Open Cross Research Articles

Animal pollination shapes fruits market features, seeds functional traits and modulates their chemistry

In this study, we experimentally addressed the impact of different pollination treatments on the morphological, reproductive and chemical traits of fruits and seeds of two crop species, the wild strawberry (Fragaria vesca L.) and cowpea (Vigna unguiculata (L.) Walp.). Multiple flowers from each plant were exposed to different pollination treatments: (1) self pollination, (2) hand cross pollination and (3) open pollination. Both crops were positively affected by open pollination in terms of morpho-chemical parameters concerning the marketability (e.g., 35% decrease in sugar/acid ratio in open pollinated strawberries compared to the autogamous ones) and the seed germination rate as a proxy of reproduction efficiency (e.g., the almost complete absence of seed abortion in the open pollination treatment). Remarkably, the pollination treatment also strongly influenced the phytochemical composition. Open-pollinated strawberries exhibited a higher relative concentration of compounds endowed with nutraceutical properties such as anthocyanins, ellagic acid derivatives and flavonoids. At the same time, cowpea seeds displayed higher concentrations of anti-nutrients in the self pollination treatments, such as saponins, compared to the open and hand cross pollinated seeds. This study suggests the presence of a link between the pollination mechanism, market quality, plant reproduction and chemical properties of fruits and seeds, supporting the intricate interplay between pollinators, plants and human nutrition, highlighting the crucial importance of animal pollination in the ecological and dietary contexts.

Nondimensional triply coupled free vibration analysis of the axially layered thin-walled beams with nonsymmetric open cross sections and its application to the frequency optimization

Nondimensional triply coupled free vibration analysis of the axially layered thin-walled beams with nonsymmetric open cross sections and its application to the frequency optimization

Endovascular Aortic Balloon control versus open Aortic cross Clamp in open ruptured abdominal Aortic aneurysm repair

To determine 30-day mortality of endovascular aortic balloon control compared to open aortic cross clamp in open surgical repair of ruptured abdominal aortic aneurysms. A retrospective cohort review was performed of all adult patients who underwent open surgical repair of an infrarenal rAAA between 2001 and 2018 at a single tertiary care center. 174 patients were identified, of which 21 patients received endovascular aortic balloon control and 137 patients received an open aortic cross clamp. Primary outcome was 30-day mortality. Two-variable multivariate logistic regression was adjusted for preoperative blood pressure and age. Endovascular aortic balloon control was non-significantly associated with lower mortality (adjusted OR = 0.75 [95%CI 0.24-2.38], p=0.63), and when placed under local anesthesia showed a trend towards improved mortality (adjusted OR = 0.34 [95%CI 0.06-1.77], p=0.19). Balloon placement under general anesthesia was non-significantly associated with worse mortality (adjusted OR = 2.50 [95%CI 0.35-9.13], p=0.46). There is no significant different in mortality with the use of endovascular aortic balloon control in rAAA patients undergoing open surgical repair, and it may be considered as an alternative approach to open aortic cross clamp in properly selected patients.

Utilizing periodic boundary conditions to save computational resources for assessing building natural ventilation in urban areas

For the first time in literature, we innovatively conducted CFD simulations with periodic boundary conditions to predict coupled indoor-outdoor airflows for a full-scale 3D six-floor residential building unit in urban areas with uniformly building clusters. A few influencing parameters on building ventilation performance are comprehensively analyzed, including the impacts of the surrounding buildings, wind incident angle (θ), external opening designs, cross or single-sided ventilation modes, and indoor facilities. Ventilation evaluation is contingent on factors including air change rate per hour (ACH), the corresponding ACH of purging flow rate (ACHPFR), and age of air (τ).Results show that the efficiency of natural ventilation on each floor differs from previous research conclusions after considering the impacts of surrounding buildings. Single-sided ventilation is significantly less effective than cross-ventilation in all scenarios. Most cross-ventilation cases have one-order greater ACH and ACHPFR values compared to those with single-sided ventilation. The window-to-wall ratio on the windward and leeward sides can affect the natural ventilation rate of the corresponding rooms. A large leeward opening helps to increase the ventilation rate, especially for the rooms on the upper floor, but it decreases the ventilation for the rooms near the ground. Indoor furniture has an insignificant impact on outdoor airflow and natural ventilation efficiency.

Interaction diagrams of thin-walled, open cross section PC beams

Thin-walled, open cross section PC (prestressed concrete) beams are widely used in precast structures. Nevertheless, the analytical computation of their load carrying capacity under bending and torsion is still an unsolved problem. This is because of the markedly non-linear behaviour of both steel and concrete and of the asymmetry of the behaviour of concrete in tension and compression. This involves a search for the correct solution from a physical point of view (among those mathematically admissible) based on trial-and-error methods of numerical analysis.This paper suggests a method to evaluate the interaction diagrams under bending and torsion. According to this method the solving system is made by two equilibrium plus two compatibility equations. Some examples show the outcomes of this approach.

Bark extract of Chaetocarpus castanocarpus (Roxb.) exhibits potent sedative, anxiolytic, and antidepressant effects through an in vivo approach in Swiss albino mice.

Standard phytochemical investigations were performed to identify the secondary metabolites in the methanol extract of Chaetocarpus castanocarpus bark (MECC) and investigate the neuropharmacological potential of MECC in Swiss albino mice. Swiss albino mice were used in the forced swimming test (FST) and tail suspension test (TST) to evaluate the antidepressant effect of MECC. Also, the hole board test (HBT) and elevated plus maze (EPM) were conducted to examine anxiolytic activities. In contrast, the open field test (OFT) and hole cross test (HCT) were employed to evaluate sleeping disorders. Alkaloids, glycosides, flavonoids, terpenoids, coumarins, and tannins are only a few secondary metabolites identified in MECC by qualitative and quantitative phytochemical investigations. The oral administration of MECC considerably shortened the immobility duration during FST and TST. Encouraging dose-dependent anxiolytic effects were also observed in all relevant experiments compared to the control. Additionally, during the OFT and HCT assessment, a noteworthy decline in the locomotor activities of the experimental animals was observed. The results of this investigation suggest that the Chaetocarpus castanocarpus bark is a possible source of therapeutic candidates for treating neurological disorders.

Numerical Evaluation of Lateral Torsional Buckling of PFRP Channel Beams under Pure Bending

The use of pultruded fiber reinforced polymers (PFRPs) in strengthening and sustainable design of bridges and other structures exposed to corrosion and resistance reduction factors is growing rapidly. However, a comprehensive understanding of the structural behavior of these materials under various loading conditions is crucial to unlock their full potential and promote their wider use in diverse structural and industrial applications. Pultrusion profiles can be also used as beams in bridges. One important aspect of the structural behavior of PFRPs is their buckling behavior, particularly in thin-walled open cross sections. Lateral torsional buckling is a probable instability mode for beams with thin-walled open cross sections that are not laterally restrained along their span. Therefore, research on the buckling behavior of PFRP members is essential. In this study, the analytical responses of channel-shaped PFRP beams in bridges under pure bending are calculated using an equation in the Eurocode 3 regulation. The buckling behavior of these beams is then investigated through numerical modeling using the finite element package Abaqus. A total of 75 specimens of PFRP channel profiles with different thicknesses in various spans and lateral restraint conditions are studied for their lateral-torsional buckling behavior. This study uniquely explores the behavior of PFRP beams with lateral restraints, a novel aspect in the field of lateral-torsional buckling research of PFRP beams. The results show that the analytical equation used for these beams needs to be modified to more accurately estimate the buckling loads of FRP beams under the conditions studied in this paper.

A dimensionless analytical analysis for buckling and lateral buckling interaction of thin-walled beams with open cross sections

This paper investigates the interaction between buckling and lateral buckling of thin-walled beams with arbitrary open cross-section using nonlinear modeling in large rotation and with warping. First, the equilibrium equations have been transformed into dimensionless ones, and within a nonlinear stability model, various dimensionless parameters are introduced to control the interaction between buckling and lateral buckling. In comparison to a reference of literature, this work focuses on the case of arbitrary sections and includes a greater number of higher-order terms in our analysis. These additions have an impact on the coefficients of the stability formula by expanding its applicability to non- symmetric sections. Then, the effect of the different dimensionless parameters, thus introduced on the stability curve, has been studied. The proposed solutions are validated and compared to numerical solutions obtained by a general finite element package including the warping developed by the authors using Asymptotic Numerical Method (ANM) to solve the initial nonlinear equations.

Effectiveness analysis of percutaneous parallel screw fixation via posterolateral "safe zone" for Hawkins type Ⅰ- Ⅲ talar neck fractures

To explore the effectiveness of the percutaneous parallel screw fixation via the posterolateral "safe zone" for Hawkins type Ⅰ-Ⅲ talar neck fractures. A retrospective analysis was conducted on the clinical data from 35 patients who met the selection criteria of talar neck fractures between January 2019 and June 2021. According to the surgical method, they were divided into a study group (14 cases, using percutaneous posterolateral "safe zone" parallel screw fixation) and a control group (21 cases, using traditional open reduction and anterior cross screw internal fixation). There was no significant difference in gender, age, affected side, Hawkins classification, and time from injury to operation between the two groups ( P>0.05). The operation time, bone healing time, complications, and Hawkins sign were recorded, and the improvement of pain and ankle-foot function were evaluated by visual analogue scale (VAS) score and American Orthopaedic Foot and Ankle Society (AOFAS) ankle and hindfoot score at last follow-up. The overall quality of life was assessed by the short form of 12-item health survey (SF-12), which was divided into physical and psychological scores; and the satisfaction of patients was evaluated by the 5-point Likert scale. The operation time in the study group was significantly shorter than that in the control group ( P<0.05). All patients werefollowed up 13-35 months, with an average of 20.6 months; there was no significant difference in the follow-up time between the two groups ( P>0.05). The time of bone healing in the study group was shorter than that in the control group, and the positive rate of Hawkins sign (83.33%) was higher than that in the control group (33.33%), and the differences were significant ( P<0.05). In the control group, there were 2 cases of incision delayed healing, 7 cases of avascular necrosis of bone, 3 cases of joint degeneration, 1 case of bone nonunion, and 3 cases of internal fixation irritation; while in the study group, there were only 2 cases of joint degeneration, and there was a significant difference in the incidence of complications between the two groups ( P<0.05). At last follow-up, there was no significant difference in VAS score between the two groups ( P>0.05), but the SF-12 physical and psychological scores, AOFAS ankle and hindfoot scores, and patients' satisfaction in the study group were significantly better than those in the control group ( P<0.05). The treatment of Hawkins type Ⅰ-Ⅲ talar neck fractures with percutaneous parallel screw fixation via the posterolateral "safe zone" can achieve better effectiveness than traditional open surgery, with the advantages of less trauma, fewer complications, faster recovery, and higher patient satisfaction.

Evaluation of In-vitro Antimicrobial, Anti-arthritis and In-vivo Analgesic and Neuropharmacological Investigation of the Bark Extract of Solanum americanum Milli

Purpose: The objective of this study was to investigate the impact of methanol-prepared bark extract of Solanum americanum Milli. Bark on several in vitro activities, including antimicrobial and anti-arthritis effects. Additionally, the study aimed to assess the analgesic and neuropharmacological properties of the extracts in an animal model.&#x0D; Place and Duration of Study: The research study was carried out from March 2023 to July 2023 at the Bangladesh Council of Scientific and Industrial Research (BCSIR) and the Laboratory of Phytochemistry and Pharmacology, Department of Pharmacy, as well as the Laboratory of Microbiology at Stamford University Bangladesh, Dhaka.&#x0D; Methodology: The methodology involved various doses of methanolic bark extract of Solanum americanum Milli (MESAB), and employed techniques such as the Disk Diffusion Method for antimicrobial test and the Inhibition of Protein Denaturation Assay for anti-arthritic test. The analgesic efficacy was assessed by the hot plate test and administration of acetic acid induced writhing responses in Swiss albino mice. The mechanism test is conducted through the cyclic guanosine monophosphate (cGMP) test. The neuropharmacological inquiry included the measurement of locomotor activity through the utilization of open field and hole cross tests.&#x0D; Results: The Disk Diffusion Test of MESAB yielded findings indicating its antimicrobial properties against all strains used in this research. The findings from the study examining the anti-arthritis properties indicate that MESAB exhibits a significant efficacy of 94.59% in inhibiting arthritis at a concentration of 1000 µg/mL. This level of efficacy is comparable to that of diclofenac sodium, which also has a similar efficacy of 98.19% at the same concentration. The findings of the present study demonstrated that MESAB displayed analgesic properties in both analgesic models, suggesting the involvement of both central and peripheral pathways. Based on the results of the study, it was observed that the administration of MESAB at a dosage of 400 mg/kg had a significant analgesic effect. The application of MB before to treatment resulted in a further enhancement of this effect, leading to an increase in the percentage of inhibition from 66.75% to 79.70%, respectively. The consideration of the involvement of the GABA-benzodiazepine receptor in neuropharmacological activity holds significant importance. In the Open Field and Hole Cross Tests, it was shown that the extract exhibited significant result compared to Diazepam in terms of increasing motor coordination.&#x0D; Conclusion: In the future, plant-derived pharmacological compounds may offer potential benefits for various clinical disorders, such as neurodegenerative illnesses. These substances possess neuropharmacological properties, antibacterial effects, and anti-arthritic activity, which could potentially serve as alternatives to non-steroidal anti-inflammatory drugs (NSAIDs).

Flexural–torsional vibration of thin-walled beams with open cross sections considering the additional torsional moment

Flexural–torsional vibration of thin-walled beams with open cross sections considering the additional torsional moment

Rigorous Analysis of Energy Conservation During Dynamic Deployment of Elastic Thin-Shell Structures

Abstract This paper studies the dynamic deployment of cylindrical thin-shell structures with open cross section, attached to a rigid base. The structures are elastically folded and then released. Previous experiments have shown that the total energy decreases while a fold moves back and forth along the structure, which was explained in terms of energy losses related to the fold “bouncing” against the boundary. This paper uses a rigorous numerical simulation, based on an in-house isogeometric shell finite element code that simultaneously eliminates shear locking and hourglassing without any intrinsic energy dissipation, to show that the total energy of the system is conserved during deployment. The discrepancy with the previous results is explained by showing that energy transfers from low-frequency, “rigid body” modes, to higher frequency modes.

Anxiolytic-like effect of succinic acid: A possible GABAergic intervention

In the modern era, physical and mental stress lead to anxiety at an alarming rate. Therefore, searching for new lead compounds that deal with anxiety has a practical demand. Our study aimed to evaluate succinic acid's (SUC) possibility of managing anxiety through in vivo and in silico studies. For this, SUC (5, 10, and 15) mg/kg were administered orally (p.o.) to the adult male Swiss mice, followed by several studies like open field, swing, hole cross, and light-dark residence tests. The GABAergic agonist diazepam (DZP-2 mg/kg) and an antagonist such as caffeine (CAF-10 mg/kg) were also studied in combination with the SUC group. In contrast to the DZP group, SUC significantly (p < 0.0001) increased the amount of time that animals spent in the light, suggesting that it may have relaxing impacts on mice. Additionally, in silico studies were carried out to understand the interaction between SUC and GABAA (α1, β2, and γ2) receptor subunits. Furthermore, pharmacokinetic and drug-like properties were examined by pkCSM and SwissADME online servers and found to be supportive of considering SUC as a potential drug candidate. Our experiment found that SUC-10 had an anxiolytic-like effect on the animals. SUC-10, when combined with DZP, produced more significant (p < 0.0001) anxiolytic effects than their individual groups, suggesting possible synergistic effects with this commonly used anxiolytic drug. SUC-10 also altered CAF-mediated effects in mice. An in silico study demonstrates that SUC has good interaction capacity with GABAA receptor subunits. Taken together, SUC-10 exerted anxiolytic-like effects in Swiss mice. It may act synergistically with DZP while acting antagonistically with CAF, possibly through GABAergic interaction pathways.

Knowledge Sharing as a Central Idea of Open Science and NDT 4.0

NDT 4.0 has become a buzz word in the world of NDT in recent years. At the same time, terms like open science, open access or open peer review cross our ways regularly and define present and future concepts to advance knowledge sharing in society. This article brings the concept of open science and NDT 4.0 together. While knowledge sharing as part of artificial intelligence and the internet of things are often in focus when talking about Industry 4.0 or NDT 4.0, this paper draws on the importance of knowledge sharing between humans as a substantial aspect of Industry 4.0, and more specifically NDT 4.0. Knowledge sharing between humans has especially become relevant with the introduction of the internet and the world wide web (www), but its importance cannot be disregarded in times where everybody is talking about technical developments, machine learning and artificial intelligence. On the contrary, sharing knowledge openly between humans remains central to advancing todays developments and innovation. The NDT community has had the benefit to share, create and exchange knowledge at an early stage of the internet through a unique platform that was established in 1996; NDT.net. After reviewing the concepts of open science and NDT 4.0, this paper illustrates how the NDT community has had the benefit of knowledge sharing since the early days of the internet through the establishment of NDT.net. This open access platform has been playing and continues to play a central role in advancing ideas of open science and NDT 4.0.

Promoting Preschool Pre-service Teachers’ Understanding of Food Additives Using the Debate Method

The aim of this research is to investigate the development of preschool education pre-service teachers’ (PST) understanding and evaluation of a socio-scientific topic, namely food additives by using debate as a teaching technique. Qualitative research was designed in a case study model with purposeful sampling in which sixty PST attended Mother and Child Nutrition course. We used qualitative data instruments including pre- and post-reflective forms (RF), assignment papers and video recordings. Data were analyzed using open coding and cross coding. The results indicated that PST’s opinions about food additives may change with the use of debate and scientific articles. The findings also showed that it can be possible to improve their understanding of scientific knowledge about food additives, sources of information, evaluation of sources of information with the help of well-designed debate applications. The evaluation of the components of evidence, sources of evidence, arguments, and expert judgment as well as inclusion of these components in teacher education programs are recommended for further research

Determination of Self-Compatibility of the 'Arsel' Olive Cultivar Obtained by Hybridization Breeding

This study was aimed to determine the fertilization biology of the 'Arsel' olive cultivar obtained by hybridization breeding. For this reason, treatments of open pollination, cross pollination, and self-pollination were performed for 2 years and self-compatibility and appropriate pollinators of this new cultivar were investigated. Among the varieties included as pollinators (‘Memecik’, ‘Gemlik’, ‘Uslu’, ‘Ayvalık’ and ‘Eğriburun Nizip’), the highest fruit set was achieved with ‘Memecik’ and ‘Gemlik’ varietes in both years (2.64%, 1.37% and 1.75%, 1.39%). For this reason, ‘Memecik’ and ‘Gemlik’ cultivars were the best pollinator for ‘Arsel’ olive was thought. On the other hand, considering the statistical analyzes and productivity index values, ‘Arsel’ variety was found to be self-incompatible. However, the data also indicated that cross pollination was effective in increasing fruit set. Therefore, it is thought that the use of pollinator cultivar in orchard establishment would be beneficial in terms of yield. Pollen viability and germination tests were performed by using 2,3,5 Triphenyl Tetrazolium Chloride (TTC) and agar in petri (15% sucrose + 1% agar + 100 ppm H3BO3) methods in the study. The highest pollen viability rate was observed in ‘Memecik’ cultivar in 2020 and there isn’t statistical differences between olive cultivars in 2018. The highest pollen germination rate was observed in ‘Arsel’ cultivar in 2018. Accordingly, differences were determined between pollen viability and germination rates of examined olive cultivars in terms of years.

Rapid survey of de novo mutations in naturally growing tree species following the March 2011 disaster in Fukushima: The effect of low-dose-rate radiation

The impact of low-dose-rate radiation on genetics is largely unknown, particularly in natural environments. The Fukushima Dai-ich Nuclear Power Plant disaster resulted in the creation of contaminated natural lands. In this study, de novo mutations (DNMs) in germ line cells were surveyed from double-digest RADseq fragments in Japanese cedar and flowering cherry trees exposed to ambient dose rates ranging from 0.08 to 6.86 μGy h−1. These two species are among the most widely cultivated Japanese gymnosperm and angiosperm trees for forestry and horticultural purpose, respectively. For Japanese flowering cherry, open crossings were performed to produce seedlings, and only two candidate DNMs were detected from uncontaminated area. For Japanese cedar, the haploid megagametophytes were used as next generation samples. The use of megagametophytes from open crossing for next generation mutation screening had many advantages such as reducing exposure to radiation in contaminated areas because artificial crossings are not needed and the ease of data analysis owing to the haploid nature of megagametophytes. A direct comparison of the nucleotide sequences of parents and megagametophytes revealed an average of 1.4 candidate DNMs per megagametophyte sample (range: 0–40) after filtering procedures were optimized based on the validation of DNMs via Sanger sequencing. There was no relationship between the observed mutations and the ambient dose rate in the growing area or the concentration of 137Cs in cedar branches. The present results also suggest that mutation rates differ among lineages and that the growing environment has a relatively large influence on these mutation rates. These results suggested there was no significant increase in the mutation rate of the germplasm of Japanese cedar and flowering cherry trees growing in the contaminated areas.

In-vitro and In-vivo Pharmacological Evaluation of Persicaria lapathifolia Available in Bangladesh

Purpose: The purpose of this research was to examine the effects of Persicaria lapathifolia (Pale smartweed) leaf and bark extracts prepared with methanol on in vitro activities like antioxidant, antimicrobial, anti-arthritis, anti-inflammatory, and cytotoxic, as well as on some in vivo activities like analgesic and neuropharmacological properties in animal model.&#x0D; Methodology: The primary method for the methanolic extract of Persicaria lapathifolia leaf (MEPLL) and methanolic extract of Persicaria lapathifolia bark (MEPLB) were investigated for phytochemical screening. It was determined to look into the plant's potential for in vitro activities, such as phytochemical screening, antioxidant, anti-arthritis, anti-inflammatory, anti-bacterial, and cytotoxic, due to the pharmaceutical interest in its component parts. Its described effects on its in vivo analgesic and neuropharmacological activities in animal models are significant compared to the standard. This research was conducted between July 2022 and November 2022 in the Stamford University Bangladesh, Dhaka, Laboratory of Physiology and Pharmacology, Department of Pharmacy, and Laboratory of Microbiology. Antioxidant, anti-arthritic, anti-inflammatory, antibacterial, cytotoxic, analgesic, and neuropharmacological activities of MEPLL and MEPLB were investigated. Phytochemical screening was performed utilizing a variety of test reagents. Antioxidant, total phenolic content, anti-arthritic, anti-inflammatory, antibacterial, and cytotoxic activities were measured at various doses using the DPPH Free Radical Scavenging Assay, the Folin-Ciocalteu technique, the Inhibition of Protein Denaturation Assay, Egg Albumin Protein Denaturation Assay, the Disk Diffusion Method, and the Brine Shrimp Lethality Bioassay. The analgesic effectiveness was evaluated by using acetic acid to elicit writhing in Swiss albino mice and then testing the animals on a hot plate. Locomotor activity was measured by open field and hole cross tests as part of the neuropharmacological investigation.&#x0D; Results: Research performed on MEPLL and MEPLB's phytochemical screening yielded results that revealed the presence of a variety of different phytochemical components. In comparison to MEPLL's IC50 value of 1.49 µg/mL, MEPLB's value of 30.45 µg/mL indicates its superior antioxidant activity. Both extracts demonstrated significant anti-arthritic and anti-inflammatory effectiveness in comparison to the standard drug. When compared to MEPLB, MEPLL exhibited much more antibacterial activity. In a lethality test using brine shrimp, MEPLL and MEPLB both had much higher LC50 values than the standard vincristine sulfate. Their respective values were 1.42 and 0.66 µg/mL. In contrast, MEPLL inhibited peripheral nociception in the acetic acid-induced writhing nociceptive paradigm with percent inhibitions of 60.72 and 67.56, respectively, while MEPLB inhibited 48.22 and 67.28, respectively, at the aforementioned doses. In addition, the hot plate test revealed a significant analgesic effect. The extract was also shown to have a more negative impact on motor coordination in the Open Field and Hole Cross Tests than the standard Diazepam.&#x0D; Conclusion: This research demonstrates a relationship between the existence of anti-oxidative, anti-arthritis, and anti-bacterial activities, as well as a strong cytotoxic, analgesic, and neuropharmacological activity, which substantiates all previously made claims against Persicaria lapathifolia.

A Novel Approach to Improve the Distortional Buckling Strength of a Stiffened Cold-Formed Steel Channel Section under Axial Compression

This study investigates the distortional buckling strength of a partially closed cold-formed steel (CFS) channel section with intermediate web stiffeners and outward lips under axial compression. Generally, a closed CFS cross section has higher torsional resistance when compared to an open cross section. However, an open cross section is more popular in the construction industry. Despite the popularity of CFS open sections, distortional buckling can reduce the load-carrying capacity of such open cross sections. To improve the distortional buckling strength of the proposed selected section, a simple spacer plate is added externally to the channel section in the transverse direction. Initially, a numerical model is developed using the finite element software ANSYS, which is then validated against the experimental results available in the literature. A detailed parametric study was also conducted to investigate the influence of thickness, depth, and spacing of spacer plates on the distortional buckling strength of stiffened CFS channel sections. From the results of the parametric study, it was found that the presence of spacer plates can increase the axial capacity of stiffened CFS channel sections by as much as 32%. Finite element results were compared with the design strengths calculated in accordance with the direct strength method (DSM).

Wind tunnel tests on the unsteady galloping of a bridge deck with open cross section in turbulent flow

Steel–concrete composite bridge decks may risk galloping instability during their bridge-launching phase, since the normally first launched steel boxes could feature bluff and lightweight cross section. In our previous study, a bridge deck of open cross section (typically used in steel–concrete composite bridges) has been found in smooth flow highly prone to the unsteady galloping instability occurring at relatively low reduced wind speed. Considering the natural wind field is usually turbulent, motivations arise to understand what role can the incident turbulence play in the galloping instability of this open cross section deck. New wind tunnel tests were therefore carried out in grid-generated turbulent flow, characterized by an integral length scale comparable to the bridge deck height and an intensity of 9% to 15%. For the interested wind angles of attack around null, static tests first indicate the incident turbulence is able to promote an even higher galloping factor than that in smooth flow, while the Strouhal number shows a decrease. This suggests a higher proneness for the galloping and vortex induced vibration to interact. In aeroelastic tests, however, the typical unsteady galloping instability due to the interaction with vortex induced vibration has never been observed. Instead, the unsteady galloping is initiated in a more complicated manner: unrestricted oscillation arises at a reduced wind speed clearly higher than the Kármán-vortex resonance one even for a very low Scruton number (the mass-damping parameter), combined with the absence of any Kármán-vortex excitation. Nevertheless, similar to the smooth flow condition, the nosed-up 4° remains to be the most unfavorable wind angle of attack in turbulent flow, featuring the lowest galloping onset in the low Scruton number condition. Finally, dependent on the magnitude of Scruton number, it is able to conclude that the incident turbulence can either suppress or promote the galloping instability of this bridge deck.