Study On Site Response Based On DEEPSOIL

Site seismic response analysis is an important part of seismic engineering,and its results can provide a fortification basis for engineering seismic design and have important engineering significance.The methods of site seismic response analysis can be divided into frequency-domain equivalent linearization method and time-domain nonlinear method.The frequency-domain equivalent linearization method has the advantages of simple principle,easy selection of parameters,and reasonable results in the weak motion,but its lack of "amplifying low frequency and underestimating high frequency" affects the reliability of the results under the complex site and strong motion.The calculation result of the time-domain nonlinear method is closer to reality,but its parameter selection is more difficult,and it is currently mainly used for the study of site response.Based on the site seismic response analysis software DEEPSOIL,using the time-domain nonlinear method and the frequency-domain equivalent linearization method,this paper separately analyzes the 47 m array of Tangshan Xiangtang in China(soil thickness is 30.5m,II site in China Class,D site in US Class),the Treasure Island Geotechnical Array(soil thickness is 88.3m,III site in China Class,E site in US Class)and the IBRH12 array in Japan(soil thickness is 20 m,II site in China Class,C site in US Class),and compares with the calculation results of Soilquake which developed by the team of Yuan Xiaoming of the Institute of Engineering Mechanics,CEA and based on the equivalent linearization method.The main research results are as follows:(1)During the weak motion,when the peak ground acceleration(PGA)is less than50 gal,the results of the above three arrays using frequency-domain equivalent linearization method and time-domain nonlinearization method can match with the actual records,and the calculation results of acceleration time history,acceleration response spectrum and Fourier spectrum are highly consistent with the actual record.(2)In strong motion,when the PGA reaches 500 gal,the results of the IBRH12array(acceleration time history,acceleration response spectrum and Fourier spectrum)which use the frequency-domain equivalent linearization method in DEEPSOIL begin to differ from the actual records,with the increase of PGA,this difference becomes larger.When the PGA reaches 800 gal,the calculated results are far less than the actual records;when the PGA is less than 800 gal,the result of the IBRH12 array which use the time-domain nonlinear method of DEEPSOIL can still be in good agreement with the actual record,when the PGA reaches 800 gal,there is a discrepancy with the actualrecord.Because we don't have the data of strong motion in Tangshan Xiangtang array and the Treasure Island geotechnical array,it is impossible to determine the PGA of the two methods when the calculation results begin to differ from the actual records.(3)In weak motion,when the PGA is less than 50 gal,for the Tangshan Xiangtang47 m array,the calculation results of Soilquake can be consistent with the actual records;for the Treasure Island geotechnical array,the calculation results which use the Soilquake are consistent with the actual record in the EW component and the NS component Soilquake,but in the UD component,the calculation result of Soilquake is larger than the actual record.For the IBRH12 array,when the PGA is less than 700 gal,the calculation results of Soilquake are in good agreement with the actual records,but when the PGA reaches 700 gal,the calculation results of Soilquake begin to differ from the actual records and the results are between the time-domain nonlinear method and frequency-domain equivalent linearization method.