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Chong X.,Hefei University of Technology | Ye X.,Hefei University of Technology | Xu Q.,HFUT Institute of Architectural Design | Li N.,China Automobile Industry Engineering Corporation
Tumu Gongcheng Xuebao/China Civil Engineering Journal

To evaluate behavior of the horizontal connections between the superimposed walls and foundations under seismic load, and the influence of edge elements among the perpendicular walls to the damage pattern of the structure, two full-scale I-shaped section specimens consisting of the perpendicular walls and the cast-in-place T-shaped edge elements were tested under cyclic reversed loads. Based on the test, the shear slip mechanics of the horizontal connections between wall and foundation is analyzed, and then numerical analysis of the specimen is conducted utilizing the 3-D nonlinear structural analysis program CANNY. The study indicates that damage of the superimposed wall mainly occurs near the horizontal connections between wall and foundation, and the inelastic region is relative small, inducing that ductility of the structure is decreased; anti-shear slip ability of the horizontal connections is mainly provided by the friction of the compress region of the cross section, and thus the relative small compress region of the I-shaped cross section is the main reason for the obvious shear slip of the specimens during the test; the 3-D MS element of CANNY is proved to be reasonable and dependable for the I-shaped superimposed walls. Source

Che Y.,Dalian University of Technology | Wang T.,Dalian University of Technology | Ban S.,Dalian University of Technology | Ban S.,China Automobile Industry Engineering Corporation | Song Y.,Dalian University of Technology
Jianzhu Jiegou Xuebao/Journal of Building Structures

Concrete specimens with different sizes confined by stirrups were tested under axial compression. Prisms with aspect ratio of 3:1 were used in the test. The specimens were divided into four groups and each group contained three identical specimens. The sectional dimensions of specimens of the four groups were 108 mm, 200 mm, 250 mm and 370 mm, respectively. To ensure identical confinement coefficient for specimens with different sizes, the same type of confining stirrups were adopted in all specimens and both diameters and spacing of confining stirrups were properly scaled. The influence of specimen size on axial compressive strength and its corresponding peak strain and ductility of confined concrete were investigated. Similar cracking patterns and failure modes were found in the test regardless of sizes of the specimens and steeper descending branches in load-axial strain curves were observed in specimens with larger sizes. It is found that there is not apparent size effect phenomenon with respect to axial compressive strength of confined concrete, while peak strains of confined concrete corresponding to the peak stresses decrease significantly with the increase of specimen sizes. The average peak strain of specimens of 370 mm is 49% of that of specimens of 108 mm showing a significant size effect. Source

LU D.-G.,Harbin Institute of Technology | Yu X.-H.,Harbin Institute of Technology | Du W.-C.,China Automobile Industry Engineering Corporation
Gongcheng Lixue/Engineering Mechanics

A pinching function is introduced into the conventional Bouc-Wen material model, and an improved Bouc-Wen material model is proposed considering the pinching behavior of materials. Such a model is incorporated into the OpenSees software platform, and is then combined with the Joint2D element to study the seismic performance of the RC beam-column joints. Two hysteretic experiments of middle beam-column joints are simulated and the improved Bouc-Wen model is verified. Finally the influence factors of RC beam-column joints are examined. The results show that the aspect ratio and the shear span ratio have significant effects on the shear strength and the ductility of joints. ©, 2015, Tsinghua University. All right reserved. Source

Chen H.,Xian Jiaotong University | Wang Y.,Xian Jiaotong University | Zhao Q.,Xian Jiaotong University | Chen Z.,Xian Jiaotong University | Zhang J.,China Automobile Industry Engineering Corporation
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering

The ash deposition characteristics of smooth tube and H-type finned tube were studied by physical and chemical analysis of ash and experiments on a cold state test bed. The results show that the microscopic property of ash is the main factor to form dry pine type ash deposition on the low temperature heating surface. The amount of ash deposition on smooth tubes decreases with the increase of air velocity and increases with the increase of feed concentration. Ash particles mainly deposit on the low velocity area of the H-type finned tube surface. In order to obtain a bigger rib effect coefficient and a smaller resistance, aligned H-type finned tubes with smaller fin pitch is suggested to use on low temperature heating surfaces of coal fired boilers. This article provide a reference for the design and optimization of low temperature heating surfaces of coal-fired boilers. © 2015 Chin. Soc. for Elec. Eng. Source

You H.-X.,Dalian University of Technology | Gao H.-J.,China Automobile Industry Engineering Corporation | Liu R.-J.,Dalian University of Technology | Chen G.,Hirosaki University | And 2 more authors.
Gao Xiao Hua Xue Gong Cheng Xue Bao/Journal of Chemical Engineering of Chinese Universities

In order to study the effect of dry methane flux on reactions at Ni-YSZ anode of solid oxide fuel cells (SOFC), dry methane with different fluxes was used. Mathematical relationship between dry methane flux/currents and anode reactions was investigated. The anode exhausted gases were measured by on-line chromatography and activation energy of methane elementary reaction was used to analyze the reaction pathway. The results show that when the current density and oxygen anion flux increase, the electrochemical reactions occur in sequence as follows: partial oxidation of methane which forms CO, H2 and electrons; and then CO, H2O, H2 and electrons; the third reaction forms CO, H2O and electrons and then complete oxidation of methane. The first two or three reactions occur for medium methane concentrations, and for high methane concentrations, only the partial oxidation reaction with the least ion consumption occurs. Based on Faraday's first law and the relationship among the reactant species, the determination of low, medium or high methane concentrations is: v(CH4) is less than or equal to I/(4F), v(CH4) is higher than I/(4F) but lower than I/(2F), and v(CH4) is higher than I/(2F), respectively. Source

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