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Chen X.,Huaqiao University | Chen X.,Nanjing Southeast University | Cai Q.,Huaqiao University | Cai Q.,Key Laboratory for Structural Engineering and Disaster Prevention of Fujian Province | And 3 more authors.
Journal of Hydrology | Year: 2016

It is well established that seismic waves disperse into higher harmonics, thereby generating waves at ultrasonic frequencies within layers. Field tests and laboratory investigations have demonstrated that ultrasonic stimulation can enhance particle release in natural systems, but the intrinsic mechanisms of ultrasonic waves are not fully comprehended. We investigated the underlying mechanics of such waves by generating increasing ultrasound stimulation upon enhanced release of trapped particles from pores. Experiments were conducted using a novel soil column apparatus that is capable of applying ultrasonic waves, controlling the confining pressures, regulating the soil column height, and controlling the temperature of the soil column. Particles with median diameters of 9.63 μm in the range of 1-35 μm were evaluated in a series of tests under three flow rates. Stimulations were applied for 60 s at power levels of 600, 1000, 1400, and 1800 W. The particle concentration in the effluent during each test was recorded. The laboratory results showed that hydrodynamic drag was the dominant force in pre-stimulation particle release. However, the flow rate was found to be constant in pre- and post-stimulation phases, and cavitation caused by ultrasound stimulation was judged to be the most likely reason for post-stimulation particle release. Furthermore, the nature of the post-stimulation particle release was distinctly different from that of the pre-stimulation release, in that an abrupt concentration change was observed in each stimulation application. These abrupt concentration changes were attributed to ultrasound stimulation, but the release concentration and the duration of particle release were controlled by the power of the ultrasound stimulation and the quantity of particles deposited in the sand. Furthermore, the release rate coefficient first decreased and then increased as the number of ultrasound stimulations increased. Two mechanisms of particle release were identified that could explain the rate change: (1) only particles deposited in the porous medium by fouling mechanisms could be released by ultrasound stimulations at power levels below a certain critical value, or (2) ultrasound stimulations at power levels above a certain critical value are sufficient to change the structure of the porous medium, producing more dead-end pore openings that allow particle flow through the porous medium. The results presented are unique in indicating that successive particle release can be induced using increasing ultrasound stimulation. © 2015 Elsevier B.V.


Peng X.,Huaqiao University | Peng X.,Key Laboratory for Structural Engineering and Disaster Prevention of Fujian Province | Shi W.,Huaqiao University | Hua C.,Huaqiao University | Hua C.,Hongyu Architectural Design Institute Co.
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition) | Year: 2015

The world cultural heritage-Fujian earth building has often affected by the typhoon and extreme weather, and the durability of its structure has decreased continuously. Using statistical methods of soil and water loss and field test, rammed earth erosion loss rule and loss measurement formula were studied, revealing the loss mechanism of rammed earth by wind and rain erosion, rainfall infiltration wall material weakening performance, and wind driven rain hiting the walls, resulting in material particle splash erosion and denudation. And it was proved that the raindrop impact load is the direct motive erosion loss. Combined with the local meteorological data, the rammed earth annual erosion was calculated, which can be used to predict the residual life of the wall, and to provide a adaptive scientific basis for protection of Fujian earth building. ©, 2015, Editorial Department of Journal of Sichuan University. All right reserved.


Gao Y.,Huaqiao University | Gao Y.,Key Laboratory for Structural Engineering and Disaster Prevention of Fujian Province | Liu Y.,Huaqiao University | Liu Y.,Key Laboratory for Structural Engineering and Disaster Prevention of Fujian Province | And 2 more authors.
Advances in Science and Technology of Water Resources | Year: 2016

A two-dimensional (2D) viscoelastic boundary element, VS2D2Bar, was developed based on the open source finite element package OpenSees. The applicability of the 2D viscoelastic boundary element was verified with a numerical example, and it was applied to the seismic response analysis of a gravity dam. Numerical results demonstrate that the peak dynamic response of the dam body according to the viscoelastic boundary element model greatly decreases in contrast to that obtained from the massless foundation model with fixed boundary conditions. As a result, the radiation damping effect of the infinite foundation should be considered in seismic response analysis of gravity dams. The results also show that OpenSees is applicable to the seismic response analysis of gravity dams. With a high efficiency in programming and debugging, OpenSees can be easily extended to the static and dynamic analysis of complex hydraulic structures. © 2016, Editorial Board of Advances in Science and Technology of Water Resources, Hohai University. All right reserved.


Wu H.,Huaqiao University | Wu H.,Key Laboratory for Structural Engineering and Disaster Prevention of Fujian Province | Guo Z.,Huaqiao University | Guo Z.,Key Laboratory for Structural Engineering and Disaster Prevention of Fujian Province | And 7 more authors.
World Information on Earthquake Engineering | Year: 2015

To achieve the feasibility of fast rehabilitation for shear wall structures or frame shear wall structures, the steel coupling beams with replaceable techniques are used. FEM models for replaceable steel coupling beams with different assembling details were established using ABAQUS to investigate the influence of assembling details and span-depth ratios to the seismic behavior of specimens. It is indicated that the replaceable part, which is mainly used for energy dissipation is much more easier to commence yielding for steel coupling beams assembled with bolted end plates than that with bolted splicing plates when the span-depth ratio of specimens is less than 2, and the initial stiffness, strength and energy dissipation capacity of the former specimens are also more better than latter. The steel coupling beams assembled with bolted end plates exhibits poor seismic behavior when the span-depth ratio exceeds 3, mainly because of the relative deformation of end plates due to the axial elongation of bolts. The relative deformation of end plates can be confined due to the lengthening of end plates and increasing of the bolts' number, thus the seismic behavior of the beams can be improved. The steel coupling beams assembled with bolted splicing plates have larger initial stiffness and strength than the beams with other assembling details. Based on the parametric study, the assembling details of steel coupling beams for different engineering applications were proposed. This paper can be referenced by the building industrialization and fast rehabilitation of structures experience seismic damage. ©, 2015, Science and Technology Periodical Press. All right reserved.


Saturated soil column experiments were conducted to determine the influences of flow direction, flow rate, and particle-size distribution characteristics on the transport and deposition of particles in saturated porous media. Two bimodal-distribution particles and one unimodal-distribution particle were employed in these studies, and soil column experiments were performed using a variety of particle-size distributions and flow conditions. In addition, a modified convection–dispersion model for particle transport and deposition was developed, considering dispersive flux on the deposition kinetics. The experimental breakthrough curves fit well with the analytical solution of the modified convection–dispersion model. Regardless of particle-size distribution, the particles’ mean velocity increases linearly with the mean interstitial fluid velocity. The particles’ mean velocity in horizontal flow is lower than that in vertical flow. Furthermore, dispersivity decreases with increasing flow rate in vertical flow. The range of the particles’ dispersivity in vertical flow is larger than that in horizontal flow. Finally, the rate of particle deposition increases with particle size. Overall, this study highlights the complicated interdependence of the effects of flow rate, flow direction, and particle-size distribution on particulate transportation and deposition. © 2014, Springer-Verlag Berlin Heidelberg.


Li H.,Huaqiao University | Li H.,Key Laboratory for Structural Engineering and Disaster Prevention of Fujian Province | Luo Y.,Tongji University | Li D.,Hefei Administrative Bureau of Key Engineering Project | Ding D.,China Wuzhou Engineering Design Group Co.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2015

The degradation characteristics of stiffness and strength, load-displacement curves, failure shape and stress distribution of 16 steel box columns and 85 numerical calculated members were investigated. The interactive mechanism between local buckling and overall instability of steel box beam-columns under cyclically lateral loading was also discussed. Based on the regressive results of experimental and numerical data, the formula of stability bearing capacity of steel box beam-columns under cyclically lateral loading was fitted. The results show that when the axial compression ratio of steel box column is less than 0.1 or the maximum slenderness ratio is less than 40, the local buckling of plate has dominated effect on the mechanical behavior of steel box columns. The width-to-thickness ratio of web plate has main effect on the ductility and the degradation characteristics of stiffness and strength of the columns. While the axial compression ratio of steel box column is more than 0.2 and the maximum slenderness ratio is more than 80, the overall instability has dominated effect on the mechanical behavior of steel box columns. The effects of axial compression ratio and slenderness ratio on the mechanical behavior of the columns are both conspicuous. ©, 2015, Central South University of Technology. All right reserved.


Liu Y.,Huaqiao University | Liu Y.,Key Laboratory for Structural Engineering and Disaster Prevention of Fujian Province | Guo Z.-X.,Huaqiao University | Guo Z.-X.,Key Laboratory for Structural Engineering and Disaster Prevention of Fujian Province | And 2 more authors.
Gongcheng Lixue/Engineering Mechanics | Year: 2015

Five prefabricated RC columns linked at the middle region and two monolithically casted RC columns were tested under axial compression loads to investigate the influence of linkage site curing time on the axial compression performance of specimens at different stages of construction. The results indicate that obvious differences in axial compression performance for prefabricated RC columns exist at different construction stages. The axial strength of the prefabricated RC column without casting concrete at the linkage site is 46.2% that of the monolithically casted RC columns. After concrete is cast, the axial strength of prefabricated RC columns increases with the increase of curing time for the linkage site. When the curing time for the linkage site is 28 days, the axial strength of the specimen is 87.9% that of the monolithically casted RC columns. Due to the pressure exerted at the cone-shaped cross section of the upper columns, the linkage site of the prefabricated RC columns expanded laterally, which gave rise to the confinement of the concrete by the stirrups. The failure modes of the specimens show distinct plastic characteristics compared with those of the monolithically casted RC columns. The mechanical analysis of axial compression for prefabricated RC columns was carried out and a calculation method for axial strength is proposed. Calculated results show good agreement with test results. This paper can be referenced for the engineering practice of prefabricated RC structures. © 2015, Engineering Mechanics Press. All right reserved.


Hou W.,Huaqiao University | Hou W.,Key Laboratory for Structural Engineering and Disaster Prevention of Fujian Province | Shi Q.-X.,Xi'an University of Architecture and Technology | Guo Z.-X.,Huaqiao University | Guo Z.-X.,Key Laboratory for Structural Engineering and Disaster Prevention of Fujian Province
Gongcheng Lixue/Engineering Mechanics | Year: 2013

In order to study the failure mechanism and seismic performance of reinforced concrete core walls under different parameters, the concrete core walls under static horizontal loads are simulated using nonlinear analysis and performance assessment program PERFORM-3D. The validity and accuracy of an elastic-plastic model is verified by the comparison between the analytical predictions and test results. On this basis, the parameters on the seismic behavior of reinforced concrete core walls are analyzed, including the effects of axial compression ratio, coupling beam span-depth ratio, coupling beam longitudinal reinforcement rate and height to width ratio. According to the calculation results, the bearing capacity of concrete core walls is improved with the increase of the axial compression ratio. However, when the value of a test axial compression ratio reaches 0.5, bearing capacities are reduced. Deformation capacity reduces with the increase of axial compression ratio. With the increase of height to width ratio, the bearing capacity of concrete core walls is reduced but the deformation capacity is improved significantly. Moreover, the failure mode of core walls with different high aspect ratios is changed. With the increase of coupling beam stiffness, the bearing capacity of core walls increases while ductility deformation capacity reduces seriously. In addition, based on the elastic-plastic damage analysis of a core walls model, the damage development order and component yield situation of core walls are obtained.

Loading Key Laboratory for Structural Engineering and Disaster Prevention of Fujian Province collaborators
Loading Key Laboratory for Structural Engineering and Disaster Prevention of Fujian Province collaborators