6. Plate movement

7. Earthquake = sudden release of energy in the Earth’s crust that creates seismic waves. They are measured by the Richter Scale, which is an exponential scale. Magnitude 3 and below are very weak and barely felt, magnitude 7 and above cause serious damage over large areas. The damage and severity of shaking depends on the earthquake’s depth.

14. Surface waves travel along the surface of the Earth after P waves and S waves.

15. Earthquake Engineering
The purpose is to mitigate earthquake hazards.
This is done through:
Preventing non-structural damage in frequent minor ground shaking
Preventing structural damage and minimizing non-structural damage in occasional moderate ground shaking
Avoiding collapse or serious damage in rare major ground shaking

16. Earthquake Engineering
Damage to structures may result from different seismic effects.
Ground failure (surface faulting and vibration of soil)
Vibrations transmitted from the ground to the structure.
Structural engineers are most concerned with the vibration of the structure in response to ground shaking at it’s foundation.

17. Seismic Structures
2012 EERI Seismic Design Competition - Stanford University – YouTube
UTAustin - Seismic Design Competition 2011 – YouTube
JohnsHopkins - Seismic Design Competition 2011 – YouTube
UCLA - Seismic Design Competition YouTube

18. Seismic Effects – Ground Failure
Soil instability during earthquakes can cause significant damage. Soil response depends on the characteristics of the soil layers, depth of the water table, and intensity/duration of ground shaking.
Liquefaction is when unconsolidated soil acts like a liquid. This can undermine the foundations of structures, causing very serious damage. Ex: Haiti

19. Seismic Effects – Ground Failure
Liquefaction works when earthquake waves cause water pressures in increase in the sediment, which causes the sand grains to lose contact with each other.

20. Seismic Effects – Ground Failure
Typical effects of liquefaction include:
Loss of bearing strength – soil cannot support structures
Lateral spreading of soil – ground slides down gentle slopes or structures move around on a buried liquefied layer
Ground oscillation – the surface layer, riding on a buried liquefied layer, is thrown back and forth by the shaking.
Settlement – when liquefied ground re-consolidates after the earthquake, the ground surface may settle or subside as the liquefied soil becomes more dense.

21. Seismic Effects – Ground Vibration
The seismic performance (degree of damage) of a structure depends on:
type of foundation
configuration of the structure
structural material
design and construction details

22. Seismic Effects – Ground Vibration
The main points to remember are that the whole structure-foundation system should work as a unit, and that the superstructure be tied or anchored properly to the foundation.

23. Design Proposal Some items to research for your design proposal are:
Base isolation systems
Shear wall system
Building elevation control
Friction pendulum bearing
Damping systems