Applied Mechanics and Materials Vols. 226-228

Abstract: In this paper, the elastic stability and elasto-plastic stability analysis on the steel spatial arch truss with 120m span and 0.2 rise-span ratio is carried out with the finite element program ANSYS. In the analyses, three conditions which are the geometric ,the geometric and material nonlinear, double nonlinear under different initial geometric defects are considered. The results show that the instability mode of arch trusses are all asymmetric instability of plane, and that the buckling load of considering double nonlinear is 13.84% that of considering geometry nonlinear, and that the coupling effect of geometry nonlinear and material nonlinear has accelerated reducing the stiffness of structure and bearing stable capacity ,and that the ratio for the buckling load of the four arch trusses with L/500, L/400, L/300 and L/200 initial geometric defects is 1.0: 0.927: 0.904: 0.87: 0.804, and that load-displacement process curves of feature node are the same change for the structures under different initial geometric defects.

Abstract: Downburst winds, which are a source of extreme wind loading and are referred to as high intensity wind (HIW) loads, have caused numerous transmission tower failures around the world. A previous investigation was conducted to study the performance of a transmission tower under downburst wind loading, where the behaviour of the tower was limited to a linear response. In the current study, a nonlinear frame element is used to assess the performance of the tower under downburst wind loading. The behaviour is studied using downburst wind field data obtained from a computational fluid dynamics (CFD) model. In order to assess the geometric nonlinear behaviour of the tower, the results are compared to a previous linear analysis for a number of critical configurations of a downburst. The nonlinear analysis predicted that peak axial loads in certain members can be up to 34% larger than those predicted by the linear analysis.

Abstract: Ring gate of Ahai hydropower Station is known to the highest ring gate in the world. In this paper, it is calculated to the driving loads of the Ahai ring gate by six hydraulic servomotors during a closure without automatic control (i.e. in case of a breakdown of the electrical control system), analyzed the behavior of the operating system of the ring gate closure with the water discharge and closure with three wicket gates not synchronized (i.e. three wicket gates remained accidentally in open position), and finally shown to how the 6 servomotors are synchronized on the basis of the driving loads. There are proved to The feasibility and the credibility of this system of ring gate by using ANSYS to a case.

Abstract: A numerical model has been developed to study wave overtopping of permeable units protected breakwater and water-structure impactions. The numerical model solves the Reynolds Averaged Navier-Stokes equations outside of porous media and solves the spatially averaged Navier-Stokes equations in porous media, respectively. The numerical model is first validated by experimental data. The validated model is then employed to investigate the breaking wave overtopping porous media protected breakwater. The overtopping discharge and impact forces on the structures behind the crown wall in different wave conditions are studied. The increase of wave height brings increasing maximum overtopping discharges and different spatial distribution of water behind the crown wall. The impact forces on the structures are determined by both incident wave height and relative positions of the structures.

Abstract: In order to determine the distribution of wind load on the roof, wind tunnel test and numerical simulation are both carried out. Then the distribution of mean wind pressure under different wind directions is obtained and the features of mean wind pressure are also analyzed. The datas show that wind pressure distribution of the roof is predominantly negative pressure; only a small area of windward side is positive pressure distribution. The peak of negative pressure appears at the roof ridge or windward long eaves, and varies as changes of wind direction. Meanwhile, the comparison between the results of the numerical simulation and wind tunnel test shows that the distribution law of both is almost the same, but in some areas that flow separation is serious, the error is larger. Then the reasons for the error are discussed.

Abstract: Hydraulic support is a key equipment of synthesis mechanization caving coal and safe production in modernization coal mine. In this paper, the parametric finite element model of ZZ10800/22/45 thin bedrock hydraulic support top beam was established by ANSYS Workbench. The distribution of stress and displacement were obtained by static analysis under the both ends load working condition. According to the FEM calculated results, the optimized mathematic model was developed and the hydraulic support top beam was calculated based on Goal-Driven Optimization(GDO) to propose a lightweight design. It is shown that the effects of lightweight design are obvious, as the optimized plan is in accordance with actual work condition by comparing the FEM check verification. This would provide a guidance and reference value for the research and development of hydraulic support products in the future.

Abstract: As an effective reinforce method, the root pile was widely used in the base of buildings for reinforcing. In this paper, the feasibility of application for the root pile to reinforce high embankment is analysed, its stability design and calculation is discussed, and its construction technology is studied. Taking the Peking-Kowloon line K2155+700~+980 as an example, the reinforcement effect is assessed. The research result shows that it is feasible to reinforce high embankment with root pile.

Abstract: Experiments on granite under uniaxial compression at high temperature of 25~850°C and after high temperature of 25~1300°C were conducted to study the effect of temperature on rock strength and deformation quality. The results show that: (1) Fitting curves between temperature strain and thermal expansion coefficient with temperature are closely first order growth exponential function relation at high temperature. Temperature strain has mutagenicity after high temperature, which can not reflect rock deformation law at high temperature exactly. (2)Mechanical properties of granite weak continuously at high temperature. Compressive strength and elastic modulus show second order attenuation trend of exponential law. But mechanical properties show mutation state after high temperature, which is closely related to the alteration of rock crystal form and brittle-ductile transition. Regression curves between compressive strength and elastic modulus with temperature are closely polynomial curve. The results reflect the fundamental regulation of granite’s interior structure changing under the action of different temperature, which will provide some reference value to rock engineering involved in high temperature.

Abstract: Since mudstone interlayer has a big influence on the mechanic property of layered rock salt, and in order to research its law, the mudstone which strength is lower than pure rock is used as a interlayer to make the regular layer of salt formation, then both the uniaxial and triaxial compression test are carried out on the layer of salt formation. The result indicates: (1) As the thickness of interlayer increases the uniaxial compressive strength and elastic modulus of layer type salt decrease. (2) On the condition that the thickness of interlayer does not change, the more the interlayer number, the stronger the uniaxial compressive strength. (3) If the total thickness of interlayer is stable and the interlayer number is same, then as the distance of interlayer increases the uniaxial compressive strength and elastic modulus of layer type salt decrease. The result provides practical value and theoretic basis on the further research of the mechanic property of layered rock soil and on the analysis of the stability of Karst underground salt cavity reservoir.

Abstract: The paper creates a three-dimensional finite element model with the Xihe Project on the Hanjiang River as a background. The space integrated finite element method is applied to analyze the dynamic characteristics of the spatial structure of the riverbed-hydroelectric station. The aim is to calculate and analyze the free vibration characteristics of the whole structure, the dynamic displacement and the dynamic stress under the two typical conditions. The calculation model is effective to consider the interaction of the upstream dam section, the main and auxiliary powerhouse and the downstream water retaining structure, as well as the foundation. The results obtained will be a valuable reference for optimizing the dynamic characteristics of the powerhouse structure of riverbed-hydroelectric station and improving the engineering design.