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- 저자 : Zhenghong Tian (검색결과 3 건)
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Visual Monitoring Method on Fresh Concrete Vibration
Zhenghong Tian,Ce Bian 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.2
An integrated visual monitoring system to determine trajectory and duration on each vibrating motion of vibrator during concreteplaced on construction site was introduced, which could graphically display vibrating status of fresh concrete. Defects on concreteplacing process such as missed vibration, insufficient vibration, or excess vibration could be quantifiably assessed, and therefore,precise and suitable remedy could be offered timely. The system consisted of four functional parts, namely, vibrating trajectoryspatial coordinate collected subsystem, vibrating duration-collected subsystem, data process subsystem, and real-time display andassesses subsystem of vibrating status. The principle of operation was explained in this article. Firstly, accurate signals combinedspatial coordinates were achieved by dual-satellite systems, e.g., GPS (Global Position System) and GLONASS (Global NavigationSatellite System), with RTK (Real Time Kinematics) mode and, duration of each vibration from start to end was determined byelectrode device, respectively. Secondly, the wireless signals were sent to the terminal computer via MCC (Mono-Chip Computer)integrated. Finally, the worked status of vibrator on terminal was displayed simultaneously supported by assessment programm oncompacting concrete. Tests results from outdoor and application in-situ proved that the system could monitor the vibration process inreal-time reliably and quantifiably while fresh concrete was placed, and an innovative informationaized method might be realized.
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Jinhui Ren,Zhenghong Tian,Jingwu Bu 한국콘크리트학회 2018 International Journal of Concrete Structures and M Vol.12 No.6
A user-defined bonded-particle model (UBM) which is based on the modified parallel bond was established in this paper to investigate the tensile and compressive failure mechanism of concrete on the three-dimensional (3D) level. The contact constitutive relation and the failure criterion of the UBM can be added to the commercial discrete element software PFC<SUP>3D</SUP> by compiling them as a dynamic link library file and loading it into PFC<SUP>3D</SUP> whenever needed. In addition, the aggregate particles can be generated according to the volume fraction and the shape of each aggregate is irregular. Then, by comparing the results of numerical simulation with the results of laboratory tests, it is found that this bonded-particle model can simulate the tensile and compressive failure process of concrete well to a certain extent. Specifically, the two have basically similar failure patterns and stress–strain responses no matter under tension or compression loading condition. All results indicate that this UBM is a promising tool in understanding and predicting the tensile and compressive failure process of concrete.
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Experimental Study on Dynamic Properties of UHMWPE and PVA Fibers Concrete
Bashir H. Osman,Zhenghong Tian,Guilin Jiang,Xiao Sun,Adrianna Carroll 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.10
The purpose of this paper is to examine the dynamic three-point bending performance of UHMWPE and PVA fiber concrete specimens by means of density variation (0, 0.6, 1.2, 1.8, 2.4 kg/m3). Additionally, the difference in performance between UHMWPE and PVA fiber concretes, as well as the impact characteristics and the damage evolution law exhibited by these fiber concretes under repeated dynamic loading were studied and discussed. A Split Hopkinson pressure bar (SHPB) apparatus was used to determine the concrete behavior at different strain rates; the accuracy of which was achieved by conducting a structural transient dynamic response analysis. The dynamic failure strength and strain rate of the specimen were derived to investigate the rate effect with different quantities of UHMWPE and PVA fiber concretes. The experimental results were then compared with those predicted from available equations, verifying the validity of the results obtained. A theoretical model for analyzing the transient elastic response of the specimen was then proposed. This paper concludes by proposing an analytical equation for predicting the dynamic compression and tensile properties of these new-type fibers.
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