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Characterization of frozen soil-cement mixture for berm construction in cold regions

Research in Cold and Arid Regions 2015年第4期7卷 300-306页

作者： HaoLin Yu XinLei Na ZhaoHui Joey Yang Key Lab of Structures and Dynamic Behavior and Control of Ministry of Education School of Civil EngineeringHarbin Institute of Technology Visiting Scholar University of Alaska Anchorage University of Alaska Anchorage

Lagoon berms in western Alaska are difficult to design and build due to limited resources, high cost of construction and materials, and warm permafrost conditions. This paper explores methods to treat locally available frozen materials and use them for berm construction. The goal is to find an optimized mix ratio for cement and additives that can be effective in increasing the strength and decreasing the thaw settlement of an ice-rich frozen silty soil. Soil of similar type and ice content to the permafrost found at a project site in Eek, Alaska is prepared in a cold room. The frozen soil is pulverized and cement, additives and fibers are added to the samples for enhancing shear strength and controlling thaw settlement. Thaw settlement and direct shear tests are performed to assess strength and settlement characteristics. This paper presents a sample preparation method, data from thaw settlement and direct shear tests, and analyses of the test results and preliminary conclusions.

关键词： frozen soil stabilization thaw settlement shear strength Portland cement

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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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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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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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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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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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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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Axial compression performances of concrete filled flax-basalt hybrid fibers reinforced FRP tubes 12

Axial compression performances of concrete filled flax-basal...

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Joint Conference of the 12th International Symposium on Fiber Reinforced Polymers for Reinforced Concrete structures, FRPRCS 2015 and the 5th Asia-Pacific Conference on Fiber Reinforced Polymers in structures, APFIS 2015

作者： Xia, Yuanyuan Xian, Guijun Li, Hui Key Lab. of Structural Dynamic Behavior and Control Harbin Institute of Technology Ministry of Education Harbin150090 China School of Civil Engineering Harbin Institute of Technology Harbin150090 China

Flax fiber reinforced polymer (FFRP) composites could be used in civil engineering as structural materials. To improve the mechanical properties and durability of FFRP, flax-basalt hybrid fiber reinforced polymer (HFRP) composite was developed. In the present study, unidirectional HFRP tubes were prepared with a winding process, and the compression performances of the concrete filled HFRP tubes were investigated. HFRP coupon was prepared and tested in tensile properties. The tensile results of the HFRP plate coupons shows linear in stress-strain, and hybrid with basalt fiber enhances the elongation at break remarkably. The tensile strength and modulus of the HFRP follow the rule of mixture. The concrete filled HFRP tubes exhibited much improved ultimate strength and ductility compared to those with the flax fiber tubes. The axial compression stress-strain curves were analyzed with the existing models. The coefficients of confinement of HFRP were higher than those of glass or carbon fiber based FRPs. © APFIS 2015. All rights reserved.

关键词： Fiber reinforced plastics

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Shape optimization based on ANSYS

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Journal of Information and Computational Science 2015年第11期12卷 4291-4297页

作者： Cui, Guoyong Cui, Changyu School of Civil Engineering Harbin Institute of Technology Harbin China Key Lab of Structures Dynamic Behavior and Control of China Ministry of Education Harbin Institute of Technology Harbin China

ANSYS has been used for structural analysis as mature finite element analysis software. This paper presents a shape optimization method which treats the ANSYS software as subroutines, therefore, eliminating the onerous compiling finite element programs and the complex theoretical derivation. The difference method sacrifices some calculation accuracy when calculating the partial differential, but it can optimize the more complex and practical problems. If the increment is small enough when calculated the partial differential, the precision can be guaranteed. Shape optimization of free-form surface is presented with the strain energy and the buckling load as objective function and optimum program complied in FORTRAN language. Studies shows that the present method is simple and effective which can be used for arbitrary structure shape optimization the average and maximum stress, the average and maximum displacement are reduced with the decrease of the strain energy and the increase of the buckling load;The ultimate strength has a large increase after optimization with considering material non-linearity and geometrical non-linearity. ©, 2015, Binary Information Press. All right reserved.

关键词： Shape optimization

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Effect of glass fiber fabrics isolation layer on the adhesion bond behaviours between CFRP plates and steel substrates 12

Effect of glass fiber fabrics isolation layer on the adhesio...

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作者： He, Jun Xian, Guijun Li, Hui Key Lab. of Structural Dynamic Behavior and Control Harbin Institute of Technology Ministry of Education Heilongjiang Harbin150090 China School of Civil Engineering Harbin Institute of Technology Heilongjiang Harbin150090 China

Strengthening of steel structures with adhesively bonded carbon fiber-reinforced polymer (CFRP) plates has received extensive attentions in recent years. Since galvanic corrosion occurs between CFRP and the steel, glass fiber fabrics (GFF) are generally applied as an isolation layer. The present paper studied the effects of GFF on the bonding performances (such as ultimate strength and bond-slip relationship) between the CFRP and steel substrates. A series of pull-off tests were performed with variables of the thickness of the GFF layer. The testing results shows that the failure mode is the CFRP plate delamination failure, rather than cohesive failure. Based on this failure mode, the bondslip relationship curves is also trapezoidal shape for ductile adhesive and the thickness of the GFF isolation layer has no influence on the bonding performances. © APFIS 2015. All rights reserved.

关键词： Plates (structural components)

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