Application of Steel-tubed Concrete Structures in High-rise Buildings

Zhou, Xuhong,Liu, Jiepeng Council on Tall Building and Urban Habitat Korea 2019 International journal of high-rise buildings Vol.8 No.3

Making full use of material strength, maintaining sufficient ductility of structural components, and ensuring simple and robust connections are crucial to the development of steel-concrete composite structures. The steel-tubed concrete structure uses thin-walled steel tube to provide confinement, so that the strength and ductility of the concrete core are improved. Meanwhile, the thin-walled steel tube is terminated at the beam-column joint to avoid the local buckling problem and simplify the connections between steel tube and RC members. A brief overview of the development of steel-tubed concrete structures is presented. Through the discussion on the structural behavior of steel-tubed concrete and the introduction of typical practical projects, the prospects for future research are highlighted.

Comparison of Lisianthus (Eustoma grandiflorum) Cultivars Based on the Selected Regeneration Media Using Anther Culture

Xuhong Zhou,Xijun Mo,Suping Qu,Min Tian,Xue Wei Wu,Min Wu,Jinze Li,Ying Luo,Jihua Wang,Min Gui 한국원예학회 2014 Horticulture, Environment, and Biotechnology Vol.55 No.2

Double haploids in lisianthus cultivars were produced using anther culture. The anther of ‘Art Peach’ wascultured on the Murashige and Skoog (MS) medium with 3% sucrose with auxin and cytokinin. The highest frequencyof calli developed from anthers (100%) and green plantlets per 100 calli (60 regenerants) was observed on the mediumcontaining 8 mg・L-1 N6-benzyladenine (BA) and 0.1 mg・L-1 naphthaleneacetic acids (NAA). When anthers were culturedon the medium supplemented with 2 mg・L-1 BA and 0.5 mg・L-1 NAA, 33.3% of calli formed plantlets. Using theanther culture, callus induction and plantlets regeneration in five cultivars were developed differently, suggesting thatthe genotype might predetermined anther culture response. These results indicate that a highly efficient new microprogationtechnique can be provided by anther culture in vitro for lisianthus. Anther culture in vitro can provide a highly efficientnew microprogation technique for lisianthus.

Numerical simulation approach for structural capacity of corroded reinforced concrete bridge

Zhou, Xuhong,Tu, Xi,Chen, Airong,Wang, Yuqian Techno-Press 2019 Advances in concrete construction Vol.7 No.1

A comprehensive assessing approach for durability of reinforced concrete structures dealing with the corrosion process of rebar subjected to the attack of aggressive agent from environment was proposed in this paper. Corrosion of rebar was suggested in the form of combination of global corrosion and pitting. Firstly, for the purposed of considering the influence of rebar's radius, a type of Plane Corrosion Model (PCM) based on uniform corrosion of rebar was introduced. By means of FE simulation approach, global corrosion process of rebar regarding PCM and LCM (Linear Corrosion Model) was regressed and compared according to the data from Laboratoire $Mat{\acute{e}}riaux$ et $Durabilit{\acute{e}}$ des Constructions (LMDC). Secondly, pitting factor model of rebar in general descend law with corrosion degree was introduced in terms of existing experimental data. Finally, with the comprehensive numerical simulation, the durability of an existing arch bridge was studied in depth in deterministic way, including diffusion process and sectional strength of typical cross section of arch, crossbeam and deck slab. Evolution of structural capacity considering life-cycle rehabilitation strategy indicated the degradation law of durability of reinforced arch bridges.

Shear behavior of short square tubed steel reinforced concrete columns with high-strength concrete

Xiang Li,Xuhong Zhou,Jiepeng Liu,Xuanding Wang 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.32 No.3

Six shear-critical square tubed steel reinforced concrete (TSRC) columns using the high-strength concrete (fcu,150 = 86.6MPa) were tested under constant axial and lateral cyclic loads. The height-to-depth ratio of the short column specimens was specified as 2.6, and the axial load ratio and the number of shear studs on the steel shape were considered as two main parameters. The shear failure mode of short square TSRC columns was observed from the test. The steel tube with diagonal stiffener plates provided effective confinement to the concrete core, while welding shear studs on the steel section appeared not significantly enhancing the seismic behavior of short square TRSC columns. Specimens with higher axial load ratio showed higher lateral stiffness and shear strength but worse ductility. A modified ACI design method is proposed to calculate the nominal shear strength, which agrees well with the test database containing ten short square TSRC columns with shear failure mode from this study and other related literature.

Axial load behavior and stability strength of circular tubed steel reinforced concrete (SRC) columns

Biao Yan,Jiepeng Liu,Xuhong Zhou 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.25 No.5

The tubed steel reinforced concrete (SRC) column is a composite column in which the outer steel tube is mainly used to provide confinement on the core concrete. This paper presents experimental and analytical studies on the behavior of circular tubed SRC (TSRC) columns subjected to axial compression. Eight circular TSRC columns were tested to investigate the effects of length-to-diameter ratio (L/D) of the specimens, diameter-to-thickness ratio (D/t) of the steel tubes, and use of stud shear connectors on the steel sections. Elastic-plastic analysis on the steel tubes was used to investigate the mechanism of confinement on the core concrete. The test results indicated that the tube confinement increased the strength and deformation capacity for both short and slender columns, and the effects on strength were more pronounced for short columns. A nonlinear finite element (FE) model was developed using ABAQUS, in which the nonlinear material behavior and initial geometric imperfection were included. Good agreement was achieved between the predicted results using the FE model and the test results. The test and FE results were compared with the predicted strengths calculated by Eurocode 4 and the AISC Standard. Based on the analytical results, a new design method for this composite column was proposed.

Numerical study of ITZ contribution on diffusion of chloride and induced rebar corrosion: A discussion of three-dimensional multiscale approach

Xi Tu,Cunjun Pang,Xuhong Zhou,Airong Chen 사단법인 한국계산역학회 2019 Computers and Concrete, An International Journal Vol.23 No.1

Modeling approach for mesoscopic model of concrete depicting mass transportation and physicochemical reaction is important since there is growing demand for accuracy and computational efficiency of numerical simulation. Mesoscopic numerical simulation considering binder, aggregate and interfacial transition zone (ITZ) generally produces huge number of DOFs, which is inapplicable for full structure. In this paper, a three-dimensional multiscale approach describing three-phase structure of concrete was discussed numerically. An effective approach generating random aggregate in polygon based on checking centroid distance and intersection of line segment was introduced. Moreover, ITZ elements were built by parallel expanding the surface of aggregates on inner side. By combining mesoscopic model including full-graded aggregate and macroscopic model, cases related to diffusivity and thickness of ITZ, volume fraction and grade of aggregate were studied regarding the consideration of multiscale compensation. Result clearly showed that larger analysis model in multiscale model expanded the diffusion space of chloride ion and decreased chloride content in front of rebar. Finally, this paper addressed some worth-noting conclusions about the chloride distribution and rebar corrosion regarding the configuration of, rebar diameter, concrete cover and exposure period.

Vibration performance characteristics of a long-span and light-weight concrete floor under human-induced loads

Cao, Liang,Liu, Jiepeng,Zhou, Xuhong,Chen, Y. Frank Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.3

An extensive research was undertaken to study the vibration serviceability of a long-span and light-weight floor subjected to human loading experimentally and numerically. Specifically, heel-drop test was first conducted to capture the floor's natural frequencies and damping ratios, followed by jumping and running tests to obtain the acceleration responses. In addition, numerical simulations considering walking excitation were performed to further evaluate the vibration performance of a multi-panel floor under different loading cases and walking rates. The floor is found to have a high frequency (11.67 Hz) and a low damping ratio (2.32%). The comparison of the test results with the published data from the 1997 AISC Design Guide 11 indicates that the floor exhibits satisfactory vibration perceptibility overall. The study results show that the peak acceleration is affected by the walking path, walking rate, and adjacent structure. A simpler loading case may be considered in design in place of a more complex one.

Influence of slenderness on axially loaded square tubed steel-reinforced concrete columns

Biao Yan,Dan Gan,Xuhong Zhou,Weiqing Zhu 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.3

This paper aims to investigate the axial load behavior and stability strength of square tubed steel-reinforced concrete (TSRC) columns. Unlike concrete filled steel tubular (CFST) column, the outer steel tube of a TSRC column is mainly used to provide confinement to the core concrete. Ten specimens were tested under axial compression, and the main test variables included length-to-width ratio (<i>L/B</i>) of the specimens, width-to-thickness ratio (<i>B/t</i>) of the steel tubes, and with or without stud shear connectors on the steel sections. The failure mode, ultimate strength and load-tube stress response of each specimen were summarized and analyzed. The test results indicated that the axial load carried by square tube due to friction and bond of the interface increased with the increase of <i>L/B</i> ratio, while the confinement effect of tube was just the opposite. Parametric studies were performed through ABAQUS based on the test results, and the feasibility of current design codes has also been examined. Finally, a method for calculating the ultimate strength of this composite column was proposed, in which the slenderness effect on the tube confinement was considered.

Immunity : Inflammatory T Cell Responses Rely on Amino Acid Transporter ASCT2 Facilitation of Glutamine Uptake and mTORC1 Kinase Activation

( Mako Nakaya ),( Yichuan Xiao ),( Xiaofei Zhou ),( Jae Hoon Chang ),( Mikyong Chang ),( Xuhong Cheng ),( Marzenna Blonska ),( Xin Lin ),( Shao Cong Sun ) 영남대학교 약품개발연구소 2014 영남대학교 약품개발연구소 연구업적집 Vol.24 No.0

Glutamine has been implicated as an immunomodulatory nutrient, but how glutamine uptake is mediated during T cell activation is poorly understood. We have shown that naive T cell activation is coupled with rapid glutamine uptake, which depended on the amino acid transporter ASCT2. ASCT2 deficiency impaired the induction of T helper 1 (Th1) and Th17 cells and attenuated inflammatory T cell responses in mouse models of immunity and autoimmunity. Mechanistically, ASCT2 was required for T cell receptor (TCR)-stimulated activation of the metabolic kinase mTORC1. We have further shown that TCR-stimulated glutamine uptake and mTORC1 activation also required a TCR signaling complex composed of the scaffold protein CARMA1, the adaptor molecule BCL10, and the paracaspase MALT1. This function was independent of IKK kinase, a major downstream target of the CARMA1 complex. These findings highlight a mechanism of T cell activation involving ASCT2-dependent integration of the TCR signal and a metabolic signaling pathway.

Analysis of Peripheral B Cell Subsets in Patients With Allergic Rhinitis

Jing Luo,Huanhuan Guo,Zhuofu Liu,Tao Peng,Xianting Hu,Miaomiao Han,Xiangping Yang,Xuhong Zhou,Huabin Li 대한천식알레르기학회 2018 Allergy, Asthma & Immunology Research Vol.10 No.3

Purpose: Recent evidence suggests that B cells can both promote and inhibit the development and progression of allergic disease. However, the characteristics of B cell subsets in patients with allergic rhinitis (AR) have not been well documented. This study aimed to analyze the characteristics of B cell subsets in the peripheral blood of AR patients. Methods: Forty-seven AR patients and 54 healthy controls were enrolled in this study, and the B cell subsets in peripheral blood of all subjects were analyzed by flow cytometry. Moreover, the serum total immunoglobulin E (IgE) and IgE concentrations secreted into the cultured peripheral blood mononuclear cells (PBMCs) were measured by using enzyme-linked immunosorbent assay. Results: We found the peripheral blood of AR patients contained higher percentages of memory B cells, plasma cells, and CD19+CD24hiCD27+ regulatory B cells (Bregs) than those of age-matched healthy controls (P<0.05), while the percentages of naïve B cells and CD19+CD24hiCD38hi Bregs were significantly lower in AR patients than in healthy individuals (P<0.05). In addition, the serum total IgE and IgE concentrations secreted into the cultured PBMCs were elevated in AR patients than in the healthy controls (P<0.05). Conclusions: Our findings indicate that AR patients were characterized by increase in terminally differentiated memory B cells or plasma cells and decreases in CD19+CD24hiCD38hi Breg cells in the peripheral blood.