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Earthquake Engineering. “8.9 Quake Strikes Japan—Nation’s worst in 140 years”. Airport, Sendai, Japan. Fukushima- Daichi nuclear power plant. Earthquakes Past and Present. Sendai, Japan (8.9 magnitude). historical Seismicity Map. http://earthquake.usgs.gov/eqcenter/recenteqsww/.

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8 9 quake strikes japan nation s worst in 140 years
“8.9 Quake Strikes Japan—Nation’s worst in 140 years”

Airport, Sendai, Japan

Fukushima-Daichi nuclear power plant


Earthquakes past and present
Earthquakes Past and Present years”

Sendai, Japan (8.9 magnitude)

historical Seismicity Map

http://earthquake.usgs.gov/eqcenter/recenteqsww/

http://earthquake.usgs.gov/earthquakes/world/seismicity_maps/world.pdf


A pan global issue
A pan-global issue…. years”

http://www.mapsofworld.com/world-major-earthquake.htm


Some major earthquakes past and present
Some Major Earthquakes, Past and Present years”

Christchurch, NZ 2011

Talca, Chile 2010

Port-au-Prince, Haiti, 2010

Guandong, China, 2008

Fukuoka, Japan, 2005

Izmit, Turkey, 1999

Northridge, CA, 1994

Mexico City, 1985


Why bother
Why bother? years”


Sendai japan earthquake 2011
Sendai Japan Earthquake 2011 years”

Amazing engineering: Buildings Sway Without Collapsing


Different buildings
Different Buildings years”

Different model parameters


The fundamental questions
The Fundamental Questions years”

  • Can we predict how different buildings will respond to an earthquake?

  • How can we use this information to engineer a safe structure


Tabas iran 1978 earthquake
Tabas years”, Iran 1978 Earthquake

Acceleration record is messy. No way to integrate Duhamel’s integral. No worries, computers to the rescue!

Relative motion of building and ground

Impulse Response Function

Measured Acceleration/USGS data


Ground acceleration (units of g) years”

z = 0.05is assumed

Z(t) meters

marks |z|max

If we found |z|max for a continuous range of wo, we’d get the Spectral Displacement

(Displacement Spectrum)

Z(t) meters

Z(t) meters


Averaged Spectra years”

To Many (88) Earthquakes

Spectra For El Centro Ground Motion

Velocity

Acceleration

Displacement

Natural Period (sec)

Figure Credits: L A Chopra, Dynamics of Structures, Chap 6

Right: G. Housner “Strong Ground Motion” in Earthquake Engineering, R Wiegel, editor.


Tripartite representation
Tripartite Representation years”

SD = spectral displacement

SV = spectral velocity

SA = spectral acceleration

SA/wo = SV = woSD


Housner spectrum
Housner Spectrum years”

Spectrum for one earthquake

Spectrum averaged over 88 earthquakes


Housner spectrum for z 0 05
Housner spectrum for years”z = 0.05


Seattle monorail
Seattle Monorail years”

  • Seattle, WA is a beautiful city, but is prone to large earthquakes. The monorail on the bridge has previously been measured to have a natural period of 2 s. Damping is assumed to be 2%. During an earthquake, is the trolley likely to derail? Use the Housner spectrum to find out!

Picture from: http://bcostin.wordpress.com/2008/02/25/seattle-worlds-fair-1962-postcards/seattle-monorail/


Beach house
Beach House years”

  • You are hired as an architectural engineer to build a California dream house on a hillside. The structure can be idealized as shown (on chalkboard). The frame is built out of concrete (E = 30x109 Pa). The support columns have a cross section of 10 inches squared. Assume damping is 5%. Determine the base shear in each column, which is more likely to fail?


What we need to guard against
What we need to guard against years”

Buckling

SmaSHING/POUNDING


Base isolation configuration
Base Isolation Configuration years”

Figure credit: Michael D. Symans, PhD Rensselaer Polytechnic Institute: http://www.nibs.org/client/assets/files/bssc/Topic15-7-SeismicIsolation.pdf


Reduced shearing in superstructure
Reduced Shearing in Superstructure. years”

Conventional Building

Base-Isolated Building

Figure credit: Michael D. Symans, PhD Rensselaer Polytechnic Institute: http://www.nibs.org/client/assets/files/bssc/Topic15-7-SeismicIsolation.pdf


Lead rubber bearing
Lead-Rubber Bearing years”

Shear Modulus

E ~ 0.5 – 1.0 MPa

Figure credit:sMichael D. Symans, Rensselaer Polytechnic Institute: http://c.ymcdn.com/sites/www.nibs.org/resource/resmgr/BSSC/Topic15-7-SeismicIsolation.pdf


Lrb decreases k eff and w o
LRB decreases years”keff and wo

Reduces shearing in columns…………but increases displacement


Lrb isolation in action
LRB Isolation in Action years”

Rubber Base Isolators


Lead rubber bearing lrb in action
Lead Rubber years”Bearing (LRB) in Action

UCSD testing facility

LBRs in Japan


How do we model what we just saw
How do we model what we just saw? years”

Displacement , u


Frictional pendulum system
Frictional Pendulum System years”

Image credit: http://www.asee.org/documents/sections/pacific-southwest/2008/Porbaha_Ali_et_al%20Base%20isolation.pdf


Concept of frictional pendulum
Concept of Frictional Pendulum years”

Image credits: http://www.asee.org/documents/sections/pacific-southwest/2008/Porbaha_Ali_et_al%20Base%20isolation.pdf

http://nees.buffalo.edu/docs/dec304/FP-DC%20Report-DEMO.pdf; laconservancy.org


Frictional pendulum
Frictional Pendulum years”

Restoring/Recentering Force

Frictional Force

Pendulum Period:

T


The quantitative model
The quantitative model years”

Frictional Force

Restoring/Recentering Force



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