Hunan Zhongda Design Institute Co ltd

Changsha, China

Hunan Zhongda Design Institute Co ltd

Changsha, China
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Wu H.-L.,Hunan Dayue Freeway Construction and Development Co. | Xie J.-J.,Hunan Zhongda Design Institute Co. | Xiong Z.,Hunan Dayue Freeway Construction and Development Co.
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2012

The element residual energy was defined and its sensitivity was analyzed. Furthermore, the structural damage identification method based on the sensitivity of element residual energy was presented and the corresponding equations were established, by solving which, damage location and severity can be simultaneously determinated. Numerical simulations show that the proposed method is effective in different damage cases.

Chen Q.,Central South University | Zhang Q.,Central South University | Wang X.,Central South University | Wang X.,Hunan Zhongda Design Institute Co ltd | And 2 more authors.
Zhongguo Kuangye Daxue Xuebao/Journal of China University of Mining and Technology | Year: 2016

In order to study the hydraulic issue of paste-like unclassified tailings backfill slurry transported by a pipeline system, the rheological behavior of paste-like was analyzed with Bingham model, the rheological parameters in different slurry mass fractions were obtained through 3D simulation in FLUENT, then, a pipeline hydraulic model of paste-like relating to inner diameter, average velocity and slurry mass fraction were constructed using MATLAB. The results show that the hydraulic gradient is inversely proportional to the pipe diameter, and proportional to average velocity of backfill slurry. The calculation error of this model can be controlled in 6% proved by annular pipeline test. © 2016, Editorial Board of Journal of CUMT. All right reserved.

Han J.-P.,Lanzhou University of Technology | Han J.-P.,Tongji University | Li D.-W.,Hunan Zhongda Design Institute Ltd Corporation
Gongcheng Lixue/Engineering Mechanics | Year: 2010

Identifying modal parameters via processing vibration signals is one of the mainstream approaches for structural health monitoring and damage diagnosis. The processing approaches based on Fourier analysis are not able to process nonlinear and non-stationary signals. In addition, most of traditional identification methods suffer from low precision to identify damping. Therefore, a new approach is proposed for identifying modal parameters based on Hilbert-Huang transform (HHT) and natural excitation technique (NExT). First, the instantaneous characteristics of the original signal are extracted by means of empirical mode decomposition (EMD) and Hilbert transform (HT). Then, NExT and basic modal analysis theory are used to identify modal frequencies and modal damping ratios. Furthermore, the original acceleration record from the shaking table test of a 12-storey RC frame model is processed and modal parameters are identified by the proposed approach. And identification results are compared with the results from other identification algorithms and finite element analysis. Comparison indicates that the proposed approach is reliable to identify modal frequencies. Although identification of modal damping ratios gets improved by comparison with half-power bandwidth method, it is still difficult to confirm the precision of the results.

Xiao J.,Central South University | Chen L.,Bridge Science Research Institute Ltd. | Xing H.,Hunan Zhongda Design Institute Co.
Jianzhu Cailiao Xuebao/Journal of Building Materials | Year: 2011

The influence of fly ash and slag powder on the autogenous shrinkage of cement mortars was studied. The experiment test results indicate that the autogenous shrinkage of cement mortar made with 1:0.5 binder to sand ratio (by mass) and 0.3 water to binder ratio (by mass) increases with development of hydration. At early age, rate of autogenous shrinkage develops sharply. Addition of fly ash reduces the autogenous shrinkage of cement mortar, and the autogenous shrinkage of cement mortar decreases with increase of fly ash content (by mass). Compared to pure cement mortar, after hydrated for 21d, the 10% and 20% of fly ash addition reduce autogenous shrinkage of cement mortar by 21.1% and 29.5% respectively. Originally within 5d, the 10%-20% (by mass) of slag powder addition decreases autogenous shrinkage of cement mortar. Compared to pure cement mortar, after hydrated for 21d, the 10% and 20% of slag powder addition increase autogenous shrinkage of cement mortar by 11.1% and 6.6% respectively.

Chen Q.-S.,Central South University | Zhang Q.-L.,Central South University | Wang X.-M.,Central South University | Wang X.-M.,Hunan Zhongda Design Institute Co. | Xiao C.-C.,Feny Corporation Ltd
Dongbei Daxue Xuebao/Journal of Northeastern University | Year: 2016

Based on indoor experiments, aggregate balance theory and fluid dynamics theory, mathematical models of vertical sand silo area and height were established. The core of sectional area calculation model is the effective sedimentation velocity which is equal to the ratio of the descent height of the liquid level and the sedimentation time. The height calculation model consists of compression layer, sedimentation layer, overflow layer, reserving sand space and stable sand height. Because the calculation of the compression layer height is the key part in the model, an equation on compression layer height and mortar concentration was put forward. Then this method was applied to a vertical sand silo. It was got that the diameter of the vertical sand silo is 10 m, and the height of vertical sand silo is 26.5 m. The field operation trial showed that the bottom flow volume fraction of sand silo can reach 44% (the mass fraction is 69%) and the volume fraction of over-flow water can be controlled under 3%, which means the concentration effect is very well. © 2016, Editorial Department of Journal of Northeastern University. All right reserved.

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