Probabilistic seismic hazard analysis of civil infrastructure - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 10

fractiles of the ground motion parameters at various probability levels can
be easily extracted to construct uniform hazard spectra.
A signifi cant advantage of using Monte Carlo simulation rather than
numerical integration to perform the hazard analysis is that it facilitates the
production of seismic deaggregation results at any probability level (i.e. to
show hazard contributions by magnitude and distance), because all infor-
mation that is needed for seismic deaggregation is kept throughout the
analysis. The process of constructing uniform hazard spectra and deaggrega-
tion results is illustrated in Fig. 1.5.
A further advantage of the simulation-based approach over conventional
numerical integration is transparency of the procedure. The calculation
steps are straightforward and intuitive: simulating earthquake time and
location, generating earthquake magnitude and fault dimensions, and then
estimating ground motion parameters for given earthquake characteristics.

Construction of uniform hazard spectra:
•

Reorganise the calculated response spectra values on the
annual maximum basis, and sort them in an ascending order
•

2.0 Uniform hazard spectra for Vancouver

Assign the annual probability of exceedance

• Select the target probability level

Annual prob.
of exceedance
:
0.0021060
0.0021058
0.0021056
0.0021054
0.0021052
:
:
:
0.0004048
0.0004046
0.0004044
0.0004042
0.0004040
:

1.0

PGA
( g )
:
0.235
0.236
0.236
0.236
0.236
:
:
:
0.487
0.487
0.488
0.488
0.488
:

SA(0.2)
( g )
:
0.577
0.577
0.577
0.577
0.577
:
:
:
1.244
1.245
1.245
1.245
1.245
:

SA(0.5)
( g )
:
0.342
0.342
0.342
0.342
0.343
:
:
:
0.749
0.749
0.749
0.749
0.749
:

SA(1.0)
( g )
:
0.185
0.185
0.185
0.185
0.185
:
:
:
0.432
0.432
0.432
0.432
0.433
:

SA(2.0)
( g )
:
0.091
0.091
0.091
0.091
0.091
:
:
:
0.227
0.227
0.227
0.227
0.227
:

0.5

10% in
50 years

0.3

0.2

Exceedance probability

0.1

2% in 50 years

2% in
50 years

10% in 50 years

0.05

PGA 0.1 0.2 0.3 0.5 1.0 2.0 3.0

Vibration period for SA (s)

Construction of seismic deaggregation:
• Each of the annual maximum response spectra values is associated
with an event in the synthetic earthquake catalogue
• Reassemble magnitude and distance information for events with response

values exceeding the target value, and produce a histogram

Seismic deaggregation (PGA) for Vancouver

0.05

0.04

0.03

9.0

0.02

8.0

0.01

0.0 7.0

Moment
magnitude

0

50 100
Distance (km)

6.0

150

200

250 5.0

1.5 Construction of uniform hazard spectra and seismic
deaggregation.