Papers by Keyword: Model Experiment

Abstract: According to the element-length errors inevitably existing in the real cable-bar tensile structures, numerical analysis on the element-length error sensitivity was firstly carried out with the help of ANSYS software, where the element length change was simulated by imposing the temperature affection. Then a cable-bar tensile structure model with the diameter of 5.0m was designed and fabricated. The element-length errors were simulated by adjusting the element length and each member in one unit was elongated 3mm respectively to explore the error sensitivity of each kind of element. The numerical analysis and experimental results indicated that different element has different error sensitivity. The error sensitivity of the hoop cables was the most sensitive, the ridge cables and diagonal cables were lower and the struts were the lowest. The experimental results performed almost consistent with the analytical results, which indicated that the proposed error sensitivity analysis method is accurate and the design of the model is effective.

Abstract: A cable-strut tensile structure model with the diameter of 5.0m was designed and made to study the prestress and static behavior on the base of theory analysis. New schemes of the boundary compression ring, the cables and struts with the adjustable length, the connection nodes were designed and the least square method to fit the element force and strain curve was proposed. The initial prestress distribution and the responses of the model under full-span node load, half-span node load and 1/4-span node load were investigated. The experimental results indicate the cable-strut tensile structure will achieve the designed initial prestress while every element was tensioned to designed length. The outer planar stiffness of the structure is poor and easy to lost stability when subjected to asymmetric loads. The measured values and computed ones are almost consistent, which indicates the validity of the model design and the accuracy of the proposed methods.

Abstract: The steel-concrete joint section is a critical structure of load transmission in cable-stayed bridge girder. Under the requirement of calculation efficiency, correct numerical simulation is an important method to acquire the inter stress and deflection on the joint section of cable-stayed bridge girder. Taken the steel-concrete joint section finite element analysis of a cable-stayed bridge as an engineering background, the whole process simulation method of cable-stayed bridge steel-concrete joint section is introduced, which considering the nonlinear bond slippage effect and ANSYS program is employed. The effect on mechanical behavior and damage pattern of structures is also compared among different stud constitutive relation. The calculation results show that the numerical results of nonlinear stud joint section FE model are in a good agreement with the model experiment testing data. The equivalent stress of bearing plate from the simulation is relatively high under the ultimate load, and, the crack distribute at the whole concrete section. The calculation results of linear stud FE joint section model are close to the results of nonlinear stud joint section FE model under the design load. Under the ultimate load, the choice of different stud shear stiff model has effect on the concrete at crack initial moment. While after the most concrete crack, there is little difference on the crack distribution between the nonlinear and linear stud joint section FE model.

Abstract: Accompanied by the substantive construction of domestic ports, the negative skin friction on pile becomes a common problem. In order to provide references for the related experiment research in the future, the designs of model experiments reported in the literatures were emphatically analyzed and compared. Compared to conventional pile model test, the model test on negative skin friction on pile needs to apply load on soil surface and it is difficult to simulate large surcharge by conventional test methods. An experimental scheme which could produce large surcharge load by conventional test conditions is given in this paper. Pile stress, displacement of pile top and layered settlement of soil was tested under different surcharge level. The depth of neutral point and the group effect of NSF are discussed.

Abstract: Micro antislide pile is more and more widely used in the emergent repair of landslide. But systematic and complete understanding about its antislide and failure mechanism is still insufficient; in addition, the theoretical study lags far behind the practical application. Through largesized physical model experiment and numerical simulation, the paper analyses the failure mechanism and failure mode of micro antislide piles in soil slope. The experiment and numerical simulation prove the fine antislide effects of micro piles, which allows large displacement of sliding mass and can delay the collapse of slope effectively, so it is applicable for emergent repair. The deformation of micro antislide pile is “S” shape, which is the tensile failure and shearcompression failure of concrete by bending deformation. At the same time, tensileshear failure happens on the reinforced bars. The largest shear of pile is located on the sliding surface and all the largest bending moment is above the sliding surface. The bending moment on the first row of plies is the largest followed by the third row and that on the second row is the smallest.

Abstract: A 1:10 tank-car 2D fluid simulation model based on the computational fluid dynamics is established, and exchange the data with tank-car vibration model while simulating. In the paper, the 2 dimension fluid-structure coupling tank-car which owns two DOF is simulated, and the affect of fluid sloshing to tank-car longitudinal vibration is analyzed through the coupled vibration experiment. In the simulation and experiment, fluid sloshing increased the tanker longitudinal vibration acceleration amplitude and slowed response time is obtained through analyzing the difference between the different volume of fluid and the relevant solid without sloshing, and the difference of longitudinal vibration between full tank and non-full tank is significant.

Abstract: The flow characteristics of fish-bone type dividing dike is very complicated. By model experiment, this paper deeply research in water surface line, velocity distribution and the flow regime of fish-bone type dividing dike. It can Provided the certain basis for the design of fish-bone type dividing dike, such as a fishbone in dam engineering stab dam ridge direction, length, and layout spacing, length.

Abstract: A comprehensive understanding of the inherent link between in-situ growth kinetics of a polymer spherulite and high-pressure constraints under controlled temperature is concerned. As a matter of fact, while the link with temperature is well illustrated, little comprehensive study has been conducted to quantify the effect of pressure. This is yet required to model ‘extreme’ polymer processing conditions.Mainly, the experimental set-ups developed to reproduce the pressure effect can be classified into four families: “simple” cells, dilatometric set-ups, differential thermal analysis and diamond anvil plus in-situ measurement. In this context, an original model experiment, named CRISTAPRESS, has been constructed. The cell design exploits the optical properties of semi-crystalline spherulites. Time-resolved light depolarizing microscopic observations are conducted concomitantly with a fine PVT control, for high pressure up to 200 MPa and temperature up to 300 °C. The physical analysis of isothermal and isobaric holding of a model polymer shows the influence of temperature and pressure on the key kinetic parameters of crystallization, i.e., the growth rate and the number of activated nuclei, as well as on the subsequent morphologies. Simple modeling dealing with the Avrami equation and the Hoffman & Lauritzen theory is established.

Abstract: This study investigates the steady-state flow pattern of throttled surge tanks with standpipe, especially the coefficients of local head losses. The experiments were carried out, and FLUENT, which solves the Reynolds-averaged Navier-Stokes equations, was applied to experimental data for solving flow fields. The results show the computed and measured local head losses agree closely. The coefficients of the local head losses are linearly proportional to diameter ratio with the slope of 0.037. The anticlockwise backflow region occurs in the standpipe, and it induces inflow into and outflow from the standpipe. For hydraulic engineering projects, the discharge into and out from standpipe does not change with velocity and diameter of main conduit, but are linearly proportional to diameter ratio with the slope of 0.0378.

Abstract: To reveal the process of geomorphic evolution of debris flow on slope, the qualitative-semi-quantitative model experiment was built from experimental model, characteristics of soil and rainfall scheme. The results indicate that the essence of geomorphic evolution of debris flow on slope is the interaction of soil and water. And the change of geomorphology is reflected by the elevation of topsoil. In antecedent rainfall, the elevation of topsoil is in increasing trend generally except some parts. During short heavy rainfall, the soil creeps intensively, mixes with water and becomes fluidization gradually. The elevation of topsoil on the top is decreasing generally, while on the button, the elevation is increasing. Moreover, because water infiltrates into slope and interacts with soil needing a period of time, the change of geomorphology falls behind the rainfall process.