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Vibration characteristics of frozen soil under moving track loads

Research in Cold and Arid Regions 2015年第4期7卷 414-420页

作者： AiPing Tang AnPing Zhao AiHua Wen Key Lab of Structures Dynamic Behavior and Control (Harbin Institute of Technology) Ministry of Education School of Civil Engineering Heilongjiang University China Academy of Architecture and Building School of Science Harbin Institute of Technology

Vibration due to moving traffic loads is an important factor which induces frozen soil damage; this paper analyzed these vibration characteristics of frozen soil foundation under track loads. Firstly, seismic observation array （SOA） technology was applied to monitor the three dimensional dynamic characteristics of frozen soil under movable track load in a per- mafrost region and seasonal frozen soil area. Secondly, a numerical simulation for the response of frozen soil under movable track load was performed based on finite element analysis （FEA）, The results show that dynamic characteristics of frozen soil in perpendicular and parallel direction of the track are obviously different. In the direction perpendicular to the track, the vertical acceleration amplitude had an abrupt increase in the 9-10 m from the track line. In the direction parallel to the track, the acceleration in vertical and horizontal direction had a quick attenuation compared to the other direction. Lastly, various parameters were analyzed for the purpose of controlling the dynamic response of frozen soil and the vibration attenuation in frozen soil layer.

关键词： moving track load dynamic response seismic observation array （SOA） permafrost seasonal frozen soil

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Flexural behaviour of precast, prestressed ribbed RPC bottom panels

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Open Civil Engineering Journal 2015年第1期9卷 535-543页

作者： Wenzhong, Zheng Xueyuan, Lu Ying, Wang Key Lab of Structures Dynamic Behavior and Control of the Ministry Education Harbin Institute of Technology Harbin150090 China

This study introduces a new type of precast, prestressed reactive powder concrete (RPC) bottom panel for a large-span composite slab. The bottom panels, which have one or two inverted ribs with openings, act as formwork during the construction stage. The paper experimentally investigated the crack characteristics, deflection, and normal section bearing capacity of four precast, prestressed ribbed RPC bottom panels under flexural load. The results indicated that the RPC ultimate strain under non-uniform compression is 5500×10-6and the plastic influence coefficient of the section modulus is linear with the longitudinal reinforcement ratio. The tensile stress of RPC at the cracked section should be considered while calculating the flexural stiffness;the equation used to determine the nominal tensile stress of RPC as a major variable for calculating the crack width at the bottom of panels was proposed. The bottom panels generally exhibit an over-reinforced failure mode behaviour without the composite layer;the calculation method of the normal section bearing capacity of this mode was established. © Wenzhong et al.

关键词： Bearing capacity

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Literature review of reactive powder concrete

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Jianzhu Jiegou Xuebao/Journal of Building structures 2015年第10期36卷 44-58页

作者： Zheng, Wenzhong Lv, Xueyuan Key Laboratory of Structures Dynamic Behavior and Control of China Ministry of Education Harbin Institute of Technology Harbin150090 China

This paper introduces the proportioning principles and technology of reactive powder concrete (RPC), and then summarizes RPC durability and high temperature resistance. It is found that in the calculation of bond-anchorage length, the appearance coefficient of steel bar is higher in RPC than in ordinary concrete. The flexural cracking strain of RPC beam is 705×10-6-864×10-6, higher than that of ordinary concrete beam, which is 80×10-6-120×10-6. The normal section limit compressive strain of RPC beam is 4 100×10-6-5500×10-6, higher than that of ordinary concrete beam, which is 3300×10-6. The plastic influence coefficient for sectional resisting moment of RPC beam increases with the longitudinal reinforcement ratio;the test value of inclined section shearing load-bearing capacity is lower than the calculated value due to lack of coarse aggregate interlock effect on both sides of inclined cracks in RPC beam. Compared with ordinary concrete, RPC possesses excellent performance of chloride ion permeability resistance, carbonation resistance, frost thawing resistance and sulfate resistance;RPC mixed with fiber appropriately can prevent thermal spalling effectively. Finally, this paper briefly introduces the pilot projects of RPC and manifested its broad application prospects. ©, 2015, Science Press. All right reserved.

关键词： Durability

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Lattice Modelling of Chloride Diffusivity of Hardened Cement Paste

Lattice Modelling of Chloride Diffusivity of Hardened Cement...

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The 14th International Congress on the Chemistry of Cement（ICCC 2015）

作者： Hongzhi Zhang Xinchun Guan Jinping Ou Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology

Based on numerical micro-structure model of cement paste,a lattice diffusion model is generated to study the influence of randomness on the chloride diffusion coefficient of capillary pore *** results indicate that,compared with regular model,random model has longer diffusion distance,consequently,in order to get same simulation diffusion results,the former's diffusion coefficient should be adjusted a lttlte *** Lattice models have been used in fracture mechanics of cement-based materials for a long ***,the use of lattice models has been extended on simulating chloride transport processes in this *** of the transport models focus on simulation method and process,but the difference of simulated results caused by randomness is generally *** this paper,a lattice diffusion model is generated to study the influence of randomness on the chloride diffusion coefficient of capillary pore element,the reason that different simulation method has different results is also found.

关键词： durability micro-scale lattice model chloride diffusion

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Experimental study on the lateral impact of fully clamped circular steel tubes

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Tianjin Daxue Xuebao (Ziran Kexue yu Gongcheng Jishu Ban)/Journal of Tianjin University Science and Technology 2016年 49卷 28-33页

作者： Zhang, Rong Zhi, Xudong Fan, Feng Wu, Qijian Key Laboratory of Structures Dynamic Behavior and Control of Ministry of Education Harbin Institute of Technology Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China

The performance of longitudinal welded steel tubes under drop hammer impact was experimentally *** order to simulate fixed conditions of specimen,loading mechanism platform and clamping device were *** influencing factors included:drop height of hammer,ratio of length to diameter of steel tube,and shape of *** results show that the failure mode of fully clamped tubes is shear failure,and with the increase of the impact energy,the deformation of circular steel tube goes through three stages:elastic small deformation stage,plastic large deformation stage,and shear failure stage. Drop height of hammer and ratio of length to diameter of steel tube have significant effects on strain growth rate,duration of impact and peak impact force. The shape of the plastic hinge is determined by the shape of the impact indenter. © 2016, Editorial Board of Journal of Tianjin University(Science and Technology). All right reserved.

关键词： Hammers

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Numerical simulation of separated and reattached flows around a backward-facing step

Numerical simulation of separated and reattached flows aroun...

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International Conference on Measuring Technology and Mechatronics Automation

作者： Yinsong Li Chaorong Zheng Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin 150090 China

ISBN: (纸本)9781467371445

Separated and reattached flows around a backward-facing step (BFS) controlled by continuous suction was numerically investigated using the turbulence model of large eddy simulation (LES) based on the dynamic kinetic energy subgrid-scale model. The effect of suction control on the flow fields was described by the suction flow coefficient, and the results indicate that suction is not only very effective in shortening the reattachment length, but also very influential in reducing the turbulence fluctuations of the reattached flows. With increasing increments of the absolute suction flow coefficient, the effect of suction control is more significant. Furthermore, comparisons of the time-averaged statistics between the numerical simulation and corresponding experiment are conducted, and it shows that the LES can acquire exact results. Therefore, feasibility of the numerical methods to simulate suction-controlled models is validated.

关键词： Backward-facing step suction large eddy simulation flow control reattachment length

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Isolation research of friction pendulum bearings in K8 single-layer reticulated domes

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Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology 2015年第12期47卷 9-15页

作者： Kong, Dewen Fan, Feng Zhi, Xudong Key Lab of Structures Dynamic Behavior and Control Harbin Institute of Technology Ministry of Education Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China

To obtain the seismic performance of single-layer reticulated domes with friction pendulum bearings (FPB), finite element refined models of FPB were applied to 80 m K8 single-layer reticulated domes FE Model. The same earthquake waves were exerted to single-layer reticulated shells with hinge support or FPB. The isolation effect of FPBs was analyzed in two main aspects including the dynamic responses of bars and nodes of reticulated domes, and the impact of FPB parameters on the seismic response of single layer latticed shell were discussed. The results indicate that the optimal friction coefficient of FPB increases with the increase of the ground motion intensity. The bigger curvature radius of FPB, the smaller seismic responses of reticulated shell structure will be. On the basis of the above research, this paper gave some discussion how friction pendulum bearings were selected for single-layer reticulated domes. © 2015, Editorial Board of Journal of Harbin Institute of Technology. All right reserved.

关键词： Friction

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Temperature and electric-field induced phase transitions, and full tensor properties of C-poled domain-engineered tetragonal 0.63Pb(Mg1/3Nb2/3)−0.37PbTiO3 single crystals

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Physical Review B 2016年第9期93卷 094104-094104页

作者： Limei Zheng Yujia Jing Xiaoyan Lu Ruixue Wang Gang Liu Weiming Lü Rui Zhang Wenwu Cao Condensed Matter Science and Technology Institute Harbin Institute of Technology Harbin 150080 China Key Laboratory of Structures Dynamic Behavior and Control of the Ministry of Education School of Civil Engineering Harbin Institute of Technology Harbin 150001 China Center for High Pressure Science and Technology Advanced Research Shanghai 201203 China Department of Mathematics Materials Research Institute The Pennsylvania State University University Park Pennsylvania 16802 USA

The phase-transition sequence of 0.67Pb(Mg1/3Nb2/3)−0.37PbTiO3 (PMN-0.37PT) single crystals driven by the electric (E) field and temperature is comprehensively studied. Based on the strain-E field loop, polarization-E field loop, and the evolution of domain configurations, the E field along the [011]C induced phase transitions have been confirmed to be as follows: tetragonal (T) → monoclinic (MC)→ single domain orthorhombic (O) phase. As the E field decreases, the induced O phase cannot be maintained and transformed to the MC phase, then to the coexistence state of MC and T phases. In addition, the complete sets of dielectric, piezoelectric, and elastic constants for the [011]C-poled domain-engineered PMN-0.37PT single crystal were measured at room temperature, which show high longitudinal dielectric, piezoelectric, and electromechanical properties (ɛ33T=10661,d33=1052pC/N, and k33=0.766). Our results revealed that the MC phase plays an important role in the high electromechanical properties of this domain-engineered single crystal. The temperature dependence of the domain configuration revealed that the volume fraction of the MC phase decreases with temperature accompanied by the reduction of ɛ33T,d31, and k31 due to the substantially smaller intrinsic properties of the T phase.

关键词： Electric polarization Ferroelectricity Phase transitions Piezoelectricity Ferroelectrics Piezoelectrics Relaxor ferroelectrics Polarization

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Ultrasonic guided waves sensing using optical fiber sensor 7

Ultrasonic guided waves sensing using optical fiber sensor

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7th International Conference on Structural Health Monitoring of Intelligent Infrastructure, SHMII 2015

作者： Zhou, W. Li, H. Dong, Y. Wang, A. Key Lab. of Structures Dynamic Behavior and Control of the Ministry of Education Harbin Institute of Technology Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China National Key Laboratory of Science and Technology on Tunable Laser Harbin Institute of Technology Harbin150001 China

Optical fiber sensors have been proven that they have potential as ultrasonic guided waves sensor for structural health monitoring and damage detection. They can be used to receive acoustic emission signals from dynamic structural damages or guided waves propagating in waveguide and excited by ultrasonic actuators. Optical fiber sensors based on Mach-Zehnder interferometer were investigated in this work. Their sensing properties were explored experimentally using Lamb waves excited by a piezoelectric wafer in an aluminum plate. Spiral shape with different size was selected to increase their sensitivity. Experiments were also conducted to examine the voltage responses received by this type of sensor, and investigate results of tuning frequency. © 2015, International Society for Structural Health Monitoring of Intelligent Infrastructure, ISHMII. All rights reserved.

关键词： Structural health monitoring

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Numerical simulations of shake-table experiment for dynamic soil-pile-structure interaction in liquefi able soils

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Earthquake Engineering and Engineering Vibration 2014年第1期13卷 171-180页

作者： Tang Liang Baydaa Hussain Maula Ling Xianzhang Su Lei Key Lab of Structures Dynamic Behavior and Control(Harbin Institute of Technology) Ministry of Education School of Civil Engineering Harbin Institute of Technology

A shake-table experiment on pile foundations in liquefi able soils composed of liquefi able sand and overlying soft clay is studied. A three-dimensional(3D) effective stress fi nite element(FE) analysis is employed to simulate the experiment. A recently developed multi-surface elasto-plastic constitutive model and a fully coupled dynamic inelastic FE formulation(u-p) are used to model the liquefaction behavior of the sand. The soil domains are discretized using a solid-fl uid fully coupled(u-p) 20-8 noded brick element. The pile is simulated using beam-column elements. Upon careful calibration, very good agreement is obtained between the computed and the measured dynamic behavior of the ground and the pile. A parametric analysis is also conducted on the model to investigate the effect of pile-pinning, pile diameter, pile stiffness, ground inclination angle, superstructure mass and pile head restraints on the ground improvement. It is found that the pile foundation has a noticeable pinning effect that reduces the lateral soil displacement. It is observed that a larger pile diameter and fi xed pile head restraints contribute to decreasing the lateral pile deformation; however, a higher ground inclination angle tends to increase the lateral pile head displacements and pile stiffness, and superstructure mass seems to effectively infl uence the lateral pile displacements.

关键词： liquefaction pile pinning soil improvement pile deformation earthquake nonlinear fi nite element method shake-table experiment

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