Research On Composite Structural Analysis And Dynamic Identification Of Hydropower House

With the increasing of the single-machine capacity and the physical dimension, a number of new problems of hydropower stations, not only about the structural design, but also the steady operation, were put forward. In this paper, research have been made fully and systematically on the effects of different modes of stay bearings and water temperature on pressure preservation spiral cases composite structures, concrete damage analysis of spiral case composite structures, dynamic parameters identification of hydropower house and coupled vibration of hydropower houses and units. The findings can be taken as significant references when making the structural design and the vibration characteristics of hydropower houses, the main part of which are listed as below.Using the technique of three-dimensional finite element and emulation, we have studied the different stay bearing modes of pressure preservation steel spiral cases in detail. Results show that the influence of the modes on stresses of concrete under steel spiral cases can not be neglected.During the construction of Three Gorges project, heat and pressure preservation was firstly put forward in order to reflect the response of spiral case composite structures. Depending on theoretical derivation and numerical computation, the relationship between water temperature and water pressure is analyzed. From the results, we can see that water temperature has great effect on the deformation of steel spiral cases, and the water temperature change is inversely proportional to the water head change within a certain range.As one of the theoretical bases and means of quantitative analysis for material and structural strength and failure mechanism, damage mechanics is widely used in the analysis of concrete material and structures. Based on the current concrete specification and the theory of the damage finite element, the three-dimensional orthotropic constitutive model is derived. Using ANSYS as the platform, a program in ANSYS Parametric Design Language (APDL) is compiled to implement the ideas.The program is applied to the damage calculation of the peripheral concrete stresses of steel spiral case in a hydropower station, and reasonable results are given. Dynamic parameter identification of large-scale and sophisticated structures is an important subject in civil engineering domain. On the basis of Morlet waveletstransform and modified genetic algorithm which adopts partheno operator, a dynamic parameter identification model is constructed. Through invoking some software, such as ANSYS, with C++ language, the system is programmed and intelligentized. This means offers a powerful way to identify dynamic parameters of large-scale and sophisticated structures.Field vibration test is the main method to monitor hydropower houses and units vibration and to testify numerical calculation. Relying on the field vibration trials of a large power house at dam-toe and its unit, the coupled system vibration characteristics of the house and the unit can be found. A coupled model is built up, and with the application of the system identification method, the axial hydraulic thrust of water turbine can be identified. This gives a new way to calculate axial hydraulic thrust during the operation.The hydropower house of two-row placed units is a special structure style. Analyzing actual signals by the methods of wavelets transform and the Fourier transformation, combining with numerical calculation and theoretical analysis, the dynamic characteristics and their interactions among superstructure, the bracing structures and water pressure fluctuation of the double draft tube are studied. Meanwhile, the frequency empirical equation of vortex belt and fluctuate whose frequency is close to the turn frequency in draft tubes are deduces.