Research On The Selection Of Ground Motion Records Based On The Spectral Parameters

The elastoplastic time history analysis is an important means to test and evaluate the seismic performance of the structure.How to select the appropriate input ground motion is the first work of the elastoplastic time history analysis.About this problem,there are many ideas at home and abroad,but these research methods do not further consider structural properties or the characteristics of ground motion records.In this paper,it is considered that natural vibration period should be taken into consideration when selecting input ground motion.Ground motion records are sorted according to the appropriate parameters and multiple records are selected according the importance or other characteristics of the structure.Based on the summary of relevant literature,this paper uses OpnSees finite element software to establish two numerical models which are 6-floor and 7-floor RC frame structure.After carrying out many elastoplastic time history analysis and calculating the kinds of spectral values correspondting to the period of the structure,the correlation between the spectral values and structural response is analyzed.Then comparing the sequences of spectral parameters and structural response,the appropriate parameters that should be considered when selecting ground motion for the RC frame structure are obtained.Lastly,a database for selecting ground motion is set up.The main work and results of this paper are as follows:(1)Since a large number of ground motion records need to be used as input,this paper takes OpenSees as an example to design a program for batch structural time history analysis which is simple and controls computing resources by executing or closing programs without conflict.(2)The response distribution of the 6-and 7-floor RC frames under the action of many gound motions is analyzed.It is found that the response distribution in different scaling factor segments is different.Based on the criterion that the probability distribution of the structural damage caused by each ground motion should be the same,it is recommended to choose the ground motion record whose scaling factor is less than 20.(3)By calculating the response spectrum and energy spectrum of the two RC frames,it is found that the constant-strength velocity spectrum and the equivalent velocity spectrum of the input energy should be considered when selecting ground motion records.These 2 parameters have highest correlation with structural response.Further,the similarity between the sorting sequence of 2 parameters and the sequence of structural response is examined.It is found that the constant-strength velocity spectrum is slightly better.(4)The constant-strength velocity spectrum(standard yield strength is 0.1)of 13731 ground motion records with PGA above 0.008g is calculated.The ground motion database is established.The site for selecting the input ground motion for the structural time history is preliminarily developed.The user can enter the structural vibration period and site type and the results are sorted according to the spectral value of the certain period.Furthermore,user can select and download the records whose magnitude,picentral distance,PGA and other parameters are provided.