Fengcheng, China
Fengcheng, China

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Deng Z.,Xi'an Jiaotong University | Deng Z.,Xi'an Shiyou University | Luo Y.,Xi'an Jiaotong University | Chen T.,Xi'an Jiaotong University | And 3 more authors.
Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University | Year: 2010

An experiment was conducted to investigate the two-phase flow instability in the vertical parallel rifled tubes and inclined parallel rifled tubes using six-head rifled tubes with a diameter of 31.8 mm in the mass flow rate range of 200-450 kg/(m2·s) in a high pressure test loop. The experimental results show that the boundary heat flux of the pressure-drop type oscillation or the density-wave type oscillation increased with the increase of the inlet pressure and the mass flow rate, and the boundary heat flux for the vertical parallel rifled tubes was greater than that for inclined parallel rifled tubes, indicating that the flow in vertical parallel rifled tubes would be more stable. The effects of inlet subcooling degree on the boundary heat flux and the oscillation period exhibited two different trends in the test. In addition, non-dimensional correlations of thresholds of heat flux both in the vertical parallel rifled tube and the inclined parallel rifled tube were obtained by the regression calculation of the test data.


Zhou T.,Chang'an University | Yang D.,Chang'an University | Yang D.,China West Airport Group | Nie S.,Chang'an University | Wu H.,Chang'an University
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2012

Eight specimens of quadruple-C built-up section cold-formed steel columns with different slenderness ratios were tested under axial compression load. The load bearing capacity of the specimens was analyzed. The finite element models involving geometric nonlinearity, materials nonlinearity and contact mechanics were presented. The results of finite element method (FEM) are close to those from the tests, proving that the FEM is reasonable. Factors that influence the behavior of members under axial compression, including slenderness ratio, spacing of screws and the width-thickness ratio, were studied. The results show that the failure modes of all specimens are local buckling and distortional buckling, and the axial bearing capacity of quadruple-C built-up section members is four times more than that of single C-section ones. The axial bearing capacity and stiffness of the quadruple-C built-up section members decrease as the slenderness ratio increases. The effect of the spacing of screws from 150mm to 450mm on the axial bearing capacity and stiffness of quadruple-C built-up section members is insignificant. The ultimate axial bearing capacity of quadruple-C built-up section members increase when width-thickness ratio of flange decreases.


Lu L.,Chang'an University | Zhang Y.,Chang'an University | Fang W.,New Era Xian Design Engineering Co. | Yang D.,China West Airport Group
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2013

The production of specimens, loading equipment and the whole test process of both single and multiple self-drilling screw connections were introduced. According to the test and failure phenomenon, the load-deformation curves, shear-carrying capacity and failure modes were testified. The feasibility and reliability of the calculating methods in GB 50018-2002 and AISI were verified by the experiment data. Through considering the influence of different base materials, screws numbers, arrangements and screw spacing, the loading stages, main failure mode and influencing factors of the test are concluded: (1) Screw numbers and spacing are the main factors to the bearing capacity of self-drilling screws connections; (2) The screw arrangements have little effect on the shearing behavior of connections; (3) In certain situations, the thickness of base metal is also one of the main factors to the shearing behavior of connections. Based on the statistical analysis of the test data, it is found that the shear-carrying capacity of self-drilling screw connections has "group reduction effect", and the range of efficiency coefficient for screws is provided as well. The screw numbers and spacing are also proved as main factors to efficiency coefficient by further analysis.


Lu L.,Chang'an University | Zhang Y.,Chang'an University | Fang W.,New era Xian Design Engineering Co. | Yang D.,China West Airport Group
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2013

Based on the previous experimental investigation and finite element program, a numerical analysis on self-drilling screw connections of cold-formed thin-walled steel was conducted by selecting appropriate elements, using face to face contact model and simulating the actual boundary conditions. Through comparing the numerical results of failure modes, load-deformation curves and shear-carrying capacity with those of experimental results, the feasibility of the numerical analysis method was verified. According to the numerical analysis, the influence of parameters such as the diameter of self-drilling screw, the thickness of connections, screw arrangements, and screw numbers and spacing was analyzed. It is found that the shear-carrying capacity of single screw connections increases with the increase of screw diameter, and it is also improved with the thickening of connections when single screw connections are in failure with screw inclining and connect plate titling. Screw numbers and spacing are the major factors to shearing property of screw connections. On the basis of parameter analysis, the design method of shear-carrying for screw connections is discussed, and the corresponding calculation method and constitution are suggested.


Lu L.,Chang'an University | Huang G.,Chang'an University | Fang W.,New Era Xian Design Engineering Co. | Yang D.,China West Airport Group
Applied Mechanics and Materials | Year: 2012

Cold-formed steel self-drilling screws connection are imitated to carry out numerical simulation analysis, in which geometric large deformation, materials nonlinear and contact problem are taken into account. From the comparison of computer analysis with experimental results, it comes out that the finite element numerical simulation method is accurate and feasible. © (2012) Trans Tech Publications.


Nie S.-F.,Chang'an University | Zhou T.-H.,Chang'an University | Yang D.-H.,China West Airport Group | Zhang Y.-J.,Chang'an University
Tumu Jianzhu yu Huanjing Gongcheng/Journal of Civil, Architectural and Environmental Engineering | Year: 2011

The finite element model involving geometric large deformation, materials and contact nonlinearity is established. Specimens of cold-formed steel quadruple-C built-up section members are simulated and the finite element models are proved to be valid. Then, numerical analysis on the behavior of specimens with different slenderness ratio and flange flakiness ratio are carried out, and then the axial bearing capacities of specimens are obtained. Based on effective width method and direct strength method (DSM) in related codes, two design methods of cold-formed steel quadruple-C built-up section members under axial compression are proposed: effective length method and correction factor method. It is shown that: the final failure characteristics of all specimens are local buckling and distortional buckling. In the case of not considering the reduction of effective length, the results calculated by each code are slightly lower than those of test and FEM when the slenderness ratio is less than 50, while the results are too conservative when the slenderness ratio is more than 50.


Lu L.,Chang'an University | Zhang Y.,Chang'an University | Fang W.,New Era Xian Design Engineering Co. | Yang D.,China West Airport Group
Applied Mechanics and Materials | Year: 2012

Recently, self-drilling screw connection is the most primary connection way in the cold-formed thin-wall steel structure, many scholars have studied its stress mechanism and shear capacity. This paper begins with several self-drilling screw stress mechanism and shear failure mode, introduces the domestic and international calculation, then summarize and analyze the research progress on the self-drilling screw. At last, prospect on the self-drilling screw shear capacity and application. © (2012) Trans Tech Publications.

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