Dynamic Response Analysis Of Isolated Structure Based On Monitoring Data

Earthquake is the most serious disaster.Once it happens,it will cause a large number of buildings to be seriously damaged,resulting in huge casualties and property losses.Traditional anti-seismic technology improves the anti-seismic ability of buildings to a certain extent,but when encountering strong earthquake,the damping effect of traditional anti-seismic structure is far less than that of isolation structure.Because isolation structure has the effect of reducing the seismic energy input of structure from the foundation,more and more engineers turn their attention from traditional anti-seismic technology to isolation technology.With the rapid development of China’s economy,the acceleration of urbanization process and the progress of engineering construction technology,China’s isolation technology has been rapid development.Isolation technology can effectively reduce the damage of earthquake to the superstructure,so it is widely used in schools,apartments,hospitals and other buildings.As the isolation technology is a new technology,it is necessary to carry out real-time monitoring and health condition analysis,non-destructive monitoring and damping performance analysis under the actual working condition of the project,detect the damping index of the isolation structure under the earthquake action,and reveal the rules of structural damage and performance degradation.The real-time monitoring and dynamic analysis of isolated structure is an important reference to study the seismic safety and disaster mechanism of isolated structure,which provides technical guidance for the popularization and application of basic isolation technology in practical engineering.In this paper,the real-time monitoring system is used to record the vibration of the teaching building of the second primary school in Wenchuan County.The seismic response and modal frequency change of the teaching building of the second primary school in Wenchuan County under the action of ground motion are studied.The dynamic response of the isolation structure under the action of dynamic load is analyzed by finite element numerical simulation.The research contents can be summarized as follows:(1)In order to understand the dynamic characteristics of the base-isolated structure more clearly,strengthen the assessment and diagnosis of the health of the base-isolated structure.This paper uses two methods,frequency domain decomposition method(FDD)and random subspace method(SSI-Cov)to identify the frequency of the teaching building of the second primary school in Wenchuan County.Based on the advantages and disadvantages of frequency identification of seismic structures,the frequency domain decomposition method is used to identify the modal frequency of the monitoring data under the excitation of the base isolation structure of the teaching building of the second primary school in Wenchuan County.(2)By comparing the acceleration response analysis of SW5(Pengzhou earthquake with m 3.7)and SW9(Wenchuan earthquake with m 2.9),it can be seen that under the action of SW5(Pengzhou earthquake with m 3.7),the isolation layer of the teaching building of the second primary school in Wenchuan County did not break through the yield point,at this time,it is in the linear stage,and the isolation effect has not been fully exerted;under the action of SW9(Wenchuan earthquake with m 2.9),the isolation layer of the second primary school in Wenchuan County did not break through the yield point The isolation layer of the primary school teaching building has reached the yield point,which plays a better role in isolation and effectively weakens the ground motion energy transmitted to the superstructure.(3)The modal analysis of isolated and non isolated structures is carried out by using the method of block lanczons,and the natural frequencies of isolated and non isolated models are obtained.Compared with the first frequency of the non isolated structure,the isolation frequency is 1 / 2 of that of the non isolated structure,and the period is doubled,which can make the isolated structure avoid the predominant period of the site and effectively reduce the damage of the upper structure caused by theearthquake.The first and second modes of isolated structure and non isolated structure are translational in the direction of long axis and short axis respectively,and the displacement at the bottom of isolated structure is large.The third mode is torsion,but the response of non isolated structure is large.Isolation technology can reduce the seismic frequency of the structure and avoid the site period,so that the deformation of the structure is concentrated in the isolation layer,and improve the seismic performance of the structure,which proves that the isolation structure is better than the traditional seismic structure.(4)From the analysis results of finite element numerical simulation,the similar error between the modal analysis results of finite element numerical simulation and the identification results of measured data is small,which shows that the finite element numerical model is reasonable and the simulation analysis results are reliable.In view of the fact that the measured data are used to analyze the dynamic characteristics of the building,the finite element analysis model is more close to the actual state of the building structure,which shows the accuracy and reliability of the finite element simulation results.(5)During the real-time monitoring of the teaching building of the second primary school in Wenchuan County,the structural vibration response data under the influence of multiple earthquakes are recorded.From the calculated results of the long and short axial transfer functions of the foundation and the top of the isolation layer,the foundation and the top of the building,it can be observed that the structure has a significant amplification effect in the 2-3hz frequency band.Combined with the relationship between the transfer functions of each measuring point and the dynamic response analysis of the structure,it is shown that the setting of the isolation layer can effectively reduce the horizontal displacement of the structure,especially in the case of large earthquake,the setting of the isolation layer is an effective method to reduce the overall displacement of the structure.