Analysis Of Dynamic Characteristics Of Hydropower House Considering The Connection Mode Of Roof Truss And Bent Column

The scale of China's hydropower projects continues to increase.The powerhouse structure of hydropower stations,especially the structure of the ground powerhouse,can withstand various loads,and its dynamic and static safety should be focused on.The mechanical properties of the connection of the plant have an important influence on the dynamic and static characteristics of the plant,but there are few research results on the bolt connection form of the superstructure of the plant.Generally,the rigid or hinge support form is used,but the connection slip and bolt preload force cannot be considered the influence of factors has a great academic and engineering significance for detailed simulation.This article studies the influence of different simulation methods of roof frame and bent frame column bolt connection on vibration characteristics,and discusses more accurate and applicable simulation methods.The thesis mainly carried out the following research work and got the following conclusions:1.The simple beam-column models of two bolt simulation methods of virtual medium method and hinged connection were established respectively,and the first-order natural frequency was calculated by finite element method,and compared with the theoretical solution.The derivation of the theoretical solution is based on the simplified hinge connection,assuming that the frame height varies randomly between 8-12 m,and the remaining conditions are the same.The results show that the hinged connection results are basically consistent with the theoretical solution,and the simulation results of the virtual medium method have certain errors,but the causes of the errors are various and the absolute value of the error is small.Therefore,it can be considered that the virtual medium method is feasible to simulate the bolt connection of.2.Simulate the connection of roof truss and upstream and downstream bent column structure with virtual medium method and two bolt simulation forms of upstream end simple support and downstream end hinge support,and calculate the self-vibration characteristics,vibration load and seismic load effect of hydropower plant structure under the dynamic response under the analysis,it is concluded that under the vibration load of the unit,the displacement and stress changes of the two schemes are the same.The vertical tensile stress and the first principal stress at the lower part of the column structure are too large and should be paid attention to;horizontal bidirectional seismic load Under the action,the displacement of the upper bent frame column is relatively large,and the dynamic response of the generator floor structure is more prominent,which should be paid attention to during the design process.3.The virtual medium method is used to simulate the bolt connection of roof truss and bent column under different preload conditions,and to calculate and analyze the natural vibration characteristics of the hydropower plant and the vibration response under the operating conditions of the unit.It is concluded that the difference in preload force to the self-vibration characteristics have little effect;Under the operating conditions of the unit,the upper structure of the hydropower plant workshop increases with the bolt preload,and the structural connection stiffness increases,so that the vibration stress increase,which is detrimental to structural safety.However,if the preload force is too small(or the bolt is loose),the integrity will be reduced,and some bolts will be damaged due to uneven stress.During the design and construction,the preload force of the bolt connection should be reasonably determined and effectively ensured.The effect of preload should also be reasonably considered and simulated.4.In order to investigate the influence of ground motion loads on the dynamic characteristics of the powerhouse structure under the bolt connection under different earthquake intensities,the dynamic responses of the hydropower plant's powerhouse at an earthquake intensity of 6,7,8,and 9 degrees were calculated.Earthquake Intensity The dynamic displacement and dynamic stress under the action of seismic load increase substantially linearly,and there is no sudden increase when the earthquake intensity increases sharply,it shows that there is no slip or failure of the bolt connection,and it also shows that the virtual medium method can better simulate the vibration characteristics of the combined structure of the plant.