Nonlinear finite element analysis of circular concrete-filled steel tube structures

Xu, Tengfei,Xiang, Tianyu,Zhao, Renda,Zhan, Yulin Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.3

The structural behaviors of circular concrete filled steel tube (CFT) structures are investigated by nonlinear finite element method. An efficient three-dimensional (3D) degenerated beam element is adopted. Based on those previous studies, a modified stress-strain relationship for confined concrete which introduces the influence of eccentricity on confining stress is presented. Updated Lagrange formulation is used to consider the geometrical nonlinearity induced by large deformation effect. The nonlinear behaviors of CFT structures are investigated, and the accuracy of the proposed constitutive model for confined concrete is mainly concerned. The results demonstrate that the confining effect in CFT elements subjected to combining action of axial force and bending moment is far sophisticated than that in axial loaded columns, and an appropriate evaluation about this effect may be important for nonlinear numerical simulation of CFT structures.

Failure Mode of Orthotropic Two-way Composite Slab under Concentrated Load

Yulin Zhan,Wenfeng Huang,Yu Qiao,Zhouyuan Xu,Renda Zhao 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.12

Ordinary reinforced concrete two-way slabs generally suffer from punching failure under concentrated loads, which is a brittle failure and unfavorable to the structures. The composite slabs with steel sheets and PBL (perfobond rib) shear connectors have been applied for reducing the damage to bridge decks from vehicles. Although it is widely used on bridges, the failure mode of the orthotropic two-way composite slabs has rarely been studied when subject to concentrated loads. Accordingly, static loading tests with concentrated forward central load was carried out on 4 two-way composite slabs, in which the effects of the thickness of steel bottom sheets and concrete plates and spacing of PBL shear connectors on mechanical properties were investigated. The test results show that about 12% of the ultimate bearing capacity decreases when the perfobond ribs are spaced farther apart from 180 mm to 240 mm or the thickness of steel bottom sheets is reduced from 10 mm to 8 mm. And the bearing capacity drops by 38.2% when the thickness of concrete plates decreases by 30 mm. The steel-concrete composite slabs exhibit clear bidirectional force characteristics during the loading process, with the main forced direction being along the perfobond ribs, which is related to the stiffness ratio of the two directions. The two-way composite slabs have high bearing capacity and ductility, with obvious signs before failure. The specimens continue to bear the load after local punching failure of concrete near the loading point, which shows the features of both bending and punching failure. Based on the test results, a bending punching failure mode is proposed, which provides a new approach for the calculation of ultimate bearing capacity. An analytical calculation method for ultimate bearing capacity of orthotropic two-way composite slabs based on the failure mode above is derived with yield line theory and plastic theory, which is in excellent agreement with the tested results.

遼東半島石棚之硏究

許玉林 원광대학교 마한백제문화연구소 1993 馬韓, 百濟文化 Vol.13 No.-

Nonlinear finite element analysis of circular concrete-filled steel tube structures

Tengfei Xu,Tianyu Xiang,Renda Zhao,Yulin Zhan 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.3

The structural behaviors of circular concrete filled steel tube (CFT) structures are investigated by nonlinear finite element method. An efficient three-dimensional (3D) degenerated beam element is adopted. Based on those previous studies, a modified stress-strain relationship for confined concrete which introduces the influence of eccentricity on confining stress is presented. Updated Lagrange formulation is used to consider the geometrical nonlinearity induced by large deformation effect. The nonlinear behaviors of CFT structures are investigated, and the accuracy of the proposed constitutive model for confined concrete is mainly concerned. The results demonstrate that the confining effect in CFT elements subjected to combining action of axial force and bending moment is far sophisticated than that in axial loaded columns, and an appropriate evaluation about this effect may be important for nonlinear numerical simulation of CFT structures.

Superior performance of K/Co2AlO4 catalysts for the oxidative dehydrogenation of ethylbenzene to styrene with N2O as an oxidant

Zhiying Liu,Yulin Li,Xiaohui Sun,Zhuyin Sui,Xiufeng Xu 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.112 No.-

This study explored the feasibility of coupling N2O decomposition with ethylbenzene (EB) oxidativedehydrogenation, as an alternative approach for greenhouse gas elimination and styrene (ST) production,on the Co-Al mixed oxides and K-modified catalysts. It was found that N2O could decompose completelyover the K/Co2AlO4 catalyst, accompanied with 62.0% of EB conversion and 85.1% of styrene selectivity,which were much better than the existing catalyst systems for EB oxidative dehydrogenation. Characterization results showed that despite the decreased specific surface area of the catalysts withincreasing the Co/Al molar ratio, the improved reducibility, the reduced acid properties as well as thehigher ratio of Co3+/Co2+ were responsible for the enhanced performance. The K modification not onlychanged the electronic properties of active metal, resulting from the charge transfer from K cation tothe Co species, but also weakened the binding energy of Co3+-O, leading to the complete decompositionof N2O. Furthermore, the optimized strong acid properties inhibited the dealkylation or ring-openingreactions and significantly reduced the coke deposition on the catalyst surface, thus improving the STselectivity.

Modification of hollow BiOCl/TiO2 nanotubes with phosphoric acid to enhance their photocatalytic performance

Guozhe Sui,Yulin Zhang,Jinlong Li,Yan Zhuang,Dongxuan Guo,Ze Luo,Rongping Xu,Shuang Liang,Hong Yao,Chao Wang 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.4

Organic pollutants in dyed wastewater are hazardous to human health and the environment. The photocatalyticdegradation of pollutants is considered a green treatment with significant social and environmental benefits. Inthis study, hollow BiOCl/TiO2 nanotubes with open pores at both ends, prepared by hydrothermal synthesis, weremodified using phosphoric acid to promote photoelectron transfer. The hollow nanotubes offer an increased numberof electroactive sites, which enhances the photoelectric transfer efficiency and reduces the electron-hole recombinationrate. The modification by H3PO4 significantly optimized the photocatalytic activity of the nanotubes. The results showthat the H3PO4 modified hollow BiOCl/TiO2 (molar ratio of BiOCl to TiO2 is 0.8) nanotubes exhibited the most efficientphotocatalytic performance toward rhodamine B (RhB) with a photodegradation efficiency of up to 98.8% undervisible-light illumination. These nanotubes have broad application prospects for the effective removal of organic pollutantsfrom wastewater and can potentially inform future research on photocatalysts.

Enhanced electrochemical performances of LiNi0.5Co0.2Mn0.3O2 cathode material co-coated by graphene/TiO2

Dang Mengyue,Li Ying,Xu Chaoxiang,He Yulin,Yu Chunpeng,Liu Wenbo,Jin Hongming,Zhu Mingyuan,Zhang Jiujun,Li Wenxian 한국물리학회 2021 Current Applied Physics Vol.32 No.-

The electrochemical performances of LiNi0.5Co0.2Mn0.3O2 (NCM523) layered cathode material, such as poor rate capacity and cycling stability caused by undesirable intrinsic conductivity and low rate of lithium ion transportation, are not fairly good especially at elevated rate and cut-off voltage. To improve these properties, in this study, the co-coating layer of graphene and TiO2 was constructed on NCM523 surface. The graphene/TiO2 coating layer could effectively prevent hydrofluoric acid (HF) attacks, suppress the side reaction, accelerate the lithium ion diffusion and facilitate the electron migration. The enhancement of cycle performance and rate capacity was contributed to the uniform co-modified surface, interacting each other and thus exhibiting synergistic effects.

Role of Estrogen Receptor-α in the Regulation of Claudin-6 Expression in Breast Cancer Cells

Liu Yafang,Wu Qiong,Ren Yue,Xu Xiaoming,Yu Lina,Zhang Mingzi,Zhang Ting,Li Yulin,Quan Chengshi 한국유방암학회 2011 Journal of breast cancer Vol.14 No.1

Purpose: In our previous studies we showed that upregulating claudin-6 (CLDN6) expression may contribute to preventing breast cancer, and that 17β-estradiol induces a concentration- and time-related effect on CLDN6 mRNA and protein expression in MCF-7 cells. However, the mechanisms of 17β-estradiol regulation of CLDN6 are still unclear. We determined the role of estrogen receptors in the regulation of CLDN6 expression in human breast cancer tissues and a cell line. Methods: CLDN6, estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ) expression in breast cancer tissues were examined using immunohistochemistry. The human breast cancer cell line, MCF-7, which expresses ERα but not ERβ was used. CLDN6 and ERα expression were measured by reverse transcriptase-PCR, Western blotting and immunofluorescent staining. Treatments with propyl pyrazole triol (PPT) and ICI 182, 780 (ICI) were performed. Results: The results revealed that CLDN6 expression was related to ERα in breast cancer tissues (p=0.033). PPT, an ERα-selective ligand, upregulated CLDN6 expression at 10^(-5) mol/L after 24 hours. The effect of PPT on regulating CLDN6 expression in MCF-7 cells was blocked by ICI. Conclusion: These findings suggest that Erα reulates CLDN6 expression in breast cancer tissues and that 17β- estradiol induces CLDN6 expression through an ERα pathway in MCF-7 cells.

Adaptive flow optimization of a turbocharger compressor to improve engine low speed performance

Yangjun Zhang,Chenfang Wang,Zheng Xinqian,Weilin Zhuge,Yulin Wu,Jianzhong Xu 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.6

To improve the engine overall performance, an adaptive flow optimization procedure is proposed in this paper to synthesize turbocharger compressor optimum designs. Two objective functions are involved in the adaptive optimization. They are the traditional compressor design and the compressor design with consideration of improving engine overall performance. The two-step decomposition approach is chosen to generate optimum designs. The optimized designs not only satisfy turbomachinery and engine constraints but also have optimum objective function values in the two fields. Performance sensitivity analysis of compressor main design variables is performed for the flow optimization design process. A centrifugal compressor is redesigned for a turbocharged gasoline engine, as an example, based on the adaptive flow optimization process. The calculating results show a more than 5% increase of isentropic efficiency in comparison with the base line compressor, resulting in a more than 19% increase of engine torque at low speed conditions.

In Situ Fabrication of TiO2/Bi3.64Mo0.36O6.55 Nanocomposite with High Visible-Light-Driven Photocatalytic Efficiency

Zhiyuan Yang,Junjie Wang,Lu Chen,Mengjun Liang,Yulin Xu,Chentao Zou,Xiaoxia Liu,Shuijin Yang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.5

In this work, we developed a simple hydrothermal method toward the fabrication of TiO2/ Bi3.64Mo0.36O6.55 heterostructure, which had superior photocatalytic performance for degrading of RhB under visible light irradiation. The as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), high-resolution transmission electron microscopy (HRTEM), UV-Vis diffuse reflectance spectroscopy (DRS) and photoelectrochemical measurements. The optimal composite with 15 wt.% TiO2/Bi3.64Mo0.36O6.55 (TBMO3) exhibits a much higher photocatalytic activity than that of Bi3.64Mo0.36O6.55 and P25 by degradation of RhB under visible light irradiation within 20 min. The enhanced performance of TBMO3 is predominantly attributed to the synergistic effect both in the higher surface area and the improved separation of photogenerated charge carriers between the two semiconductors. Recycling experiments indicated that TiO2/Bi3.64Mo0.36O6.55 photocatalysts had excellent cycle performance and stability. The photocatalytic mechanism of nanocomposite photocatalysts was proposed, which is confirmed by the active species trapping experiments and photoluminescence tests.