With conventional force-based seismic design, the most important information for the structural zT5@wm
engineer has been the effective peak ground acceleration. This number is comparatively V=,VOw4
insignificant in displacement-based or performance-based seismic design, where the key data are |
D jgm7$*
peak spectral response displacement, and the “corner” period at which this occurs. There appears Gf{FFIe(
to be a disagreement between seismologists on opposite sides of the Atlantic about these data, K qt,sJ
which the structural engineer views with concern, since ductile structural response will often be in g^EkRBU
this region of the corner period. Dependable information on the reduction of displacement z"C+r'39d=
response with damping or ductility is also needed for design approaches utilizing secant stiffness ekj@;6
d]
characterization. Other areas needing clarification include the issue of how to develop S4?N_"m9
accelerograms for time-history analysis compatible with the design seismicity using an acceptably J0vCi}L
small number of accelerograms, and how to reconcile the statistical nature of seismicity ywRw i~
characterization with the structural engineer’s preference for deterministic analysis. There is some ch%-Cg~%
evidence that a consequence of this is invalid averaging of response characteristics by structural .(8sa8{N
engineers.
