| With the continuous growth of economic level and the advancement of technology,the proportion of economic costs of nonstructural components in buildings has far exceeded that of the primary systems,while the seismic research of nonstructural components is lagging behind that of the primary systems.In response to the issue of lagging seismic research on nonstructural components,this paper conducted shaking table tests on three types of structures: seismic resistant structures,LNR based isolation structures,and LRB based isolation structures,respectively,under two conditions: coupling secondary systems and uncoupling secondary systems.We used MATLAB software to compile program for continuous wavelet transform and inverse wavelet transform,and compared the time-frequency spectrum obtained from wavelet transform with traditional Fourier spectrum to analyze the acceleration response of the primary systems and primary systems under the action of four different time-frequency characteristics of seismic waves.Using ABAQUS finite element software for numerical simulation,the dynamic responses of three structural forms,two systems,and six secondary systems with different connecting rod diameters under 13 seismic waves were analyzed,which were the same as those in shaking table tests under frequent and rare earthquakes.The seismic waves were reconstructed in the time-frequency domain through wavelet analysis to study the frequency bands in which the response of the primary systems and secondary systems had a significant impact.By using the time-frequency spectrum to identify the frequency corresponding to the seismic peak value range,the seismic peak value range is extended,and the impact of continuous high peak action on the primary systems and secondary systems is studied.The following conclusions are drawn:(1)The dynamic response of a structure is not directly related to the total energy corresponding to seismic waves at the main frequency of the structure,but directly related to the concentration of energy at the main frequency of the structure in the time domain.It is most significantly affected by the fundamental frequency band.When other frequency bands have a significant impact,the peak response of the structure depends on the "effective superposition" of each frequency band.Fourier spectrum can only reflect the distribution of seismic waves in the overall frequency domain and cannot be refined to local areas.Therefore,there may be some errors in analyzing the relationship between seismic waves and structural frequencies.Wavelet analysis can not only reflect the total energy of frequency seismic waves,but also reflect the concentration of energy at that frequency in the time domain,and perform local analysis of seismic waves.(2)The dynamic response of structures and substructures is significantly influenced by the time-frequency characteristics of seismic waves,and the response will vary significantly under different seismic waves.In most cases,the upper structure and secondary structure of the basic isolation structure have good seismic reduction effects.When designing isolation,it is necessary to avoid the main frequency of the isolation structure being close to the predominant frequency of seismic waves,and to consider factors such as the frequency ratio of the structure and secondary structure to avoid resonance between the isolation structure and the secondary structure.The coupling effect of the secondary systems on the dynamic response of the primary systems cannot be ignored.(3)Extending the duration of the seismic peak value segment does not necessarily increase the response of the primary systems and secondary systems.The two responses depend on the distribution of energy in the seismic peak value segment in the time-frequency domain.When the energy in the seismic peak value segment is concentrated in the time domain and the corresponding frequency is close to the main frequency of the structure,the dynamic response of the primary systems and secondary systems is significantly amplified.When the frequency corresponding to the local seismic wave energy peak is far from the structural frequency,The impact of increasing earthquake duration on the upper primary systems and secondary systems,and isolation layer can be ignored. |
