Incremental dynamic analysis (IDA) applied to seismic risk assessment of bridges - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 567

subduction interface and inslab earthquakes) on the IDA results were
studied by Tehrani et al. (2012) for the case of a continuous 4-span bridge.
The properties of the bridge studied are shown in Fig. 21.4. The bridge was
designed using the 2010 CHBDC (CSA, 2010) for Vancouver, soil type C,
and an importance factor of 1.5. The middle column had a longitudinal
reinforcement ratio of 2%, while the other columns contained 1% of lon-
gitudinal reinforcement. The columns also had a spiral reinforcement ratio
of 1.2% for confi nement. For the case of the restrained transverse move-
ments at the abutments the fundamental period of the bridge was 0.7 s. To
investigate the effects of different record selection methods and earthquake
types, only the transverse response of the bridge was studied. Ground
motion records were selected from two extensive databases, the PEER-
NGA database and the K-NET/KiK-NET database. Some limitations were
imposed on the minimum magnitude (M), PGA and PGV of the records to
consider strong ground motions available in the database. The characteris-
tics of the records from the PEER-NGA database (179 records from 28
earthquakes) and the KNET/KIK-NET database (189 records from 23
earthquakes) are described by Goda and Atkinson (2009).
The IDA results including the IDA curves, 16%, 50% and 84% percen-
tiles, and the standard deviation of the results (i.e., due to record-to-record
variability) are presented in Fig. 21.5 and Table 21.2 for different record
selection methods. The results are also summarized for different damage
states including yielding, cover spalling and collapse. The use of the epsi-
lon-based record selection resulted in highest median collapse capacity
prediction. When different earthquake types are considered, it is necessary
to increase the number of records to improve the predictions of the median

50 m 50 m 50 m 50 m

H 1 = 5 m
D = 1.5 m

H 2 = 5 m
D = 1.5 m

H 3 = 5 m
D = 1.5 m

Superstructure
cross-section

Column cross-section

2000

D

1500 3 @ 3000 = 9000 mm 1 50 0

12 000 mm

21.4 Bridge properties.