Seismologists, earthquake engineers and seismic code experts understand the science of earth that moves and the structures built on it, but many of the concepts involved may be too abstract for architects, builders and the public. This presentation offers an analogy to help explain seismic design and presents three different construction techniques used in Chile, Japan and the United States that counter an earthquake’s effects.
The ground exerts seismic forces upon a building following a particular spectral acceleration, like a musician playing an instrument according to a given score. In both cases, there are several elements that determine how energy is transferred, and describe how it is felt.
Understanding Resilience through a Musical Analogy
1. 2016 International Conference on Natural Hazards and Infrastructure
Understanding Resilience
through a Musical Analogy
Ramon Gilsanz, PE, SE, FSEI
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A Musical Analogy
Earthquake ↔ Music
Soil ↔ Musician
Seismic Spectrum ↔ Score
Building ↔ Instrument
Bldg. Response ↔ Melody
Occupants ↔ Audience
Social Context ↔ Concert Hall
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Soil
Magnitude
Acceleration
Shaking Duration
Frequency
Musician
Dynamics (Loudness)
Tempo (Speed)
Time (Length of Piece)
Musical Pitch
Soil-Musician
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Soil-Musician
Types of Waves
Bolt, B. (1993) “Earthquakes and Geological Discovery”
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Soil-Musician
Types of Waves
Atkinson Physics (YouTube)
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• Density (Granite): 156-168 lbs/sf3
• P-Waves: 19,700 ft/s
• S-Waves: 10,800 ft/s
Soil-Musician
Solid Rock
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• Density: 94 lbs/sf3
• P-Waves: 1,310 ft/s
• S-Waves: 330 ft/s
Soil-Musician
Sand
Rachel Barton Pine
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Soil-Musician
Liquefaction
Christchurch, New Zealand, 2011
nzraw.co.nz
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Soil-Musician
Liquefaction
Assam, India, 1897
Oldham, R.D. “Report on the great earthquake of 1897”
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Soil-Musician
Clay and Silt
Indiana University Southeast
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• Measure of energy an earthquake
releases
• An increase in magnitude
of 1 is a 32-fold increase
in energy released
• Seismic Moment =
(Strength of soil) x (Rupture area) x
(Fault displacement)
(Adopted by USGS in 2002)
Soil-Musician
Magnitude
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• Peak Ground Acceleration (PGA)
– Maximum acceleration experienced by
a particle at ground level
• Peak Floor Acceleration (PFA)
– Maximum acceleration experienced at
a floor level
Soil-Musician
Accelerations
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Building-Instrument
Resonance
Missouri S&T, Prof. O. Kwon (YouTube)
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Role of the Engineer
• Static Analysis
• Response Spectrum
• Non-linear / Time History
(measures duration)
Building-Instrument
Ways to Design
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Approximate acceleration
experienced by a building, when
modeled as a particle on a vertical
mass-less rod, with an identical
period as the building
Building-Instrument
Ways to Design
Acceleration
T
F ~ m x SA
GMS
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Building-Instrument
Ways to Design
Acceleration
PERIOD
SA
T
ACCELERATION
SDS
SD1
PGA
GMS
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NEHRP SDS SD1
2003 0.24 0.047
2000 0.28 0.063
1997 0.28 0.063
Design accelerations for
Zip Code: 10016
Assuming Site Class B
Rock
Standard Steel building
Ordinary moment frame
Ie =1
R = 3.5
Ts = 0.195 seconds
Building-Instrument
Ways to Design
Acceleration
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• Approach: Redundant shear wall
construction
• Goal: Immediate occupancy
• Downside: High non-structural
damage, architectural constraints
Building-Instrument
Design Approach:
Chile
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Building-Instrument
Design Approach:
Chile
FEMA-350 (2000)
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Building-Instrument
Design Approach:
Japan
• Approach: Base isolation
• Goal: Immediate occupancy
& minimal damage
• Downside: High cost
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Building-Instrument
Design Approach:
Japan
Photos: GMS
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Building-Instrument
Design Approach:
Japan
Shimizu Corporation
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Building-Instrument
Design Approach:
United States
• Approach: Energy dissipation
through plastic deformations
of the structure
• Goal: Cost effective life safety
• Downside: Significant damage
to building
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Building-Instrument
Design Approach:
United States
Photo: GMS
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Building-Instrument
Plastic Hinge
FEMA-350 (2000)
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Building-Instrument
Plastic Hinge
FEMA-350 (2000)
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Occupants- Audience
Modified Mercalli Earthquake Intensity Scale
imgur.com
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Collapse
Unusable
Usable
Source: CATDAT Damaging Earthquakes Database (via earthquake-report.co
Building Damage
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Context-Concert Hall
South African National Youth Orchestra
Chrisian Mehlfurer
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U.S. Approach
Protects the individual…
• 0.5% of all crashes are fatal
• 1.07 fatalities per 100 mil VMT
(US DOT NHTSA)
…but cripples the system (city)
(US DOT FHWA)
Bottle-
necks
25%
Collisions
Bad
weather
Work
zones
Poor Signal
Other
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Context-Concert Hall
Lisbon, 1755
Bettman Archives
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Context-Concert Hall
Lisbon, 1755
Voltaire Rousseau
Nature is so cruel…
Look at this
devastation in Lisbon!
Nature is so cruel…
Look at this
devastation in Lisbon!
Nature did not construct
twenty thousand houses of
six to seven stories there!
Nature did not construct
twenty thousand houses of
six to seven stories there!
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Context-Concert Hall
San Francisco, 1906
Wikimedia Commons
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Context-Concert Hall
San Francisco, 1906
Over 3,000 deaths
Total damage ~ $350 million
Estimates of % damage due to earthquake:
3% - Colonel Francis W. Fitzpatrick, ISBC, 1906.
About 4% - Horace D. Dunn, engineer, 1906.
3 to 10% - Architect and Engineer, 1907.
Less than 5% - A.M. Hunt, insurance adjuster, 1925.
20% - Professor Karl Steinbrugge, University of CA, 1982.
5% - Professor Stephen Tobriner, University of CA.
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Great Kantō
earthquake struck
Tokyo at 11:58:44 a.m
September 1, 1923
Because the
earthquake struck at
lunchtime when many
people were cooking
meals over fire, many
people died as a result
of the many large
fires that broke out
3 hour
6 hour 12 hour
Building Damage
3 hour
Courtesy of Michigan State University
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• How many instruments must break
before a performance gets canceled?
• How important are those instruments?
• Not only individual buildings, but the
entire neighborhood must be resilient.
• It is important that the neighbor remains
standing
Context-Concert Hall
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• The most vulnerable elements of the city
are most in need of protection.
• 9/11 attack
– Economically strong neighborhood
– Newer construction
– Localized damage
– City is not paralyzed
• Hurricane Sandy
– Economically weak neighborhoods
– Older construction
– Widespread damage
– More difficult to respond
Context-Concert Hall
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Credits
Staring
Ramon Gilsanz
Supporting Roles
Verónica Cedillos
Dan Eschanasy
Ayse Hortacsu
Sissy Nikolaou
Len Joseph
Produced by
Petr Vancura
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Thank you
Gilsanz Murray Steficek
Engineers and Architects