measured and compared.
Multi‐Level Joints and Element Design
Authors: Wald František , Vild Martin , Vesecký Jan , Legner Štěpán , Kabeláč Jaromír , Šabatka Lubomír
Published: September 2019

This paper describes the principles multi‐level joints and element design in steel structures. The system response quantity and application features of Component Based Finite Element Method (CBFEM) for design of eccentric gusset plate connection of a truss steel member. Research oriented finite element model (ROFEM) is validated on experiments. The models are analysed by geometrically and materially non‐linear analysis with imperfections (GMNIA). The ROFEM is compared with simplified CBFEM model which includes only the joint. The proper behaviour of components, e.g. of bolts, anchor bolts, welds etc., is treated by introducing components representing its behaviour in term of initial stiffness, ultimate resistance and deformation capacity. To show this process a contribution is prepared, which summarises the history of achievements of FEA application in structural connections. Contribution shows the current trends in advanced modelling of connection components and differences of the research oriented and design oriented FEA models. Both have their roles in advanced analyses. On the eccentric gusset plate connection of diagonal steel member is shown the coming models with coupling of element and its joint design.
Comparative numerical investigations into the determination of slip factors according to the EN 1090‐2 and RCSC
Authors: Afzali Nariman , Abraham Christoph , Stranghöner Natalie
Published: September 2019

Slip‐resistant connections are used in bolted connections when deformations in the connections have to be for sure avoided either for serviceability or ultimate limit state reasons. On European level EN 1090‐2 and on North American level the “Specification for Structural Joints Using High‐Strength Bolts” by RCSC (2014) specify slip factors for often used surface conditions for carbon steel. For deviating conditions, slip factors can be determined experimentally according to the specified test procedures. However, not only the test procedure but also the test specimen geometry, clamping length, preload level etc. vary between both standards/guidelines. Generally, the resistance to slip in a slip‐resistant connection mainly depends on the condition of the faying surfaces and the preload level in the bolts but the variation of other key parameters may also result into different slip factors for the same surface treatment. For this reason, in a first step, comparative numerical investigations have been carried out for the test procedures specified in EN 1090‐2 and RCSC. The numerical models have been developed and calibrated on the basis of experimental tests carried out at the Institute for Metal and Lightweight Structures. Based on the calibrated numerical models, a parametric study has been conducted in order to prove the comparability of both test procedures and their resulting slip‐factors. In a second, future step, comparative experimental investigations will be carried out for both test procedures. In the frame of this contribution, the first numerical results will be presented.
Effect of Support Width on Stress Resultants in Ring Beams Interacting with Silo Shells
Authors: Zeybek Özer , Topkaya Cem
Published: September 2019

Elevated cylindrical metal silos are often supported on a ring beam which rests on discrete column supports. The ring beam plays an important role in redistributing the majority of the discrete forces from the column supports into a more uniform stress state in the cylindrical wall, which is necessary to reduce the potential for buckling of the shell wall. Traditional design treatments for ring beams assumed that the ring is supported by knife‐edge supports and is under the action of a uniformly distributed transverse loading. The interaction between the silo shell and the ring beam is generally neglected. Previous studies have shown that the stress resultants in ring beams depend strongly on the silo shell to ring beam stiffness ratio. This new study explores the effects of different support widths on the stress resultants and transverse displacements. Pursuant to this goal, a finite element parametric study has been conducted to evaluate stress resultants for different support width to radius ratios and considering different combinations of ring beams interacting with silo shells of differing dimensions. The results indicate that the width of the support has a very significant influence on the stress resultants and transverse displacements. These response quantities decrease significantly as the support width is increased from a knife‐edge to a finite width support. An increase in the support width directly reduces the ring beam clear span which in turn results in a reduction in all the key responses. Designers often ignore the effect of a finite support width but these findings indicate that this is a very conservative choice. A simplified treatment based on the clear span and the shell to ring beam stiffness ratio has been developed herein for calculating the stress resultants.
ACCIDENTAL TORSION WITH INDUSTRIAL BUILDINGS – OVER‐CONSERVATIVE RULES IN EC8
Authors: Knoedel Peter , Ummenhofer Thomas
Published: September 2019

This paper is related to seismic design of industrial steel buildings, such as warehouses and plant skeleton structures. Designers will be encouraged to skip rules of EC8 under certain circumstances, which lead to over‐conservative results.

Seismic design according to EC8 contains a general clause on accidental torsion. There, the possibility of an offset of the resulting masses within a storey and the spatial variation of the seismic motion is considered. Consequently, this leads to an unintended torsion (e.g. rotation of the structure about its vertical axis). Different magnitudes of additional loads in the vertical bracing planes may follow depending on the location of the bracing in the structure. Even in the favorable case of the bracing being located in the outmost walls (which is given in typical warehouses anyway), the bracing forces are to be increased by a factor of 1.3 according to the provisions of EC8 lateral force method. In this paper, the determination of the bracing forces is followed in two examples of industrial buildings, a warehouse with a crane bridge and a plant skeleton structure with heavy equipment on different levels. Based on these examples it will be shown, that the provisions of EC8 are way too conservative. Advice is given, on how the designer can come up with robust, but much lower forces for the vertical bracing planes.
Novel Building Diaphragm Layouts Generated through Topology Optimization
Authors: Fischer Astrid W. , Guest James K. , Schafer Benjamin W.
Published: September 2019

The objective of this paper is to explore the layout of floor diaphragms in steel buildings subject to demands generated from lateral loads, such as those from wind and earthquakes, optimized for shear stiffness and minimum weight. The design of floors is typically dominated by considerations for gravity loads. In some classical cases, e.g. the works of Nervi, optimized floor topologies have been expressed in non‐grid patterns, such as through ribs oriented in principal stress directions. Floor designs employing steel deck generally express only one‐way action spanning between joists. Layouts of floor diaphragms are investigated here for improved lateral stiffness through topology optimization. To handle the widely different equivalent stiffness properties of steel deck the classic topology optimization algorithm is augmented to allow for orthotropic material in the formulation and material orientation as a design variable. A range of possible orthotropic stiffness properties are developed from a database of existing designs for bare steel deck and composite steel‐concrete deck diaphragms. The floor designs are generally found to follow the principal stress trajectories developed in the model under the considered shear loading. This work is the first step in an effort to develop optimized floor layouts under combined gravity and lateral (seismic) load and is part of a larger initiative (www.steeli.org) that aims to better understand and optimize the role of diaphragms in the seismic response of steel buildings.
Laboratory tests on a real crane runway girder with welded box section and eccentric wheel loading
Authors: Kettler Markus , Unterweger Harald
Published: September 2019

The design of crane runway girders is strongly affected by the local stresses at the web top due to wheel loads (mainly fatigue design, but also web buckling). A realistic approach of these local stresses due to centric and eccentric wheel loading is very important for economic design.

In this paper, experimental tests on a real crane runway girder with welded box section are presented. Centric as well as eccentric wheel loading is investigated. The tests have been conducted with and without longitudinal stiffeners in the web under the crane rail. Therefore, the influence of these stiffeners on the local vertical stresses can be highlighted.

For all tests, additional comprehensive finite element analyses have been conducted. The results of the numerical calculations are compared with the test results and with the predictions of a sophisticated engineering model that takes into account the typical load carrying behaviour of welded box sections.
Proof of concept of a demountable steel‐concrete composite flooring system
Authors: Gîrbacea Ioan Andrei , Nijgh Martin Paul , Veljkovic Milan
Published: September 2019

Environmental concerns steer the construction industry towards more sustainable developments such as demountable and reusable structures. Composite structures are a frequent solution for multi‐story buildings and bridges, however the use of welded shear connectors requires labour and energy intensive disassembly. Two bays of a demountable flooring system for a multi‐storey car park building were erected in the laboratory. The flooring system consists of large prefabricated concrete decks connected to tapered steel beams. The feasibility of assembly and disassembly of the flooring system was tested under laboratory condition. Shear interaction was achieved by an embedded bolt and coupler which are connected to the top flange of the steel beam by an external injection bolt. Oversized holes are used in the top flange of the steel beam to accommodate fabrication and execution deviations and the deformations occurring during construction. Extensive imperfection measurements and finite element models were used to design the oversized hole diameter to 32 mm. The hole clearance must be compensated either by pretensioning or injecting the bolt‐to‐hole clearance with an epoxy resin to enable instantaneous composite action under live loads. Experimental injection of 150 injection bolts confirms that epoxy resin can reliably fill the hole clearance, and that the injection process takes 30 seconds per bolt. Various non‐uniform shear connector arrangements were considered to minimize construction costs and maximize the speed of execution. The mechanical behaviour of the demountable composite beam was tested experimentally and numerically.
3D printing in steel construction with the automated Wire Arc Additive Manufacturing
Authors: Kühne Ronny , Feldmann Markus , Citarelli Sandro , Reisgen Uwe , Sharma Rahul , Oster Lukas
Published: September 2019

The classic 3D printing of metallic components using powder bed processes has so far mainly been used in the aerospace industry or in mechanical engineering. For the production of large structural components, such as those used in steel construction, laser powder‐based additive manufacturing processes are too expensive. Wire and Arc Additive Manufacturing (WAAM) can offer a possibility to realize 3D printing of large steel components. This process, also known as “shape welding”, has become interesting for the building industry in combination with flexible robot technology and low energy welding processes. This is not only because of the vast variety of design options, as digitalisation and integration into computer‐supported design, planning and manufacturing processes also open up new possibilities for steel construction. Additionally, WAAM is also well‐suited for the production of load‐optimised components in particular. This study describes the current and future fields of application, the characteristics of production and the load‐bearing capacity of the achievable component types.
Fatigue Failure of runway beams due to wheel loads
Authors: Citarelli Sandro , Feldmann Markus
Published: September 2019

The introduction of the Eurocode 3 led to a significantly stricter fatigue classification, especially for flange to web connections of runway beams of heavy duty cranes compared to former national design rules like DIN 4132. At present, this leads to a doubling of the cross‐sectional thicknesses, which e.g. can result into web plates with extreme thicknesses of 80 mm. Execution as well as monitoring of such flange to web connections using full penetration tee‐butt welds are quite critical and thus no longer to be realized reasonably.

On this account new fatigue strengths for the runway beam specific fatigue detail “Top flange to web junction of runway beams” in EC3‐1‐9 Table 8.10 have been established within the FOSTA‐research project “Fatigue failure of runway beams due to wheel loads in heavy smeltery cranes” as recommendations for an eventually modification or even extension of the current codes. In Particular, the detail executed using full penetration tee‐butt welds has been investigated in the framework of this research project.

The essential core of the methodical approach is that real existing crane runway girders have been examined, documented and evaluated in regard of fatigue failure of the flange to web connection. In this way, a direct quantitative assessment of safety against fatigue failure for the investigated detail could be derived. In addition, synthetic notch cases have been investigated numerically. The results of both methodologies have been prepared for a proposal of amendment of the current codes. This paper provides an insight into the methodological approaches and the main results achieved.
Temperature distribution of trapezoidal sheeting in fire
Authors: Cábová Kamila , Lišková Nikola , Arha Tesfamariam , Malaska Mikko , Alanen Mika , Mela Kristo , Pajunen Sami , Wald František
Published: September 2019

Trapezoidal sheeting has been used for stabilizing steel members for a long time. In recent years several documents which include the comprehensive theoretical background and design guidelines for practice have been published. ECCS published the design recommendations including an example of considerable cost savings in steel constructions when sheeting is used for stabilization. However, these documents did not cover the fire limit state.

The study presented in this paper is aimed at stabilization of steel members through the trapezoidal sheeting in fire. The papers describes four full‐scale fire tests carried out on a horizontal furnace for fire resistance testing. The test specimens were assembled from a fire protected steel beam and trapezoidal sheeting. The profile of the steel beam was a HEA 160 (S355) in two of the tests, and a RHS 150×150x8 (S420) in the remaining tests. Two different profiles of the trapezoidal sheeting were used during the tests.

Experimental testing was conducted to determine the temperature fields in trapezoidal sheeting and in the supporting structural steel sections as well as in the connectors with special attention given to the temperatures at the joint above the steel beam section.

The results of the tests show that at the failure of the specimens the screw temperatures were between 720°C and 780°C. The screw temperatures were lower than the temperature of trapezoidal sheets but higher than the temperatures of the top flanges of fire protected steel beam.

The results of the tests provided experimental data for the critical variables related to building stabilization in fire through the cladding systems which is under investigation of RFCS project STABFI.
Repeated loading and unloading of steel material in fire
Authors: Shakil Saani , Lu Wei , Puttonen Jari
Published: September 2019

The effects of permanent strains on the use of a group of stress‐strain curves defined at different temperatures for modelling the steel material under repeated loading and unloading in fire are studied using finite element (FE) method. As a benchmark test for numerical simulations, experimental results received from the literature for a restrained beam exposed to fire including heating and cooling stage are used. The behaviour of both statically determinate and indeterminate steel members are studied using Abaqus/Explicit solver. The mechanical response of the studied members are well predicted based on the assumptions made for the modelling of steel materials in the design‐fire considering the cooling stage. However, the results highlight the need for further studies of modelling the behaviour of steel material subjected to temperature oscillations as in the case of travelling fires.
Experimental study on temperature distribution of sandwich panel joints in fire
Authors: Malaska Mikko , Alanen Mika , Cábová Kamila , Lišková Nikola , Mela Kristo , Pajunen Sami , Wald František
Published: September 2019

Previous research have demonstrated that significant cost savings can be achieved, if cladding panels forming the building envelope are used to provide stability. There is research information and design guidance available for normal temperature design. However, the information available for fire conditions is very limited and it is not known if the panels are able to stabilize steel frame members also at elevated temperatures. The stiffness and resistance of joints, cladding panels and connectors are required for the assessment of interaction between cladding and frame in fire. Temperatures of those components are in important role when evaluating the stabilization effect. This paper presents an experimental research conducted to determine the temperature fields in sandwich panels, supporting structural steel members and screw connectors. Eight full‐scale fire tests were carried out where the structural steel sections supporting sandwich panels were exposed to ISO 834 fire attack on three sides. The test specimen consisted of a fire protected steel beam and load‐bearing sandwich panels with both mineral wool and polyisocyanurate (PIR) core. Two different steel beam sections were used in the tests: HEA 160 (S355) and RHS 150×150x8 (S420). This paper introduces the experimental research and the main observations related to the temperatures. The results show that at failure of the specimens the measured screw temperatures were very different in HEA and RHS tests. The temperatures in HEA tests were much higher than in RHS tests the maximum difference in screw point temperatures being over 400°C. In all the specimens, screw head temperatures were very low throughout the tests, well below 100°C. The tests were part of ongoing RFCS project STABFI.
Experimental Study of Welding Effect on S690Q High Strength Steel Butt Joints
Authors: Chiew S.P. , Cheng C. , Zhao M.S. , Lee C.K. , Fung T.C.
Published: September 2019

In this study, welding effects on grade S690Q high strength steel butt joint are investigated experimentally in terms of microstructure, micro‐hardness, and tensile behaviour. Three butt joints with 16 mm thickness are fabricated with reheated, quenched and tempered S690Q high strength steel (HSS) plates by using Shielded Metal Arc Welding with different welding heat inputs. Post‐welding microstructure transformation is revealed in base material, coarse‐grained heat‐affected zone (CGHAZ), fine‐grained heat‐affected zone (FGHAZ) and tempering zone. It is found that the main microstructure of S690Q high strength steel is tempered martensite. After welding, the microstructure is transformed to granular bainite in CGHAZ and to ferrite & cementite in FGHAZ. While, in tempering zone, some temper martensite decomposed to ferrite. Then, micro‐hardness tests performed for the butt joints confirmed the existence of a soft layer within the HAZ due to the microstructure transformation. The HAZ width increased when higher welding heat input is adopted. Subsequent coupon tensile tests showed that all the welded joint fractured within the HAZ. The tensile strength of the butt joints deteriorated with the increase of the welding heat input since the soft layer became bigger in HAZ.
Prediction of ultimate resistance by application of damage theory with special regard to HSS
Authors: Schaffrath Simon , Feldmann Markus
Published: September 2019

It is a general question as to whether the established rules for predicting ultimate resistance under global tension can also be applied to structures made from HSS, i.e. up to = 960 MPa. Apart from the welding issue, for the base material, this question refers to several items, e.g. the plastic flow curve, the yield stress level, the yield ratio, the upper‐shelf ductility and strainability and the lower‐shelf toughness. It reveals that predicting the ductile fracture of steel components can only be an approximation, and neither allows for a deeper understanding of the real ductile crack development up to ultimate load nor leads to a realistic extrapolation if high‐strength steels are used. The research work presented therefore suggests an innovative extension of the FEM analysis by implementing appropriate damage mechanics based failure criteria. After an introduction to the principles of this methodology, possibilities for its use in structural steel research and design as well as further insights into the structural behaviour of steel components, especially HSS up to S960, are presented – insights that are not possible by traditional testing or simulation.
Shell Structures Made of Curved Sandwich Panels: Assessment of the Load‐Bearing Capacity
Authors: Grimm Sören , Lange Jörg
Published: September 2019

Lightweight constructions made of sandwich panels became well established for roof and wall claddings of industrial structures. Due to their good heat insulation, their excellent weight to load ratio and high load‐bearing capacity as well as the economical manufacturing and erection process, sandwich structures are build frequently. Besides the mentioned advantages the linear manufacturing process of sandwich panels usually limits the possible building cubature to rectangular shapes. In an interdisciplinary project, architectural, civil engineering and mechanical engineering institutes of Technische Universität Darmstadt are working on a design concept building shell structures with linear manufactured curved sandwich panels.

A preliminary study indicates that arched sandwich beams have a high potential regarding the load‐bearing capacity. The comparison between arched and single span sandwich beams shows that, even for asymmetric loads, resulting stresses in the two‐hinged arches are significantly lower than in the related simply supported single span beams.

To verify the results of the numeric study full‐scale tests on curved sandwich panels will be performed. Furthermore, an assessment of the load‐bearing behavior of the panels joints loaded with axial forces is planned. Based on the results further numeric studies will be conducted to investigate the behavior of whole shell structures following the developed design principle by taking into account realistic load cases for exemplary building applications, giving special attention to asymmetrical loads.

Moreover, further research regarding the requirements for supporting structures as well as for the connection between the shell structure and the supporting structure is necessary to take into account the high axial forces, which are not common in sandwich structures.
Loss of prestress in spiral strand guy ropes in masts
Authors: Koppány Susanna
Published: September 2019

It's known since long that guy ropes in masts lose prestress over time. In many cases this leads to increased utilization of the mast. The problem is usually solved by regularly retightening the guys. The cause of the loss of prestress is not entirely clear, but guys in masts exposed to frequent and large vibrations, seem to be the most affected.

Lately at manufacture, the guys undergo a number of large load cycles, thereby enabling the threads to get relocated and tightened in the spiral strand guy rope, in order to reduce the loss of prestress. Certificates describe the load cycles, strains and calculated Young's Modulus during this process. Apparently Young's Modulus doesn't only vary with the load range, but it also differs when loading and unloading. All together this means, when unloading the guy during a large enough load cycle, it will not completely regain its previous length, but instead gain a small remaining elongation.

By being exposed to large vibrations in masts, guys can be elongated, something that in this paper is referred to as an explanation for the loss of prestress.

This paper presents an analytical model, describing the loss of prestress over time in a guy, exposed to large vibrations in a mast. Prestress measurements from mast inspections also show consistency with the model.

Based on three prestress measurements of a guy, carried out with a minimum of a few years interval, the model offers an efficient strategy for choosing when to retighten, or estimating if the expected loss of prestress is small enough not to require adjustment. In addition, the model offers guidelines for choosing guy dimension and initial prestress, in order to actively reduce the loss of prestress and extend the time between retightenings.