PREDICTION OF FREE-FIELD EARTHQUAKE GROUND MOTIONS

The existing strong motion data and the work of previous researchers have been studied with regard to the problems in predicting the spectra of free-field earthquake ground motions. The main problems associated with the prediction of both fourier and response spectra that are addressed in this paper are the effects due to several types of soil-structure interaction and local soil conditions and the possible biasing of spectral predictions from the use of a large amount of data from the 1971 San Fernando earthquake. In general one type of soil-structure interaction may have significantly modified the ground motions recorded in multi-story buildings with relatively large base dimensions and foundation mass. This type of interaction was a suppression of high frequency wave amplitudes by the foundations of these buildings. As a result, differences in spectra that have been previously attributed to local soil conditions may be due in part to this type of soil-structure interaction. A comparison was made between the spectra predicted using two Fourier spectra attenuation relations, one derived from a small amount of San Fernando data and another derived using all San Fernando data. Response spectra derived exclusively from San Fernando data are similar to response spectra from other southern California earthquakes of comparable size, similar local soil conditions, and whose source to recording station distances are fairly well known. Comparisons are not as agreeable between San Fernando response spectra and response spectra from northern California and Washington earthquakes where the location of the fault ruptures are not well known. /Author/

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 359-379

Subject/Index Terms

Filing Info

  • Accession Number: 00179755
  • Record Type: Publication
  • Report/Paper Numbers: Proceeding
  • Files: TRIS
  • Created Date: Oct 12 1978 12:00AM