Earthquake Hazards
and
Seismic Design
Richard P. Ray Ph.D. P.E.
Direct Effects
• Ground failures
(instabilities)
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Surface faulting
Vibration of soil
Ground cracking
Liquefaction
Ground lurching
Differential settlement
Lateral spreading
Landslides
• Vibrations transmitted
from the ground to the
structure
xt
m
x
c
k/2
xg
k/2
Direct Effects
xt
x
m
k/2
c
k/2
xg
mx  mxg  cx  kx  0
mx  cx  kx  mxg  Pearthquake (t )
Indirect Effects
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Tsunamis
Seiches
Landslides
Floods
Fires
Seismic Resistant Construction
• Prevent non-structural damage from
minor shaking
• Prevent structural damage and minimize
non structural damage in occasional
moderate shaking
• Avoid collapse or serious damage in
rare, major ground shaking
Soil Movements
Wood Frame Houses
Masonry Structures
Concrete Structures
Steel Structures
Earthquake Resistant Designs
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Construction and Maintenance
Need for more comprehensive approach
Importance of conceptual design
Decrease of demands
Action of the soil-structure system
Good Pile Design
Bridge Foundation and Supports
Integral Action of All Parts
Proper Building System
• Building should be light
• Simple, symmetric, regular
• Uniform and continuous distribution of mass
(m), stiffness (k), strength (σy), ductility (μ).
• Avoid long spans and long cantilever
• Non-structural elements
– Separated completely
– Tied to structure
Proper Building System
• Control inelastic regions
• More than one defense line
• Stiffness and strength of building matches
stiffness and strength of foundation and
Building Should Be Light
Building Should Be Simple,
Symmetric, and Regular
Building Should Have Uniform
and Continuous Distribution of
Mass Stiffness Strength Ductility
Retrofitting Soft Stories
Non-Structural Should Be
Integrated With Structural
Structures Should Have the
Largest Number of Defenses
Building Should Have Balanced
Stiffness, Strength, Ductility
Between Members, Connections,
Supports
Construction Aspects
Building Research
Newer Designs