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Utilities
include
water,
wastewater,
fuel,
electricity,
gas, and
telecommunications
systems.
The basic
components
of
utilities
include
supply and
storage
equipment,
transmission
lines, and
the
connections
between
these
components.
Utility
components
may be
located
above
ground or
underground,
and rely
on poles,
grade
level
foundations,
or soils
for
support.
Utilities
commonly
suffer
earthquake
damage for
two
reasons:
-
Above
ground
utility
equipment,
tanks,
pipelines,
and
connections
are
often
inadequately
braced
or
inadequately
secured
to
their
foundation
structures.
Like
buildings
and
other
facilities,
utilities
tend
to
be
designed
for
vertical
gravity
loads.
As
a
result,
the
equipment
anchorage
and
pipeline
bracing
may
not
be
strong
enough
to
carry
the
large
lateral
forces
associated
with
earthquakes.
- Underground
utility
pipelines
and
connections
are
often
too
weak
or
inflexible
to
withstand
earthquake
ground
movements
and
differential
settlements,
causing
them
to
crack
or
fail.
Materials
that
are
too
flexible,
however,
also
cannot
handle
additional
displacements
from
earthquake
forces.
Types
of Damages
to
Utilities.
Typical
types of
utility
damage are
described
below:
-
Supply
equipment.
Supply
equipment
such
as
electrical
transformers,
pumps,
or
generators
are
typically
located
on
grade
level
foundations
or
elevated
support
structures.
When
this
equipment
is
not
supported
or
anchored
properly
it
may
topple
or
fall
from
its
supports
during
an
earthquake.
Supply
equipment
mounted
on
separate
foundations
can
also
be
damaged
by
differential
settlements
or
movements
between
the
foundations.
Porcelain
components
of
electrical
transformers
are
brittle
and
can
break
during
an
earthquake.
-
Utility
transmission
lines.
Utility
transmission
lines
include
pipes
with
joints
for
water,
wastewater,
fuel,
gas,
and
electrical
conduits
that
run
underground
or
above
grade
level.
Damage
to
above
ground
transmission
lines
typically
occurs
along
unsupported
line
sections
when
lines
crack,
leak,
or
fail.
Damage
to
underground
transmission
lines
usually
occurs
in
areas
of
soil
failure
where
the
line
sections
cannot
withstand
soil
movements
or
differential
settlements.
-
Connections.
Damage
to
connections
between
utility
pipeline
sections
and/or
between
utility
transmission
lines
and
equipment
occur
where
the
connections
can
not
withstand
soil
movements
or
differential
settlements.
-
Tank
structures.
Tank
structures
may
be
oriented
vertically,
horizontally,
at
grade,
or
elevated.
Tall
vertical
tank
structures
or
standpipes
are
often
damaged
by
a
combination
of
the
structure's
reactions
to
ground
shaking
and
dynamic
forces
generated
by
water
sloshing
inside
the
tank.
Tank
foundation
supports
fail
and
denting
of
thin
tank
wall
sections
often
result.
The
most
serious
type
of
vertical
tank
damage
occurs
when
the
tank
walls
crush
near
the
base,
triggering
tank
leakage
or
collapse.
Horizontal
tanks
are
often
damaged
when
tanks
are
not
securely
anchored
to
the
foundations.
Elevated
tank
structures
may
be
damaged
due
to
buckling
of
the
cross
braces
between
the
tank
legs.
In
addition
to the
types of
damage
listed
above,
damage to
utilities
can
trigger
secondary
damages
that
affect the
community
at large.
Leaking or
broken
utilities
can cause
water
damage,
fire or
explosion.
Since
these
systems
are
interconnected,
a loss of
one
utility
system
(such as
electrical
power) can
often lead
to a loss
of other
systems.
A
structural
engineer
may need
to be
consulted
to
identify
whether
certain
mitigation
measures
are
appropriate.
Some
measures
included
in this
section
are not
appropriate
for all
utilities.
Be aware
that
choosing
the wrong
measure
may cause
more
problems
than not
doing any
retrofit
at all.
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