With conventional force-based seismic design, the most important information for the structural FuG4F
engineer has been the effective peak ground acceleration. This number is comparatively 6*4's5>?D
insignificant in displacement-based or performance-based seismic design, where the key data are ?_x
q-
peak spectral response displacement, and the “corner” period at which this occurs. There appears ? &G`{Ey
to be a disagreement between seismologists on opposite sides of the Atlantic about these data, uzmk6G
v
which the structural engineer views with concern, since ductile structural response will often be in s4Sd>D 7
this region of the corner period. Dependable information on the reduction of displacement [yl sz?
response with damping or ductility is also needed for design approaches utilizing secant stiffness KH)D 08
characterization. Other areas needing clarification include the issue of how to develop nkxzk$
accelerograms for time-history analysis compatible with the design seismicity using an acceptably LZJA4 ?C
small number of accelerograms, and how to reconcile the statistical nature of seismicity Hgeg@RP
Q
characterization with the structural engineer’s preference for deterministic analysis. There is some Ee)[\Qjn
evidence that a consequence of this is invalid averaging of response characteristics by structural cMyiW$;
engineers.
