Modspec©
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.

Modspec
Interactive Spectrum Modification
Spectrum to use
  
 
Current existing Type:
  Model:
Generate empirical spectrum
Generate from attenuation relationship
 Current spectrum
 Model:    Type:
 Linear Options
  
Convert:  from to
Change damping  from to  

 using
Scale to PGA  New PGA (g)
Add directivity  Convert component to
 
Convert to nonlinear  
 Use model:
Ductility m:
  Reloads initial elastic spectrum

Numerical Values:


Copyright 1999 Janise Rodgers, Pacific Earthquake Engineering Research Center, University of California, Berkeley.