Some Major Earthquakes, Past and Present 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
Slide 6
Slide 7
Amazing engineering: Buildings Sway Without Collapsing
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Different model parameters
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Can we predict how different buildings will respond to an
earthquake? How can we use this information to engineer a safe
structure
Slide 10
Acceleration record is messy. No way to integrate Duhamels
integral. No worries, computers to the rescue! Relative motion of
building and ground Impulse Response Function Measured
Acceleration/USGS data
Slide 11
is assumed marks |z| max If we found |z| max for a continuous
range of o, wed get the Spectral Displacement (Displacement
Spectrum) Ground acceleration (units of g) Z(t) meters
Slide 12
Spectra For El Centro Ground Motion Averaged Spectra To Many
(88) Earthquakes Figure Credits: L A Chopra, Dynamics of
Structures, Chap 6 Right: G. Housner Strong Ground Motion in
Earthquake Engineering, R Wiegel, editor. Natural Period (sec)
Displacement Acceleration Velocity
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Tripartite Representation S D = spectral displacement S V =
spectral velocity S A = spectral acceleration S A = S V = S D
Slide 14
Spectrum for one earthquakeSpectrum averaged over 88
earthquakes
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Slide 16
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/
Slide 17
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 = 30x10 9 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?
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BUCKLINGSMASHING/POUNDING
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Figure credit: Michael D. Symans, PhD Rensselaer Polytechnic
Institute:
http://www.nibs.org/client/assets/files/bssc/Topic15-7-SeismicIsolation.pdf
Slide 20
CONVENTIONAL BUILDINGBASE-ISOLATED BUILDING Figure credit:
Michael D. Symans, PhD Rensselaer Polytechnic Institute:
http://www.nibs.org/client/assets/files/bssc/Topic15-7-SeismicIsolation.pdf
Slide 21
Figure credit:s Michael D. Symans, Rensselaer Polytechnic
Institute:
http://c.ymcdn.com/sites/www.nibs.org/resource/resmgr/BSSC/Topic15-7-SeismicIsolation.pdf
Shear Modulus E ~ 0.5 1.0 MPa
Slide 22
Reduces shearing in columnsbut increases displacement
