Solid Column Research Articles

Compressive behavior of axially loaded circular hollow concrete columns reinforced with GFRP bars and spirals

This study explored the use glass-fiber-reinforced-polymer (GFRP) bars and spirals as reinforcing materials in hollow concrete columns in order to mitigate steel-related corrosion problems and understand the fundamental behavior of such construction system under the applied loads. Four concrete columns 250 mm in external diameter and reinforced longitudinally with six 15.9 mm diameter GFRP bars were cast with different inner diameters (0, 40, 65, and 90 mm) and tested under concentric axial loading. Based on the experimental results, increasing the inner-to-outer diameter ratio up to 0.36 in hollow GFRP reinforced columns changed the failure behavior from brittle to pseudo-ductile. Moreover, the hollow GFRP reinforced columns exhibited higher deformation capacity and higher confinement efficiency compared to the GFRP-reinforced solid columns and steel-reinforced hollow columns. A theoretical model considering the confined-concrete compressive strength and axial strain of 0.0025 in longitudinal GFRP bars can accurately predict the axial-load capacity of hollow concrete columns.

Seismic Analysis of Steel Solid Web Girder-RC Tubular Column Hybrid Structure

This paper aims to investigate the seismic performance of a novel type of steel–concrete hybrid supporting structure consisting of reinforced concrete (RC) tubular columns, steel solid web girder platform, and A-shaped steel frames. It is typically used to house air-cooled condensers (ACC) in thermal power plants (TPPs). First, the finite-element (FE) model was implemented in ABAQUS and the simulation approaches were validated by pseudo-dynamic test results of a scaled steel-concrete hybrid supporting structure. Then, the elasto-plastic time-history analysis of the steel solid web girder-RC tubular column hybrid structure was conducted. The El Centro (NS) record was scaled to peak ground acceleration (PGA) of 0.07, 0.20, 0.40 and 0.62 g to reflect the frequent, basic, rare, and very rare earthquakes. The dynamic characteristics, base shear force, lateral deformation performance, stiffness deterioration, and damage evolution characteristics were analyzed. The numerical results showed that the first vibration mode of this hybrid structure is torsion, due to its small torsional stiffness and the nonuniform distribution characteristics of stiffness and mass in the vertical direction; the lateral deformation shape is shear mode; and the damage mainly occurred on the RC tubular columns, while the steel components did not yield under severe earthquakes. In general, the overall seismic performance of the steel solid web girder-RC tubular column hybrid structural system could meet the seismic design requirements with respect to the high-intensity earthquakes.

A unified interaction equation for strength and global stability of solid and hollow concrete-filled steel tube columns under room and elevated temperatures

On the basis of plastic limit analysis, this paper proposes a novel, simple and unified interaction equation (N-M) for Concrete-filled Steel Tube (CFST) columns subjected to combined compression and bending. A unique feature of the new N-M equation is that the single equation is valid for a range of columns that can be solid, hollow, circular, polygonal, short or long. The single equation can also apply to columns under both room and elevated temperatures. Validations against independent laboratory test, analytical and numerical results are carried out to assess the accuracy and applicability of the equation. The new equation agrees well with most of the results used in the comparisons. It can be concluded that the simple and unified equation can be used in practical design with sufficient accuracy.

Interlocking glass spiral as building structure of the watch museum “La Maison des Fondateurs”

La Maison des Fondateurs in Le Brassus Switzerland is going to represent the watch making manufacture Audemars Piguet. Audemars Piguet stands for the finest quality, precision as well as innovation based on traditional watchmaking expertise and craftsmanship. La Maison des Fondateurs has been developed from a competition proposal to the execution project by the architects BIG—Bjarke Ingels Group. The created interlocking all glass spiral evolves the building volume out of the rough, natural landscape providing a perfect linear museum path for the building program. Despite the severe loading and weather conditions, inspired by the high values of Audemars Piguet the project team designed the building to the technical limits. The curved and very large insulated facade glass units as well as the curved glass partition walls of the interlocking glass spiral are forming the load bearing structure. All vertical and horizontal loads are transferred by these glass components making solid columns and shear wall obsolete. The article reflects the close collaboration of the designers, engineers, specialist contractor and industry. The global structural concept, transfer of the concentrated point loading into the curved structural glass element, testing procedures as well as the structural bonding beyond standards and the context of energy efficiency are discussed and elaborated.

Strength Evaluation of Hybrid Reinforced Concrete Columns under Eccentric Loads

This study presents an experimental investigation of the behavior of hybrid circular columns composed of outer precast reactive powder concrete (RPC) tubes filled with normal concrete (NC). The column specimens were subjected to an eccentric load producing both flexural and axial stresses within the section. The specimens consisting of 200 mm outer diameter with 400 mm height. The column specimens were divided into three groups, each group contains two specimens of thicknesses of outer RPC walls of 50 and 25 mm that filled with NC, in addition to RPC solid column section. The columns of first group were without any reinforcement. While the second group specimens were longitudinally reinforced, in addition to 180 mm spaced ties. The third group is composed of the same details as that of group two but with 90 mm ties spacing. The results show that, All RPC solid specimens give a higher load capacity from that of the hybrid specimens about 48%. It is noticed that increasing the RPC outer wall thickness improves the ultimate load capacity by 11% for hybrid specimens with 50 mm thickness wall than that of hybrid specimens with 25 mm thickness wall. Also, longitudinal and transverse reinforcement noticeably enhance the ductility and strength of the tested specimens compared with corresponding plain specimens.

Vanillin production by biotransformation of phenolic compounds in fungus, Aspergillus luchuensis

Vanillin is valuable and popular flavor used in foods and cosmetics. Many bacteria species have the ability to decarboxylate substituted cinnamic acids in order to form vanillin. However, the phenolic biotransformation including vanillin production in a common fungus, the Aspergillus luchuensis, which is used in distilled beverages, has not yet been clarified. This study focused on elucidating the vanillin production due to phenolic biotransformation in A. luchuensis during fermentation. The phenolic metabolites were extracted by a solid phase column and they were determined using on LC/MS and LC/MS/MS in a selective ion mode. As a result, ferulic acid, vanillin and vanillic acid, were detected in the rice koji fermentationed by A. luchuensis and also fermentated with yeast. In addition, the accurate molecular formula of vanillin glucoside (C14H17O8, 313.0927, (M-H)− and its production ions was also determined by HRESI-mass spectrometry. Based on the results including the phenolic metabolites and related genes found in A. luchuensis genome, this study proposed the vanillin production mechanism due to the side chain cleavage of ferulic acid through Coenzyme A (CoA) and feruloyl-CoA hydratase/lyase, to form vanillin and acetyl-COA. In this study, another possible vanillin production pathway also was proposed due to the neutral hexose hydrolysis of vanillin glucoside. The subsequent dehydrogenation of vanillin produced vanillic acid. In addition, vanillin was detected in the distilled alcohol indicating its contribution to the aroma profile of beverages. It has been unknown that the vanillin in the distilled solution is derived from the vanillin produced during rice-koji and/or moromi mash fermentations.

A Convenient Method for Extraction and Analysis with High-Pressure Liquid Chromatography of Catecholamine Neurotransmitters and Their Metabolites.

The extraction and analysis of catecholamine neurotransmitters in biological fluids is of great importance in assessing nervous system function and related diseases, but their precise measurement is still a challenge. Many protocols have been described for neurotransmitter measurement by a variety of instruments, including high-pressure liquid chromatography (HPLC). However, there are shortcomings, such as complicated operation or hard-to-detect multiple targets, which cannot be avoided, and presently, the dominant analysis technique is still HPLC coupled with sensitive electrochemical or fluorimetric detection, due to its high sensitivity and good selectivity. Here, a detailed protocol is described for the pretreatment and detection of catecholamines with high pressure liquid chromatography with electrochemical detection (HPLC-ECD) in real urine samples of infants, using electrospun composite nanofibers composed of polymeric crown ether with polystyrene as adsorbent, also known as the packed-fiber solid phase extraction (PFSPE) method. We show how urine samples can be easily precleaned by a nanofiber-packed solid phase column, and how the analytes in the sample can be rapidly enriched, desorbed, and detected on an ECD system. PFSPE greatly simplifies the pretreatment procedures for biological samples, allowing for decreased time, expense, and reduction of the loss of targets. Overall, this work illustrates a simple and convenient protocol for solid-phase extraction coupled to an HPLC-ECD system for simultaneous determination of three monoamine neurotransmitters (norepinephrine (NE), epinephrine (E), dopamine (DA)) and two of their metabolites (3-methoxy-4-hydroxyphenylglycol (MHPG) and 3,4-dihydroxy-phenylacetic acid (DOPAC)) in infants' urine. The established protocol was applied to assess the differences of urinary catecholamines and their metabolites between high-risk infants with perinatal brain damage and healthy controls. Comparative analysis revealed a significant difference in urinary MHPG between the two groups, indicating that the catecholamine metabolites may be an important candidate marker for early diagnosis of cases at risk for brain damage in infants.

A unified formula for calculating bending capacity of solid and hollow concrete-filled steel tubes under normal and elevated temperature

Bending is one of the most common forms of deformation that may cause failure of a structural member, such as a column, especially when the member is exposed to fire. Fire resistance design is therefore an important factor that must be considered in the design process of modern building structures. Based on the authors' previous work on the unified formulation of axially loaded CFST hollow and solid columns with circular and polygonal sections, a unified formula for calculating the ultimate bending moment of solid and hollow CFST columns at room temperature is proposed first in this paper. The formula is then extended to include elevated temperature using the average temperature method. Finally, a unified formula for both room and elevated temperature are presented. Validations are carried out through comparisons with the results from experimental tests and finite element simulations.

High throughput routine determination of 17 tyrosine kinase inhibitors by LC–MS/MS

Several studies have shown that therapeutic drug monitoring of tyrosine kinase inhibitors (TKI) can improve their benefit in cancer. An analytical tool has been developed in order to quantify 17 tyrosine kinase inhibitors and 2 metabolites in human plasma (afatinib, axitinib, bosutinib, crizotinib, dabrafenib, dasatinib, erlotinib, gefitinib, imatinib, lapatinib, nilotinib, ponatinib, regorafenib, regorafenib M2, regorafenib M5, ruxolitinib, sorafenib, sunitinib, vandetanib). Drugs were arranged in four groups, according to their plasma concentration range: 0.1–200ng/ml, 1–200ng/ml, 4–800ng/ml and 25–5000ng/ml. Solid phase extraction was used and separation was performed with HPLC using a gradient system on a solid core particle C18 column (5×2.1mm, 1.6μm). Ions were detected with a triple quadrupole mass spectrometry system. This assay allows rapid determination of 19 TKI in less than 5min per run. This high throughput routine method will be useful to adjust doses of oral anticancer drugs in order to improve treatments efficacy.

A New UPLC-MS/MS Method for the Characterization and Discrimination of Polysaccharides from Genus Ephedra Based on Enzymatic Digestions.

Ephedra sinica polysaccharides have been reported to possess important activities, so quality evaluation of polysaccharides from the genus Ephedra is urgent. In this study, enzymatic digestions were performed to establish multiple saccharide fingerprints by ultra-performance liquid chromatography with electrospray ionization triple quadrupole linear ion trap mass spectrometry (UPLC-ESI-TQ-MS/MS) based on a multiple-reaction monitoring in negative mode. Under optimum UPLC-ESI--TQ-MS/MS conditions, excellent separation and quantification of 21 constituents were achieved within 20 min on a solid core column with a 1.6 μm particle using pre-column derivatization with a PMP reagent. This method, coupled with enzymatic digestions and principal component analysis, has been successfully applied to characterize and discriminate Ephedra polysaccharides attributed to different species and plant parts. The results suggest that the proposed analytical strategy could achieve a quality evaluation of plant polysaccharides from traditional Chinese medicines.

Hydrodynamic Study of a Gas–liquid–solid Bubble Column Employing CFD–BPBM Method

AbstractThe computational fluid dynamics – bubble population balance model (CFD–BPBM) was employed to predict the hydrodynamic characteristics of a gas–liquid–solid bubble column. A 3D time dependent numerical study was performed and the bubble size distributions at the conditions of different superficial gas velocity (0.089 m/s–0.22 m/s), solid volume fraction (0.03–0.30) and particle density (2500 kg/m3–4800 kg/m3) in the three–phase system were investigated, and the simulation results were compared with the experimental results. The bubble diameters ranging from 1 mm to 64 mm were divided into ten classes. The predicted pressure changing with the bed height had a good agreemeet with the experimental result. The bubble number density predicted decreased when the bubble size increased at each superficial gas velocity, and the bubble coalescence rate became greater than the breakup rate when Ugshifted from 0.089 m/s to 0.16 m/s. The bubble interaction was similar at 0.16 m/s and 0.22 m/s both at particle size dp= 75 μm and 150 μm. The bubble size corresponding to the maximum of the bubble volume fraction increased as Ugincreased. The particles can make the bubble break up and coalesce simultaneously when the solid volume fraction was larger than 0.20, and therefore the particles had a contribution to both of the bubble coalescence and breakup in the bubble coalescence regime (Ug= 0.16 m/s). The effect of the particle density was similar with that of the solid volume fraction. Increasing the particle density can enhance the breakup rate of the large bubbles.

Performance assessment of novel hollow and solid RC columns using simulation of shaking table test

The purpose of this study was to investigate the seismic performance of novel hollow and solid reinforced-concrete (RC) columns with triangular reinforcement details when subjected to impulsive near-fault ground motions. The results of numerical simulations of shaking table tests on six hollow columns and six solid columns are presented. The developed reinforcement details are shown to be economically feasible and rational, and they facilitate shorter construction periods. The use of a sophisticated non-linear finite-element analysis program enhanced the accuracy and objectivity of the assessment process. The computer program RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used to analyse the RC structures. The equations of motion were solved by numerical integration using the Hilber–Hughes–Taylor algorithm. The numerical method used gave a realistic prediction of seismic performance throughout the input ground motions for several column specimens investigated. As a result, the developed triangular reinforcement details were considered to be superior to existing reinforcement details in terms of the required seismic performance. Such an analysis to study the seismic response of novel hollow and solid RC columns should lead to realistic and safe design.

Application of linear gradient elution in countercurrent chromatography for the separation of triterpenoid saponins from the roots of Pulsatilla koreana Nakai.

A linear gradient elution method using countercurrent chromatography was developed for the separation of four triterpenoid saponins from the roots of Pulsatilla koreana Nakai, including hederacolchiside E, which is responsible for the neuroprotective activity of this plant. The target fraction was obtained by 80% methanol elution of solid phase column chromatography. The partition coefficients of the target compounds were very different, which means they are difficult to separate with a single biphasic solvent system. Several important parameters for gradient elution, such as addition of alcohol content to the solvent system, starting point of the second mobile phase, and the time for the gradient change were logically determined and optimized. Four triterpenoid saponins could ultimately be separated, analyzed by high-performance liquid chromatography, and their structures were identified by comparing the mass spectra and NMR spectra with the literature data. The compounds and yields were: hederasaponin B (1; 21.3mg/100mg), hederacolchiside E (2; 19.8mg/100mg), cernuoside A (3; 18.4mg/100mg), and cernuoside B (4; 17.3mg/100mg). Gradient-elution countercurrent chromatography allows the effective separation of compounds with a wide polarity range.

Effect of protection against hot climate on growth performance, physiological response and endocrine profile of growing lambs under semi-arid tropical environment.

In the hot semi-arid tropical region, extreme summer is a major constraint in sheep production. The growth performance of growing lambs is impaired during the summer. Therefore, the present study was conducted to assess the effect of protection against hot climate on growth performance, physiological response, and endocrine profile of growing lambs under semi-arid tropical environment. All the data in the experiment were presented as mean±SE. Thirty Malpura lambs with the age of 122.7±6.05days and body weight of 19.52±0.42kg were allotted into three groups, viz. G1 (control, lambs kept in open area under tree shade), G2 (lambs kept in conventional asbestos-roofed shed), and G3 (lambs kept in designed shed). The allotment was based on their initial body weight so that the mean body weight of each group was similar. In all three types of protection, lambs were provided with sufficient space to move and social interaction. In asbestos-roofed shed (G2), all the four sides from ground to the roof were fenced with strong galvanized iron chain link. But in G3, all the four sides were constructed in a manner that there was 0.13m air space between inner and outer solid brick columns of the wall up to 1.37m height, and rest up to the roof was fenced with bamboo splint net. The air space between the two columns of the wall was filled with sand, and it was kept in moist condition by continuous water drips which provide extra evaporative cooling. The designed shed was basically constructed with bamboo. Tree shade was assured under the natural shades of large trees. The shaded area was protected by wire fences. The experiment was conducted for 45days during very high temperature (May-June). The lambs were provided with ad libitum green fodder, dry roughage, 300g concentrate, and ad libitum drinking water. The respiration rate at morning and afternoon, pulse rate at morning and afternoon and rectal temperature at afternoon was significantly (P<0.05) lower in lambs of G3 as compared to other groups. The final body weight did not differ significantly between the groups, but average daily gain (g/day) was higher in G3 (150.06±11.13) as compared to the G1 (109.69±18.10). The feed conversion rate (FCR) was significantly (P<0.05) better in G3 (5.49±0.08) as compared to G1 (7.65±0.08) and G2 (6.60±0.08). The hemoglobin level was significantly (P<0.05) higher in G1. The endocrine profile did not vary significantly (P>0.05) among the groups, but insulin-like growth factor-1 (IGF-1) was higher in G3. It can be concluded from this study the lambs provided with better protection during summer remained in more comfortable condition, showed better FCR, and although not statistically significant showed better growth performance.

Behavior of FRP-Steel Confined Concrete Tubular Columns Made of Expansive Self-Consolidating Concrete under Axial Compression

AbstractA total of 32 fiber-reinforced polymer (FRP) confined concrete columns are manufactured and tested under axial compression including 8 FRP-confined solid columns (FCSCs), 4 FRP-confined con...

Analysis and Design of Hollow Reinforced Concrete Columns

A hollow concrete section is oftenly used for column design, particularly for very tall bridge columns in earthquake prone areas for reducing the mass and to reduce the self-weight contribution to the inertial mode of vibration during an earthquake. The hollow columns enable to reduce foundation dimensions and thus save the construction cost substantially. Hence, these advantages have promoted the use of hollow columns instead of similar solid members in construction of building structures as well. This study includes analysis of a G+4 commercial building with solid columns analysed in ETABS2016. The analytical data is being used to design a hollow column for the same structure under worst load combinations using software CSICOL9. The best design is being proposed with advantages of hollow columns over solid columns.

Behaviour of circularized and FRP wrapped hollow concrete specimens under axial compressive load

Circularizing a square column by bonding concrete segments onto the sides of the column and then wrapping with fibre reinforced polymer (FRP) is considered an effective technique in strengthening square solid columns. This paper investigates the suitability of the circularization technique for strengthening square hollow concrete specimens. Eight specimens in two groups (four solid specimens and four hollow specimens) were cast and tested under axial compression. The first specimen from each group was the reference specimen. The corners of the second specimen were rounded to 20mm radius and wrapped with two layers of carbon fibre reinforced polymer (CFRP). The third specimen was circularized with full length concrete segments and wrapped with two layers of CFRP. The fourth specimen was circularized with concrete segments shorter than the length of the specimen and wrapped with two layers of CFRP. The test results demonstrate that circularization of hollow specimens similar to the circularization of solid specimens reduces the stress concentration at the corners and enhances the ultimate load carrying capacity and ductility. The circularization with short concrete segments is more effective for hollow specimens than the circularization with full length concrete segments when the ductility is of main concern.

Analysis of axially loaded concrete filled circular hollow double steel tubular columns exposed to fire

A series of new unified design formulas for calculating the temperature field and fire resistance under axial compressive loading of a circular solid or hollow concrete filled double steel tubular (CFDST) short and slender columns exposed to fire are presented in this paper. The results of the experiments are firstly derived from exploring the fundamental behavior of the CFSDT slender columns under the ISO 834 standard fire and temperature distributions. Failure modes and axial deformation versus time curves are also obtained and discussed. It was realized that a solid or slender CFDST column has different temperature fields, stronger limiting temperature and better fire resistance, as compared to columns filled with plain concrete. Also, the load ratio and steel ratio have no evident difference between the results of the solid and hollow CFDST columns. A three-dimensional finite element analysis (FEA) model is developed to calculate the temperature field of CFDST columns. After calibration of the FE model, the influences of important parameters on the temperature field of the composite columns are investigated and a unified formula for calculating average temperatures of the columns’ cross-section is obtained. Combining the average temperature with the “Unified theory” under axial compression, a simplified design method is put forward, which provides a unified formulation for both the plain CFST and CFDST columns relating to the axial bearing capacity at room and elevated temperature. The proposed formulas are calibrated through comparisons with fire tests on the columns, and it was found that the method produces safe results on average.

HPLC同时测定黄檗种子中4种内源植物激素

本文以东北天然红松林重要伴生植物黄檗(Phellodendron amurense)种子为研究材料，采用高效液相色谱法对种子中的植物激素进行分析，以探讨植物种子中的植物激素测定方法。黄檗种子经80%甲醇浸提，C-18固相萃取柱萃取，反相C18柱分离，流动相：甲醇:乙腈:水 = 1:1:8 (体积比)。检测波长：GA为206 nm、IAA 225 nm、ABA与玉米素Z的检测波长为254 nm，首先在HPLC预设置206 nm (GA)和225 nm (IAA)两个波长，在样品运行7分钟时，手动更改检测波长为254 nm。利用该方法测定赤霉素、吲哚乙酸、玉米素和脱落酸4种内源植物激素的回收率在93%以上，相对标准偏差小于4.1%，精密度和重现性均较好。表明该方法适用于黄檗种子中植物激素含量的检测。 Four endogenous phytohormones: Gibberellins, indoleacetic acid, zeatin and abscisic acid in the seeds of Phellodendron amurense, were examined by High Performance Liquid Chromatography (HPLC) to provide effective and reliable methods for identification of phytohormones in plant seeds. The four analytes were extracted from P. amurense seeds by 80% methanol and C-18 solid extraction column, and then separated by Agilent C18 column, using methanol, acetonitrile, water (1:1:8, V/V/V) as mobile phases. Detection wavelength: GA was 206 nm, IAA was 225 nm, ABA and Zeatin were 254 nm. First, the HPLC preseted 206 nm (GA) and 225 nm (IAA) as detection wavelengths, and when the sample ran for 7 minutes, the detection wavelength was changed to 254 nm. This method had been applied to the determination of gibberellin, indole acetic acid, zeatin and abscisic acid in the seeds of P. amurense, and the recovery rate of 4 kinds of endogenous phytohormones was more than 93%, relative standard deviation less than 4.1%. The results showed that phytohormones was well separated, and the ideal quantitative data of phytohormones in P. amurense seeds were obtained, and this method suited the purpose of the determination for phytohormones in P. amurense seeds.

Optimized Multiresidue Analysis of Organic Contaminants of Priority Concern in a Daily Consumed Fish (Grass Carp).

The organic contaminants, including polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs), are of priority concern because of their persistence, toxicity, and long-distance transportation in global environment. Their residues in a daily consumed fish (grass carp) pose potential threat to human health and aquatic ecosystems. The present study optimized an analytical protocol of microwave-assisted extraction (MAE), lip-removal by gel permeation chromatography (GPC), cleanup by solid phase cartridge (SC) or adsorption chromatography column (CC), and gas chromatography-mass spectrometry (GC/MS). Besides traditional statistical parameters, some indicators were calculated to judge the performances of extraction by various methods. The optimization experiment showed that n-hexane/acetone was the best MEA extraction solvent; an optimal fraction time of 10–39 min could simultaneously elute all the target chemicals in a single GPC run. Both CC and SC showed good recoveries. However, CC performed better than SC (p < 0.05) for OCPs, and SC performed better than CC for PBDEs (p < 0.05). We also emphasized the limitations and advantages of SC and CC and finally proposed SC as the promising cleanup method because of its low-cost materials, time-saving steps, being free of manual filling, and operation by automated SPE system.