With conventional force-based seismic design, the most important information for the structural T%q@jv{c
engineer has been the effective peak ground acceleration. This number is comparatively 3&`LVhx
insignificant in displacement-based or performance-based seismic design, where the key data are ~[a6
peak spectral response displacement, and the “corner” period at which this occurs. There appears L"[2[p
to be a disagreement between seismologists on opposite sides of the Atlantic about these data, L/*D5k%J
which the structural engineer views with concern, since ductile structural response will often be in = 2 J^
'7
this region of the corner period. Dependable information on the reduction of displacement -}:;
EGUtd
response with damping or ductility is also needed for design approaches utilizing secant stiffness V)<Jj
characterization. Other areas needing clarification include the issue of how to develop ;8Qx~:c
accelerograms for time-history analysis compatible with the design seismicity using an acceptably |[. /jg"
small number of accelerograms, and how to reconcile the statistical nature of seismicity ; ,9:1.L
characterization with the structural engineer’s preference for deterministic analysis. There is some }o,-@R~
evidence that a consequence of this is invalid averaging of response characteristics by structural \k
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engineers.
