Challenges for the Next Generation of Seismic Codes - Earthquake Engineering for Structural Design - page 483

- For the Northridge earthquake it is clear that Type 2 and T p = 1.0 sec are the
pulse parameters due to the fact that this earthquake is produced by a thrust
fault characterized by a single pulse.
- Contrary, for the Kobe earthquake, produced by a strike-slip earthquake with
multiple sources and two pulses, Type 3 and T p = 0.9 sec are the pulse
parameters.
Figure 10.6 compares the story shear distribution obtained from a standard
design methodology, based on modal combination, and the one from a time-history
analysis. The following observations can be made (Alavi and Krawinkler, 2001):
- For structures with T/T p > 1.0, the dynamic shear force distributions are

relatively smooth, but for structures with T/T p < 1.0, these distributions show a
clear effect of a wave traveling up the structure. Thus, for long period
structures analyzed with standard design methodology, the early yielding has
been expected in the upper stories (see the damaged buildings in Kobe).

Figure 10.6 Normalized elastic story shear forces (after Alavi and Krawinker,
2001)