Interactive Spectrum Modification
Use this program
to modify response spectra generated by attenuation relationships or empirical
methods. Modifications available are: converting from Sa to Sv or Sd,
changing the damping ratio [R1],
scaling with respect to PGA, converting to fault normal or fault
parallel Sa spectra [R2], and converting
spectra from linear to nonlinear using strength reduction factors.
You may choose more than one modification at once, but some modifications will not work if certain previous modifications have been performed (ie. adding directivity, only defined for Sa, after converting a spectrum to Sv or Sd). Additional information regarding the methods used in this program can be found in the course notes. Please be aware that large modifications cause the spectrum to lose its physical meaning.