Tishk International University
Civil Engineering Department
Third Year (2020-2021)
Earthquake Engineering
Asst. Prof. Dr. Najmadeen Mohammed Saeed
Part 1Earthquake Engineering
Introduction to Earthquakes I
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Dynamic Characteristics of Structures
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Natural DisastersIntroductionTerminologiesInternal Structure of EarthEarthquake Fatalities
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Earthquake Tornado, Cyclone
FireFloods
Natural Disasters
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VolcanoHurricane
Natural Disasters
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Global Loss Due To Natural Disasters
Loss of life from natural disasters(Source: Herath and Katayama, 1994)
Loss of built environment
from natural disasters (Source: Andrew and Robin, 2002)
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Earthquake Shaking
Earthquakes are UNPREDICTABLE!!!
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Dead & Live Loads
Direction Of Dead
& Live loads
Depends on self
weight and
functional aspects
of building
Direction Of Dead
& Live loads
Depends on self
weight and
functional aspects
of building
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Wind Loads
Direction Of wind loads
Depends on Wind
intensity and exposed
area of the building
&
Distribution is uniform
along the height
F = p * area
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Seismic Loads
Direction of seismic forces
Depends on acceleration
and weight of the building
&
Distribution is not uniform
Earthquake motion
F = Mass *Acceleration
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Effects of Earthquake
ACCELERATION
DECELERATION
Inertia Force F = m a
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Static Vs Dynamic Loading
P
Y
Y(t)
Static Loading Dynamic Loading
F = m a
Y(t)
P(t)
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Types of Dynamic Loading
RAPID OR TRANSIENT LOADING
MONOTONIC LOADING
SLOW
LOADING
TIME
CYCLIC OR REPETITIVE
LOADING
LO
AD
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Earthquake Engineering:
Earthquake engineering can be
defined as the branch of
engineering dedicated for
minimizing earthquake hazards.
Introduction
■ An Earthquake :is the motion or vibration, sometimes
violent, of the earth’s surface that follows a release of
energy in the earth’s crust. This energy can be generated
by a sudden dislocation of segments of the crust, by a
volcanic eruption, or even by manmade explosions.
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Scope:
Earthquake engineering involves planning, designing,
constructing and managing earthquake-resistant
structures and facilities.
• Seismicity ,Nature, Measures and Recording of
earthquakes.
• Planning for Seismic Risk Assessment &
Mitigation
• Analysis, Design and Construction of Earthquake
Resistant Structures
• Evaluation of Buildings for Earthquake Resistance
• Retrofitting of Earthquake damaged Structures
Introduction
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Main causes of earthquake: tectonic ground motions,
Volcanism, landslides, rock bursts, and man-made
explosions. Among these, naturally occurring tectonic-
related earthquakes are the largest and most important.
Causes of Earthquake
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Causes of Earthquake
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- Tectonic-related earthquakes are caused by the fracture and sliding of
rock along faults within the Earth’s crust.
- A fault is a zone of the earth’s crust within which the two sides have
moved .
- faults may be hundreds of miles long, from one to over one hundred
miles deep, and are sometimes not readily apparent on the ground
surface.
- Earthquakes initiate a number of phenomena or agents, termed seismic
hazards, which can cause significant damage to the built environment,
these include fault rupture, vibratory ground motion , tsunami, dam
failure, fire.
- For most earthquakes, shaking is the dominant and most widespread
agent of damage.
* The word seismology originated from Greek words,
‘seismos’ meaning earthquake and ‘logos’ meaning science.
Terminologies
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- Fault rupture is a process that takes seconds or at most a few minutes.
- Shaking near the actual earthquake rupture lasts only during the time
when the fault ruptures.
- The seismic waves generated by the rupture propagate long after the
movement on the fault has stopped, however, spanning the globe in
about 20 min. Typically, earthquake ground motions are powerful
enough to cause damage only in the near field (i.e., within a few tens
of kilometers from the causative fault)
- in a few instances, long period motions have caused significant
damage at great distances, to selected lightly damped structures. A
prime example of this was the 1985 Mexico City Earthquake, where
numerous collapses of mid- and high-rise buildings were due to a
magnitude 8.1 Earthquake occurring at a distance of approximately
400 km from Mexico City.
Terminologies
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Tsunami or Harbor Wave: This Japanese
word is represented by two Characters;
(Tsu=Harbor) and (Nami=Wave).
Why did the earthquake cause a tsunami?
- Shallow focus earthquake
- Large volume of oceanic crust displaced
- The movement of the crust also
displaces a large volume of water.
Terminologies
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Terminologies
Japan Tsunami, 2011
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The earth’s shape is an oblate spheroid with a diameter along the
equator of about 12740 km with the polar diameter as 12700km.
The higher diameter along equator is caused by the higher
centrifugal forces generated along the equator due to rotation of
earth.
Interior of the earth can be classified into three major categories as
Crust, Mantle and Core
Internal Structure of Earth
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• The earth's radius is 6371 km.
The Crust:
• The crust is a thin outer shell, about 30 km in thickness on average.
• Its thickness exceeds 70 km in some mountain belts, such as the
Himalayas.
• Its thickness ranges from 3 km to 15 km in oceanic crust.
The Mantle:
• It is a solid rocky layer.
• It extends to a depth of about 2900 km.
The core:
Inner core:
• Its radius is 1200 km.
• The inner core is solid due to generated pressure.
• It is made of iron.
Outer Core:
· Its radius is about 2200 km.
· It is made of iron mixed with other elements.
Internal Structure of Earth
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Region Radius
(km)
Inner Core 1200
Outer Core 2200
Mantle 2900
Crust 5 to 70
Anatomy of Earth
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- The upper most part of the earth is considered to be divided into two
layers with different deformation properties.
- The upper rigid layer, called the lithosphere, is about 100 km thick
below the continents, and about 50 km under the oceans, and consists
of Crust and rigid upper-mantle rocks.
- The lower layer, called the asthenosphere, extends down to about 700
km depth.
- The rigid lithospheric shell is broken into several irregularly shaped
major plates and a large number of minor or secondary plates.
- The lithospheric plates are not stationary, on the contrary, they float in
a complex pattern, with a velocity of some 2-10 cm/year on the soft
rocks of the underlying asthenosphere like rafts on a lake.
Internal Structure of Earth
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Internal Structure of Earth
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- This theory requires a source that can generate great force is
acting on the plates.
- The widely accepted explanation is based on the force offered by
convection currents created by thermo-mechanical behavior of
the earth’s subsurface. The variation of mantle density with
temperature produces an unstable equilibrium. The colder and
denser upper layer sinks under the action of gravity to the
warmer bottom layer which is less dense. The lesser dense
material rises upwards and the colder material as it sinks gets
heated up and becomes less dense (refer to the figure in previous
slide).
- These convection currents create shear stresses at the bottom of
the plates which drags them along the surface of earth.
Theory of occurring earthquakes
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Earthquake Fatalities
Bam earthquake struck the Kerman
province of southeastern Iran
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Earthquake Victims
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Earthquake Victims
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• UBC, “Structural engineering design provisions. In: Uniform Building Code.
International Conference of Building Officials”, vol. 2. 1997
• BS EN. 1998-1: Eurocode 8, “Design of structures for earthquake resistance. Part 1:
General rules, Introduction seismic actions and rules for buildings”, 2004
• IBC 2012, “ International Building Code”, International Code Council, 2011
• American Society of Civil Engineers, ASCE 7-10 ,“Minimum Design Loads for
Buildings and Other Structures”, 2010
• FEMA 356, “Prestandard and commentary for the seismic rehabilitation of buildings”,
Washington. DC: Federal Emergency Management Agency, 2000
• American Society of Civil Engineers, ASCE 41-06 , “Seismic Rehabilitation of
Existing Buildings”, 2007
• ACI 318-11, “ Building Code Requirement for Structural Concrete and Commentary”,
American, Earthquake Engineering & Structural Dynamics – 2012 Concrete Institute,
Detroit, 2011
• NZS 1170.5, “Structural Design Actions-Part 5 : Earthquake actions New Zealand”,
Standards, Association of New Zealand, 2004
• DIN 4149, “Buildings in Germany earthquake areas - Design loads, analysis and
structural design of buildings”, German Safety Standard Commission, 2005
Bibliography - Codes
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