Provide help in the study of earthquake resistant design

1. EARTHQUAKES AND
EARTHQUAKE-RESISTANT
DESIGN OF STRUCTURES

2. SCOPE OF PRESENTATION
• EARTHQUAKE AND ITS
CHARACTERIZATION
• EARTHQUAKE-RESISTANT DESIGN
• REPAIR & RETROFITTING OF
STRUCTURES
• EARTHQUAKE ANALYSIS OF STRUCTURES
• ADVANCED TECHNOLOGIES

3. EARTHQUAKE
An earthquake may be simply
described as a sudden shaking
phenomenon of the earth's
surface due to disturbance inside
the earth.

4. CLASSIFICATIONS AND
CAUSES OF EARTHQUAKE
• Tectonic Earthquakes
• Non-tectonic Earthquakes

5. TECTONIC EARTHQUAKES
Due to disturbances or adjustments of geological
formations taking place in the earth's interior.
Due to slip along geological faults.
Less frequent.
More intensive.
More destructive in nature.

6. ELASTIC REBOUND THEORY

8. NON-TECTONIC EARTHQUAKES
Due to external or surfacial causes such as:
Volcanic eruptions
Huge waterfalls
Occurrence of sudden and major landslides
Man-made explosions
Impounding in dams and reservoirs
Collapse of caves, tunnels etc.
Very frequent, minor in intensity
generally not destructive in nature.

9. EARTHQUAKE TERMINOLOGY
Seismograms
Focus or Hypocentre
Epicentre
Focal Depth
Hypocentral Distance
Epicentral Distance
Isoseismal-lines of equal seismic
intensity
Coseismal-lines designating the affected
area

10. EARTHQUAKE PHENOMENON

11. Energy is released in the form of waves and radiates in
all directions from its source, the focus.
What Happens During an Earthquake?

12. EARTHQUAKE WAVES
P Waves:
Primary waves, Longitudinal waves, etc.
Speed 8 to 13 km/s
S Waves:
Shear waves, Transverse waves, etc.
Speed 5 to 7 km/s
L Waves:
Long waves or Surface waves, etc.
Speed 5 to 7 km/s

13.  Body Waves
 Travel through Earth’s interior.
 Two types based on mode of travel.
 Primary (P) Waves
 Push-pull (compress and expand – compressional waves) motion,
changing the volume of the intervening material.
 Therefore, can travel through solids, liquids, and gases.
 Generally, in any solid material, P waves travel about 1.7 times faster
than S waves.

14.  Seismic Wave
Motion Animation
#77

15.  Body Waves
 Secondary (S) Waves
 “Shake” motion at right angles to their direction of travel that
changes the shape of the material transmitting them (shear waves).
 Therefore, can travel only through solids.
 Slower velocity than P waves.
 Slightly greater amplitude than P waves.
 Lesser amplitude than L Wave.

16.  Seismic Wave
Motion Animation
#77

17.  Surface Waves
 Travel along outer part (surface) of the Earth.
 Complex motion (up-and-down motion as well as side-to-side
motion).
 Cause greatest destruction.
 Exhibit greatest amplitude and slowest velocity.
 Waves have the greatest periods (time interval between crests).
 Often referred to as long waves, or L waves.

18.  Seismic Wave
Motion Animation
#77

19.  Seismic Wave
Motion and Surface
Effects Animation
#78

20.  Sensitive instruments, called
seismographs, around the world
record the earthquake event.
 Seismographs record seismic
waves.

21.  Seismographs record the movement of Earth
in relation to a stationary mass on a rotating
drum or magnetic tape.
 More than one type of seismograph is needed
to record both vertical and horizontal ground
motion.

22.  Seismographs Animation #79

24. 1. Three station recordings
are needed to locate an
epicenter.
2. Each station determines
the time interval
between the arrival of
the first P wave and the
first S wave at their
location.

25. 3. A travel-time graph is used to determine
each station’s distance to the epicenter.

26. 4. A circle with a
radius equal to the
distance to the
epicenter is drawn
around each station.
5. The point where all
three circles
intersect is the
earthquake
epicenter.
6. This method is
called triangulation.

27. MAGNITUDE OF EARTHQUAKE
•Related to the amount of energy released by the
geological rupture.
•Measure of the absolute size of the earthquake,
without reference to distance from the epicentre.
•Richter (1958) defined magnitude as the logarithm to
the base 10 of the largest displacement of a
standard seismograph situated 100 km from the
focus.
•Largest magnitude of earthquake recorded = 8.9
Log E M10 4 8 15= +. .
(E = Energy in joules; M = Magnitude)

28.  Intensity – a measure of the degree of
earthquake shaking at a given locale based on
the amount of damage.
TheThe
drawback ofdrawback of
intensityintensity
scales is thatscales is that
destructiondestruction
may not be amay not be a
true measuretrue measure
of theof the
earthquake’searthquake’s
actualactual
severity.severity.

29.  Magnitude – estimates the amount of energy
released at the source of the earthquake.

30. Richter ScaleRichter Scale

Based on the amplitude of the largest seismic wave recorded.Based on the amplitude of the largest seismic wave recorded.

Accounts for the decrease in wave amplitude with increased distance.Accounts for the decrease in wave amplitude with increased distance.

Each unit of Richter magnitude increase corresponds to a tenfold increaseEach unit of Richter magnitude increase corresponds to a tenfold increase
(logarithmic scale) in wave amplitude and a 32-fold energy increase.(logarithmic scale) in wave amplitude and a 32-fold energy increase.
How Are Earthquakes Measured?How Are Earthquakes Measured?

31.  Destruction from Seismic Vibrations
1. Ground Shaking
2. Liquefaction of the Ground
3. Seiches
4. Tsunamis, or Seismic Sea Waves
5. Landslides and Ground Subsidence
6. Fire

32.  Amount of structural damage attributable to
earthquake vibrations depends on:
 Proximity to populated areas
 Magnitude
 Intensity and duration of the vibrations
 Nature of the material upon which the
structure rests
 Design of the structure

33.  Regions within 20 to 50 kilometers of the
epicenter will experience about the same intensity
of ground shaking.
 Destruction varies considerably mainly due to the
nature of the ground on which the structures are
built.
Damage Caused by the 1964Damage Caused by the 1964
Anchorage, Alaska QuakeAnchorage, Alaska QuakeDamage to I-5 during theDamage to I-5 during the
Northridge, CA Earthquake in 1994Northridge, CA Earthquake in 1994

34.  Unconsolidated materials saturated with
water turn into a mobile fluid.
 Can cause underground structures to
migrate to the surface, and buildings and
other aboveground structures to settle and
collapse.

35.  Liquefaction of the Ground
 Dry Compaction and Liquefaction
Animation #21

36.  Result from vertical displacement along a
fault located on the ocean floor.
 Result from a large undersea landslide
triggered by an earthquake.

37.  Advance across oceans at great speeds ranging from ~500 to
950 km/hour (~310 to 590 miles/hour).
 In the open ocean, height is usually < 1 meter.
 Distances between wave crests range from 100 to 700 km.
 In shallower coastal waters, the water piles up to heights that
occasionally exceed 30 meters (~100 feet).

38.  As a tsunami leaves the deep water of the open ocean and travels into the shallower water
near the coast, it transforms.
 A tsunami travels at a speed that is related to the water depth – hence, as the water depth
decreases, the tsunami slows.
 The tsunami's energy flux, which is dependent on both its wave speed and wave height,
remains nearly constant.
 Consequently, as the tsunami's speed diminishes as it travels into shallower water, its
height grows.
 Because of this shoaling effect, a tsunami, imperceptible at sea, may grow to be several
meters or more in height near the coast.
 When it finally reaches the coast, a tsunami may appear as a rapidly rising or falling tide, a
series of breaking waves, or even a bore. http://www.geophys.washington.edu/tsunami/general/physics/physics.html

39.  As a tsunami approaches shore, it begins to slow and grow in height.
 Just like other water waves, tsunamis begin to lose energy as they rush onshore – part of the
wave energy is reflected offshore, while the shoreward-propagating wave energy is dissipated
through bottom friction and turbulence.
 Despite these losses, tsunamis still reach the coast with tremendous amounts of energy.
 Tsunamis have great erosional potential, stripping beaches of sand that may have taken years
to accumulate and undermining trees and other coastal vegetation.
 Capable of inundating, or flooding, hundreds of meters inland past the typical high-water
level, the fast-moving water associated with the inundating tsunami can crush homes and
other coastal structures.
 Tsunamis may reach a maximum vertical height onshore above sea level, often called a runup
height, of 10, 20, and even 30 meters.
http://www.geophys.washington.edu/tsunami/general/physics/physics.html
Tsunami at Hilo, Hawaii (April 1, 1946) that originated in the Aleutian Islands near Alaska,
was still powerful enough to rise 30 to 55 feet when it hit Hawaii.

40.  Tsunami Animation #91

41.  The rhythmic sloshing of water in lakes,
reservoirs, and enclosed basins.
 Waves can weaken reservoir walls and cause
destruction.

42. Landslide caused by the 1964Landslide caused by the 1964
Alaskan EarthquakeAlaskan Earthquake

43. San Francisco in flames after the 1906 EarthquakeSan Francisco in flames after the 1906 Earthquake

44.  Short-Range Predictions
 Goal is to provide a warning of the
location and magnitude of a large
earthquake within a narrow time frame.
 Research has concentrated on monitoring
possible precursors – such as
measuring:
 uplift
 subsidence
 strain in the rocks
 Currently, no reliable method exists for
making short-range earthquake
predictions.

45.  Long-Range Forecasts
 Give the probability of a certain
magnitude earthquake occurring on a time
scale of 30 to 100 years, or more (statistical
estimates).
 Based on the premise that earthquakes are
repetitive or cyclical.
 Using historical records or paleoseismology
 Are important because they provide
information used to
 Develop the Uniform Building Code
 Assist in land-use planning

46. EARTHQUAKE FORCE
Force due to earthquake is
W = weight of structure;
g = acceleration due to gravity;
a = peak earthquake acceleration.
IS:1893-2002 provides the general principles and
design criteria for earthquake loads.

47. ACCELERATIONACCELERATION
DECELERATIONDECELERATION

48. Shear Wall
Cripple Wall
Foundation
Floor
Diaphragm
Roof Diaphragm
f1
f2
f3
fsum = f1 + f2 + f3

50. BEFORE AN EARTHQUAKEBEFORE AN EARTHQUAKE
1. Store heavy objects near ground or floor.
2. Secure tall objects, like bookcases to the wall.
3. Secure gas appliances to prevent broken gas lines
and fires.
4. Learn where your exits, evacuation route, and
meeting places are. Know the safe spot in each
room.
5. Keep emergency items , such as a flashlight, first
aid kit and spare clothes, food in your car or office.

51. DURING AN EARTHQUAKEDURING AN EARTHQUAKE
1. If indoors, stay in the building.
2. Take shelter under solid furniture, i.e. tables or desks,
until the shaking stops.
3. Keep away from overhead fixtures, windows, cabinets
and bookcases or other heavy objects that could fall.
Watch for falling plaster or ceiling tiles.
4. If driving- STOP, but stay in the vehicle. Do not stop
on bridge, under trees, light posts, electrical power
lines or signals.
5. If outside, stay outside. Move to an open area away
from buildings, trees, power lines and roadways.

52. AFTER AN EARTHQUAKEAFTER AN EARTHQUAKE
1. Check for injuries. Give first aid as
necessary.
2. Check for safety hazards: fire, electrical,
gas leaks, etc. and take appropriate actions.
3. Do not use telephones and roadways unless
necessary so that these are open for
emergency uses.
4. Be prepared for aftershocks, plan for cover
when they occur.
5. Turn on your radio/TV for an emergency
message. Evacuate to shelters as
instructed.
6. Remain calm, try to reassure others.
Avoid injury from broken glasses etc.

53. 2001 GUJARAT EARTHQUAKE
Houses Collapsed = 2, 33, 660
Partially Collapsed=9, 71, 538
Damage to R.C.C. Structures in Ahmedabad
(700 Killed).
Total Casualties = 13,811
Injuries = 1,66,836 (20,217 seriously).
Magnitude = 6.9~7.9

54. An aerial view of the destruction
of houses in Bhachau and Anjar
towns during the Gujarat, 2001
earthquak

55.
Devastated village - Jawaharnagar which was relocated at
this site after the Anjar earthquake of 1856. The same has
collapsed as no aseismic design interventions were made
during the rehabilitation and reconstruction of this village.

56. 1993 LATUR EARTHQUAKE
• The earthquake struck at 3.56 Hrs. on 30-9-1993 with
epicentre at Killari Dist. Latur(Maharashtra).
• The intensity of earthquake was 6.4 on the Richter
Scale.
• 3,670 people died in Latur District.
• 446 were seriously injured making them handicapped.
• 37 Villages were totally collapsed.
• 728 villages suffered damages of varying degree.
• Nearly 1,27,000 familites were affected.

57. Post Office Building, Killari
Damaged but not collapsed

58. Public Building in Sastoor
Damaged but not collapsed

59. MEERP Programme
Before
MEERP
After
MEERP

62. EARTHQUAKE-RESISTANT DESIGN
OF NON-ENGINEERED BUILDING
Symmetric Plan
Less Opening

63. Interlocking
of
Stones

64. Interlocking by Through Stones (Haider)

65. Through Stones in Existing Walls

66. Seismic Bands (Very Important)

67. Construction Practice
(Marathwada Region)

68. Construction Practice
(Satara, Kolhapur Region)

69. Strengthening
of
Existing Houses

70. Confidence in
Earthquake-resistant
Measures

71. Confidence
Building in
Retrofitting

72. EARTHQUAKE-RESISTANT DESIGN
OF ENGINEERED BUILDINGS
Collapse of open ground story RC frame residential building in Bhuj.

73. 2001 Gujarat
Earthquake

74. 2001 Gujarat
Earthquake

75. Buildings with
First-Soft Story

76. Buildings
with
Heavy
Water
Tanks

77. EARTHQUAKE ANALYSIS
xm
gx
SDOF system

78. EQUATION OF MOTION
m
)( gxxm  +
kx
xc 
Free Body Diagram
Governing Equation
gxmkxxcxm  −=++
m = mass of the SDOF system
c = damping constant
k = stiffness
x = displacement of the system
gx = earthquake acceleration.

79. (a) MDOF system
m1
m2
mN
k1
kN
k2
2x
1x
gx
Nx
(b) Free body diagram
mi
)( 11 ++ − iii xxk
)( 11 ++ − iii xxc 
)( 1−− iii xxk
)( 1−− iii xxc 
)( gii xxm  +
MDOF System
Figure 2.4

80. DESIGN CRITERIA FOR EARTHQUAKE
LOADS (IS-1893-1984)
Country is
divided into five
zones for the
purpose of
design of
structures for
earthquake
loads

81. SEISMIC ZONING
SEISMIC ZONE MMI α0 F0
I ≤ V 0.01 0.05
II VI 0.02 0.10
III VII 0.04 0.16
IV VIII 0.05 0.24
V IX & above 0.08 0.36
α0 = Basic horizontal seismic coefficient
F0 = Seismic zone factor

83. DUCTILE DETAILING OF R.C.C.
STRUCTURRES (IS:13920-1993)
• To Add Ductility and Toughness
(Special confining reinforcement)
• Should be applied for all R.C.C. Structures
Seismic Zone IV and V
Seismic Zone III but I >1
Seismic Zone III (Industrial Buildings)
Seismic zone III (> 5 Storey)
• Flexural Memberes
Stress > 0.1 fck
b/D > 0.3
b > 200 mm
D > Clear Span/4

84.  Tapping by hammer
 Rebound Hammer
 Indentation method
 Ultrasonic Pulse Velocity Transmission Test
 Covermeter / Pachometer
 Radiography
 Chloride Content
 Testing for Depth of Carbonation
 Tests on Concrete Cores

85. New stirrups
New reinforcement
Old reinforcement
Roughened surface
Drilled hole in slab
Roughened surface
Slab
Stirrups
Beam
Jacket
Strengthening of column

86. New stirrups
New reinforcement
Old reinforcement
Anchor bars
Drilled hole in slab
New reinforcement
Old reinforcement
New stirrups
Strengthening of column

87. weld
Roughened
surface
New reinforcement
Beam Strengthening

88. Strengthening of bare frame

89. Strengthening of masonry

91. FRP strengthening

92. CONVENTIONAL SESIMIC DESIGN
• Sufficient Strength to Sustain
Moderate Earthquake
• Sufficient Ductility under Strong
Earthquake
Disadvantages
• Inelastic Deformation Require Large Inter-
Storey Drift
• Localised Damages to Structural Elements
and Secondary Systems
• Strengthening Attracts more Earthquake
Loads

96. BASE ISOLATION
• Aseismic Design Philosophy
• Decouple the Superstructure from
Ground with or without Flexible
Mounting
• Period of the total System is
Elongated
• A Damper Energy Dissipating Device
provided at the Base Mountings.
• Rigid under Wind or Minor
Earthquake

97. Advantages of Base Isolation
• Reduced floor Acceleration and Inter-storey Drift
• Less (or no) Damage to Structural Members
• Better Protection of Secondary Systems
• Prediction of Response is more Reliable and Economical.
Non-isolated Base-isolated

98. Fixed base building Base-isolated building

99. SEISMIC BASE ISOLATION
gx
1x
2x
Nx
m1
m2
mN
k1
kN
k2
mb
Base isolator
Figure 3.2 Concept of base isolation.
Period
Displacement
Increasing
damping
Increasing
damping
Period shift
Acceleration

100. BASE ISOLATION SYSTEMS
• LRB System
• NZ System
• P-F System
• R-FBI System
• EDF System
• S-RF System
• Friction Pendulum System (FPS)
• High Damping Rubber Bearing

103. 36
110
6
1.5
30
Steel Plate
Rubber
12
12

104. Response of five-story building isolated by LRB system
0 5 10 15 20
-15
-10
-5
0
5
10
xb
(cm)
Time (sec)
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
Fixed base
Isolated
Topflooracceleration(g)

105. Response of a five-story isolated by FPS system
0 5 10 15 20
-15
-10
-5
0
5
10
xb
(cm)
Time (sec)
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
Fixed base
Isolated
Topflooracceleration(g)

106. DAMAGE OF BRIDGES DURING EARTHQUAKES

107. DUCTILE DETAILING
OF R.C.C. STRUCTURES
(IS:13920-1993)
• To Add Ductility and Toughness
• Should be applied for all R.C.C. Structures
Seismic Zone IV and V
Seismic Zone III but I >1
Seismic Zone III (Industrial Buildings)
Seismic zone III (> 5 Storey)
• Flexural Memberes
Stress > 0.1 fck
b/D > 0.3
b > 200 mm
D > Clear Span/4

108. SEISMIC ISOLATION OF BRIDGES

109. 0 5 10 15 20 25 30
-10
0
10 Abutment Pier
Bearingdisplacement(cm)
Time (sec)
-0.4
-0.2
0.0
0.2
0.4
W = Weight of bridge deck
Non-isolated Isolated
Pierbaseshear/W
-1.0
-0.5
0.0
0.5
1.0
Figure 8.2 Time variation of bridge response in longitudinal direction to El-Centro, 1940 excitation.
Non-isolated Isolated
Deckacceleration(g)

110. The American River Bridge & installed friction pendulum bearing

111. Thjorsa Bridge with Elastomeric seismic isolation bearings
(Ice land)

112. Figure 7.1 Demonstration building in Indonesia (1994)
Location: 1 k.m. SW of
Pelabuhan
Building : 4-Storeyed
MR RCC.
Isolator : 16 HDR
Manufacturer: MRPRA,
UK

113. Figure 7.2 Foothill Communities Law and Justice Center,
Rancho Cucamonga,California (photo by I.D. Aiken).
Location: Rancho Cucamonga
California.
Isolator :HDR
Engineers: Taylor & Gaines;
Reid & Tarics.
Year :1985

114. Figure 7.3 University of Southern California, University Hospital
(Photo by P.W. Clark).
Location: Los Angeles,
California.
Isolator : LRB
Engineers: KPFF
Year :1991

115. Figure 7.4 Fire Command and Control facility, Los Angeles, California
(Naeim and Kelly 1999).
Location: East Los Angeles
California.
Isolator :HDR
Engineers: Fluor-Daniel
Year :1990

116. Figure 7.9 Tohoku Electric Power Company, Japan (Kelly, 1997).
Location: Sendai,
Miyako Provience
Isolator :HDR
Year :1990

117. SAN FRANCISCO CITY HALL

118. Tuned mass damper, Huis Ten Bosch tower, Nagasaki

119. m1,n
kd
cd
kd
cd
kd
cd
kd
cd
c1,1
c1,2
c1,3
c2,1
c2,2
c2,3
c2,mc1,i
c1,n-1
c1,n
k1,1
k1,2
k1,3
k1,i
k1,n-1
k1,n
m1,1
m1,2
m1,3
m1,i
m1,n-1
k2,1
k2,2
k2,3
k2,m
m2,1
m2,2
m2,3
m2,m
Building BBuilding A
gx
Damper Connected Buildings

120. CONCLUDING REMARKS
• Earthquakes are not predictable
• Construct Earthquake-Resistant
Structures
• It is possible to evaluate the earthquake
forces acting on the structure.
• Design the structure to resist the above
loads for safety against Earthquakes.
• Base isolation can also be used for
retrofitting of structure.