Lecture 18

Lecture 18 - Earthquake
Engineering
 and
Safety
...

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Unformatted text preview: Earthquake
Engineering
 and
Safety
 Damage
mi4ga4on
 Earthquake
Hazard
depends
on:
 
1)
Proximity
to
known
ac4ve
faults
for
which
we
must
assess:
 
 
a)
The
maximum
credible
earthquake
(ever!)
 
 
b)
The
maximum
probable

earthquake
(in
a
specified
period
of
4me)
 
2)
Local
geological
condi4ons
 
 
a)
Bedrock
is
best
 
 
b)
Unconsolidated
sediments
are
bad
 
 
c)
Water
saturated
unconsolidated
sediments
are
the
worst.
 
 
 
Liquifac4on
can
occur
 
 
Resonance
of
sedimentary
basins
produce
the
“bowl
of
jello
effect”
 1989
Loma
Prieta
Earthquake
 Mexico
City
1985

Juarez
Hospital
 Mexico
City
 Aztec
Empire
1325
 Earthquake
Risk
depends
on:
 
1)
Earthquake
Hazard

 
2)
Building
Design
 
 
a)
Flexible
is
good
 
 
b)
Rigid
is
bad
 Resonance
is
bad
 
Resonant
period
of
a

steel
frame
building:

T
=
NA
 
 
T
=
Resonant
period
in
seconds
 
 
N
=
Number
of
stories
 
 
A
=

Constant
(0.1‐0.3)
 
Example:
N=50
stories,
A=0.2,

gives
T=10
seconds
 
 
 
In
range
of
surface
waves
(bad)
 Shear
Walls
 Webb
Tower
USC
 Sob
First
Story
Failure
 Base
Isola4on
 The
first
base‐isolated
building
in
the
United
States
is
the
Foothill
Communi4es
Law
and
 Jus4ce
Center,
a
$30
million
legal
services
center
in
Rancho
Cucamonga
San
Bernardino
 County,
about
97
km
(60
miles)
east
of
downtown
Los
Angeles.
Completed
in
1985,
the
 building
is
four
stories
high
with
a
full
basement
and
sub‐basement
for
the
isola4on
system,
 which
consists
of
98
isolators
of
mul4layered
natural
rubber
bearings
reinforced
with
steel
 plates.
The
superstructure
of
the
building
has
a
structural
steel
frame
s4ffened
by
braced
 frames
in
some
bays
 Personal
Safety
during
an
Earthquake
 1)
Tie
down
water
heater
with
plummers
tape
to
prevent
falling
 2)
Know
where
to
turn
off
water
in
case
of
ruptured
pipe
 3)
Know
where
to
turn
off
gas
in
case
of
ruptured
pipe
–
but
only
if
you
smell
gas!
 4)
Have
emergency
supplies
(flashlight,
food,
water)
for
3
days.
 5)
Secure

tall
furniture
such
as
bookshelves
to
wall.
 6)
During
and
earthquake:
Do
not
run
outside,
Protect
your
head.
 7)
Aber
earthquake:
Check
yourself
for
injury,
put
on
shoes.
Get
out
of
 
ques4onable
building
before
large
abershock.
 ...
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