With conventional force-based seismic design, the most important information for the structural :s_.K'4?a
engineer has been the effective peak ground acceleration. This number is comparatively K
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insignificant in displacement-based or performance-based seismic design, where the key data are ^_@[1'^
peak spectral response displacement, and the “corner” period at which this occurs. There appears 6Y ]P 7j
to be a disagreement between seismologists on opposite sides of the Atlantic about these data, A NBuX6q
which the structural engineer views with concern, since ductile structural response will often be in h'&<A_C-7
this region of the corner period. Dependable information on the reduction of displacement vA_,TS#Bo
response with damping or ductility is also needed for design approaches utilizing secant stiffness Oo; ]j)z
characterization. Other areas needing clarification include the issue of how to develop i4i9EvWp
accelerograms for time-history analysis compatible with the design seismicity using an acceptably TxF^zx\
small number of accelerograms, and how to reconcile the statistical nature of seismicity U&])ow):
characterization with the structural engineer’s preference for deterministic analysis. There is some "i#g [x
evidence that a consequence of this is invalid averaging of response characteristics by structural _";w*lg}
engineers.
