Correlation between ground motion intensity indices and SDOF system responses based on the data of Wenchuan earthquake

From Sichuan stations during Wenchuan earthquake of 12 May 2008, 18 suites horizontal components whose peak ground acceleration values higher than 200Gal were chosen as ground motion input. The bilinear SDOF system is with 1.0 s period and 5% damping ratio. With time-history analysis method, the representative seismic responses of the bilinear SDOF system were calculated respectively, like acceleration, velocity and displacement. With the statistical analysis method, we also investigated the correlation between the linear/nonlinear maximum responses of the SDOF system and the different ground motion intensity indices such as peak ground acceleration(PGA), cumulative absolute velocity(CAV), Arias intensity(AI), velocity spectrum intensity(VSI), acceleration spectrum intensity(ASI), root-mean-square of acceleration(Arms), characteristic intensity (Ic), Housner intensity(HI). The results show that there is a large difference in the correlation between different ground motion intensity indices and the maximum responses of the SDOF system, among the results VSI and HI have the best correlation with SDOF maximum responses, ASI and PGA have the worst correlation with them. In addition, VSI and HI have better correlation with the nonlinear maximum responses than with the linear maximum responses of the SDOF system. Thus, further investigation on the rationality and reliability of the traditional method to select and adjust ground motion records for time history analysis based on PGA is still needed.