Report - PEER - University of California, Berkeley

elong to the far field so that come from stations at over 25 km in distance in order tobetter avoid directivity pulse-type effects.2.2.1 Class of Target SetsSimilarly to what presented in Iervolino and Cornell (2004) the target sets for therecord selection study are designed to be representative of specific scenarios; i.e.duration. Three sets of 20 records each have been set up to be I D specific in themedian (I D = 5, I D = 13, I D = 20). Scatter around the median values are due tounavailability of enough records with required features in the database, this scatterwill affect results especially in I D = 20 sets where it is stronger.6050Trifunac and NovikovaTrifunac and BradyDuration [s]4030201000 5 10 15 20 25 306050Trifunac and BradyTrifunac and NovikovaID(a)Duration [s]4030201000 5 10 15 20 25 30ID(b)Figure 4. I D vs. duration in the T (target sets) (a) and A (arbitrary sets) (b).Duration characteristics of target sets are shown in Figure 4(a) where I D isrepresented versus other duration definitions (Trifunac and Brady, 1975; Trifunac andNovikova, 1994). In order to best represent what might occur in the future and toreduce correlation due to event commonality, it is desirable to have the records ineach set coming from different events. This requirement conflicts with the desire tohave a large sample. Target sets have been split in two of size ten which is the orderof magnitude used in recommended earthquake engineering practice, but also toformally compare different sets with the same I D . The size ten sets are named: T5a,314