With conventional force-based seismic design, the most important information for the structural HNa]H;-+5
engineer has been the effective peak ground acceleration. This number is comparatively &X`u9 V
insignificant in displacement-based or performance-based seismic design, where the key data are i.iio-
peak spectral response displacement, and the “corner” period at which this occurs. There appears .BO<
to be a disagreement between seismologists on opposite sides of the Atlantic about these data, Bn]K+h\E
which the structural engineer views with concern, since ductile structural response will often be in Uz%Z&K
this region of the corner period. Dependable information on the reduction of displacement gLL-VvJ[
response with damping or ductility is also needed for design approaches utilizing secant stiffness {OT:3SS7
characterization. Other areas needing clarification include the issue of how to develop ID1?PM
accelerograms for time-history analysis compatible with the design seismicity using an acceptably Aox3s?
small number of accelerograms, and how to reconcile the statistical nature of seismicity %Hi~aRz
characterization with the structural engineer’s preference for deterministic analysis. There is some d0er^ ~
evidence that a consequence of this is invalid averaging of response characteristics by structural A%Z)wz{
engineers.