With conventional force-based seismic design, the most important information for the structural NRJp8G Z%U
engineer has been the effective peak ground acceleration. This number is comparatively |xcC'1WU
insignificant in displacement-based or performance-based seismic design, where the key data are f"P866@oWn
peak spectral response displacement, and the “corner” period at which this occurs. There appears `dG;SM$T,
to be a disagreement between seismologists on opposite sides of the Atlantic about these data, q%e'WM G~n
which the structural engineer views with concern, since ductile structural response will often be in -5+Yz9pv[
this region of the corner period. Dependable information on the reduction of displacement H"8B4~*7H
response with damping or ductility is also needed for design approaches utilizing secant stiffness k|?[EWIi^
characterization. Other areas needing clarification include the issue of how to develop
IPK1g3Z
accelerograms for time-history analysis compatible with the design seismicity using an acceptably cI @qt>&
small number of accelerograms, and how to reconcile the statistical nature of seismicity q,@#
cQBV
characterization with the structural engineer’s preference for deterministic analysis. There is some 2m:K
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evidence that a consequence of this is invalid averaging of response characteristics by structural h! %y,4IBR
engineers.
