Study On The Prediction Equations Of Arias Intensity In Southwest China

This paper uses the strong motion records to build the horizontal Arias intensity prediction equations in southwest China.The applicable magnitude range is Mw4-6.7,and the distance range is RRUP0-200km.In terms of strong motion data,this paper collects digital strong earthquake records and related parameters in southwest China from 2008 to 2019,including Wenchuan,Lushan,Jiuzhaigou and other major earthquake data.The basic database contains a total of 92 earthquakes and 855 sets of three-component time histories records.In terms of parameter selection,the moment magnitude that will not saturate with the magnitude is used as the magnitude parameter,which is also the magnitude parameter used by the existing Arias intensity prediction equations.The fault distance(the shortest distance from the field point to the fault plane)is used as the distance parameter,and the site classification index is used according to the site classification principle of the National Earthquake Hazards Reduction Program(NEHRP).For the Arias intensity,two methods,the classical model and the peak acceleration PGA correlation model,are used to establish the corresponding prediction equations respectively.The Newmark displacement prediction equation in southwest China is established with Arias intensity as the parameter.Using the selected strong motion records in southwest China,and adopting the step-by-step regression method,the attenuation characteristics of horizontal Arias intensity in southwest China with magnitude,distance and site conditions are analyzed.The relationship between Arias intensity and commonly used ground motion parameters is studied in detail.On this basis,the new prediction model was regressed.The distribution of Newmark displacement with Arias intensity or critical acceleration AC was analyzed,and a new Newmark displacement prediction equation with Arias intensity as parameter was constructed.The residual analysis shows that the regression residuals of the three models in this paper are basically discretely distributed near the zero value,and there is no obvious trend with the magnitude and distance,indicating that the regression results in this paper are stable and unbiased.Using the same analysis method and regression model,an empirical prediction equation of Arias intensity in the western America and an Arias intensity prediction model with PGA as the main parameter were established,and the differences in Arias intensity in the southwest China and the western America were compared.In this research work,the main results are as follows:(1)The applicability of the existing Arias intensity prediction model in southwest China was evaluated.The results show that when the magnitude is low,the existing model fits the strong earthquake records in southwest China better,and when the magnitude is high,the existing model fits well.The predicted results of the model are generally higher than the actual records in Southwest my country.Based on strong motion records in southwest China,an Arias intensity prediction model suitable for Southwest my country is established.(2)The logarithmic correlation between Arias intensity and ground motion parameters such as PGA and PGV was analyzed,and it was revealed that PGA and Arias intensity had a significant logarithmic correlation.Based on the difference distribution,a new Arias intensity prediction model in southwest China was established with the easily available parameter PGA as the main independent variable.(3)The variation law of Newmark displacement with Arias strength and critical acceleration AC is analyzed.The results show that the logarithm of Newmark displacement has a good linear relationship with the logarithm of Arias intensity and critical acceleration AC.A best-fit model of Newmark displacement with Arias intensity and AC was constructed.(4)The empirical prediction equation of Arias intensity in the western region of the United States and the prediction equation with PGA as the parameter are established,and the differences between the Arias intensity prediction models in the southwestern China and the western America are compared.