Incremental dynamic analysis (IDA) applied to seismic risk assessment of bridges - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 577

collapse (when scaled). It should be noted that IDA can be performed using
fewer records (e.g., 22 records based on ATC-63).
The prediction of the epsilon values of the records using the AB06
GMPE (Atkinson and Boore, 2006) for eastern North America and the
deaggregation of the seismic hazard for Montreal indicated that the mean
epsilon values of the records considered (in the range of periods of the
bridge studied) are similar to the mean epsilon values obtained from the
seismic hazard deaggregation. Therefore no modifi cation of the results for
the spectral shape effects was necessary.

21.7.5 Seismic hazard in Montreal

An updated seismic hazard model developed by Atkinson and Goda (2011)
was used. The uniform hazard spectra at different hazard levels (i.e., 10%
and 2% probability of exceedance in 50 years) obtained using the updated
model along with the 2010 NBCC design spectra are shown in Fig. 21.8 for
Montreal.

21.7.6 Seismic performance and risk assessment
using IDA

To develop the IDA curves the spectral acceleration at the fundamental
period of the bridges is used as the IM and the maximum drift ratio of the
columns is used as the DM. The preferred choice of an IM in the case where
the two axes of the structure have different fundamental periods has not

0.70

2010 NBCC median spectrum (2% in 50 years)
Updated mean spectrum (2% in 50 years)
Updated mean spectrum (10% in 50 years)

0.60

0.50

0.40

0.30

0.20

0.10

0.00

0 0.5 1.0 1.5

T (s)

2.0 2.5 3.0

21.8 Uniform hazard spectra (UHS) at different hazard levels for
Montreal and site class C.