ENGINEERING FOR EARTHQUAKES

badwaterreflectiveΠολεοδομικά Έργα

29 Νοε 2013 (πριν από 3 χρόνια και 4 μήνες)

79 εμφανίσεις

ENGINEERING FOR EARTHQUAKES

By Mrs. Shaw

What is an Engineer?


Engineering

is the application of scientific and
technical knowledge to solve human problems.



There are many types of engineers, some are listed
below:


Civil


includes Structural / Architectural


Aerospace


Chemical


Biomedical

What do Structural Engineers do?


Structural Engineers
must
identify, understand, and
integrate the constraints on a
design in order to produce a
successful result.



For example
:


Designs for Buildings planned
for close to the beach must take
into account the wind load,
water effects and erosion
issues.


Earthquake Resistant Buildings


The focus of our project is to use some of the same
design elements that structural engineers use to create
buildings in areas where earthquakes happen
frequently.



Where would they happen more frequently than
anywhere else?

What is a fault line?


A fault line is where
two tectonic plate
boundaries meet.



Review of Earthquakes


An
earthquake

is what happens when two blocks of the
earth suddenly slip past one another.



The
surface where they slip
is called the
fault

or

fault
plane
.



The
area where the earthquake energy is generated
is
called the
focus
.



The
location directly above the focus it on the surface
of the earth

is called the
epicenter
.



How do Earthquakes happen?


Most
earthquakes result from plate boundaries
gliding past each other creating frictional stress.



When the frictional stress exceeds a critical value that
results in a
violent displacement of the Earth’s crust
and the
elastic strain energy is released and radiated
out.

How is the energy measured?


Seismometers

are instruments that measure motions
of the ground, including those of
seismic waves
generated by
earthquakes
,
volcanic eruptions
, and
other
seismic sources.



seismograph

Seismometer

Building movements in EQ’s


In an earthquake, the building base experiences
high
-
frequency movements, which results in inertial
forces.


**
Review
:
Inertia

is the ability of an object to resist
a change in motion.




Example of inertial strain


During an earthquake, if a rigid block is free
-
standing it
will move freely in the direction opposite the ground
movement.







If the block is solidly founded in the ground, it must absorb
the inertial force internally and the result will be a crack
near the base.

EQ Resistant Building Designs


Engineers choose from various structural components
when designing buildings to withstand earthquakes.



Examples include:


Diaphragms




Shear walls


Braced frames


Base isolation


Energy dissipation devices

Diaphragms


Diaphragms are horizontal resistance elements,
generally floors and roofs that transfer the lateral
forces between the vertical resistance elements
(shear walls or frames).

Shear Walls


Shear walls are vertical walls that are designed to
receive lateral forces, from diaphragms and
transmit them to the ground.




Braced Frames


A
Braced Frame

is a
structural system which is
designed primarily to
resist wind and
earthquake forces.


Members in a braced
frame are designed to
work in tension and
compression, similar to a
truss.


Braced frames are almost
always composed of steel
members.



Base Isolation


A base isolated structure is supported by a series of
bearing pads, which are placed between the
buildings and building foundation.





Energy dissipation devices


Dampers are
mechanical devices
designed to absorb
kinetic energy.


Dampers are
mechanical devices
designed to absorb
kinetic energy.



They are used in base
isolation designs.