Capacity Of Columns Research Articles

Co-adsorption performance and mechanism of ammonium and phosphate by iron-modified biochar in water

To recover nitrogen and phosphorus from water bodies and reduce their potential risk of causing eutrophication, high-temperature pyrolysis-produced biochar (HBC) modified by ferric chloride (Fe-HBC) was adopted to investigate its surface modification on the co-adsorption performance of nitrogen and phosphate. In comparison to HBC, Fe-HBC exhibited superior specific surface area, well-developed pore structure, and enriched surface functional groups while successfully loading Fe2+ and Fe3+. It has been determined that the co-adsorption mechanism of ammonium and phosphate by Fe-HBC involves a combination of pore filling, ion exchange, functional group coordination, electrostatic attraction, and coprecipitation. The results from the batch adsorption experiments indicate that the ammonium adsorption capacities for Fe-HBC1, Fe-HBC2, and Fe-HBC3 were 10.59 mg/g, 10.38 mg/g, and 7.59 mg/g, respectively, while the phosphate adsorption capacities were 13.46 mg/g, 10.46 mg/g, and 15.22 mg/g, respectively. The results of the column adsorption experiments showed that too high or too low biochar percentage and flow rate were not conducive to improving the adsorption capacity of the adsorption column, and the maximum adsorption capacity of the adsorption column was achieved at a biochar percentage of 1 % and a flow rate of 1 mL/min. This study demonstrates the potential of this iron-modified biochar derived from agricultural wastes for practical application in the removal of ammonium and phosphate from wastewater.

Behavior of CFRP confined rectangular high-strength concrete-filled steel tubular columns under eccentric compression

This paper presents an experimental study on the eccentric compression behavior of rectangular high-strength concrete-filled steel tubular columns confined with carbon fiber reinforced polymer (CFRP- CFST). Seventeen specimens were tested under eccentric compression, examining key parameters involving eccentricity, number of transverse CFRP layers, slenderness ratio, corner radius, CFRP partial wrapping scheme, and CFRP orientation. The effects of these parameters on failure mode, load-displacement relationship, strain development, and ultimate mechanical properties were analyzed and discussed. The ultimate bearing capacity (Nu) of CFRP-CFST columns improved with an increase in transverse CFRP layers, corner radius, and CFRP wrapping proportion, while it decreased with increasing eccentricity and slenderness ratio. Partial wrapping schemes reduced the effectiveness of CFRP confinement, with the outward local buckling of the steel tube primarily occurring in areas without CFRP confinement. Longitudinal CFRP provided less improvement to Nu compared to transverse CFRP under small eccentricity conditions. A theoretical model based on the fiber element method was developed to predict the ultimate bearing capacity and implemented through a custom program to facilitate calculations. The model was validated using a test database comprising results from this study and previous research. Additionally, axial force-bending moment (N-M) interaction curves were rapidly generated, providing a theoretical basis for the design and practical application of CFRP-CFST columns in practical engineering.

Eccentric compression performance of coral concrete-filled aluminum alloy tube (CCFAT) circular short columns

Coral concrete, utilizing coral reef bodies in place of traditional aggregates, shows promising prospects use in island projects. The use of aluminum alloy-reinforced coral concrete columns effectively enhances the load-bearing capacity of these structures. This study aims to investigate the performance of aluminum alloy circular tube-reinforced coral concrete short columns under eccentric compression. The study involved designing fifteen short columns for eccentric compression experiments, focusing on key parameters such as aluminum content (α), eccentricity (e0), and coral concrete strength (fc). The study obtained failure modes, bearing capacities, and load-deformation relationships, and analyzed the impacts of aluminum content, eccentricity, coral concrete strength, and hoop coefficient (ξa) on the columns’ strength, stiffness, and ductility. Subsequently, a finite element parameter expansion analysis using Abaqus was performed. Ultimately, a correction coefficient model was developed, compared with existing international specifications, and used to establish a suitable calculation model for the bearing capacity of CCFAT eccentric short columns. The results indicated that CCFAT eccentric short columns predominantly experienced bending failure. The stresses in the aluminum alloy round tube can reach the conditional yield strength, effectively collaborating with the concrete. The load-deformation relationship did not exhibit an intensification stage, and the lateral deflection curves tended to follow sinusoidal half-wave patterns. During the initial loading stage, adherence to the plane-section assumption was observed, with the hoop effect primarily manifesting in the compression zone. The strength index showed an approximately quadratic relationship with ξa, the stiffness index showed a positive correlation with ξa, and the ductility index demonstrated a strong positive association with ξa. The correction coefficient model, along with AIJ (2001), can be employed for calculating the bearing capacity of CCFAT eccentric short columns. This study introduces the novel concept of aluminum alloy tube-reinforced coral concrete columns as a composite structure for island civil engineering construction. Beyond the benefits of traditional steel tube concrete, these composite columns are expected to reduce engineering costs, shorten construction timelines, and address durability concerns through the incorporation of marine coral stones and fragments as concrete aggregates.

Effect of concrete strength on the seismic performance of circular reinforced concrete columns confined by basalt and carbon fiber-reinforced polymer

This paper investigated the effect of concrete strength on the seismic performance of circular reinforced concrete (RC) columns confined by basalt and carbon fiber-reinforced polymer (BFRP and CFRP). Eight confined columns and four control columns were tested under a low cyclic lateral load. The variables in the test included concrete compressive strength (i.e., 22.4 MPa, 31.4 MPa, 42.5 MPa and 57.8 MPa) and FRP type (i.e., basalt and carbon fiber). The test results demonstrated that all the columns exhibited flexural failure after confinement. The strength, ductility and energy dissipation capacity of the confined columns were effectively enhanced. With the same confining stress, the peak loads of the BFRP- and CFRP-confined columns were nearly the same. However, the BFRP-confined columns with low and moderate concrete strength showed larger ductility and energy dissipation capacity compared with the CFRP-confined counterparts, and these capacities of the CFRP-confined column with a concrete strength of 57.8 MPa were slightly better than those of the BFRP-confined equivalent. This showed that the FRP jackets with larger modulus had better confinement effect on the columns with higher concrete strength. Finally, formulas for calculating the load carrying and ductility capacities of different FRP-confined circular RC columns were proposed based on the experimental results.

Experimental investigation on the compression-bending performance of rubberized concrete columns confined by galvanized corrugated steel tubes

In the construction of building structures, numerous components simultaneously experience axial pressure and lateral bending moments. This concurrent influence plays a pivotal role in structural design considerations. This paper presents an experimental investigation of the compression-bending performance of rubberized concrete-filled corrugated steel tubes (RuCFCST). Twenty-two specimens were tested to evaluate the effect of eccentricity, length-diameter ratio, and confinement factor on the failure mode, load-displacement response, stiffness, compression-bending capacity, and ductility of the columns. The study also conducted a stress analysis on the corrugated steel tube to understand its confinement effect on the core rubberized concrete. The results demonstrate that the confinement factor emerges as a pivotal and sensitive parameter that impacts the compression-bending bearing capacity of RuCFCST columns. The study further elucidated the non-uniform confinement and failure mechanisms of the RuCFCST column, and subsequently assessed the applicability of the specimen's compression-bending bearing capacity as calculated by current specifications. The proposed RuCFCST columns offer new insights and serve as a reference for developing composite member systems with large hoop stiffness, small wall thickness, and environmental sustainability.

Comparative Studies of Diclofenac Sodium (NSAID) Adsorption on Wheat (Triticum aestivum) Bran and Groundnut (Arachis hypogaea) Shell Powder using Vertical and Sequential Bed Column

Wheat bran and groundnut shell powder have been used to study the mechanism of diclofenac sodium adsorption from aqueous solution using batch as well as column modes and maximum uptake is 84.3% for wheat bran and 82.4% for groundnut shell powder at pH 6, drug concentration 1 mg/L at 298 K for 30min. Isotherm and error analysis reveals that Freundlich and Langmuir isotherms fitted well. Kinetic studies show that the adsorption process follows second-order kinetics and thermodynamic study shows endothermic adsorption process. Column adsorption study is important for industrial scale adsorption and column studies have been carried out using vertical bed and sequential bed adsorption columns at pH 6 which is the optimum pH for maximum adsorption for batch experiments. Vertical and sequential bed columns setup is simple and economical which provides flow under gravity. The effect of varying inlet feed concentration and flow rate on the breakthrough and exhaustion time of columns has been studied to determine the bed capacities of both columns. Thomas model and Yoon-Nelson models fitted well with experimental data for continuous flow column studies.

Effect of Preload on Box-Section Steel Columns Filled with Concrete under Axial Load: A Numerical Study

External loads applied to a box-section steel column before it is filled with concrete to increase its efficiency due to modifications in structural systems or design errors may reduce its ultimate capacity and change its structural behavior. To examine this effect, finite element modeling (FEM) has been used to simulate these columns under preloading at different ratios with many variables in the geometric dimensions of the columns. The FEM results have been investigated using 38 experimental specimens obtained from previous studies without preloading. The results demonstrated high accuracy in modeling these columns in structural behavior and ultimate load capacity. After verifying the results, 84 Concrete-Filled Steel Columns (CFSC) were modeled under different preload ratios. The results indicated that some variables have directly affected the value of the decrease in column capacity in terms of its height, wall thickness, yield stress, and preload ratios, while others were inversely proportional in terms of the cross-section dimensions and concrete strength. The preload effect ratio had two separate limits, where when it reached 70%, the maximum value of the decrease in column capacity was 10.90%. The value increased sharply reaching 19.90% when there was a preload equal to 80%. New equations have been proposed to predict the ultimate capacity of CFSC under preloading with suitable accuracy with a correlation coefficient of no less than 0.949.

A Review of the Properties of Different Concrete-Filled Steel Tube Columns

This paper mainly analyzes different types of concrete-filled steel tube columns to compare different parameters such as loading angle, eccentricity, different steel pipe thickness, different strength grades of concrete, different cross-sectional shapes, etc., and elaborates the changes of mechanical properties of the specimens under the influence of different parameters. The formulas of axial compression and flexural bearing capacity of different concrete-filled steel tube columns and the bearing capacity of concrete-filled steel filled steel tubes after fire were proposed, and the interaction of various materials in the components was studied in depth. The proposed studies are summarized.

Experimental investigation of heat-damaged reinforced concrete columns strengthened with different schemes

This paper experimentally investigates the efficacy of two jacketing techniques in the rehabilitation of square and circular reinforced concrete (RC) columns that were exposed to highly elevated temperatures. Twenty-four RC columns were tested under an axial compression load, which was divided into three groups. The first group consisted of the control specimens without applying any strengthening approach. Group 2 consisted of the columns with the strengthening configuration of near-surface-mounted (NSM) rebars and carbon fiber-reinforced polymer (CFRP) layers. Regarding the third group, columns were strengthened using two layers of welded-wire mesh (WWM) and ultra-high-performance fiber concrete (UHPFC) jacketing. Four columns from each group were subjected to an elevated temperature of 600 °C for a duration of 3 h, while the remaining half were subjected to room temperature. The results showed that after three hours at a temperature of 600 °C, both strengthening schemes successfully restored and exceeded the initial load-carrying capability of all columns. Utilizing WWM with UHPFC jacketing as new strengthening technique proved to be the most efficient method for reinstating the load-carrying capability of circular columns (+321.8 %) and square columns (+140.6 %) that were subjected to high temperatures. Additionally, an analytical model was proposed to estimate the ultimate load capacity of RC columns after rehabilitation.

Fire Performance of FRCM-Confined RC Columns: Experimental Investigation and Parametric Analysis

This study presents an experimental investigation of the fire response of six columns strengthened with polyparaphenylene benzobisoxazole (PBO) FRCM system, and tested in a large-scale furnace following ASTM E119 standards. The parameters investigated included the number of PBO-FRCM layers and the presence of a fireproofing insulation layer. Test results highlighted the effectiveness of PBO-FRCM in insulating the column, with the strengthened column showing a substantial 31.9% reduction in temperature readings at the concrete surface compared to its unstrengthened counterpart. Furthermore, the presence of Sikacrete 213F fireproofing system reduced temperature readings within the column's section by an average of 65%. Based on the experimental results, a parametric numerical study were developed and verified using ABAQUS software. The parameters studied included the number of PBO-FRCM layers (0, 1, and 2 layers), the presence of a 30 mm thick insulation layer, and the axial preloading taken as 40, 60, and 75% of the ultimate column's capacity. The model accurately predicted the temperature readings across the columns. Strengthening the columns with PBO-FRCM significantly increased their resistance during fire, doubling fire-resistance duration with one layer. Adding fireproof insulation led to significant increase in load resistance duration. The percentage drop in temperature after 1 hour of fire exposure was around 70% at the FRCM surface for the insulated column strengthened with one layer of FRCM. Higher preload percentages reduced both the fire-resistance duration and ductility of the columns. For the group of columns strengthened with one layer, increasing the preloading percentage to 60% and 75% resulted in decreases in the fire-resistance duration of 35% and 73%, respectively.

Axial compression behaviour of circular concrete-filled stainless-clad bimetallic steel tubular stub columns

The axial compression behaviour of circular concrete-filled stainless-clad bimetallic steel tubular (CFSCBST) stub columns is addressed in this paper by experimental and numerical investigations. A total of five specimens were fabricated and subjected to axial compression loading. The varying parameters in the experimental study included the clad ratio of steel tube, the diameter-to-thickness ratio and the strength of the concrete. A three-dimensional finite element (FE) model was developed and validated against both dependent and independent test data to further study the axial compressive behaviour of circular CFSCBST stub columns in this paper. The parametric studies considering five major parameters, including the strength of the concrete, the substrate steel grade, the clad ratio, the diameter-to-thickness ratio and different bonding conditions of the stainless-clad (SC) bimetallic steel, were carried out by using the verified FE model. The applicability of existing design codes to the circular CFSCBST stub columns was further analysed through comparisons with the numerical results. New design methods based on unified and superposition theory have been proposed herein, which have improved accuracy for predicting the ultimate compression capacity of such circular CFSCBST stub columns.

Experimental study on the compressive behavior of UHPC filled stainless steel tubes subjected to monotonic and cyclic loading

Ultra-High Performance Concrete Filled Stainless Steel Tubular (UHPCFSST) column is a novel type of composite columns appealing to be adopted in corrosive and marine environment. To explore the axial performance of UHPCFSST columns, this paper initiates an experimental program containing 14 UHPCFSST columns subjected to either monotonic or cyclical axial compressive loading. The test variables in this program mainly include the column dimension, tube thickness and the loading schemes. Based on the test results, the damage evolution process, ultimate failure mode, load-deformation response and the typical mechanical performance indexes inclusive of loading-carrying capacity, stiffness degradation, as well as ductility coefficient are thoroughly examined. After that, theoretical analysis is carried out to explore the interaction behavior between UHPC and stainless-steel tube and hence judge the degree of confinement effect. To assess the applicability of the code equations stipulated in current international design guidelines and the empirical formulas proposed by other researchers, a small-scale dataset containing 41 UHPCFSST columns was compiled to make comparison of axial capacity between test results and analytical predictions. In view of the limited accuracy or the burdensome calculation process, a new formula considering actual loading carrying mechanism was proposed to calculate the axial capacity of UHPCFSST columns, which exhibits enhanced accuracy and efficiency than the current formulas.

Evaluation of retrofitting effect of concrete filling in hollow RC columns using XFEM

Hollow RC columns are widely utilized in the construction of high piers in mountainous regions. Recently, precast hollow RC columns have been increasingly used to enhance transportability and ease of handling, aiding Accelerated Bridge Construction. This paper evaluated the effectiveness of concrete-filling retrofitting measures for hollow RC columns using eXtended Finite Element Method (X-FEM). Our focus was particularly on instances where original hollow sections and post-filled concrete sections don't behave as unified structures. The proposed X-FEM model's reliability was validated through simulations replicating compressive strength tests on molded concrete specimens and previous static loading tests on hollow RC columns conducted to evaluate the efficacy of concrete-filling retrofitting for hollow RC columns. The proposed X-FEM model successfully represents the compressive softening and fracture behavior of concrete under uniaxial compression. It also successfully replicated the lateral load capacity and the crack patterns of hollow RC columns observed in the previous experiments. When comparing the component ratios of bending and shear deformation of the columns, the shear deformation component of the hollow RC column retrofitted with the concrete filling was about 1.5 times larger than that of the solid RC column at each displacement. This result indicates that concrete-filling retrofitting might not enhance the shear capacity of hollow RC columns to the anticipated level in scenarios where the pre-existing hollow portion and the post-filled concrete portion fail to function as unified structures. Based on these findings, this study investigated the efficacy of anchor reinforcement in hollow RC columns filled with concrete to enhance the structural unity of existing and filled portions. The results indicate that anchor reinforcement improved the shear resistance properties by enhancing the structural unity between the pre-existing hollow portion and the post-filled concrete portion.

Axial compression performances and bearing capacity prediction of self-compacting fly ash concrete filled circle steel tube columns

To solve the problem of a large amount of fly ash accumulation and study the axial compression and bearing capacity prediction of the self-compacting fly ash concrete filled circle steel tube (SCCFST) columns, eight specimens are designed to explore the impact of concrete strength grade, internal structural measures, and additional parameters. The stress, progression of deformation, and failure mode of each specimen are observed during the loading process. The load–displacement curves, load-strain curves, characteristic load and displacement, ductility, and stiffness degradation are analyzed. The findings revealed that shear deformation occurred predominantly in the middle and upper portions of the steel tubes. Enhancing the strength of the concrete or adopting internal structural measures could increase the bearing capacity and ductility of the specimens. The peak load and ductility could be increased by up to 17.6 and 53.6%, respectively. The proposed unified calculation equation for the axial compression bearing capacity of SCCFST columns demonstrates notable reliability and precision. Furthermore, these tests offer valuable references for the engineering application of various forms of SCCFST columns, which are of significant importance in practical engineering.

Regression-classification ensemble machine learning model for loading capacity and bucking mode prediction of cold-formed steel built-up I-section columns

This paper presents a regression-classification ensemble machine learning (ML) model for loading capacity and, in particular, buckling mode prediction with respect to cold-formed steel (CFS) I-section columns. The ML model comprises two sub-models, including the regression sub-model for load capacity prediction and the classification sub-model for buckling mode prediction. A total of 541 experimental and numerical data for CFS built-up I-section columns with varies geometric dimensions, material properties and buckling modes were collected from the literature to construct a dataset. To improve the accuracy and the explainability of the ML model on relative small-scale dataset, physical information-enhanced features based on the knowledge of the direct strength method were adopted as the input features of the ML model, including the yield strength, the elastic local buckling load, the elastic distortional buckling load and the elastic global buckling load, instead of directly using the parameters of geometric dimensions and material properties as the input features. The appropriateness of seven classical machine learning algorithms was compared, namely Decision Tree (DT), Random Forest (RF), Support Vector Machine (SVM), K-Nearest Neighbour (KNN), Adaptive Boosting (ADA), Extreme Gradient Boosting (XG), and Categorical Boosting (CB). The statistical analysis showed that the XG algorithm had the highest level of accuracy for both loading capacity and buckling mode prediction. In addition, the explainability analysis indicated that the developed ML model successfully learned the mechanical characteristic of CFS built-up I-section columns. Finally, the developed ML model was further compared with the existing codified method in the literature. The comparison results indicated that the developed ML model can significantly improve the level of accuracy for loading capacity and buckling mode prediction, which provides a promising alternative choice for the design of CFS built-up I-section columns

An interpretable machine learning approach for predicting the capacity and failure mode of reinforced concrete columns

During seismic events, reinforced concrete (RC) columns play a crucial role in maintaining buildings’ structural integrity. This motivated engineers and practitioners to search for key parameters that influence the load-carrying capacity and failure mechanisms of such columns. However, the complexity and nonlinearity of seismic effects along with the intricate nature of RC columns as a composite system challenge the capabilities of analytical and empirical approaches to accurately capture the response of RC columns. Subsequently, the present study utilizes Machine Learning (ML) techniques to identify the failure modes and predict the corresponding capacities of RC columns based on both their geometrical and material properties. Decision trees and different ensemble methods were employed to predict both the columns’ failure mode and ultimate capacity. A multivariate dataset consisting of 486 cyclically loaded rectangular and circular columns was used to develop and validate the models. In addition, different embedded variable selection techniques were employed to evaluate the significance of input parameters in predicting the performance of columns. Moreover, partial dependence plots and accumulated local effects were employed to uncover the interrelationships between the input features and the modelled outputs. The developed models yielded an average accuracy of 90% and 95% for predicting the failure mode and ultimate capacity of RC columns, respectively. Given such high accuracy, it can be inferred that, ML techniques have the potential to provide efficient and reliable prediction tools to support seismic design and assessment decisions - mitigating seismic risks and empowering resilience planning in the face of extreme events.

Design of improved multi-cell L-shaped CFST columns under compression and bending

In recent years, there has been a notable surge in proposals for various forms of special-shaped concrete-filled steel tubular (CFST) columns. Despite various methods developed by researchers for determining the bearing capacity of multi-cell special-shaped CFST columns under different loading conditions, these methods remain lack unified. In this study, FE models were developed to simulate performances of improved multi-cell L-shaped CFST (ML-CFST) column under compression and bending. Parametric analyses have been performed to evaluate impact of various factors, including steel yield strength fy, compressive strength of concrete fcu, steel thickness t, loading direction θ, web height c, and axial load ratio n, on performances of ML-CFST columns. The findings of study indicate that the unidirectional flexural capacity of ML-CFST member exhibits a nearly linear relationship with the variables of t, fy, and c, with a minimal impact observed from fcu on flexural capacity. The width of extended section b, fcu, fy, and t have a certain effect on flexural capacity at any angle, particularly fy, t, and b. While fcu, fy, and t exert some influence on N/Nu-M/Mu correlation curves, their influences are marginal compared to the loading direction, which is the predominant influencing factor. Additionally, Mx0/Mπ/4-My0/M3π/4 curves gradually protrude outward with the increase in n. The effects of t, fy, and fcu on the shape of Mx0/Mπ/4-My0/M3π/4 curve were relatively insignificant. Simplified unidirectional flexural capacity calculation models were proposed based on stress analysis of cross-section under ultimate states. Given that flexural capacities estimated by simplified calculation model are slightly conservative, it is recommended to increase the flexural capacities by 10 %. Furthermore, an elliptical equation was formulated to predict the flexural capacity at any angle, with the predictions being slightly conservative. Based on ultimate equilibrium theory, a simplified calculation method was presented to predict unidirectional eccentric bearing capacities of ML-CFST columns. Through regression analysis, a simplified calculation method expressed as polar coordinate form for biaxial eccentric bearing capacity was established, with calculated values aligning well with FE results.

Monomer-mediated growth of β-cyclodextrin-based microporous organic network as stationary phase for capillary electrochromatography.

CD-MONs (β-cyclodextrin-based microporous organic networks), derived from β-cyclodextrin, possess notable hydrophobic characteristics, a considerable specific surface area, and remarkable stability, rendering them highly advantageous in separation science. This research aimed to investigate the utility of CD-MONs in chromatography separation. Through a monomer-mediated technique, we fabricated an innovative CD-MON modified capillary column for application in open-tubular capillary electrochromatography (OT-CEC). The CD-MON-based stationary phase on the capillary's inner surface was analyzed using Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). We assessed the performance of the CD-MON modified capillary column for separation purposes. The microstructure and pronounced hydrophobicity of CD-MON contributed to enhanced selectivity and resolution in separating diverse hydrophobic analytes, such as alkylbenzenes, halogenated benzenes, parabens, and polycyclic aromatic hydrocarbons (PAHs). The maximum column efficiency achieved was 1.5 × 105 N/m. Additionally, the CD-MON modified capillary column demonstrated notably high column capacity, with a methylbenzene mass loading capacity of up to 197.9pmol, surpassing that of previously reported porous-material-based capillaries. Furthermore, this self-constructed column was effectively utilized for PAHs determination in actual environmental water samples, exhibiting spiked recoveries ranging from 93.2 to 107.9% in lake water samples. These findings underscore the potential of CD-MON as an effective stationary phase in separation science.

Experimental and numerical investigation of bias performance of steel fiber-reinforced GRC-CFFT columns

Geopolymer concrete-filled glass fiber-reinforced polymer (GFRP) tube columns show significant potential in marine engineering due to their excellent durability and mechanical properties. This study investigated the bias performance of steel fiber-reinforced geopolymer recycled aggregate concrete-filled GFRP tube (SGRC-CFFT) columns, considering variables such as load eccentricity, GFRP tube thickness, fiber winding angle, and recycled coarse aggregate (RCA) replacement rate. The failure modes, load-displacement behaviors, and strain distribution were analyzed and discussed. Furthermore, a high-precision finite element model was established based on the test data. The test results indicated that increasing load eccentricity significantly reduced both the load-bearing and axial deformation capacity of CFFT columns. When the load eccentricity reached 0.40, the peak load of the specimen was only 39 % of that of the corresponding axial compression specimen. A higher RCA replacement rate would cause a more pronounced reduction in bias-bearing capacity, with a maximum decrease of 24.6 %. Before 80 % of the peak load, the axial deformation of the column mid-span section accorded to the plane section assumption. Due to the eccentric load, the hoop deformation of the CFFT column was concentrated on the compression side. The fiber winding angle was the critical factor influencing both the peak load and the peak moment of the biased SGRC-CFFT column.

Target-specific affinity separation of the bioactive compounds from herbal extract using the spin column packed with the immobilized protein microspheres prior to LC-MS analysis

Excellent pretreatments before instrumental analysis are critical for separation and determination of target compounds for discovery of new drugs from herb medicines. We developed a rapid and highly-selective method to separate the bioactive compounds from herbal extract using protein affinity-selection spin column, which was packed with the new sorbent materials from integrating the recombinant β2-adrenoceptor (β2-AR) directly out of cell lysates onto the surface of microspheres. Protein affinity-selection spin column was placed in a centrifugal tube, where after the non-specific binders were released to the filtrate under the operational centrifugation, the specific binders on the spin column were cleaned with a washing solvent for LC-MS analysis. The known agonists of β2-AR were retained/released on protein affinity-selection spin column but not on control column, demonstrating the method with good recovery (79.4∼95.7 %) and high repeatability (RSD < 3.5 %). The adsorption features of three ligands on the spin column were described best by Prism saturation binding model, and the high-affinity binding and the large binding capacity of the spin column make it feasible to trap the trace analytes effectively. It was applied in separating bioactive compounds from Alstoniae Scholaris extract, two of which were identified as picrinine and oleanolic acid in combination with LC-MS and verified as the potential agonists towards β2-AR though molecular docking and cell experiments. Our study demonstrated that, the spin column with the immobilized protein sorbents in the centrifugal filter device represents a promising tool, enabling rapid and target-specific affinity separation of the bioactive compounds from herbal extract.