Seismic risk management for water pipeline networks - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 618

23
Seismic risk management for water
pipeline networks
T. KOIKE, Kyoto University, Japan
DOI : 10.1533/9780857098986.4.626
Abstract : This chapter discusses a seismic risk management method
for a deteriorating lifeline network system based on the probability of
system-performance failure. The chapter fi rst reviews seismic damage
to buried water pipelines and their facilities, and then discusses seismic
risk assessment methods of lifeline networks in which structural and
functional failures are correlated. Numerical studies are carried out
for a water distribution network system by considering several seismic
investment strategies to support the decision-making process in seismic
disaster mitigation planning.
Key words : existing lifeline systems, performance-based design, seismic
risk assessment, disaster prevention investment, probability of value loss.
23.1 Introduction
Since a lifeline network system is responsible for the lives and health of its
users in addition to providing a social benefi t, it is essential to keep the
supply service functioning as much as possible even when a severe seismic
event occurs. Originally, lifelines in Japan were designed to satisfy seismic
load requirements that were based on the past signifi cant events. Such an
approach may underestimate possible damage in future scenarios, as past
experiences are not necessarily the worst situation. Therefore, it is impor-
tant to enhance seismic performance of existing lifelines by implementing
reinforcement and retrofi tting actions (Eidinger and Avila, 1999). Further-
more, these lifelines fail due to various causes, such as corrosion, traffi c load,
and third-party accidents (Imai and Koike, 2011), and so the original design
seismic strength is not maintained.
Any existing lifeline system is composed of many pipe segments, i.e.
various mixtures of old- and new-type joints (Kubota, 1992). Generally
speaking, old-type joints have poor resistance against large ground motions.
Approximately 80% of existing lifeline networks in Japan have old-type
joints, and so it will take considerable time to replace all of them. Since
many unit pipes have a very long life, replacing old-type with new-type
joints will require an enormous investment. Therefore, it is necessary to
consider a partial and selective retrofi tting scheme, which means that some
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