First European conference on earthquake engineering and seismology, September 2006

With conventional force-based seismic design, the most important information for the structural engineer has been the effective peak ground acceleration. This number is comparatively insignificant in displacement-based or performance-based seismic design, where the key data are peak spectral response displacement,and the "corner" period at which this occurs. There appears to be a disagreement between seismologists on opposite sides of the Atlantic about these data, which the structural engineer views with concern, since ductile structural response will often be in this region of the corner period. Other areas needing clarification include the issue of how to develop accelerograms for time-history analysis compatible with the design seismicity using an acceptably small number of accelerograms, and how to reconcile the statistical nature of seismicity characterization with the structural engineer's preference for deterministic analysis.There is some evidence that a consequence of this is invalid averaging of response characteristics by structural engineers.