With conventional force-based seismic design, the most important information for the structural [1{uK&$e
engineer has been the effective peak ground acceleration. This number is comparatively }_L,Xg:I
insignificant in displacement-based or performance-based seismic design, where the key data are V8.o}BWY
peak spectral response displacement, and the “corner” period at which this occurs. There appears Fv"jKZPgzz
to be a disagreement between seismologists on opposite sides of the Atlantic about these data, # Y;_W;#
which the structural engineer views with concern, since ductile structural response will often be in V/ }g' _E
this region of the corner period. Dependable information on the reduction of displacement Ov=^}T4zl
response with damping or ductility is also needed for design approaches utilizing secant stiffness z<c@<M=Q*
characterization. Other areas needing clarification include the issue of how to develop "]C$"J R
accelerograms for time-history analysis compatible with the design seismicity using an acceptably ZkZTCb `/l
small number of accelerograms, and how to reconcile the statistical nature of seismicity Dy_Za.N2
characterization with the structural engineer’s preference for deterministic analysis. There is some UFy"hJchO
evidence that a consequence of this is invalid averaging of response characteristics by structural y0D="2)
engineers.
