Download Earthquake Engineering - Harlem Children Society

Darren Alphonse and Winifred Lao
Stevens Institute of Technology
Mentor: Frank Xu
Co-Mentor: Cooper Hu
Civil Engineering
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Basics of Earthquakes
Goal of Research
Technology and Designs of Earthquake
Engineering
Acoustic band gap
Theory: Seismic Waves vs. Sound Waves
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An earthquake is the shaking of the ground caused by
sudden breaking and movement in large sections of plate
tectonics.
Most earthquakes happen along fault lines when the plates
tectonic slide past each other or collide against each other.
This area is called the hypocenter (or focus)
The magnitude of the earthquake depends on displacement
of the plate tectonics
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The feeling of earthquakes can be explained by the elastic
theory.
Elastic Theory-energy is spread during earthquakes.
When the plate tectonics move, they absorb energy, but as
they break, they release energy. This energy is how we feel
shaking.
The energy that travels from the hypocenter is also known as
seismic waves.
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Collapse buildings and bridges
Destruction of vehicles and railroads
Broken power and gas Lines
Landslides
Snow Avalanches
Tsunamis
All of these events will
cause many deaths…
List of Death Caused by Earthquakes
Rank
Death Toll
Event
Location
Date
1
830,000
Shaanxi earthquake
China
1556
2
255,000
Tangshan earthquake
China
1976
3
240,000
Haiyuan earthquake
China
1920
4
230,000
Aleppo earthquake
Syria
1138
5
229,866
Indian Ocean earthquake
Indonesia, Sri Lanka, India, Thailand
2004
6
200,000
Damghan earthquake
Iran
856
7
150,000
Ardabil earthquake
Iran
893
8
137,000
Hokkaidō earthquake
Japan
1730
9
110,000
Ashgabat earthquake
Turkmenistan
1948
10
105,000
Great Kanto earthquake
Japan
1923
11
100,000
Messina earthquake
Italy
1908
12
100,000
Lisbon earthquake
Portugal
1755
13
100,000
Chihli earthquake
China
1290
14
86,000
Pakistan
2005
15
85,000 Great Ansei Nankai earthquakes Japan
1854
16
80,000
Shamakhi
Azerbaijan
1667
17
77,000
Tabriz Earthquake
Iran
1727
18
70,000 Changma, Gansu earthquake China
1932
19
69,197
Sichuan earthquake
China
2008
20
66,000
Ancash earthquake
Peru
1970
Kashmir earthquake
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Seismic waves are the energy released from the movement of the
faults.
There are two types of seismic waves: body waves and surface
waves
Body waves travels within the earth’s crust and consists of
◦ P waves: also known as primary or compressional waves
◦ S Waves: also known as secondary or shear or transverse waves
Surface waves travels along the earth’s surface and consists of:
◦ L waves: also known as Love waves
◦ R waves: also known as Rayleigh waves
Body vs. Surface waves
◦ P waves cause the ground
to move up and down and
is parallel to the direction
of the wave
◦ S Waves cause the ground
to move back and forth
and is perpendicular to the
direction of the wave
◦ L waves cause the ground
to move sideways and up
and down.
◦ R waves cause the ground
to move in a rippling up
and down motion.
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Resonance is the vibration frequency the object receives from
sudden movement
Example:
A push will
increase the
motion of the
swing, meaning
the swing moves
faster for a longer
period of time.
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How it applies to earthquakes:
◦ P waves come first and moves the ground, causing
preliminary damage.
◦ S waves come and moves the ground at the same frequency
as the P waves did, thus creating resonance: increase of
movement and greater damage.
◦ R waves and L waves arrive, creating damage in the same
manner as the S wave.
Idea: To prevent resonance on a building from occurring.
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To find better technology from the effects of earthquakes,
specifically movement of buildings.
Mr. Frank Xu’s research is to design technology to absorb
energy released by earthquakes to prevent movement of
buildings. He is still in preliminary research.
Our goal of this summer is to assist in his preliminary
research to help find more methods to prevent earthquake
damages.
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Diaphragms are horizontal resistance elements (ex. floor or
roof)
Shear walls are vertical resistance elements (ex. walls)
Brace frames are diagonal resistance elements, can be
connected in many different ways.
It is very important that the connection between diaphragms
and shear walls are strong.
Different types of brace
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Moment Resistant Frames are the skeletal structure of a
building consisting of columns and beams
They must be strongly bolted together
Example of bolted connection
Example of Moment Resistant Frames
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Base Isolation is a popular choice of design
It is when there are structures placed between the building
and foundation.
Two known base isolation designs are:
◦ Lead-Rubber Bearing
◦ Sliding Isolation System
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The building is connected to lead-rubber bearings, which are
also attached to the foundation
When an earthquake occurs, the building itself should not be
affected, but the lead-rubber bearings are.
The lead absorbs the kinetic energy of the movement of the
ground and releases it as heat. The rubber is deformed.
Before and during an
earthquake, snapshot of leadrubber bearings
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There is a half spherical bearing, which supports the building
and has low friction.
When the ground is in motion because of earthquake, the
building moves on the bearing in a pendulum motion.
Different size bearings results in different pendulum period
length.
Example of Sliding Isolation System
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The idea of damping is to dissipate the energy that is
concentrated on one area.
The base isolation designs considered damping the energy
from earthquakes because:
◦ Lead-Rubber Bearings Design: the energy is converted to
heat
◦ Sliding Isolation System: the movement of the building in
the pendulum motion cancels out with the energy causing
the movement of the building
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P waves and sound waves are similar because they are both
mechanical waves (meaning the wave requires a medium to
transport their energy)
P waves and sound waves also travel similarly:
One particle vibrates and hits the next one and continues pattern
How a sound is created (using tuning fork)
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Acoustic Band gap- is the acoustic wave
equivalent of an electronic or photonic band gap.
Where a wide range of frequencies are forbidden to exist in a
structured material.
If acoustic bandgap is used, then the amount of sound is
control.
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Since P-waves and Sound waves are similar in movement we
can apply the same idea of controlling sound wave
frequencies to controlling seismic wave frequencies.
Sound can be controlled by acoustic bandgap.
Theory: Seismic waves can be controlled by a technology
similar to acoustic bandgap.
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Earthquakes are caused by breakage of plate tectonics.
The energy released from breakage of plate tectonics is
seismic waves and that is how we feel earthquakes.
There are four types of seismic waves: P waves, S waves, L
waves, R waves.
Resonance is damaging to buildings.
Base isolation is used to dissipate energy from being
concentrated in one area
There are two types of base isolation: lead-rubber and sliding
isolation system
Sound waves and P waves are very similar
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To test theory
Comparing different types of earthquake designs.
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Ahmadizade, Mehdi. Structural Properties. 25 July 2006.
<http://mceer.buffalo.edu/connected_teaching/lessons/aboutEQen
gineering.pdf>.
Bertero, V. V. Earthquake Engineering. October 1997.
<http://nisee.berkeley.edu/bertero/index.html>.
Henderson, Tom. The Nature of Sound. 2009.
<http://www.physicsclassroom.com/Class/sound/u11l1a.cfm>.
Leung-Wai, Jason and Ganesh Nana. "Economic Impact of Seismic
Isolation Technology." Report to: Ministry of Research Science and
Technology. June 2004.
Mork, Peter. Earthquake Resisting Systems. 29 June 1999.
<http://www.atcouncil.org/pdfs/bp1c.pdf>.
Naderzadch, Ahmad. "Application of Seismic Base Isolation
Technology in Iran." Feb 2009.
Taylor, Andrew W. and Takeru Igusa. Primer on seismic isolation.
ASCE Publications, 2004.
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Mentor Frank Xu
Co Mentor Cooper Hu
Stevens Institute of Technology
Rockefeller University
Harlem Children Society
Dr Sat
Staff