With conventional force-based seismic design, the most important information for the structural t@\op}Z-M
engineer has been the effective peak ground acceleration. This number is comparatively H:M;H =0
insignificant in displacement-based or performance-based seismic design, where the key data are : 0RfA%
peak spectral response displacement, and the “corner” period at which this occurs. There appears . 'rC'F T
to be a disagreement between seismologists on opposite sides of the Atlantic about these data, G[5z3
which the structural engineer views with concern, since ductile structural response will often be in SV96eYT<
this region of the corner period. Dependable information on the reduction of displacement F%>`?NG+c
response with damping or ductility is also needed for design approaches utilizing secant stiffness Vy[ m%sEP
characterization. Other areas needing clarification include the issue of how to develop 3F6=/
accelerograms for time-history analysis compatible with the design seismicity using an acceptably |#=4]]>m
small number of accelerograms, and how to reconcile the statistical nature of seismicity C!}9[X!7@:
characterization with the structural engineer’s preference for deterministic analysis. There is some seo.1.Da2
evidence that a consequence of this is invalid averaging of response characteristics by structural u|]`gsFZ\
engineers.
