Seismic risk assessment of water supply systems - Seismic Risk Analysis and Management of Civil Infrastructure Systems - page 669

operations for both the LADWP water supply and electric power systems.
Each of these simulations relies on information about damage states,
as provided by the system simulation model developed in previous
sections.
24.8 Futuretrends
The seismic risk assessment of the LADWP water supply system has focused
on the seismic responses of pipelines and their impact on the overall system
performance. The seismic responses of other components, such as pump
stations, regulation stations, ground water wells, and tanks and reservoirs,
are not included. It is useful to incorporate the seismic responses of those
components and to integrate their impacts to the seismic risk assessment.
The framework and procedures described in this chapter can be readily
adapted to other components, provided that fragility information for those
components is developed.
Because of the diffi culty in predicting the occurrence of permanent
ground deformation and delineating the spatial distribution of permanent
ground deformation, the PGD effects on the system component perfor-
mance during earthquakes were not incorporated in seismic risk assessment
of the LADWP water supply system. It is also valuable to incorporate the
PGD effects on the seismic responses of system components, as well as the
overall system. The framework and procedures described herein can be
easily modifi ed to incorporate PGD effects.
Interdependencies among different lifeline systems (e.g., water and
power systems) are one of the most prominent characteristics of lifeline
systems. The damage and disruption of seismic hazards in other systems
may affect the system being assessed because of physical proximity and/or
operational interaction. For example, the loss of electricity affects water
supply systems by rendering pumps and automatic valves inoperable,
thereby affecting the fl ow and pressure in the water supply systems. There-
fore, one important aspect in the lifeline seismic risk assessment is the
interaction of the system under scrutiny with other lifeline systems.
In addition, since detailed simulation of a large water supply system is
often complex and time consuming, the computational time and efforts are
obviously demanding for seismic risk assessment of water supply systems.
Such computational diffi culty is particularly prominent for seismic risk
mitigation in which repeated seismic risk assessments are needed for various
mitigation options. Further studies on how to improve computational effi -
ciency in seismic risk assessment and mitigation for water supply systems
are therefore worthwhile to pursue. Some preliminary investigations have
been performed using conditional samples from a single run of Monte Carlo