*CC Chang / HKUSTEarthquake Response Chapter 6

Some QuestionsEarthquake: what do you know?How big can it get? What can we do about it?

Earthquake as We Speak

Largest earthquakes(Since 1900)

LocationDate UTCMagnitude1.Chile1960 05 229.52.Prince William Sound, Alaska1964 03 289.23.Off the West Coast of Northern Sumatra2004 12 269.14.Sendai2011 03 119.05.Kamchatka1952 11 049.06.Offshore Maule, Chile2010 02 278.87.Off the Coast of Ecuador1906 01 318.88.Rat Islands, Alaska1965 02 048.79.Northern Sumatra, Indonesia2005 03 288.610.Assam - Tibet1950 08 158.611.Andreanof Islands, Alaska1957 03 098.6

Largest earthquakes(2013)

Most destructive known earthquakes on record in the world

DateLocationDeathsMagnitudeCommentsJanuary 23, 1556China, Shansi830,000 ~ 8January 12, 2010Haiti316,0007.0July 27, 1976China, Tangshan242,769 8.0Estimated death toll as high as 655,000August 9, 1138Syria, Aleppo230,000December 26, 2004Indonesia, Sumatra227,898 9.1Deaths from earthquake and tsunamiDecember 22, 856+Iran, Damghan200,000December 16, 1920China, Ningxia200,0007.8Major fractures, landslides.March 23, 893+Iran, Ardabil150,000September 1, 1923Japan, Kwanto142,8007.9Great Tokyo fireMay 12, 2008China, Sichuan87,5877.9

Earthquakehttp://environment.nationalgeographic.com/environment/natural-disasters/earthquake-profile.html

Seismic Damage of InfrastructureDirect EffectsGround failures; Surface rupture; Soil vibration; Ground liquefaction; Others Structural vibration and damageIndirect EffectsTsunamisSeichesLandslidesFloodsFires

Ground failures/Surface ruptureNormal fault. Scarp near Beni Rached1980 El Asnam Earthquake

Soil vibration; Ground liquefaction

Soil vibration; Ground liquefaction

Soil vibration; Ground liquefactionChi-Chi Earthquake 1999

Soil vibration; Ground liquefactionDisplacement and tilting of houses due to soil liquefaction in the Turnagain Height area of Anchorage during the 1964 Alaska Earthquake

Others New mountain created during Chi-Chi Earthquake 1999

Others Chi-Chi Earthquake 1999

Structural Vibration and DamageFailure of the unreinforced masonry walls of a five-story reinforced concrete building during the 1972 Managua Earthquake

Structural Vibration and DamageImperial Valley County, California. Collapse of a steel tank during the 1979 Imperial Valley Earthquake.

Structural Vibration and DamageFailure of a building at central Kobe after 1995 Kobe earthquake [4]

Structural Vibration and DamageFailure of a building at central Kobe after 1995 Kobe earthquake

Structural Vibration and Damage

Structural Vibration and Damage

Tsunamishttp://www.eri.u-tokyo.ac.jp/topics/kiihantouoki2004/index-e.html

Tsunamis

Fires1995 Kobe earthquake

FiresChi-Chi Earthquake 1999

Estimated economic losses of some recent earthquakes Hong Kong (2012) revenues: $360 billion HKD or $46 billion USD Stonecutters Bridge costs around 0.5 billion USD

LocationDate UTCMagnitudeEstimated economic loss (in billion US dollars)Loma Prieta, California1989 7.17Northridge, California1994 6.713-20 [1]Kobe, Japan1995 6.995-147 (repair only [2])Chi-Chi, Taiwan19997.67.8

Philosophy of Seismic Resistant Design for StructuresMinor earthquake: prevent non-structural damageModerate earthquake: prevent structural damage and minimize non-structural damageMajor earthquake: avoid collapse to save lives

How to design structures under earthquake?EQIssues: Different EQs different characteristics Structural modeling and performance

How to design structures under earthquake?

Generalized Coordinates?

Earthquake Response SpectraEOMis a function of

Response SpectraUnder a specific earthquake

Response SpectraMaximum responses

Response SpectraDisplacement, velocity and acceleration response spectra for a SDOF system under the NS component of the 1940 El Centro earthquake ground excitation ( )

Pseudo-Response SpectraDisplacement, pseudo-velocity and pseudo-acceleration response spectra for a SDOF system under the NS component of the 1940 El Centro earthquake ground excitation ( )Pseudo-velocityPseudo-acceleration

Actual and PseudoResponse Spectra

DVA Response Spectrum

Equivalent Static Force,Shear and MomentEquivalent Static ForceShear ForceMoment

Example E4.1A SDOF Frame under 1940 El Centro EQ Estimate the maximum base shear forces and the maximum bending moment for the building frame under the 1940 El Centro earthquake excitation. The damping ratio of the frame can be assumed to be 2%.

Example E4.1A SDOF Frame under 1940 El Centro EQThe natural period of the building frame is Stiffness

Example E4.1A SDOF Frame under 1940 El Centro EQBase shear for each columnTotal overturning moment

DVA Response Spectrum: Discussion

Elastic Design SpectrumThe DVA spectrum depends on the Earthquake used

Elastic Design Spectrum

Elastic Design Spectrum

Constructing Elastic Design Spectrum

A, gD, me

Constructing Elastic Design Spectrum

Example A SDOF Frame under Design Spectrum Estimate the maximum base shear forces and the maximum bending moment for the building frame under the elastic design spectrum obtained previously. The damping ratio of the frame is assumed to be 3%.

ExampleA SDOF Frame under Design Spectrum The natural period of the building frame is 1.4gBase shear for each columnTotal overturning moment

Eurocode 8

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