Seismic risk management for water pipeline networks - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 623

D joint

l d

Locking ring
Stopper DCIP

(a) Before seismic elongation

Pulling
force

Pulling
force

l eff

(b) After seismic elongation

23.4 Restraining mechanism of the new-type DCIP joint (Wada et al. ,
2010).

23.2.2 Seismic performance of pipelines

There are two useful seismic design guidelines of segmented pipelines,
which are issued from the American Lifeline Alliance (ALA, 2005) and the
Japan Water Works Association (JWWA, 1997). These current seismic
design methods are reviewed and compared below and on page 635. These
procedures are suitable for existing segmented pipelines. On page 635, a
design procedure for new-type segmented pipelines is discussed. Subse-
quently, on page 638, a general analysis method for evaluating seismic fragil-
ity of segmented pipelines is summarized.

Seismic performance design procedure of existing segmented
pipelines in the USA

The ALA (2005) has developed a design procedure for segmented joint
pipes for earthquake loading. An unrestrained and segmented pipe has
joints with low strength and stiffness relative to the pipe barrel. An example
is a DCIP with push-on, bell-and-spigot gasketed joints as shown in Fig.
23.3(b). The axial displacement that is accommodated by the joint can be
taken as follows (El Hamadi and O'Rourke, 1990):

Δ joint = 7 l d ε [23.1]

soil

Δ joint is the capacity against the joint pull-out at the time of the earth-
quake, l d is the length of the pipe segment as shown in Fig. 23.4 (a), and
ε soil is the ground strain in the axial direction of the pipe. For design pur-
poses, the ALA guidelines recommend the use of seven times the average
joint movement, based on El Hamadi and O'Rourke (1990). The ALA
seismic design method of the joint suggests that the pull-out movement

where