With conventional force-based seismic design, the most important information for the structural ? r!o~|9|
engineer has been the effective peak ground acceleration. This number is comparatively DW3G
insignificant in displacement-based or performance-based seismic design, where the key data are #s9aI_
peak spectral response displacement, and the “corner” period at which this occurs. There appears ^kSqsT"
to be a disagreement between seismologists on opposite sides of the Atlantic about these data, x|29L7 i
which the structural engineer views with concern, since ductile structural response will often be in K.yb
^dg5
this region of the corner period. Dependable information on the reduction of displacement &,)&%Sg[
response with damping or ductility is also needed for design approaches utilizing secant stiffness -7|H}!DFT
characterization. Other areas needing clarification include the issue of how to develop |V7*l1
accelerograms for time-history analysis compatible with the design seismicity using an acceptably (QiAisE
small number of accelerograms, and how to reconcile the statistical nature of seismicity Y|/ 8up
characterization with the structural engineer’s preference for deterministic analysis. There is some Y\hBd$lQ~
evidence that a consequence of this is invalid averaging of response characteristics by structural fd9k?,zM
engineers.
