Experimental research on free vibration of curved composite box-girders with corrugated steel webs

Yunsheng Li,Qingnian Dai,Chaoxing Liu,Yanling Zhang 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.41 No.1

The curved composite box-girders (CBGs) with corrugated steel webs (CSWs) have been used widely in bridges due to their great advantages and the demand of the road alignment, but the curvature makes both the static and dynamic behaviors more complex. To research the free vibration performance of the curved CBGs with CSWs, 5 simply-supported test girders were designed with the span-to-radius ratio (λ=L/R), the number of the cells of the box section, and the number of the diaphragms as parameters. The natural frequencies and mode shapes were measured in the experiment. The experimental results were compared with the numerical results using ANSYS software, and a satisfying agreement was obtained. The parametric analysis shows that for the curved CBG with CSWs, the vertical mode shapes are combined flexural and torsion, and the contribution of the torsional effects to the mode shapes and frequencies improve with the increase of λ, which leads to a decrease in the vertical and lateral frequencies and increase in the torsional frequency. The corrugated angle of the steel web has little effect on the natural frequencies of the curved CBGs with CSWs. Increasing the thickness of the steel web and the number of the diaphragms can improve the torsional rigidity of the curved CBG with CSWs effectively; while the deck width has a great contribution on the lateral rigidity.

LANE KEEPING CONTROL BASED ON MODEL PREDICTIVE CONTROL UNDER REGION OF INTEREST PREDICTION CONSIDERING VEHICLE MOTION STATES

Zeng Li,Gaojian Cui,Shaosong Li,Niaona Zhang,Yunsheng Tian,Xiaoqiang Shang 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.4

To address the failure to consider vehicle states in region of interest (ROI) prediction, we propose the use of a Kalman filter to estimate the position of vehicles relative to lanes by vehicle states on the basis of a vehicle–road micro traffic model in the world coordinate system. The central position of the ROI is determined through a combination of optimal preview time theory with the ROI prediction. The range of the ROI is determined by offsetting upward, downward, leftward, and rightward from the central position of the ROI. The left and right ROI are processed separately to detect lane lines. Simulation results show that the proposed prediction method reduces the ROI range, and the model predictive control controller can make the vehicle run smoothly from the initial position to the road centerline.

Study on the Flexural Performance of Prestressed Concrete Solid Square Piles and Resilient Clamping Connections

Yunsheng Xu,Zhongfan Chen,Ji Fan,Zhiqiang Li,Kai Zhang,Xuesong Tu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.1

The length of a single prestressed square pile is usually between 6 and 15 meters. For square piles larger than 15 meters, increasing the pile length is generally achieved by a mechanical connection. Currently, the longitudinal reinforcement ratios of square piles are the same, resulting in steel waste. To reduce steel usage in prestressed concrete solid square piles and improve construction efficiency, the safe and reliable use of two different reinforced square piles connected by resilient clamping must be ensured. In this paper, the bending test of a single square pile with different reinforcements is initially carried out. Then, the tensile performance of the resilient clamping connection joint is verified, and finally, a bending test is carried out on prestressed square piles with different reinforcements. The load?displacement curves, flexural bearing capacities and crack developments of the components are studied. The test results show that increasing the longitudinal reinforcement ratio of a single prestressed concrete solid square pile improves its crack and bending resistance to a certain extent. Resilient clamping connects the prestressed square piles with the same reinforcement and different reinforcements, and their crack resistance and bending resistance are almost the same, which demonstrates that the resilient clamping connection of different reinforcement square piles has application value. At the end of the test, the joints were intact, and the pile body was damaged before the resilient clamping connections, which indicated that the resilient clamping connections were safe and reliable and could be used as connecting joints for square piles. The failure of square piles goes through three stages: an elastic stage, a working stage with cracks and a failure stage. Compared with a single square pile, there is no obvious yield stage for a resilient clamping connected square pile.

Preparation, Properties and Microstructure of Fly Ash Based Geopolymer Concrete

Zongjin Li,Zhang Yunsheng,Sun Wei 단국대 부설 리모델링연구소 2005 리모델링 연구소 논문집 Vol.3 No.2

In this paper, fly ash was investigated as a basic Si-Al ingredient of geopolymer. Based on compressive and flexural strength, the replacement percentage of fly ash and 3 types of curing regimes were studied to obtain the optimum synthesis condition. The results showed that geopolymer containing 30% fly ash that was prepared at 80˚C for 8 hours, exhibited high mechanical strength. The compressive and flexural strength of the fly ash based geopolymer were 32.2 and 7.15MPa, respectively. In order to investigate the durability behavior of fly ash based geopolymer concrete, CI permeability, freeze-thaw tests were also carried out. The measured results indicated that fly ash based gopolymer concrete had 2.63 times lower coefficient of chloride-ion diffusion and could withdraw 2.2 times more freeze-thaw cycles as compared to Portland concrete with the same compressive strength.

SPATIAL-BASED PREDICTIVE CONTROL FOR VEHICLE COLLISION AVOIDANCE BY STEERING MANEUVERS

Shaosong Li,Yunsheng Tian,Xiaofeng Yue,Niaona Zhang,Shujun Wang 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.1

A hierarchical vehicle collision avoidance control method based on model predictive control is presented in this study. In the upper level of the controller, a spatial-based two-degree-of-freedom vehicle model is used for dynamic path planning to decrease the computational burden of the algorithm. Obstacles and road boundaries are translated into spatialbased constraints on system states. An objective function that considers tire adhesion margin is introduced to the path tracking controller to enhance vehicle safety. Meanwhile, the dynamic constraints of vehicle lateral acceleration, sideslip, and tire slip angles are designed in accordance with the tire-road adhesion coefficient. A time-based nonlinear model predictive controller is also designed and compared with the proposed method to verify the effectiveness and superiority of the latter. Theoretical analyses and simulation results indicate that the proposed collision avoidance control system has good ollision avoidance effect.

Crystallization Kinetics of PVDF Filled with Multi Wall Carbon Nanotubes Modified by Amphiphilic Ionic Liquid

Ali Bahader,Yunsheng Ding,Haoguan Gui,Yu Li,Pei Xu 한국고분자학회 2015 Macromolecular Research Vol.23 No.3

The special electric properties of the poly(vinylidene fluoride) (PVDF) is strongly dependent on its crystallinestructural morphology. In this study, modification in the crystal structure of PVDF was achieved by utilizingthe long alkyl chain ionic liquid (1-hexadecyl-3-methylimidazolium bromide, [C16mim][Br]) and ionic liquid modifiedmultiwalled carbon nanotubes (MWCNT). The developed crystal pattern was analyzed by XRD and the compatibilityand dispersion characteristics of MWCNT in the matrix was observed by FESEM. The isothermal and non-isothermalcrystallization kinetics were studied by DSC and different models namely; Avrami, Jeziorny and Ozawa were appliedto fit the data. The results demonstrate that crystal structure of PVDF is significantly changed and the dispersion ofMWCNT was enhanced with the addition of ionic liquid (IL). Kinetically, the crystallization was influenced andbecame fast due to the presence of [C16mim][Br] at the PVDF/MWCNT interface. Furthermore, the data well fittedin the model with significant linearity. The positive effect on the crystallization of PVDF may be ascribed to not onlydue to the existence of π-cation interaction between the imidazolium cation and the aromatic multiwall carbon nanotubesstructure, but also due to the electrostatic interaction between the > CF2 of the polymer backbone and imidazoliumcation, which speed up the crystallization kinetics.

Ultrafast liquid chromatographytandem mass spectrometry determination of donepezil in human plasma: application to a bioequivalence study

Yan-Wen Huang,Li Ding,Yuan-Ming Chen,Wei-chen Lin,Fei Lin,Yunsheng Hsieh 대한임상약리학회 2022 Translational and Clinical Pharmacology Vol.30 No.1

A liquid chromatography equipped with tandem mass spectrometric method using multistage flow rates was developed for the determination of donepezil in human plasma to support a randomized, crossover bioequivalence (BE) study in which healthy volunteers each received a single oral dose of the reference and test formulations of 10 mg donepezil hydrochloride. This integrated liquid chromatography with tandem mass spectrometry (LC-MS/MS) system with electrospray ionization and a deuterium-labeled internal standard (IS) were employed for the positive multiple-reaction-monitoring (MRM) analyses. The baseline separation using a high-resolution monolithic column under gradient and flexible flowrate conditions between donepezil and multiple interfering peaks from the extracted quality control, calibration standard and study plasma samples following simple protein precipitation extraction procedures was accomplished within 1.5 minutes. The ultrafast monolithic column performance in terms of chromatographic separation efficiency, peak asymmetry and resolution and retention time reproducibility was found to be sustainable. The linear dynamic range was detected over a concentration range of 0.2–50 ng/mL. The intra- and inter-day assay accuracy and precision were within 15% for the analyte in individual biological fluids. A positive correlation coefficient (r) greater than 0.995 for donepezil concentrations in study plasma samplers measured by the proposed and the other validated LC-MS/MS methods in support of a bioequivalence study was observed.

A New Practical System for Evaluating the Pharmacological Properties of Uricase as a Potential Drug for Hyperuricemia

Juan Feng,Xiang Li,Xiaolan Yang,Chun Zhang,Yonghua Yuan,Jun Pu,Yunsheng Zhao,Yanling Xie,Huidong Yuan,Youquan Bu,Fei Liao 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.11

The use of uricase-deficient mammals to screen formulations of engineered uricases as potential drugs for hyperuricemia involves heavy costs and presents a technical bottleneck. Herein, a new practical system was investigated to evaluate the pharmacological significance of a bacterial uricase based on its ability to eliminate uric acid in plasma in vitro, its pharmacokinetics in vivo in healthy rats, and the modeled pharmacodynamics in vivo. This uricase, before and after modification with the monomethyl ether of poly(ethylene glycol)-5000, effectively eliminated uric acid in vitro in rabbit plasma, but its action was susceptible to xanthine inhibition. After intravenous injection of the modified uricase without purification, a bi-exponential model fit well to uricase activities in vivo in the plasma of healthy rats; the half-life of the modified uricase was estimated without interference from the unmodified uricase leftover in the sample and was nearly 100-fold longer than that of the unmodified uricase. Using a model of the elimination of uric acid in vivo taking into account of uricase pharmacokinetics and xanthine inhibition, modeled pharmacodynamics supported that the half-life of uricase and its susceptibility to xanthine are crucial for the pharmacological significance of uricase. Hence,this practical system is desirable for doing preliminary screening of formulations of engineered uricases as potential drugs for hyperuricemia.

Influence of Initial Damage Degree on the Degradation of Concrete Under Sulfate Attack and Wetting–Drying Cycles

Yujing Lv,Wenhua Zhang,Fan Wu,Huang Li,Yunsheng Zhang,Guodong Xu 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.5

The previous researches on the degradation process of concrete under sulfate attack mainly focus on non-damaged concrete. It may lead to an excessive evaluation of the durability of the structure, which is detrimental to the safety of the structure. In this paper, three different damage degrees of concrete specimens with non-damaged (D0) and initial damage of 10% (D₁) and 20% (D₂) were prefabricated and subjected to sulfate attack and wetting–drying cycles. With the increase of sulfate attack cycles (0, 30, 60, 90, 120, 150 cycles), the changes in mass loss, relative dynamic modulus of elasticity, and the stress–strain curve were studied. The results show that the mass of the D0 specimen had been increasing continuously before 150 sulfate attack cycles. The mass of D₁ and D₂ had been increasing before 60 cycles, and decreasing after 60 cycles. At 150 cycles, the mass loss of D0, D₁, D₂ were − 1.054%, 0.29% and 3.20%, respectively. The relative dynamic modulus of elasticity (RDME) of D0 specimen increases continuously before 90 sulfate attack cycles. After 90 cycles, the RDME gradually decreases. However, for D₁ and D₂ specimens, the RDME began to decrease after 30 cycles. The damage degree has an obvious influence on the compressive strength and elastic modulus. For the D0 specimen, the compressive strength and elastic modulus increased continuously before 90 cycles and decreased after 90 cycles. The compressive strength and elastic modulus of D₁ and D₂ specimens began to decrease after 30 cycles. The stress–strain curves of concrete with different initial damage degrees were established, and the fitting results were good. Finally, based on the analysis of experimental data, the degradation mechanism of concrete with initial damage under the sulfate wetting–drying cycle was discussed.

Novel designs of polycarboxylate superplasticizers for improving resistance in clay-contaminated concrete

Xiao Liu,Jianan Guan,Guanghong Lai,Yunsheng Zheng,Ziming Wang,Suping Cui,Mingzhang Lan,Huiqun Li 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.55 No.-

Certain clays attached around the aggregates contaminate the concrete and also greatly affect the concrete workability, the mechanism of which was investigated through calculating the volume change of solid and liquid phases of concrete mixture containing clay. To minimize this detrimental effect, two novel designs based on the transfer of theory and techniques from polymer science, i.e., molecular design of polycarboxylate superplasticizer (PCE), were proposed. The one was “intercalator” synthesized via Hofmann rearrangement and cationization, and the other was “star-shaped polycarboxylate super- plasticizer (SPCE)” synthesized via a route of “core first and arm second”. The results of Infrared Spectroscopy (IR) and 1H Nuclear Magnetic Resonance (1H NMR) confirm the designed structures. The applications of these polymers in clay-contaminated cement paste and concrete were tested. The results showed that, the dispersing capacities of “Intercalator + Comb-shaped polycarboxylate superplasticizer (CPCE)” and SPCE were less affected by adding clay in both cement paste and concrete. Adsorption and Xray diffraction (XRD) experiments revealed less harmful intercalation for SPCE and preferential occupation in the interlayer space of clay for intercalator to protect other workable PCEs. It is interesting that optimizing charge characteristic and “disassembling-assembling” molecular arrangement can contribute to excellent resistance towards clay. The aim of this study is to offer two promising alternatives, which attractively provide the theoretical basis and technological application in researching advanced materials in clay-contaminated concrete.