The Influence Study Of Differences Between Chinese And American Seismic Code On Design Of Powerhouse Of Hydropower Station

The study on seismic resisitance of hydropower projects has always been an important research project.With the development of our hydropower cause expanding to other countries,studying the influence of differences between Chinese and American seismic code on the design and seismic performance of powerhouse structure of hydropower station is of great significance for improving the Chinese seismic code of hydropower projects and promoting the development of our overseas hydropower cause.The differences between Chinese and American seismic code is studied from such aspects as seismic regulation,seismic safety evaluation,reinforcement calculation and effect evaluation of seismic measures,and the problems in seismic design are also discussed.The main research contents are as follows:(1)The similarities and differences of seismic fortification criterion,ground motion parameters,ground motion components and combination,calculation method,calculation model and seismic safety design and evaluation between Chinese and American seismic code are compared and analyzed,which indicate that although there are some differences between Chinese and American seismic code,the theory of design is basically consistent.(2)In order to study the influence of differences between Chinese and American sesmic code on practical project,the seismic calculation,safety evaluation and reinforcement design of a practical diversion-type ground powerhouse are carried out according to Chinese and American code,adopting the mode-superposition response spectrum method.The results indicate that the rigidty of the two-stage seismic fortification criterion of American code is similar and the seismic fortification criterion of Chinese code is much more rigorous than American code in the evaluation of seismic performance of plain concrete structure.And in design of reinforcement,American code is more conservative compared with Chinese code,the calculation reinforcement of American code is larger than that of Chinese code both under the static condition and static and dynamic combination condition.The differences of calculation reinforcement between these two codes is more obvious when earthquake is considered.(3)The seismic measures in weak parts of anti-seism of powerhouse structure are proposed and evaluated according to Chinese and American seismic code.The results indicate that the change of structural seismic response will be different in the evaluation of the impact of seismic measures adopting Chinese and American seismic code,but the conclusion of evaluation is consistent.(4)Compared with the calculation results of different design schemes,it is suggested that the mass of upper structure should be decreased to reduce the adverse influence of whiplash effect under the action of earthquake.And increasing the flow direction stiffness of weak parts of upper structure can improve the seismic performance of the structure greatly,but try not to increase the mass of upper structure.The connection of grid roof to the upstream and downstream bent column is not beneficial to the seismic resistance of powerhouse structure,the limit sliding support of free type is suggested to be used to reduce the connection of grid to the bent column.Finally,it summaries all contents and points out the shortcomings of this paper and the research direction about this field in future.