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numerical investigations of the compressive behavior of carbon fiber-reinforced polymer-strengthened tubularsteel T-joints

Peng DENG, Boyi YANG, Xiulong CHEN, Yan LIU

《结构与土木工程前沿（英文）》 2020年 第14卷 第5期   页码 1215-1231 doi: 10.1007/s11709-020-0663-y

摘要： A method for strengthening damaged tubular steel T-joints under axial compression by wrapping them with carbon fiber-reinforced polymer (CFRP) sheets was proposed and evaluated. The influence of the CFRP strengthening on the failure mode and load capacity of T-joints with different degrees of damage was investigated using experiments and finite element analyses. Five T-joints were physically tested: one bare joint to obtain the peak load and corresponding displacement ( ), two reinforced joints to provide a reference, and two pre-damaged then retrofitted joints to serve as the primary research objects. The ratio of the pre-loaded specimen chord displacement to the value of was considered to be the degree of damage of the two retrofitted joints, and was set to 0.80 and 1.20. The results demonstrate that the maximum capacity of the retrofitted specimen was increased by 0.83%–15.06% over the corresponding unreinforced specimens. However, the capacity of the retrofitted specimen was 2.51%–22.77% lesser compared with that of the directly reinforced specimens. Next, 111 numerical analysis models (0.63≤ ≤0.76, 9.70≤ ≤16.92) were established to parametrically evaluate the effects of different geometric and strengthening parameters on the load capacity of strengthened tubular T-joints under different degrees of damage. The numerical analysis results revealed that the development of equivalent plastic strain at the selected measuring points was moderated by strengthening with CFRP wrapping, and indicated the optimal CFRP strengthening thickness and wrapping orientation according to tubular T-joint parameters. Finally, reasonable equations for calculating the load capacity of CFRP-strengthened joints were proposed and demonstrated to provide accurate results. The findings of this study can be used to inform improved CFRP strengthening of damaged tubular steel structures.

关键词： tubular T-joint     carbon fiber-reinforced polymer     degree of damage     numerical analysis     equivalent plastic strain    

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Performance study on T-stub connected semi-rigid joint between rectangular tubular columns and H-shaped

Guochang LI, Hongping YU, Chen FANG

《结构与土木工程前沿（英文）》 2013年 第7卷 第3期   页码 296-303 doi: 10.1007/s11709-013-0217-7

摘要： This paper investigates the performance of T-stub connected semi-rigid joint of rectangular tubular columns and H-shaped steel beams. The finite element analysis software ABAQUS is used to analyze the nonlinear performance of the joint under monotonic loading. Meanwhile, the dimensions of T-stub, column and beam are considered as analytic parameters to discuss the performance of the joint. The analysis shows that the thickness and the length of T-stub webs, the height of beam section, bolt diameter, shear connector and the preloaded force affect the performance of the joint largely, and the thickness of the steel tube, the thickness and length of T-stub flange, bolt spacing have relatively little influences on the performance of the joint. The research results indicate that this joint is semi-rigid joint.

关键词： rectangular tubular columns     T-stub     semi-rigid     nonlinear finite element analysis     moment-rotation curves    

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Cyclic behavior of stiffened joints between concrete-filled steel tubular column and steel beam withnarrow outer diaphragm and partial joint penetration welds

Chunyan QUAN,Wei WANG,Jian ZHOU,Rong WANG

《结构与土木工程前沿（英文）》 2016年 第10卷 第3期   页码 333-344 doi: 10.1007/s11709-016-0357-7

摘要： This paper presented an investigation on a stiffened joint in practical engineering which was between concrete-filled steel tubular column and steel beam with narrow outer diaphragm and partial joint penetration welds. Through the low-frequency cyclic loading test, the cyclic behavior and failure mode of the specimen were investigated. The results of the test indicated the failure mode and bearing capacity of the specimen which were influenced by the axial compression ratio of the concrete-filled tubular column. On the contrary, the inner diaphragm and inner stiffeners had limited impacts on the hysteretic behavior of the joint. There was no hysteresis damage fracture on the narrow outer diaphragm connected to the concrete-filled steel tubular column with partial joint penetration welds. Due to the excellent ductility and energy dissipating capacity, the proposed joint could be applied to the seismic design of high-rise buildings in highly intensive seismic region, but axial compression ratio should be controlled to avoid unfavorable failure modes.

关键词： narrow outer diaphragm     concrete-filled tubular column     joint     inner and outer stiffening     cyclic behavior    

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Modelling and experimental verification on concrete-filled steel tubular columns with L or T section

LU Xilin, LI Xueping, WANG Dan

《结构与土木工程前沿（英文）》 2007年 第1卷 第2期   页码 163-169 doi: 10.1007/s11709-007-0017-z

摘要： Concrete-filled steel tubular columns with L or T sections were analyzed in this paper. According to the confining mechanism, the stress-strain constitutive model was put forward, and calculated results were compared with experimental records. After that, the hysteretic rules for the in-filled concrete were constructed, aiming at the analysis on the seismic behavior of composite members. The simulation analysis was performed by programming it in Fortran. The models in this paper can be applied in the program of time history analysis on tall buildings with concrete-filled steel tubular columns with L or T sections.

关键词： hysteretic     confining mechanism     Concrete-filled     in-filled     composite    

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Typical diseases of a long-span concrete-filled steel tubular arch bridge and their effects on vehicle-induced

Jianling HOU, Weibing XU, Yanjiang CHEN, Kaida ZHANG, Hang SUN, Yan LI

《结构与土木工程前沿（英文）》 2020年 第14卷 第4期   页码 867-887 doi: 10.1007/s11709-020-0649-9

摘要： A long-span concrete-filled steel tubular (CFST) arch bridge suffers severe vehicle-induced dynamic responses during its service life. However, few quantitative studies have been reported on the typical diseases suffered by such bridges and their effects on vehicle-induced dynamic response. Thus, a series of field tests and theoretical analyses were conducted to study the effects of typical diseases on the vehicle-induced dynamic response of a typical CFST arch bridge. The results show that a support void results in a height difference between both sides of the expansion joint, thus increasing the effect of vehicle impact on the main girder and suspenders. The impact factor of the displacement response of the main girder exceeds the design value. The variation of the suspender force is significant, and the diseases are found to have a greater effect on a shorter suspender. The theoretical analysis results also show that the support void causes an obvious longitudinal displacement of the main girder that is almost as large as the vertical displacement. The support void can also cause significant changes in the vehicle-induced acceleration response, particularly when the supports and steel box girder continue to collide with each other under the vehicle load.

关键词： long-span arch bridge     expansion joint disease     vehicle-bridge coupling vibration     dynamic response    

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A toughness based deformation limit for X- and K-joints under brace axial tension

Bo GU,Xudong QIAN,Aziz AHMED

《结构与土木工程前沿（英文）》 2016年 第10卷 第3期   页码 345-362 doi: 10.1007/s11709-016-0333-2

摘要： This study reports a deformation limit for the initiation of ductile fracture failure in fatigue-cracked circular hollow section (CHS) X- and K-joints subjected to brace axial tension. The proposed approach sets the deformation limit as the numerically computed crack driving force in a fatigue crack at the hot-spot location in the tubular joint reaches the material fracture toughness measured from standard fracture specimens. The calibration of the numerical procedure predicates on reported numerical computations on the crack driving force and previously published verification study against large-scale CHS X-joints with fatigue generated surface cracks. The development of the deformation limit includes a normalization procedure, which covers a wide range of the geometric parameters and material toughness levels. The lower-bound deformation limits thus developed follow a linear relationship with respect to the crack-depth ratio for both X- and K-joints. Comparison of the predicated deformation limit against experimental on cracked tubular X- and K-joints demonstrates the conservative nature of the proposed deformation limit. The proposed deformation limit, when extrapolated to a zero crack depth, provides an estimate on the deformation limits for intact X- and K-joints under brace axial loads.

关键词： circular hollow section (CHS)     tubular joint     fracture failure     deformation limit     J-integral    

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A numerical study of prestressed high strength steel tubular members

Michaela GKANTOU, Marios THEOFANOUS, Charalampos BANIOTOPOULOS

《结构与土木工程前沿（英文）》 2020年 第14卷 第1期   页码 10-22 doi: 10.1007/s11709-019-0547-1

摘要： The structural behavior of prestressed high strength steel (HSS) tubular members is investigated through the execution of advanced finite element modeling. Numerical models are developed and validated against published experimental data on HSS tubular members subjected to different levels of initial prestress and loaded either in tension or compression. The effect of the presence or absence of grouting on the strength and ductility of the members is also considered. To numerically replicate the structural response recorded in the tests, some key modeling features including the employed numerical solver, the adopted material models and the element types warrant careful consideration. Upon developing of the finite element models, the numerically generated ultimate loads, the corresponding failure modes and the full load-deformation curves are compared to the experimental ones, indicating a successful validation. As anticipated, prestressing enhances the load-bearing capacity for the tensile members, whereas it is detrimental for the compressive ones. A series of parametric studies is performed to assess the influence of key factors on the structural response of prestressed HSS members and the obtained results are discussed. Design guidance for tensile and compressive prestressed tubular members is also provided.

关键词： finite element     prestressing     tubular members     grout     high strength steel    

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Joint user association and resource partition for downlink-uplink decoupling in multi-tier HetNets Article

Zhi-yong FENG, Ze-bing FENG, T. Aaron GULLIVER

《信息与电子工程前沿（英文）》 2017年 第18卷 第6期   页码 817-829 doi: 10.1631/FITEE.1700031

摘要： 传统蜂窝网络要求移动用户上行和下行连接在相同基站上。然而，由于用户与基站发射功率存在差异，在不同无线环境下，将会导致用户从某基站接收到最强下行信号，但该基站并不能提供最强接收信号的上行链路。而且，由于大量机器设备接入蜂窝网络中，网络上行流量需求增大，从而导致基站下行和上行流量存在严重不对称。在多层异构蜂窝网络环境下，提出了基于上下行解耦的联合用户接入与资源划分模型。区别于现有用户接入异构蜂窝网络的准则，如基于最大用户接收功率和小区范围扩展，提出了基于联合博弈的机制以实现上下行解耦条件下的用户最优接入。对该机制的稳定性和收敛性作了证明，且证明其收敛到纳什均衡点的速率呈几何级数增长。此外，基于上述用户上下行接入的结果，得到了考虑用户公平性条件下的基站下行和上行最优带宽划分。仿真结果显示：相比现有其他用户接入策略，提出的机制有效地提升了网络速率。

关键词： 上下行解耦；用户接入；资源划分；异构蜂窝网络；联合博弈    

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Theoretical study on flow and radiation in tubular solar photocatalytic reactor

《能源前沿（英文）》 2021年 第15卷 第3期   页码 687-699 doi: 10.1007/s11708-021-0773-9

摘要： In this paper, based on the mixture flow model, an optimized six-flux model is first established and applied to the tubular solar photocatalytic reactor. Parameters influencing photocatalyst distribution and radiation distribution at the reactor outlet, viz. catalyst concentration and circulation speed, are also analyzed. It is found that, at the outlet of the reactor, the optimized six-flux model has better performances (the energy increase by 1900% and 284%, respectively) with a higher catalyst concentration (triple) and a lower speed (one third).

关键词： photocatalytic hydrogen photoreactor     nume- rical simulation     solar energy     flow model     radiation model    

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Analytical algorithms of compressive bending capacity of bolted circumferential joint in metro shield

《结构与土木工程前沿（英文）》   页码 901-914 doi: 10.1007/s11709-023-0915-8

摘要： The integrity and bearing capacity of segment joints in shield tunnels are associated closely with the mechanical properties of the joints. This study focuses on the mechanical characteristics and mechanism of a bolted circumferential joint during the entire bearing process. Simplified analytical algorithms for four stress stages are established to describe the bearing behaviors of the joint under a compressive bending load. A height adjustment coefficient, α, for the outer concrete compression zone is introduced into a simplified analytical model. Factors affecting α are determined, and the degree of influence of these factors is investigated via orthogonal numerical simulations. The numerical results show that α can be specified as approximately 0.2 for most metro shield tunnels in China. Subsequently, a case study is performed to verify the rationality of the simplified theoretical analysis for the segment joint via numerical simulations and experiments. Using the proposed simplified analytical algorithms, a parametric investigation is conducted to discuss the factors affecting the ultimate compressive bending capacity of the joint. The method for optimizing the joint flexural stiffness is clarified. The results of this study can provide a theoretical basis for optimizing the design and prediciting the damage of bolted segment joints in shield tunnels.

关键词： shield tunnel     segment joint     joint structural model     failure mechanism    

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Preventive effect of Shenkang injection against high glucose-induced senescence of renal tubular cells

Biqiong Fu, Jie Yang, Jia Chen, Lirong Lin, Kehong Chen, Weiwei Zhang, Jianguo Zhang, Yani He

《医学前沿（英文）》 2019年 第13卷 第2期   页码 267-276 doi: 10.1007/s11684-017-0586-8

摘要： Shenkang injection (SKI) is a classic prescription composed of , rhubarb, , and . This treatment was approved by the State Food and Drug Administration of China in 1999 for treatment of chronic kidney diseases based on good efficacy and safety. This study aimed to investigate the protective effect of SKI against high glucose (HG)-induced renal tubular cell senescence and its underlying mechanism. Primary renal proximal tubule epithelial cells were cultured in (1) control medium (control group), medium containing 5 mmol/L glucose; (2) mannitol medium (mannitol group), medium containing 5 mmol/L glucose, and 25 mmol/L mannitol; (3) HG medium (HG group) containing 30 mmol/L glucose; (4) SKI treatment at high (200 mg/L), medium (100 mg/L), or low (50 mg/L) concentration in HG medium (HG+ SKI group); or (5) 200 mg/L SKI treatment in control medium (control+ SKI group) for 72 h. HG-induced senescent cells showed the emergence of senescence associated heterochromatin foci, up-regulation of P16 and cyclin D1, increased senescence-associated β-galactosidase activity, and elevated expression of membrane decoy receptor 2. SKI treatment potently prevented these changes in a dose-independent manner. SKI treatment prevented HG-induced up-regulation of pro-senescence molecule mammalian target of rapamycin and p66Shc and down-regulation of anti-senescence molecules klotho, sirt1, and peroxisome proliferator-activated receptor- in renal tubular epithelial cells. SKI may be a novel strategy for protecting against HG-induced renal tubular cell senescence in treatment of diabetic nephropathy.

关键词： Shenkang injection     senescence     renal tubular epithelial cells     diabetic nephropathy    

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Finite element analysis on the seismic behavior of side joint of Prefabricated Cage System in prefabricated

Yunlin LIU, Shitao ZHU

《结构与土木工程前沿（英文）》 2019年 第13卷 第5期   页码 1095-1104 doi: 10.1007/s11709-019-0538-2

摘要： The Prefabricated Cage System (PCS) has the advantages of high bearing capacity and good ductility. Meanwhile, it is convenient for factory production and it is beneficial to the cost savings, construction period shortening. Side joint is the weak region of PCS concrete frame and has great influence on seismic behavior of the whole structure. Thus systematically study on the seismic behavior of PCS concrete side joint is necessary. This paper presents a finite element study on behavior of the side joint under seismic loading. In the finite element model, PCS concrete and the reinforced concrete (RC) is modeled by the solid element and fiber-beam element, respectively. The numerical results is compared with the experimental results and it is found that the results of model based on fiber-beam element is in better agreement with the experimental results than solid element model. In addition, the overall seismic behavior of the side joints in PCS concrete is better than that of the RC with the same strength.

关键词： PCS concrete side joint     numerical simulation     fiber-beam element joint model     solid element joint model     seismic behavior    

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Factors affecting production of nonaqueous peracetic acid in tubular packed reactors

ZHANG Tengyun, FAN Hongbo, ZHONG Li, CHUANG Karl

《化学科学与工程前沿（英文）》 2008年 第2卷 第2期   页码 196-203 doi: 10.1007/s11705-008-0037-9

摘要： The synthesis of nonaqueous peracetic acid in acetone by acetaldehyde oxidation was carried out in a tubular packed reactor. The influencing factors of the reacting system including packing material, oxygen carrier, and reactor configuration were investigated. The results show that porous materials are inappropriate for peracetic acid synthesis and only non porous material with appropriate surface area can provide good peracetic acid selectivity and yield. Among the six kinds of packing material investigated, SA-5118 is the best one. As oxidizing gas, pure oxygen is superior to air. The optimum length-to-inner diameter ratio of the reactor is about 40. Under the proper reaction conditions, the highest peracetic acid yield of 84.15% and the highest selectivity of 93.34% can be achieved which indicates that the novel reacting system is effective and economical for nonaqueous peracetic acid production.
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Moment-curvature relationship of FRP-concrete-steel double-skin tubular members

Mingxue LIU, Jiaru QIAN

《结构与土木工程前沿（英文）》 2009年 第3卷 第1期   页码 25-31 doi: 10.1007/s11709-009-0012-7

摘要： Tests were conducted on 3 specimens to study the flexural behavior of fiber reinforced polymer (FRP)-concrete-steel double-skin tubular members (DSTMs). The strip method was used to calculate the section moment-curvature curves of the 3 specimens and 12 models. A theoretical formula is presented for the flexural strength of DSTMs. The test results show that the tension zone of the specimen FRP tubes was in hoop compression while the compression zone was in hoop tension. The load-carrying capacity did not decrease even when the mid-span deflection reached about 1/24 of the span length. The tests, simulation and theoretical analysis resulted in a simplified formula for the flexural strength of DSTMs and a tri-linear moment-curvature model was expressed as a function of the section bending stiffness for DSTMs.

关键词： fiber reinforced polymer (FRP)     concrete     steel     double-skin tubular members (DSTMs)     moment-curvature curve     flexural strength    

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Review of the crushing response of collapsible tubular structures

Vivek PATEL, Gaurav TIWARI, Ravikumar DUMPALA

《机械工程前沿（英文）》 2020年 第15卷 第3期   页码 438-474 doi: 10.1007/s11465-019-0579-1

摘要： Studies on determining and analyzing the crushing response of tubular structures are of significant interest, primarily due to their relation to safety. Several aspects of tubular structures, such as geometry, material, configuration, and hybrid structure, have been used as criteria for evaluation. In this review, a comprehensive analysis of the important findings of extensive research on understanding the crushing response of thin-walled tubular structures is presented. Advancements in thin-walled structures, including multi-cell tube, honeycomb and foam-filled, multi wall, and functionally graded thickness tubes, are also discussed, focusing on their energy absorption ability. An extensive review of experimentation and numerical analysis used to extract the deformation behavior of materials, such as aluminum and steel, against static and dynamic loadings are also provided. Several tube shapes, such as tubes of uniform and nonuniform (tapered) cross sections of circular, square, and rectangular shapes, have been used in different studies to identify their efficacy. Apart from geometric and loading parameters, the effects of fabrication process, heat treatment, and triggering mechanism on initiating plastic deformation, such as cutouts and grooves, on the surface of tubular structures are discussed.

关键词： monolithic structure     crashworthiness     energy absorber     static and dynamic loadings     multicellular tube structure     filled tube    

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标题 作者 时间 类型 操作

numerical investigations of the compressive behavior of carbon fiber-reinforced polymer-strengthened tubularsteel T-joints

Peng DENG, Boyi YANG, Xiulong CHEN, Yan LIU

期刊论文

Performance study on T-stub connected semi-rigid joint between rectangular tubular columns and H-shaped

Guochang LI, Hongping YU, Chen FANG

期刊论文

Cyclic behavior of stiffened joints between concrete-filled steel tubular column and steel beam withnarrow outer diaphragm and partial joint penetration welds

Chunyan QUAN,Wei WANG,Jian ZHOU,Rong WANG

期刊论文

Modelling and experimental verification on concrete-filled steel tubular columns with L or T section

LU Xilin, LI Xueping, WANG Dan

期刊论文

Typical diseases of a long-span concrete-filled steel tubular arch bridge and their effects on vehicle-induced

Jianling HOU, Weibing XU, Yanjiang CHEN, Kaida ZHANG, Hang SUN, Yan LI

期刊论文

A toughness based deformation limit for X- and K-joints under brace axial tension

Bo GU,Xudong QIAN,Aziz AHMED

期刊论文

A numerical study of prestressed high strength steel tubular members

Michaela GKANTOU, Marios THEOFANOUS, Charalampos BANIOTOPOULOS

期刊论文

Joint user association and resource partition for downlink-uplink decoupling in multi-tier HetNets

Zhi-yong FENG, Ze-bing FENG, T. Aaron GULLIVER

期刊论文

Theoretical study on flow and radiation in tubular solar photocatalytic reactor

期刊论文

Analytical algorithms of compressive bending capacity of bolted circumferential joint in metro shield

期刊论文

Preventive effect of Shenkang injection against high glucose-induced senescence of renal tubular cells

Biqiong Fu, Jie Yang, Jia Chen, Lirong Lin, Kehong Chen, Weiwei Zhang, Jianguo Zhang, Yani He

期刊论文

Finite element analysis on the seismic behavior of side joint of Prefabricated Cage System in prefabricated

Yunlin LIU, Shitao ZHU

期刊论文

Factors affecting production of nonaqueous peracetic acid in tubular packed reactors

ZHANG Tengyun, FAN Hongbo, ZHONG Li, CHUANG Karl

期刊论文

Moment-curvature relationship of FRP-concrete-steel double-skin tubular members

Mingxue LIU, Jiaru QIAN

期刊论文

Review of the crushing response of collapsible tubular structures

Vivek PATEL, Gaurav TIWARI, Ravikumar DUMPALA

期刊论文