Seismic Analysis Of Story Isolation Structure Based On Wavelet Decomposition

Story isolation technology is a new type of isolation based on the need of engineering practice.It provides a new design method for the reinforcement of the old structure,building near the sea and the river and the vertical irregular building to resist earthquakes.It solves the limitations of the base isolation technology in practical application and widens the application range of seismic isolation technology.But the theoretical research on the story isolation structure is not perfect,mostly only for a specific engineering case study.In the story isolation structure,with the change of the isolation story position,the dynamic characteristics of the structure will show different characteristics,and the seismic response of the story isolation structure under different frequency components is very different.In this paper,the seismic wave is divided into different frequency components based on wavelet method and the isolation effect and seismic response law of story isolation structure with different frequency bands are studied.This paper first introduces the classification of seismic isolation technology and advantages,application scope and research status of story isolation technology.Second,the dynamic analysis model of story isolation structure is selected and the dynamic equations of motion are derived.Then the standard response spectrum is established according to the site conditions and seismic fortification intensity.The two actual earthquake records are selected from the wenchuan earthquakedatabase according to the two frequency method and decomposed into wavelet components of different frequency segments.Finally,the displacement response,acceleration response and base shear force of story isolation structure under different frequency bands are calculated.The results show that the seismic responses of story isolation structure under different spectral wavelet components are very different.No matter how the location of the isolation story changes,the wavelet component of the lower frequency under 6.25 Hz plays an important role in the seismic response of the structure and the high frequency wavelet component has little effect on the seismic response of the structure.When the position of the isolation story is changed,the lower the isolation story is,the better the isolation effect of the structure is;When the isolation story is below third layer,the first mode response of the 0-1.56 Hz band wavelet is the most prominent,which contributes the most to the overall seismic response of the structure.When the isolation story is located on the fourth level and above,the vibration response of the second mode of 1.56-6.25 Hz band wavelet is larger than that of the first mode.Therefore,the isolation story should be selected according to the actual situation.In order to isolate the earthquake,it is necessary to control the first natural vibration period of the structure,but also to keep away from the second natural vibration period.