Seismic Analysis Of Yingxian Wooden Tower Considered The Effect Of Tower Base And The Discussion For The New Set Of Enhancement Programme

This paper built 2 kind of Yingxian Wooden Tower models,by using ANSYS APDL finite element analysis software,only wooden frame is considered in the first model and the second one was frame-foundation union tower model,to study the dynamic characteristics and seismic reactions difference between two models.Both models were built based on the field surveying and mapping data and the related experimental results.Four kinds of waves,eight kinds of working conditions bidirectional transient loading simulation ware applied to these models.The partial model of Yingxian Wood Tower was also built in this paper to be applied by three direction seismic waves.The parameters such as the displacement of the column,the maximum acceleration and the maximum inter-layer displacement angle are used as the references.The simulation results show that the rammed earth octagonal platform has a high frequency of self vibration,the difference of adjacent frequencies is small and the frequency range of the platform base is relatively dense;The change amplitude of the self vibration frequency of the tower body is large,and the influence of the Yingxian Wood Tower platform on the dynamic characteristics of the wooden tower in the low frequency range can be neglected.However,when the upper frequency of the frame structure is close to the base frequency,the self vibration frequency of the whole structure will change.The transient simulation results show that the bottom base has a certain influence on the dynamic characteristics of the whole structure under the high order vibration.Regarding the magnitude of five layers' column top displacement as reference index,the influence grade to the wooden tower caused by the four seismicwaves should be ordered as follows: Tianjin > El-Centro ? Taft >Lanzhou.From the results of making average of the increase percentage of the fifth floor's column top displacement and the increase of the dynamic coefficient in the eight working conditions,it can be seen that the frame-foundation union tower model's fifth floor's column top displacement has nearly 30% lager than that of the single frame structure.The dynamic coefficient of the top of the column is sustained around 8%,so it is necessary to consider the effect of the platform foundation on the upper frame in the dynamic analysis of the ground motion of the pagoda.A new reinforcement scheme is also proposed for the severe damaged second floor.The new type of inter column energy dissipation strengthening device with viscous dampers in the Yingxian Wood Tower reinforcement project is simulated and verified by using the method of seismic response spectrum analysis in ANSYS APDL.The results show that the new reinforcement device has a certain reference for the renovation of Yingxian Wood Tower by means of reinforcement to restrict the displacement and deformation of the wooden frame.