With conventional force-based seismic design, the most important information for the structural O0{v`|w9+
engineer has been the effective peak ground acceleration. This number is comparatively G? _,(
insignificant in displacement-based or performance-based seismic design, where the key data are L"-&B$B:
peak spectral response displacement, and the “corner” period at which this occurs. There appears k m|wB4
to be a disagreement between seismologists on opposite sides of the Atlantic about these data, hBqu,A
which the structural engineer views with concern, since ductile structural response will often be in w`v\/a_
this region of the corner period. Dependable information on the reduction of displacement dk]ro~ [
response with damping or ductility is also needed for design approaches utilizing secant stiffness }N|/b"j9
characterization. Other areas needing clarification include the issue of how to develop 0ND7F
accelerograms for time-history analysis compatible with the design seismicity using an acceptably S8cFD):q
small number of accelerograms, and how to reconcile the statistical nature of seismicity >WEg8'#O
characterization with the structural engineer’s preference for deterministic analysis. There is some u J y@
evidence that a consequence of this is invalid averaging of response characteristics by structural vSL{W T]m
engineers.
