With conventional force-based seismic design, the most important information for the structural dms R>Q
engineer has been the effective peak ground acceleration. This number is comparatively P#\L6EO.
insignificant in displacement-based or performance-based seismic design, where the key data are ` :eXXE
peak spectral response displacement, and the “corner” period at which this occurs. There appears ~b+4rYNxU_
to be a disagreement between seismologists on opposite sides of the Atlantic about these data, 4.$ <o/M
which the structural engineer views with concern, since ductile structural response will often be in HUuL3 lYka
this region of the corner period. Dependable information on the reduction of displacement ?k<i e2
response with damping or ductility is also needed for design approaches utilizing secant stiffness w(U-6uA
characterization. Other areas needing clarification include the issue of how to develop Li( }_
accelerograms for time-history analysis compatible with the design seismicity using an acceptably q]T {g*lT
small number of accelerograms, and how to reconcile the statistical nature of seismicity cx_ FtD
characterization with the structural engineer’s preference for deterministic analysis. There is some F&<si:}KB
evidence that a consequence of this is invalid averaging of response characteristics by structural /B.\ 6
engineers.
