With conventional force-based seismic design, the most important information for the structural 8+
F}`lLA
engineer has been the effective peak ground acceleration. This number is comparatively C]yQ "b
insignificant in displacement-based or performance-based seismic design, where the key data are [~c'|E 8Q
peak spectral response displacement, and the “corner” period at which this occurs. There appears 3'*%R48P`
to be a disagreement between seismologists on opposite sides of the Atlantic about these data, H9VXsFTW
which the structural engineer views with concern, since ductile structural response will often be in IAF;mv}'
this region of the corner period. Dependable information on the reduction of displacement ()M@3={R
response with damping or ductility is also needed for design approaches utilizing secant stiffness Secq^#]8
characterization. Other areas needing clarification include the issue of how to develop 7k =F6k0)
accelerograms for time-history analysis compatible with the design seismicity using an acceptably 5 k%9>U%$
small number of accelerograms, and how to reconcile the statistical nature of seismicity MiH}VfI
characterization with the structural engineer’s preference for deterministic analysis. There is some 2FIR]@MQd
evidence that a consequence of this is invalid averaging of response characteristics by structural 6w"( y~c1
engineers.
