With conventional force-based seismic design, the most important information for the structural :$=|7v
engineer has been the effective peak ground acceleration. This number is comparatively V1<ow' ^i
insignificant in displacement-based or performance-based seismic design, where the key data are }sv!=^}BY3
peak spectral response displacement, and the “corner” period at which this occurs. There appears q]px(
to be a disagreement between seismologists on opposite sides of the Atlantic about these data, .eo~?u<j&
which the structural engineer views with concern, since ductile structural response will often be in q xfLfgu^
this region of the corner period. Dependable information on the reduction of displacement ^IBGYl 5n
response with damping or ductility is also needed for design approaches utilizing secant stiffness ~n
WsP}`n
characterization. Other areas needing clarification include the issue of how to develop & g:%*>7P
accelerograms for time-history analysis compatible with the design seismicity using an acceptably #+9rjq:v#]
small number of accelerograms, and how to reconcile the statistical nature of seismicity 7i 8eg*Gl
characterization with the structural engineer’s preference for deterministic analysis. There is some ]}kI)34 /
evidence that a consequence of this is invalid averaging of response characteristics by structural GuT6K}~|D
engineers.
