Applied Mechanics and Materials Vols. 638-640

Abstract: Using ABAQUS to analyze the response of tall building under expected rare earthquake, usually the gravity field can be derived by the implicit method as the initial condition of simulation for seismic wave executed in the explicit method. In practice of engineering, oscillation of gravity often occurred at the beginning of explicit method which would lowered accuracy and reliability of time-history results. Three main reasons including stress level, constitutive model and the software ABAQUS itself are researched in this paper by numerical examples, and an extra analysis step is proposed for eliminating oscillation before loading the seismic wave.

Abstract: Governing equations of 1D high-order numerical manifold method with partially overlapping covers have been deduced by the general method of weighted residuals. By using the proposed method, a highly oscillatory differential equation has been solved. In addition, a posteriori error method is adopted for evaluating the accuracy of the algorithm. Meanwhile, several factors affect the accuracy are also discussed. The results indicate that accuracy of solution increase with the decrease of overlapping ratio and the order of cover function. When higher order cover function such as 6th is used, higher accuracy will matched even for second derivative of unknowns. This paper attempts to enrich the theory and practical field of the NMM.

Abstract: Fatigue of steel and other metal materials focused on fatigue strength and fatigue damage accumulation in two ways. Continuous hot air axially deformed bars fatigue tests showed that fatigue failure often occurs at the maximum defect reinforced, and bending fatigue tests of reinforced concrete structures, fatigue failure often occurs in areas of reinforced concrete curved split effective cross-sectional area decreases place. This paper studies the construction of reinforced fatigue effect on the structural performance and the fatigue reliability theory has some theoretical significance.

Abstract: In this paper, through the comparison of elastic mechanics and material mechanics of rod research methods, understand their common and different points, advantages and disadvantages, and further clarify their respective plays an important role in engineering application.

Abstract: A systematic parametric study was carried out to investigate the elastic and elastic-plastic buckling behaviors of imperfect steel shell subject to axial compression and internal pressure. Studied parameters include the magnitude of internal pressure, steel strength, and ratio of cylinder radius to shell thickness. Design equations were proposed for calculating the elastic and elastic-plastic buckling strength of imperfect steel shells under combination of axial compression and internal pressure. The buckling strength predicated by proposed equations agrees well with that from the numerical simulation.

Abstract: The cylindrical shells under global bending with different geometric parameters display different failure behavior. The size of typical buckles under axial compressive stress regimes is rather small and extends over a very small zone, with the axial compressive stress reaching the critical value. The first estimate of the elastic buckling strength in bending is the condition in which the most compressed fiber reaches the buckling stress for uniform axial compression. For short cylinders, local bifurcation buckling occurs at the middle of the most compressed side of the shell, and geometric nonlinearity has a little effect on the buckling strength, while for medium-length and long cylinders, the geometric nonlinearity and the ovalization of the cross-section should be considered. This paper explores the failure behavior in elastic cylinders in pure bending.

Abstract: By taking the 3D Laplace equation as the basic governing equation, a mathematical model with respect to the interaction between linear waves and arbitrary 3D structures was founded. With an example of wave action with four cylinders, numerical results show that when incident wave direction is 22.5°, wave force F_x on 1# cylinder and 2# cylinder is the biggest and when incident wave direction is 0°, wave force F_x on 3# cylinder and 4# cylinder is the biggest; wave force F_y and the wave height on origin point increases with incident wave direction increasing for the given layout and incident wave conditions.

Abstract: In view of the question that the inlet boundary conditions of turbulence information for the large eddy simulation process is difficult to be settled, the target wind field was divided into blocks along the height direction firstly. Under the assumption of the same height and its nearby area, fluctuating wind field characteristics are the same, the one-to-one relationship between time-history data and the target area was established, using the classical WAWS to simulate the fluctuating time-history data of wind field. Then the time-history data were given to the homologous grid of the target wind field during the process of large eddy simulation, and fluctuating information of the large eddy simulation in the whole entrance was obtained consequently. Finally, a secondary development of the commercial software FLUENT was proceeding, and a simulation of the flow field without any obstacles was established. The fluctuating time-history data were written in by using the method presented in this thesis, and the entrance boundary conditions were generated. By analyzing the wind field’s power spectrum and correlation at different positions, we find that the wind field generated by the method presented in the paper can satisfy the basic characteristic of the fluctuating wind field, and it also provides references for the refine research of the large eddy simulation boundary conditions.

Abstract: Internal waves will break in the process of communication, the broken will make water in upper and lower mixing, which has significant influence on the hydrodynamic and layered characteristics of density stratification of the water. In order to reveal the propagation of internal solitary waves, a 3d numerical wave flume was built. The research of the propagation of internal solitary waves in the regular topography and broken on slopes was based on FLUENT. Comparing the fragmentation degree of different slope angle and researching the energy dissipation of the wave propagation process , which are supposed to successfully match the results with the experiment results, can provide new methods and means for the further study of internal wave breaking characteristics and the improvement of ecological environment of water bodies.

Abstract: In order to point out the main factors in MDOF pseudo-dynamic test design of high-rise flexible, the key points in pseudo-dynamic test design using equivalent MDOF system were analyzed based on the theoretic derivation and numerical simulation, and the problems to notice in test design were pointed out, the pseudo-dynamic test results validity of high piers based on equivalent SDOF system was discussed, and the impact of high mode to the earthquake response of high-rise flexible structure was acquired. The results of numerical simulation of lumped-mass model prove that the contribution of high mode to the displacement of high flexible structure is little, and the displacement is mainly provided by the first-order mode, which is nothing to do with the selection of seismic waves. However, the high mode have great influence on seismic base shear and base moment of high flexible structure, and the influence level is associated with the properties of seismic wave spectrum. Under one specific earthquake wave, the second-order vibration may play a main contribution to seismic base shear and base moment of high-rise flexible structure. Therefore, it is proper to use equivalent two-degree of freedom system in pseudo-dynamic test of high piers. However, if using equivalent SDOF system, the structural displacement response is correct while the strain data and experimental phenomenon may be untrue. The conclusion proposed is significant in guiding the pseudo dynamic test design of high-rise flexible structure and ensuring the rationality of test.