Study On Selection Method Of Ground Motion Records For Time History Analysis

Building structure is developing towards gigantism and irregularity,and with the continuous improvement of computer computing ability,the seismic dynamic time history analysis method of buildings becomes more and more important.In this paper,8699 sets of strong motion records are obtained from the strong motion databases in the world,and the acceleration time history is corrected,and an alternative database of ground motion is established.Taking the selection criterion of seismic acceleration time history in China’s seismic code as the research object,based on the principle that the response spectrum of seismic acceleration is consistent with the design spectrum of the code,considering the factors such as site seismic environment conditions,spectrum consistency control parameters and matching errors,a selection scheme of seismic records based on three levels is proposed and verified by two models.The specific research contents are as follows:（1）This paper summarizes the requirements of seismic codes in China,the USA and EU for the selection of seismic acceleration time history,and analyzes the differences between China’s seismic codes and foreign countries in the selection of seismic acceleration time history.In this paper,the research progress of time history selection methods of ground motion acceleration by scholars and institutions at home and abroad is studied,and the current selection methods are summarized into three categories:based on site seismic environment,based on target spectrum and based on seismic intensity index.（2）This paper analyzes the strong motion databases characteristics of China National Strong Motion Network Center,NGA-West2,VDC,K-NET and Ki K-net of Japan,and the methods of obtaining records from each database.This paper points out the shortcomings of China’s strong ground motion database,which mainly shows that China should unify the data format,supplement metadata information,and facilitate data sharing,etc.The error sources,current filtering techniques and baseline correction methods in the ground motion records are analyzed,and the strong ground motion records collected in this paper are corrected one by one.Finally,the collected information of all ground motion records is calibrated,and a ground motion alternative database is established based on My SQL database technology.（3）Based on the physical significance of ground motion records used in time history analysis,the importance of site seismic environment conditions to the selection of ground motion records is expounded.The intensity attenuation relationship and PGA attenuation relationship in the fifth generation ground motion zoning map are used to determine the corresponding relationship between magnitude and epicentral distance range when selecting ground motion records with different fortification requirements.The transformation relationship between V_s30 and V_s20 is fitted,the method of calculating the overburden thickness according to V_s30 and V_s20 is studied,the method of determining the site type according to China’s double indexes according to the calculated Vs20 and overburden thickness is put forward,and the collected records are discriminated for the site type.The correlation analysis of the calculation method of characteristic period is also carried out.（4）Various conditions of influencing record selection,such as spectrum consistency control parameters,matching error limit and matching range,are analyzed,and a set of three-level ground motion acceleration time history selection process is put forward,which takes into account factors such as site seismic environment conditions,spectrum matching and structural dynamic characteristics.Three-dimensional finite element models of 7-story and 12-story RC frame structures are established.The three-level selection method,dual-band method and PEER mean square error method are used to select ground motions.The results show that the three-level selection method in this paper is more accurate.（5）The 7-storey and 12-storey structures are selected according to the code design spectrum of rare earthquakes,and the number of selected records is studied.The selected records are input into the structure for elastic-plastic time-history analysis,and the response values of base shear force,vertex displacement and maximum inter-story displacement angle are obtained.（6）Based on the GUI function of MATLAB software,a program for selecting ground motion records based on China Seismic Code was compiled,and the selection function based on three levels was realized.The operation steps of the function were explained and the selection results were verified.