Seismic Analysis Of Flip Bucket Based On Endurance Time Method

The southwestern China is rich in water resources,and the topographical conditions are conducive to the construction of water conservancy projects.Therefore,a large number of hydropower stations have been built and put into production,and have become an important hydropower energy output base for the “West-East Power Transmission” project.According to the theory of plate motion,the southwestern region is located at the junction of the Asia-Europe plate and the Indian Ocean plate,where is a high-intensity seismic zone in China.The earthquake poses a serious threat to the structural safety.The seismic performance of hydraulic structures is related to the safety of national life and property,and must be paid enough attention to the seismic reinforcement design.Taking the Lianghekou Hydropower Station as an example,the finite element software Abaqus is used to analyze structure's seismic response and evaluate the effect of reinforcement measures.The main work of this paper is:1.Considering the issue of structure-foundation interaction,intercepting finite area foundation with artificial boundary used to replace infinite foundation.The 3D consistent viscous-spring artificial boundary can simulate the scattering effect of seismic waves and the elastic recovery ability of semi-infinite media.Adding the boundary unit to model is convenient,which only set its spring and damping parameters,and the artificial boundary have good applicability and sufficient accuracy.Therefore,the 3D consistent viscous-spring artificial boundary is used as a local artificial boundary,which is applied to the interaction of structure-foundation.2.The background and concept of the endurance time analysis are introduced,and the generation method of the ET accelerogram is explained.Based on the code for seismic design of hydraulic structures of hydropower project,three ET accelerograms are generated.Then ET accelerograms are converted into equivalent loads and applied to the 3D consistent viscous-spring artificial boundary to analyze the stress,displacement,dissipation of energy and damage development of the structure.3.Considering the effect of steel-concrete interaction,post-cracking stiffness of concrete is modified to simulate the effect of tension stiffening.Based on separate reinforced concrete model,the seismic analysis of the structure under different reinforcement ratios is carried out.The influence of reinforcement ratios on acceleration magnification,damage expansion,energy dissipation,were studied.The results show that the reinforcement can weaken the development of damage,improve the stress condition,but it has little effect on stress,displacement and acceleration.