Seismic risk management for water pipeline networks - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 647

1.0

0.8

0.6

0.4

0.2

0.0

0 0.2 0.4 0.6 0.8 1

Investment ratio, C s / C 0

23.19 Old-pipe replacement for seismic investment (Wada et al. ,
2010).

1.E-01

1.E+00

1.E-02

Minor
Moderate
Major

Minor
Moderate
Major

1.E-03

1.E-01

1.E-04

1.E-05 1.E-02

0
Investment ratio, C s / C 0

0.5 1 0.00

Investment ratio, C s / C 0

0.50 1.00

(a) Probability of value loss for
various seismic investments

(b) Probability of structural failures for
various seismic investments

23.20 Probability of system failure for various seismic investments
(Wada et al. , 2010).

for various C s / C 0 values when the retrofi tting period T n is 30 years. The
probability of value loss increases for larger C s / C 0 , while the probability of
system-performance failure are monotonically decreased. The seismic per-
formance clearly changes at C s / C 0 0.4. Notably, this probability in the

minor-damage mode shows a sudden drop. This result indicates that the
existence of old-type joint pipes affects the seismic performance of a dete-
riorated network system. It is important that the stakeholders can make a
decision on the optimal seismic investment by comparing these probabili-
ties for various C s / C 0 .
Figure 23.21 indicates the effects of deterioration on seismic-retrofi tting
cost due to occurrence timing of a seismic event. Since the severe deteriora-
tion case shows a higher retrofi tting cost, durability of the pipe material is
also an important factor in the seismic performance of the lifeline network.

=