Transcript INTRODUCTION TO EARTHQUAKE ENGINEERING

INTRODUCTION TO
EARTHQUAKE
ENGINEERING
EQ1
Sequence
 Plate movement
 Type of faults
 Wave motion
 Energy release
 Urban earthquake risk
 Structural performance level
 Evaluation approach
EQ2
8/10
Large Earthquakes
EQ4
Elastic Rebound Theory
Indian Plate
EQ6
Historical Earthquakes in the Himalaya
EQ7
Southern Asia
EQ8
EQ9
Plate Movement
4-5 m slip
@1 cm/yr
=4-500 years
EQ10
Indian Plate
EQ11
Himalayas
Tibetan Plateau
Indian Plate
EQ12
Tibet
Indian Plate
EQ13
Tibet
Indian Plate
EQ14
Tibet
critical stress
Tibet
EQ15
2-20 m
surface rupture
great earthquake
1.5 m co-seismic
subsidence
Tibet
4-10 m
the longer the inactivity the bigger the 'quake’
EQ16
Faults
Through the study of faults and their effects, much can be learned
about the size and recurrence intervals of earthquakes. Faults
also teach us about crustal movements that have produced
mountains and changed continents. Stresses often continue to
build until they exceed the strength of the bond in that section of
crust. The rock then breaks, and an earthquake occurs,
sometimes releasing massive amounts of energy.
Faults vary in length from a few centimeters to hundreds of
kilometers across. Displacements of one side of the fault over the
other vary from fractions of a meter to many kilometers. In many
cases the displacement is not confined to a single fracture but is
distributed throughout a fault zone. Many faults do not rupture the
surface, but when the surface is broken, the fault line is visible as
a fault trace or outcrop.
EQ17
Contd…
Faults
Vertical or horizontal movement may occur along a fault plane.
Sometimes both vertical and horizontal movement occur
simultaneously. Faults are named according to the type of
movement that has occurred. The term slip is used to indicate
relative displacement across the fault. When the movement along
the fault plane is generally horizontal, it is a strike-slip fault. These
are also called lateral faults. Offset streams are found along active
strike-slip faults. A transform fault is a zone of lateral movement
along which the ridges and rises have been offset and along
which the displacement suddenly stops or changes form and
direction. When the movement along the fault plane is
predominately vertical, it is a dip-slip fault. There are subclassifications within this category.
EQ18
Contd…
Faults
A normal fault occurs when the earth above the
fracture moves down in respect to the earth below the
fracture. A reverse fault occurs when the rocks above
the fracture move up with respect to those below. A
reverse fault with an angle of less than 45 degrees is
called a thrust fault. Thrust faults are generally
characterized by older rocks resting on younger rocks,
although in some cases younger rocks may be thrust
over older rocks.
EQ19
Left Lateral Fault
EQ21
Left Lateral Fault
EQ22
Left Lateral Fault
EQ23
Right Lateral Fault
EQ24
Right Lateral Fault
EQ25
Right Lateral Fault
EQ26
Normal Faulting
EQ27
Normal Fault
EQ28
Thrust Faulting
EQ29
Thrust Fault
EQ30
Wave Motion
EQ33
Wave Path
EQ35
Energy Release
EQ37
Energy Release
EQ38
ELEMENTS OF URBAN EARTHQUAKE RISK
HAZARDS
EXPOSURE
RISK
VULNERABILITY
EQ40
LOCATION
EQ41
EQ42
EQ43
EQ44
Structural Performance Levels
Joe’s
Joe’s
Great
Food!
Serviceability
0%
EQ46
Great
Food!
Immediate
Occupancy
Damage
Collapse
Prevention
99%
Serviceability Level


Joe’s
Great
Food!


EQ47
Negligible structural
and nonstructural
damage
Utilities are available
Facility is available for
immediate re-use
Repair costs are
minimal to nil
Immediate Occupancy Level

Negligible structural damage

Minor nonstructural damage

Building is safe to occupy but
may not function
Joe’s
Great
Food!

Limited interruption of
operations

EQ48
Repair Cost < 15%
Immediate Occupancy
EQ49
Life-Safety
EQ50
Collapse Prevention Level
EQ51

Extensive structural and
non-structural damage

Extended loss of use

Repair may not be
practical

Repair costs >> 30%
Collapse Prevention
EQ52
Collapsed
EQ53
EQ56
Global Response & Performance
Joe’s
Loading Severity
Great
Food!
Great
Food!
Structural Displacement D
EQ57
4- Determine
5- Determine
Drift & Component Performance
Demands
1- Select Hazard
Level
Joe’s
10-1
10-2
D
10-3
Beer!
Food!
Lateral Force - V
Annual Probability of Exceedance
Evaluation Approach
10-4
Collapse
margin > 1.0
Life Safety
margin = 1.33
to 1.5
0
10-5
0
.5
1.0
1.5
2.0
2.5
Immediate
Occupancy
Collapse Prevention
margin = 1.0
Great
Food!
DLS
DCP
Lateral Displacement - D
Spectral Acceleration at Period T
t
2- Determine ground
Motion Sa
EQ58
3- Run Analysis 6- Pass or Fail Criterion
evaluated on component
by component basis