Shape Of Column Research Articles

Numerical modeling of the punching shear behavior of biaxially loaded RC footings

In this study, the punching shear behavior of footings under biaxial eccentric loads is numerically investigated. Load eccentricities usually encountered in practice were primarily investigated on flat slabs, whereby the research on footings is still limited. Since the structural behavior of thick footings is significantly different compared to that of thin ones due to fracture mechanics, further investigations are required. To gain a deep understanding of the punching shear behavior of footings under biaxial eccentric loads, a numerical investigation was conducted. A finite element model was developed and validated against multiple experimental results in terms of load-deflection behavior and crack patterns. The validated model was then employed to examine the effect of different biaxial load eccentricities, different shear spans to effective depth ratios, column sizes, and column shapes. Finally, the numerical results were used for analyzing the design approach of the latest version of Eurocode 2 (FprEC2-2023). The numerical results showed a gradual transition between a fully developed punching shear cone to a partially formed cone without shear crack formation on the less loaded side with increasing load eccentricities. Additionally, larger load eccentricities lead to significantly increased rotation of the footing accompanied by a reduction of the punching shear capacity. A more pronounced influence of the effect of unbalanced moments on the punching shear capacity was identified in footings with a larger shear span to effective depth ratio. Furthermore, the effect of column size was more pronounced in small shear spans under concentric loads, while the effect was greater in footings with a larger shear span to depth ratio under eccentric loads. However, the beneficial effect of a larger column size was more pronounced for eccentric loads compared to concentric loading. Overall, the results indicate a good agreement with the design approach of Eurocode (FprEC2) for square columns. However, in some cases, the prediction was underestimated. Modified approaches from the literature for considering the effect of load eccentricity were found to address the underestimated cases safely. The results of this study demonstrated the applicability of the new design approaches for eccentric punching shear in footings under biaxial eccentric loads.

Role of Activating Flux in Weld Bead Symmetricity during Dissimilar Metal Joining

Ferritic/martensitic steels and austenitic stainless steels are high‐strength steels, and highly recommended in high‐temperature and high‐pressure application. In general, multimetallics with different Inconel alloys are used for joining. This is quite a complex and time‐consuming procedure. The current work demonstrates the efforts made to weld 8 mm‐thick P91 steel and 316L SS plates in a single pass using activating flux tungsten inert gas (A‐TIG) welding process without any interlayers. The main challenge is to get the symmetric weld bead profile. Flux coating is optimized in terms of flux composition, coating density, and coating pattern to get the full penetration with symmetric appearance. The current work discusses the possible cause and their solution of asymmetricity during dissimilar welding. Differential flux coating density is found to be very effective in controlling the arc column shape, fluid flow, and consequently the bead geometry. High coating density is used in the P91 side compared to 316L side. Symmetric weld profile with full penetration is achieved by applying multicomponent flux (33–38% TiO2, 38–43% SiO2, 13–17% NiO, and 8–10% CuO) during A‐TIG welding.

Blast performance of RC columns with different levels of concrete grades and reinforcing ratios

AbstractThe present article aims to study the behavior of RC columns under blast loading. A nonlinear dynamic Three‐Dimensional (3D) Finite Element FE model‐based explicit solver available in ABAQUS Software is used. A parametric study is investigated to enhance the blast resistance of RC columns under three different scaled distances z of an explosion, that is, 0.23, 0.5, and 1.07 m/kg1/3 for close, intermediate, and Far in‐distance. In addition, three levels of concrete grades are used, which are Normal Strength Concrete (NSC), High Strength Concrete (HSC), and Ultra High‐Performance Concrete (UHPC). The study also considers Three reinforcement ratios for longitudinal and transverse reinforcement ratios of (ρL = 1.28%, 2.4%, and 3.1%) and (ρs = 0.6%, 0.9%, and 1.35%), respectively. Further, three different Axial Load Ratios, ALR = 0.01, 0.2, and 0.4, are considered to examine the effect of increasing ALR on the RC column under close explosion. For more investigation, the parametric analysis considers two geometrical shapes of RC columns (square and circular). The material behaviors of concrete and reinforcing steel bars are represented using Concrete Damage Plasticity (CDP) and Johnson–Cook (J–C) models, respectively, available in ABAQUS Software. The FE model has been initially validated against experimental study. The FE‐predicted deflection and damage were observed and agreed with the practical cases. In addition, the parametric study's results demonstrate that the RC column's blast deflection is significantly reduced with increasing reinforcement ratios. However, increasing concrete grade could efficiently reduce blast damage and deflection. Furthermore, compared with NSC, UHPC significantly reduced maximum damage and deflection by around 60% for square and 55% for circular columns, respectively.

Influence of the shape of a conducting chamber on the stability of rigid ballooning modes in a mirror trap

MHD stabilization of flute and ballooning modes in an axisymmetric mirror trap is studied under the assumption of strong finite Larmor radius effect that suppresses all perturbations with azimuthal numbers m⩾2 and makes the m = 1 mode ‘rigid’. The rigid mode can be effectively suppressed using perfectly conducting lateral wall without any additional means of stabilization or in combination with end MHD anchors. Numerical calculations were carried out for an anisotropic plasma produced in the course of neutral beam injection into the minimum of the magnetic field at the right angle to the trap axis. The stabilizing effect of the conducting shell made of a straightened cylinder is compared with a proportional chamber, which, on an enlarged scale, repeats the shape of the plasma column. It is confirmed that for convincing wall stabilization of the rigid modes, the plasma beta (β, the ratio of the plasma pressure to the magnetic field pressure) must exceed some critical value βcr2 . When conducting lateral wall is combined with conducting end plates imitating MHD end anchors, there are two critical betas and, respectively, two stability zones β<βcr1 and β>βcr2 that can merge, making the entire range 0<β<1 of betas allowable for stable plasma confinement. The dependence of the critical betas on the plasma anisotropy, mirror ratio, width of the vacuum gap between the plasma column and the lateral wall, radial pressure profile and the axial magnetic field profile is examined.

Small- to medium-sized mammals show greater morphological disparity in cervical than lumbar vertebrae across different terrestrial modes of locomotion.

During mammalian terrestrial locomotion, body flexibility facilitated by the vertebral column is expected to be correlated with observed modes of locomotion, known as gait (e.g., sprawl, trot, hop, bound, gallop). In small- to medium-sized mammals (average weight up to 5 kg), the relationship between locomotive mode and vertebral morphology is largely unexplored. Here we studied the vertebral column from 46 small- to medium-sized mammals. Nine vertebrae across cervical, thoracic, and lumbar regions were chosen to represent the whole vertebral column. Vertebra shape was analysed using three-dimensional geometric morphometrics with the phylogenetic comparative method. We also applied the multi-block method, which can consider all vertebrae as a single structure for analysis. We calculated morphological disparity, phylogenetic signal, and evaluated the effects of allometry and gait on vertebral shape. We also investigated the pattern of integration in the column. We found the cervical vertebrae show the highest degree of morphological disparity, and the first thoracic vertebra shows the highest phylogenetic signal. A significant effect of gait type on vertebrae shape was found, with the lumbar vertebrae having the strongest correlation; but this effect was not significant after taking phylogeny into account. On the other hand, allometry has a significant effect on all vertebrae regardless of the contribution from phylogeny. The regions showed differing degrees of integration, with cervical vertebrae most strongly correlated. With these results, we have revealed novel information that cannot be captured from study of a single vertebra alone: although the lumbar vertebrae are the most correlated with gait, the cervical vertebrae are more morphologically diverse and drive the diversity among species when considering whole column shape.

Characterization and in vitro digestion of alkali-extracted polysaccharides from Grifola frondosa and its impacts on human gut microbiota

Grifola frondosa is a highly valued, edible and biologically active fungus in which the polysaccharide component plays a major role. To investigate the fundamental structure, in vitro digestion and fermentation characteristics of Grifola frondosa polysaccharides (GFP), GFP from the waste residue of Grifola frondosa after water extraction was re-extracted by alkaline solution. The carbohydrate and β-glucan contents of GFP were 91.61% and 60.57%, respectively, and were mainly composed of glucose. GFP can form triple supercoils and combine with Congo red, and the surface of GFP was smooth and dense, and the particles were in the shape of long column, sheet and ellipse. Analysis of carbohydrate, reducing sugars, and further chromatogram data also showed that GFP was not degraded by the simulated digestion process of the mouth, stomach and small intestine. Fecal fermentation of GFP significantly increased the abundance of Bacteroidota, and decreased Proteobacterias in both normal weight and obese subjects in vitro. The short-chain fatty acid (SCFA)-producing bacteria, Faecalibacterium, Erysipelotrichaceae_UCG_003, Lactococcus were increased, and Dorea and Escherichia-Shigella were reduced after GFP treatment. Thus, the molecular of GFP was utilized and degraded by the gut microbiota and metabolized into SCFAs. This decreased pH, H2S, and NH3, as well as increased CO2 in the fermentation broth. In conclusion, GFP can modulate the composition of the gut microbiota and is a potentially functional product.

Воздействие криогенных сред и струйного горения на эпоксидные интумесцентные композиции, предназначенные для защиты оборудования и строительных конструкций нефтегазового комплекса

The article discusses the studies of epoxy intumescent fire-protective coating of steel structures impacted by cryogenic media and jet fire, in accordance with the requirements of the methodology developed at the Orenburg branch of the Federal State Autonomous Educational Institution of Higher Education VNIIPO EMERCOM of Russia, and harmonized with the international standards ISO 22899-1:2021, ISO 20088-1:2016, and ISO 20088-3. The tests have been conducted with the epoxy fire- and cryogenic-protective intumescent composition «Plamkor-5» (produced by JSC Scientific and Production Holding «VMP», Yekaterinburg, Russia). According to the results of the test for resistance of a square-shaped sample with internal dimensions 1500×1500×500 mm and a central shelf made of 10 mm thick carbon steel coated with the fire-retardant composition «Plamkor-5» to cryogenic fluid spill, it has been established that the sample does not reach the critical temperature of minus 49 °C with an actual 22.37 mm dry layer thickness. The average sample temperature at the 60th minute of the test was minus 32.09 °C. The results of the test of a similar sample in order to determine the resistance of the fire-protective composition «Plamkor-5» to a jet fire with an actual 10,89 mm thickness of the protective dry layer have shown that the sample does not reach the critical temperature of 500 °С during 60-minute fire exposure, whereas the average temperature of the sample was only 37 % (184.84 ºС) of the temperature limit value. According to the results of the test for resistance of a steel column shape sample of I-section 25K2 coated with the fire-retardant composition «Plamkor-5» to spill under the pressure of the cryogenic liquid, it has been established that the sample does not reach the critical temperature of minus –49 °С with an actual 23.78 mm dry layer thickness, whereas the average temperature of the sample at the 60th minute of test was minus 48.38 °С. The obtained results are comparable with the effect of the best import analogs; therefore, «Plamkor-5»-based fire-protective coatings can be used for the design and development of fire protection of building structures, at the facilities of the oil and gas industry, in tunnel structures, and civil engineering.

Study and Analysis of Seismic Performance of RC Structures with Various Building Classes and Orientations

In the framework of this project, an attempt was made to find out the influence of the shape, size and direction of the rectangular columns of the construction plan on the general stiffness and seismic response of the building suffering from the earthquake. A multistory RC building is modeled using ETABS software with different column shapes (square and rectangular), column sizes (different cross-sectional area at building height), and column orientations to determine the effect of each on the stiffness and seismic response of the building. . . The analytical results of each model were compared in terms of base movement, overburden displacement, layer deflection and time period. Keywords –Moment resisting System, Lateral Loads, ETABS, Seismic response etc

Evolution and diversity of biomineralized columnar architecture in early Cambrian phosphatic-shelled brachiopods

Biologically-controlled mineralization producing organic-inorganic composites (hard skeletons) by metazoan biomineralizers has been an evolutionary innovation since the earliest Cambrian. Among them, linguliform brachiopods are one of the key invertebrates that secrete calcium phosphate minerals to build their shells. One of the most distinct shell structures is the organo-phosphatic cylindrical column exclusive to phosphatic-shelled brachiopods, including both crown and stem groups. However, the complexity, diversity, and biomineralization processes of these microscopic columns are far from clear in brachiopod ancestors. Here, exquisitely well-preserved columnar shell ultrastructures are reported for the first time in the earliest eoobolids Latusobolus xiaoyangbaensis gen. et sp. nov. and Eoobolus acutulus sp. nov. from the Cambrian Series 2 Shuijingtuo Formation of South China. The hierarchical shell architectures, epithelial cell moulds, and the shape and size of cylindrical columns are scrutinised in these new species. Their calcium phosphate-based biomineralized shells are mainly composed of stacked sandwich columnar units. The secretion and construction of the stacked sandwich model of columnar architecture, which played a significant role in the evolution of linguliforms, is highly biologically controlled and organic-matrix mediated. Furthermore, a continuous transformation of anatomic features resulting from the growth of diverse columnar shells is revealed between Eoobolidae, Lingulellotretidae, and Acrotretida, shedding new light on the evolutionary growth and adaptive innovation of biomineralized columnar architecture among early phosphatic-shelled brachiopods during the Cambrian explosion.

Evolution and diversity of biomineralized columnar architecture in early Cambrian phosphatic-shelled brachiopods.

Biologically-controlled mineralization producing organic-inorganic composites (hard skeletons) by metazoan biomineralizers has been an evolutionary innovation since the earliest Cambrian. Among them, linguliform brachiopods are one of the key invertebrates that secrete calcium phosphate minerals to build their shells. One of the most distinct shell structures is the organo-phosphatic cylindrical column exclusive to phosphatic-shelled brachiopods, including both crown and stem groups. However, the complexity, diversity, and biomineralization processes of these microscopic columns are far from clear in brachiopod ancestors. Here, exquisitely well-preserved columnar shell ultrastructures are reported for the first time in the earliest eoobolids Latusobolus xiaoyangbaensis gen. et sp. nov. and Eoobolus acutulus sp. nov. from the Cambrian Series 2 Shuijingtuo Formation of South China. The hierarchical shell architectures, epithelial cell moulds, and the shape and size of cylindrical columns are scrutinised in these new species. Their calcium phosphate-based biomineralized shells are mainly composed of stacked sandwich columnar units. The secretion and construction of the stacked sandwich model of columnar architecture, which played a significant role in the evolution of linguliforms, is highly biologically controlled and organic-matrix mediated. Furthermore, a continuous transformation of anatomic features resulting from the growth of diverse columnar shells is revealed between Eoobolidae, Lingulellotretidae, and Acrotretida, shedding new light on the evolutionary growth and adaptive innovation of biomineralized columnar architecture among early phosphatic-shelled brachiopods during the Cambrian explosion.

Determination of the shape of the CFGFT cylindrical column based on laboratory tests

Analyses were carried out on glass-fibre-reinforced polymer tube columns with reference to laboratory tests. The angles of the glass fibre beams were 20°, 55° and 85°. The study employed non-classical operational calculus. Various modulated harmonic signal shapes were considered for columns and tubes at buckling. The buckling loads were assessed and compared for different models.

Studying the effect of using CFRP warping on strength of husk rice concrete columns

Abstract This research presents the effect of carbon fiber-reinforced polymer (CFRP) on a strength of concrete containing rice husk. Two shapes of columns (circular and square) were used to compare these two types in terms of resistance axial loading. Twelve concrete columns were casting; six are square and others are circular cross-section. All columns of each shape were divided into three groups, and each group consisted of two columns: the first group without CFRP, the second group covered with one layer of CFRP, and the last group covered with two layers of CFRP. The dimensions of the square columns were 300 mm × 300 mm and the height was 900 mm, with reinforced 4–6 mm steel bars. The circular columns were 300 mm in diameter with same height 900 mm and reinforced with 6–6 mm steel bars. Burnt rice husks are added at a rate of 10% of the amount of cement that should be added to the concrete mix. The test results showed the circular columns were the strongest and most resistant to axial loading than square columns. Also, the CFRP wrapping is very effective in strengthening circular concrete columns but significantly less effective in strengthening square concrete columns because the latter have sharp corners and flat sides.

Stream ecosystem puzzle: understanding how water column and sediment variables shape macroinvertebrate patterns in some Afrotropical streams.

Although the interaction of water column and sediment variables in streams is intricate, minimal studies have been conducted on how they influence macroinvertebrate community patterns. This study, therefore, aimed to evaluate the influence of water column and sediment variables on macroinvertebrate community patterns in selected Afrotropical streams. Spatiotemporal scales of water column and sediment variables were analysed following standard methods while macroinvertebrates were sampled using the kick sampling technique. Redundancy analysis (RDA) and variation partitioning were used to assess the relationship of macroinvertebrates with water column and sediment variables. Significant differences were observed between seasons amongst water column variables such as total dissolved solids (p=0.046), turbidity (p=0.027), dissolved oxygen (p=0.011), chemical oxygen demand (p=0.002), bank vegetation (p=0.013), velocity (p=0.04), phosphates (p=0.031), and sediment variables such as total organic matter (p=0.01), pH (p=0.024), electrical conductivity (p=0.014). This accounted for the shift in biotic communities across the two seasons. In the studied area and seasons, Baetidae, Chironomidae, and Thiaridae were the most abundant families of macroinvertebrates representing 21.5%, 17.8%, and 6.9% of the 5266 recorded individuals belonging to 68 families. The water column was the most important predictor of macroinvertebrate community patterns (57%) compared to sediments (35%). Therefore, the use of both water column and sediment variables in ecological studies and biomonitoring should be emphasised because the two compartments provide complementary information. This enables researchers to gain a more complete understanding of the ecological health of aquatic habitats, useful in the development of effective management strategies.

The Primary Breakup and Atomization Characteristics of Liquid Jet in Crossflow at the Fixed Momentum Ratio and Weber Number

ABSTRACT The primary breakup behaviors of injected fuel were investigated by high fidelity simulation. The influence of various parameters on the breakup and atomization was analyzed at the fixed momentum ratio and Weber number. The results indicated that a simultaneous increase of the surface tension coefficient and the velocity of crossflow will hardly affect axial waves. The air density primarily affected the friction acting on the liquid column near the nozzle, while the liquid density affected the liquid flow in the liquid column to the sides. These variations lead to differences in breakup modes. The evolution of liquid column shape at different penetration heights suggested that the formation of sheet-like structures on the sides of liquid column was one of the main reasons for its deflection. The deflection of liquid column was enhanced by the increase of air density, and it was weakened at the increase of surface tension coefficient. In addition, it was also observed that for different parameters, the change of the boundary of spray plume in the y direction corresponded to variations in liquid column deflection. The diameter distribution of droplets generated by the primary breakup was predominantly influenced by density, with only a slight impact from the surface tension coefficient.

Structural performance of the concrete-filled tube column with internal triangular units subjected to axial compression.

This study introduces a novel concrete-filled tube (CFT) column system featuring a steel tube comprised of four internal triangular units. The incorporation of these internal triangular units serves to reduce the width-thickness ratio of the steel tube and augment the effective confinement area of the infilled concrete. This design enhancement is anticipated to result in improved structural strength and ductility, contributing to enhanced overall performance and sustainability. To assess the effectiveness of the newly proposed column system, a full-scale test was conducted on five square steel tube column specimens subjected to axial compression. Among these specimens, two adhered to the conventional steel tube column design, while the remaining three featured the new CFT columns with internal triangular units. The shape of the CFT column, the presence of infilled concrete and the presence of openings on the ITUs were considered as test parameters. The test results reveal that the ductility of the newly proposed CFT column system exhibited a minimum 30% improvement compared to the conventional CFT column. In addition, the initial stiffness and axial compressive strength of the new system were found to be comparable to those of the conventional CFT column.

A New Optimization Approach for the Tallest Column Design

Motivated by the classical brachistochrone we present a new pattern of finding the shape of a vertical column that attains the maximum height if its material and volume are prescribed. It comprises the optimal control problem with a free end point. Besides, the constitutive equation of the column is such that it can suffer flexure, compression and shear. The critical load of a heavy compressed column for the finite values of shear and extensional rigidity and the novel use of the Pontryagin maximum principle with the corresponding first integral yielding the non-vanishing optimal cross section as a solution of a quadratic equation are main novelties of this work. The classical solution for the tallest column under selfweight is covered as a special case for infinite values of shear and extensional rigidity.

Columns Cross-Section Shape Effect on Punching Shear in Reinforced Concrete Flat Slabs

Punching shear is one of the possible failures that must be taken into consideration in designing concrete slabs and foundations. Several factors control the occurrence of this failure mechanism, such as slab thickness, concentrated loads, and the cross-section area of the supporting columns. The cross-section shape of columns may also affect the punching shear in flat slabs. Therefore, this research was specified to study the effect of the columns' cross-section shape on the punching shear in flat slabs by conducting a simulation analysis for two multi-story concrete buildings with a flat slab but with different structural stability systems, building layout, and column distribution, where five cross-section shapes (square, rectangular, circular, hexagonal, and octagonal) were tested. ETABS 2016 software was adopted for modeling and analysis to identify the optimum column shape leading to minimizing punching shear. Although the cross-section area and the reinforcement area of the columns were fixed while changing the models’ column shapes, it was found, in both buildings, that hexagonal columns performed better than others under punching shear and provided the lowest punching shear ratio. In contrast, circular columns gave the lowest resistance. Octagonal, square, and rectangular columns, respectively, follow the hexagonal columns in resisting punching shear.

Electrochemical Property of Activated Carbon Monolith from Potato for Supercapacitor Electrode

Electrochemical property of activated carbon monolith from potato was studied for possible application in supercapactor electrode. First, potato powder was purchased and used to prepare column shape samples via pressing. Then, they were subjected to two-step pyrolysis to avoid cracking, such as the 1st step at 300 °C at 0.5 °C/min heating rate and the 2nd pyrolysis at 400, 500 or 600 °C under N2 flow in a tube furnace. Next, the samples were cut into 1 mm thickness and then grinded into 0.5 mm, followed by immersing in 6M KOH solution and then the activation at 700 °C under N2 flow. Finally, the electrochemical properties of activated carbon monoliths were evaluated with a three-electrode system by cyclic voltammetry, galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). In addition, two-electrode system was also studied with the samples having highest specific capacitances, being from 400 °C pyrolysis. The samples were characterized by Raman, XRD, XPS and SEM, and specific surface area was also measured. Specific capacitance of 382 F/g was obtained from 400 °C pyrolysis, followed by 321 and 253 F/g from 500 and 600 pyrolysis, respectively.

머신러닝을 이용한 기후변화에 따른 천궁 생리 활성 성분 예측 모델 연구

Climate change has emerged as a global problem, with frequent temperature increases, droughts, and floods, and it is predicted that it will have a great impact on the characteristics and productivity of crops. Cnidium officinale is used not only as traditionally used herbal medicines, but also as various industrial raw materials such as health functional foods, natural medicines, and living materials, but productivity is decreasing due to threats such as continuous crop damage and climate change. Therefore, this paper proposes a model that can predict the physiologically active ingredient index according to the climate change scenario of Cnidium officinale, a representative medicinal crop vulnerable to climate change. In this paper, data was first augmented using the CTGAN algorithm to solve the problem of data imbalance in the collection of environment information, physiological reactions, and physiological active ingredient information. Column Shape and Column Pair Trends were used to measure augmented data quality, and overall quality of 88% was achieved on average. In addition, five models RF, SVR, XGBoost, AdaBoost, and LightBGM were used to predict phenol and flavonoid content by dividing them into ground and underground using augmented data. As a result of model evaluation, the XGBoost model showed the best performance in predicting the physiological active ingredients of the sacrum, and it was confirmed to be about twice as accurate as the SVR model.

Investigations of the Atomization Characteristics and Mechanisms of Liquid Jets in Supersonic Crossflow

In the combustion chamber of scramjets, fuel jets interact with supersonic airflow in the form of a liquid jet in crossflow (LJIC). It is difficult to achieve adequate jet–crossflow mixing and the efficient combustion of fuel in an instant. Large eddy simulation (LES), the coupled level-set and volume of fluid (CLSVOF) method, and an adaptive mesh refinement (AMR) framework are used to simulate supersonic LJICs in this article. This way, LJIC atomization characteristics and mechanisms can be further explored and analyzed in detail. It is found that the surface waves of the liquid column exist in a two-dimensional form, including vertical and spanwise directions. Column breakup occurs when all the spanwise surface waves between adjacent vertical surface waves break up. Bow shock waves, composed of multiple connected arcuate shock waves, are dynamic and will change with the evolution of the liquid column. The vortex ring movement of supersonic LJICs, whose trends in the vertical and spanwise directions are different, is relatively complex, which is due to the complex and time-dependent shape of liquid columns.