Currently accepted procedures for estimating design response spectra such as those proposed by Hall et al. and Mohraz are in general independent of magnitude. Based on these procedures, normalized, constant spectral shapes are developed which are then scaled to a prescribed magnitude-dependent peak acceleration. However, the amplitude and shape of the long period portion of a spectrum should change to reflect increased long period motions associated with increasing magnitude. A study was performed for near source rock sites using a procdure similar to that proposed by Mohraz. However, the procedure was modified with the express purpose of quantitatively incorporating magnitude dependency. Ground motion ratios and amplification factors for acceleration, velocity, and displacement were estimated for a range of magnitudes. Near source response spectra for Magnitude 7, 7-1/2, and 8 events were constructed, and the results were compared with those of Mohraz. The resulting spectra are nearly identical at short periods. Howver, the amplitude in the long period portion of the response spectrum systematically increases as a function of magnitude. Results of the study indicate the feasibility and importance of incorporating magnitude dependency into near source design spectra. /Author/

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 530-539

Subject/Index Terms

Filing Info

  • Accession Number: 00179765
  • Record Type: Publication
  • Report/Paper Numbers: Proceeding
  • Files: TRIS
  • Created Date: Oct 12 1978 12:00AM