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Chen S.,Harbin Institute of Technology | Ling X.,Harbin Institute of Technology | Zhu Z.,Sichuan Agricultural University | Xu X.,Harbin Institute of Technology | Liu Y.,SCIVIC Engineering Corporation
Journal of Earthquake Engineering and Engineering Vibration | Year: 2012

Based on the previous studies on fitting functions of power spectrum density (PSD) of track vertical irregularity, the different effects of common and high-speed track spectra on the performance of train, such as running stability safety and wheel-track dynamic response have been compared. The results indicate that the running sta-bihty of the TKY main line spectrum and the CSTDXY track spectrum is superior to that of the American track spectrum of sixth grade, while the wheel-track dynamic response resulted from TKY main line spectrum lies between those induced by the fifth and sixth grade American track spectra, and the dynamic response induced by the CSTDXY track spectrum is almost identical with that by the sixth grade American track spectrum; the running stability induced by the spectra of 120 km/h and 160 km/h classification, respectively, all lie between those from the sixth and fifth grade American spectra, and the wheel-track forces are almost identical with the sixth grade Amen-can spectrum; the running stability of TKY high-speed spectrum and the spectrum of 200 km/h classification is in the middle level compared with German track spectra of high interference and low interference, and the wheel-track force induced by German interference track spectra, which was comparative with that induced by the latter, is seller than the force induced by the fanner. Simultaneously, according to the vehicle - track vertical coupling dynamic model, applying trigonometric series method to transfer the functions of PSD into time domain samples as an input of wheel-track excitation, the wheel-track vertical forces were calculated,while the vehicle YZ25T passing by under common irregularity spectra excitation with the velocity of 90 km/h, and under high-speed spectra excitation with the velocity of 200 km/h, respectively, which can well be the validation of wheel-track dynamic effectiveness obtained by the PSD of track vertical irregularity. The results can be used for the selection of wheel-track interaction mput, which can further provide certain insights into the study on vibration responses induced by passing trains.


Che Y.,Dalian University of Technology | Wang J.,Dalian University of Technology | Zheng X.,Dalian University of Technology | Zheng X.,SCIVIC Engineering Corporation | Song Y.,Dalian University of Technology
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2013

Six reinforced high-strength concrete beam-type specimens of different sizes with stubs columns in the middle were fabricated, and tested under low-cycle reversed loading to investigate the effect of depths on flexural behavior of reinforced high-strength concrete beams. The parameters of specimens varied in depths and ratios of longitudinal reinforcement on the top of cross sections, while the depth-width ratios of cross sections, shear span-to-depth ratios and ratios of longitudinal reinforcement on the bottom of cross sections and stirrups were constant. C70 concrete was used to cast the specimens and HRB 400 steel bars were used as longitudinal reinforcement. The influence of beam depths on nominal cracking moment, nominal yield moment, nominal ultimate moment, displacement ductility, plastic rotation capacity, stiffness degradation and energy dissipation capacity of high-strength concrete beams were investigated. It is shown that there is no apparent size effect observed on nominal cracking moment, nominal yield moment and nominal ultimate moment of reinforced high-strength concrete beams, and that all specimens subjected to cyclic loading clearly show similar stiffness degradation which is independent of beam depths, while the displacement ductility factors, rotational capacity as well as work index of specimens decrease with increasing of depths, showing significant size effect.


Che Y.,Dalian University of Technology | Zheng X.,Dalian University of Technology | Zheng X.,SCIVIC Engineering Corporation | Wang J.,Dalian University of Technology | Song Y.,Dalian University of Technology
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2012

Reinforced high-strength concrete beams subjected to bending were tested to investigate the effect of depth on flexural behavior of beams. The geometry of specimens varied in cross sections with the depth-width ratios of the cross sections, the shear span ratios and longitudinal reinforcement ratios of specimens being constant. C70 concrete was used to cast the specimens and HRB 400 steel bars were used for the longitudinal reinforcement. The influence of beam depth on the nominal cracking moment, nominal yield moment, nominal ultimate flexural moment, ductility, and plastic rotation capacity of high-strength concrete beams was investigated. It is shown that there is no apparent size effect on nominal cracking moment, nominal yield moment and nominal ultimate moment of reinforced high-strength concrete beams. But the displacement ductility ratio and plastic rotation capacity show significant size effect. The displacement ductility factor and the rotational capacity of high-strength concrete beam decrease with the increasing of cross section.


Zhu T.,Dalian University of Technology | Wang M.,Dalian University of Technology | Sheng Z.,Scivic Engineering Corporation
Chinese Journal of Mechanical Engineering (English Edition) | Year: 2010

The existing research on shrinkage of the injection molded plastic part mainly focuses on various shrinkage ratios of the part dimensions, and the relevant experimental studies belong to mere dimension measurement after demoulding. Obviously, measuring after the plastic part is demoulded from the cavity can not offer shrinkage displacements of points on the plastic part. However, shrinkage displacements of points on an injection molded plastic part are essential for exposing the inner relation among shrinkage ratios of various dimensions of the part. So visualization of the in-mold plastic part which can indicate the location relationship between the part and the cavity is needed. In this paper, a visual injection mold was fabricated by adopting the half mold structure and light transmission manner. With the visual mold, in-mold shrinkage images of injection molded plastic parts were photographed after the plastic part stayed in the injection mold for 24 h. By means of digital image processing of the in-mold shrinkage images, the experimental data of shrinkage displacements of points on injection molded parts were researched. From the experimental data, it is found that shrinkage directions of points on an injection molded part are related with both positions of the gate and of the part centroid, and either the gate or the centroid will exert more influence on the shrinkage direction of some point which is closer. Furthermore, some point at the later filled area has more shrinkage distance than the point at the earlier filled area. Combination of shrinkage directions and shrinkage distances of points on an injection molded part determine shrinkage ratios for various dimensions of the part, and shrinkage directions are more influential to shrinkage ratios of dimensions. This experimental research of shrinkage displacements offers a unique approach to understand the shrinkage principles of injection molded parts.


Dong Y.,Chongqing University | Chen S.,Chongqing University | Li X.,SCIVIC Engineering Corporation
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2013

Many ground motion records from the 2011 Tohoku earthquake in Japan show double-plateau characteristic in time histories which is mainly caused by multiple rupture events and wave propagation. In this paper, a piece-wised envelope model with double-plateau is proposed to describe the energy distribution in time of this kind of records and the optimization algorithm is used to determine the corresponding model parameters. Then, ground motions with double-plateau are identified by using regression analysis and the corresponding attenuation laws of model parameters are derived. Lastly, spatial distribution pattern of these double-plateau records are investigated based on analysis results.

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