The Correlation Between Strong Ground Motion Parameters And Seismic Intensity

The Wenchuan Ms8.0 earthquake-one of the greatest earthquakes which have occurred ever since the foundation of new China-covering wide area, caused large destructibility and brought high difficulty to emergency relief. Although the earthquake caused large loss of staff and property, it gave us valuable seismic damage research data of structures, baseing on which our structures seismic damage analysis is established. Because the analysis of structures seismic damage demands strong earthquake ground motion parameters, so the non-uniform distribution of ground motion stations in Wenchuan earthquake turns into a pity. How to estimate the value of ground motion parameters during the analysis of structures seismic damage data, which were collected in Wenchuan earthquake, by using the limited ground motion stations and relative rich seismic intensity materials is the emphasis of this paper. The research in this paper was carried out from four aspects, some conclusions can be drawn.(1) After Wenchuan earthquake, many areas rich in earthquake investigation data came up, yet these regions are lack of strong earthquake observation records. How to reasonably estimate the value of ground motion parameters so as to deal with the analysis of these disaster areas becomes the core of this paper work, which also needs to be done urgently. This paper took these areas which is rich in earthquake investigation data but lack of strong earthquake observation records as the ground motion parameters estimation areas. In consideration of the differences of ground motion between the two sides of a fault, we divided the estimation region as two parts and analyzed them separately. Based on the attenuation relationship of equivalent ground motion parameter, we estimated the PGA?PGV and 0.3s?1s?3s spectral accelerations in Wenchuan earthquake areas. so that the value of ground motion parameters for the earthquake data analysis was provided. Besides, the PGA and PGV isolines were also shown in this paper.(2) By collecting 226 three-component records from 9 earthquakes which occured in China and America as data resources and using the least square method, the correlation relationships between sixteen strong ground motion parameters and seismic intensity were presented. The results indicated that among the sixteen strong ground motion parameters analyzed in this study, cumulative absolute velocity and spectrum intensity were the best two parameters with the largest recognition rate, which could be used to predicate the instrumental intensity. According to the statistic results, the instrumental intensity determined by the model of univariate regression may sometimes have significant differences from the actual intensity, so the model of multiple linear regression between magnitude and different ground motion parameters combinations is established. The statistic result shows that the model of multiple linear regression has higher recognition correct rate in identification seismic intensity than the model of univariate regression. The combination of spectral intensity(SI0.2) and standard cumulative absolute velocity(CAVs) is the best ground motion parameter combination with the largest recognition rate, which could be used to predicate the instrumental intensity.(3) In this article, most Chinese accelerograms come from the Wenchuan earthquake. The next main part work is to use these accelerograms to develop the attenuation relationship of different ground parameters in this area, but the instrumental intensity determined by these ground parameters is not in line with the actual intensity, so these accelerograms are divided into several groups by their characteristic period of response spectrum. The difference between instrumental intensity and actual intensity are calculated, and then the error was modified. In the process of the modification of the model of univariate regression, sixteen equivalent ground motion parameters are introduced. The instrumental intensity determined by the equivalent ground motion parameters have higher recognition correct rate in identification seismic intensity than the other ground motion parameters which have no equivalent processing.(4) In consideration of higher recognition correct rate in identification seismic intensity determined by the equivalent ground motion parameters, attenuation relationships for 16 equivalent ground motion parameters,16 ground motion parameters and 35 spectral accelerations in Wenchuan region of China were determined by statistical analyses of acceleration records obtained in several destructive earthquakes and after shocks of Wenchuan Ms8.0 earthquake. The results indicate that the fitting results determined by the equivalent ground motion parameters have smaller standard deviation than the other ground motion parameters which have no equivalent processing.