Seismic risk management for water pipeline networks - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 632

10.000 1.E+00

1.000 1.E-01

r =0.15
r =0.2
r =0.25

CIP
DCIP
(old type)
JWWA

0.100 1.E-02

0.010 1.E-03

0.001 1.E-04

0 50 100 150 200
Response velocity spectrum
(cm/s)

350 400 450 500
Response velocity spectrum (cm/s)

(a) Old-type joints (b) New-type joints

23.9 Damage rates for CIP and DCIP (Wada et al. , 2010).

DCIP (new-type joint) with three different connection factors is a

factor to control the number of mechanically locked joints for the effective
length l eff along the seismic wave propagation. This damage rate for DCIP
(new-type joint) suggests that the pull out joint failure can initiate for a
large response velocity more than 350 cm/s, however, which is not possible
to be produced by the Level 2 ground motion. This is the reason why any
damage examples of DCIP (new-type joint) were not observed in the past
earthquakes.

ρ . The ρ

23.2.3 Effects of deterioration
The mechanical joints of the old segmented pipelines may be damaged by
various reasons, such as ground shaking by traffi c, uneven settlement of the
alluvial ground, corrosion cracks in the corroded soil, and third party acci-
dent. such pipe damage is often reported as deterioration. The deterioration
process of pipe joints under traffi c load vibration is assumed to be modeled
by the following deterioration factor:

d

t
D

2

() =− ⎛

⎞
⎟

ψ t 1 d [23.25]

⎜

1

T

where d 1 and d 2 are parameters describing the deterioration behavior
(typical values of d 1 and d 2 for new and old joints are shown in Table 23.4),
and

DTT
DTT

=−
=−

before retrofitting
after retrofitting

T p 0

[23.26]

T Dp

in which T D is the service period of the pipeline system and T p is the time
at which the retrofi tting is conducted as shown in Fig. 23.10. These two
deteriorating factors for pipe joints as shown in Table 23.3 are derived from
the corrosion rates of buried water pipes (Imai and Koike, 2009).