STUDY ON THE TIME HISTORY ENVELOPE FUNCTION OF GROUND MOTION BASED ON INPUT ENERGY

The conversion between power spectral density functions and response spectra is widely used in random vibration analysis and procedure of generating artificial ground motions, where the envelope function of ground motion has significant influence on the conversion results. In order to determine the parameters of the envelope function model reasonably, the conversion between nonstationary power spectra and input energy spectra is established based on the method of exact computation of input energy spectra from Fourier amplitude spectra. The influence of different parameters on power spectrum and input energy spectrum is analyzed. The average input energy spectrum of the natural ground motions matching the design spectrum is used for comparison. The values of different parameters of the envelope function model are obtained for the conversion between power spectra and design spectra of different site condition through comparing with the input energy spectra converted by design spectra. The rationality of the values of parameters is validated by the characteristics of input energy spectra of artificial records.