Earthquake engineering
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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.

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Earthquake Engineering

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Earthquake engineering

Earthquake Engineering

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

Sendai, Japan (8.9 magnitude)

historical Seismicity Map

A pan global issue

A pan-global issue….

Some major earthquakes past and present

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

Why bother

Why bother?

Sendai japan earthquake 2011

Sendai Japan Earthquake 2011

Amazing engineering: Buildings Sway Without Collapsing

Different buildings

Different Buildings

Different model parameters

The fundamental questions

The Fundamental Questions

  • 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, 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

Earthquake engineering 2368941

Ground acceleration (units of g)

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

Earthquake engineering 2368941

Averaged Spectra

To Many (88) Earthquakes

Spectra For El Centro Ground Motion




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

SD = spectral displacement

SV = spectral velocity

SA = spectral acceleration

SA/wo = SV = woSD

Housner spectrum

Housner Spectrum

Spectrum for one earthquake

Spectrum averaged over 88 earthquakes

Housner spectrum for z 0 05

Housner spectrum for z = 0.05

Seattle monorail

Seattle Monorail

  • 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:

Beach house

Beach House

  • 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



Base isolation configuration

Base Isolation Configuration

Figure credit: Michael D. Symans, PhD Rensselaer Polytechnic Institute:

Reduced shearing in superstructure

Reduced Shearing in Superstructure.

Conventional Building

Base-Isolated Building

Figure credit: Michael D. Symans, PhD Rensselaer Polytechnic Institute:

Lead rubber bearing

Lead-Rubber Bearing

Shear Modulus

E ~ 0.5 – 1.0 MPa

Figure credit:sMichael D. Symans, Rensselaer Polytechnic Institute:

Lrb decreases k eff and w o

LRB decreases keff and wo

Reduces shearing in columns…………but increases displacement

Lrb isolation in action

LRB Isolation in Action

Rubber Base Isolators

Lead rubber bearing lrb in action

Lead Rubber 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?

Displacement , u

Frictional pendulum system

Frictional Pendulum System

Image credit:

Concept of frictional pendulum

Concept of Frictional Pendulum

Image credits:;

Frictional pendulum

Frictional Pendulum

Restoring/Recentering Force

Frictional Force

Pendulum Period:


The quantitative model

The quantitative model

Frictional Force

Restoring/Recentering Force

Force vs displacement hysteresis loop

Force vs. Displacement Hysteresis Loop

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