Now a days Earthquake Engineering is the most
needed and essential part to save many lives from Earthquakes comes in many
counties. There a lot of effects of Earthquake can be seen in Nepal and its
belonging countries.
Definition
of Earthquake Engineering:
An
earthquake is a sudden slipping or movement of a portion of the Earth's crust
or plates, caused by a sudden release of stresses. Earthquake epicenters are
usually less than 25 miles below the Earth's surface and are accompanied and
followed by a series of vibrations.
What
causes earthquakes and where do earthquakes happen
The
earth has four major layers: The inner core, outer core, mantle and crust. The
crust and the top of the mantle make up a thin layer on the surface of earth.
But this layer is not a single cover, it is made up of many pieces like jigsaw
covering the surface of the earth. These keep slowly moving around each
other, slide past one another and bump into each other. These puzzle pieces
are called tectonic plates, and the edges of the plates are called the plate
boundaries. The plate boundaries are made up of many faults, and most of the
earthquakes around the world occur on these faults. Since the edges of the
plates are rough, they get stuck while the rest of the plate keeps moving.
Finally, when the plate has moved far enough, the edges unstick on one of the
faults and there is an earthquake.
Types
of earthquakes
Most
earthquakes in the world occur along the boundaries of the tectonic plates and
are called Inter-plate Earthquakes. A number of earthquakes also occur within
the plate itself away from the plate boundaries, called Intra-plate
Earthquakes.
How
are earthquakes recorded
Earthquakes
are recorded by instrument called seismographs. The
recording they made, is called a seismogram. The seismo gram
consists of two parts, a base and a weight, to held it firmly in the ground.
When an earthquake causes the ground to shake, the base of the seismograph
shakes too, but the hanging weight does not. Instead the spring or string that
it is hanging from absorbs all the movement. Thus the difference between the
moving and immovable part is recorded.
The
size of an earthquake depends on the size of the fault and the amount of slip
on the fault, but this cannot be measured directly as faults are deep in the
earth. The seismogram recordings made on the seismographs at the surface of the
earth are used to determine the intensity of earthquake. A short line with less
zigzag portions represents a small earthquake and a lengthy line with a lot of
zigzag sections shows a large earthquake. The length of line on the seismograph
depends on the size of the fault and the wigginess of the line depends upon the
amount of slip of the fault. The size or intensity of earthquake is called
Magnitude of earthquake.
Earthquake Engineering
Earthquake
Engineering can be defined as the branch of engineering devoted to mitigating
earthquake hazards. Earthquake engineering covers the investigation
and solution of the problems created by damaging earthquakes, and hence
the work involved in the practical application of these solutions in planning,
designing, constructing and managing earthquake-resistant structures and
facilities.
Purpose
and background of earthquake engineering
According to
the IS 1893:2002 some consideration of seismic resistant design is required for
most building structures in the United States. Effective use of these documents
requires a thorough understanding of the principles of earthquake engineering,
from ground motion seismology, to structural dynamics, to inelastic behavior,
to design and detailing. understanding to practicing professional engineers
that have little or no previous training in earthquake engineering. While other
seismic seminars focus on the design aspect of earthquake engineering, the
purpose of this seminar is to concentrate on the fundamentals. The course
begins with a historical and philosophical review of earthquake engineering and
seismic code development, followed by an overview of the latest code approaches
to seismic resistant design. These code approaches are then broken down into
their basic components, and a detailed step-by-step explanation is provided on
how and why each component was developed. The seminar includes a description of
a variety of seismic resistant structural systems in
reinforced concrete and structural steel. The seminar ends with a
brief look towards the future: passive energy systems, seismic isolation, and
performance based concepts in earthquake engineering. Whenever possible, the
material is taught by example. The powerful NONLIN computer program, developed
by FEMA for earthquake engineering education, serves a prominent role during
the first day of the course. To maximize your ability to continue to learn
about earthquake engineering, detailed reference material is provided for each
slide presented in the seminar. The course also gives you the latest
information on earthquake engineering materials available on the World Wide Web.
Aims
and Objectives of earthquake engineering study
The
main objective of this volume is to illustrate to students of structural and
architectural engineering the problems and solutions in attaining efficient
earthquake-resistant structures and facilities. To achieve this objective,
after a brief discussion of the general goals in seismic-resistant design and
construction of structures and facilities, the different sources of damage that
can be triggered by an earthquake are discussed and illustrated.
Emphasis
is placed on the discussion and illustration of damage induced by vibration on
timber, masonry, concrete and steel structures. The importance of a
comprehensive approach to the problem of earthquake resistant construction is
emphasized next and the need for placing more emphasis on conceptual design is
discussed by offering guidelines for and illustrations of efficient
seismic-resistant design. The need for research in earthquake-resistant design
and construction is briefly discussed and examples of integrated experimental
and analytical investigations in the development of modern seismic-resistant
design are also shown.
What
earthquake engineer should study / know
- Geotechnical
earthquake engineering
- Performance-based
seismic engineering
- Disaster
planning
- Earthquake
resistant design and analysis
- Engineering
seismology
- Risk
and reliability seismic engineering
- Soil
dynamics
- Structural
dynamics
Steven
L. Kramer. Geotechnical Earthquake Engineering. Prentice Hall, 1996. ISBN:
0133749436 Software and Computer tools to be used Many of the problems in this
course will require numerical solutions. Matlab, MathCAD or similar softwares
and environments will be used for such purpose. Examples of numerical exercises
will be spectral analysis using FFT, Response Spectra, and so on. SHAKE will be
used for 1-D ground response analysis.
