Earthquakes and Ground Motions - Earthquake Engineering for Structural Design - page 261

Figure 7.38 Definition of significant pulse (after Aptikaev and Erteleva, 2005)

30

24

25

20

15

10

10

7 7

5

0

One pulse Two pulses Three pulses Four pulses

Figure 7.39 Number of significant pulses (after Rodriquez-Marek, 2000)

The majority of records contain two significant pulses (i.e., one full cycle of pulse
type ground motion). Somerville (1998) suggests that the number of half pulses in
the velocity time history might be associated to the number of asperities in a fault.
This is a difficult phenomenon to be estimated a priori. There are no models
currently available for predicting the number of significant pulses in the velocity
time history. For the majority of cases, the number will vary from 1 to 3, but the