RESILIENT STRUCTURAL SYSTEMS

1. GURUVIGNESH N 1
RESILIENT STRUCTURAL SYSTEMS
(EARTHQUAKE RESISTANCE)
Submitted by
GURUVIGNESH N
Reg. No :910018413004
M.E.-STRUCTURAL ENGINEERING (FULL TIME)
ANNAUNIVERSITY REGIONAL CAMPUS
MADURAI

2. INTRODUCTION
 Including mechanical devices in
structural systems can lead to
enhancement of performance of
structures to extreme loadings
 these devices can be designed to
provide required strength while
controlling behavior to protect
structural elements from damage
 system can be designed to fuse
during such extreme events as strong
earthquake ground motion
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3. EARTHQUAKES WORK
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One of the most terrifying phenomena
Until recently - unsubstantiated guesses as to what
caused earthquakes
Today – much clearer understanding
 Identified forces of earthquakes
 Technology that can tell an earthquake’s
magnitude
 Technology that can tell an origin
OBJECTIVES
 To find a way of predicting earthquakes
 To find way to protect people and property

4. THEORY OF PLATE TECTONICS
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 The surface layer of the
earth  the lithosphere
slide over another
layer
 three different things
o Plates slide against
each other
o Plates can move apart
o Plates can push
together

5. SEISMIC WAVES
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 sudden break or shift occurs in the earth's crust, -
the energy radiates out as seismic waves
 In every earthquake, there are several different
types of seismic waves
 Body waves move through the inner part of the earth
 Surface waves travel over the surface of the earth.
 Surface waves -- sometimes called long waves, or
simply L waves -- are responsible for most of the
damage associated with earthquakes, because they
cause the most intense vibrations. Surface waves
stem from body waves that reach the surface.

6. CAUSES OF EARTHQUAKE
 An earthquake is a vibration that
travels through the earth's crust.
Natural causes
o Volcanic eruption
o Water pressure in reservoir
o Meteor impacts,Rock fall
o Movements of the earth’s
plates
Man made causes
o Collapsing structures
o Under ground explosions
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THEORIES
1.ELASTIC
REBOUND
THEORY
2.TECTONIC
PLATE THEORY

7. Surface wave:
The slowest traveling seismic
waves
Their movement is greatest at
the earth's surface, and gets
smaller
P-wave
A longitudinal wave
Travelrock, liquid and the air
The fastest traveling seismic
wave
S-wave
A transverse wave
Travel rock, but not through
liquid and the air
slower than a P-wave, but
faster than a surface wave
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SEISMIC WAVES

8. BUILDING HEIGHT TYPICAL NATURAL PERIOD
2 story .2 seconds
5 story .5 seconds
10 story 1.0 seconds
20 story 2.0 seconds
30 story 3.0 seconds
BUILDING HEIGHTS & NATURAL
FREQUENCY
Natural period = no of stories * 0.1

9.  Buildings are designed to withstand
vertical forces. If earthquakes only
moved the ground vertically, buildings
might suffer little damage because all
structures are designed to withstand
vertical forces associated with gravity
 But the rolling waves of an
earthquake exert extreme horizontal
forces on standing structures.
 These forces cause lateral
accelerations.
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FORCES

10. SEISMIC
ZONE
II III IV V
Seismic
intensity
Low Moderate Severe Very
severe
Z 0.10 0.16 0.24 0.36
SEISMIC
ZONE LEVEL
REMARK
III,IV and V Depth b/w 5
to 10 m
II(for
important
structure
only)
Depth b/w 5
to 10 m
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11. SEISMOLOGY
 They do this with a seismograph,
a machine that registers the
different waves
 To find the distance between the
seismograph and the focus,
scientists also need to know the
time the vibrations arrived
 With this information, they
simply note how much time passed
between the arrival of both
waves and then check a special
chart that tells them the
distance the waves must have
traveled based on that delay.
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12.  These two ratings describe the power of the
earthquake from two different perspectives.
o The Richter Scale is used to rate the
magnitude of an earthquake -- the amount of
energy it released
o This is calculated using information gathered
by a seismograph.
 Mercalli ratings only give you a rough idea of
the actual impact of an earthquake
MAGNITUDE – NUMBER-ENERGY RELATED
INTENSITY -NOTATION – DAMAGE RATE
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RICHTER SCALE RATING AND
MERCALLI SCALE RATING

13. EARTHQUAKE RESISTANT
BUILDINGS
Earthquakes can cause buildings to vibrate
Every building has a number of ways, or
modes, in which it can vibrate naturally. In
each mode, the building vibrates to a
particular distorted shape called its mode
shape.
Earthquakes usually make buildings vibrate
most strongly in their fundamental mode, the
mode of vibration with the lowest frequency
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14. STRENGTHENING BUILDINGS
FOR EARTHQUAKES
 Earthquakes cause sideways forces on
buildings
 These are some of the structural
systems used to resist sideways forces
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1.HORIZONTAL
STRUCTURAL SYSTEM
2.VERTICAL STRUCTURAL
SYSTEM

15. HORIZONTAL STRUCTURAL
SYSTEMS
Usually floors and roofs
They share the sideways forces on
the building between its vertical
structural members.
They include:
Diaphragms
Trussing
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16. HORIZONTAL DIAPHRAGMS
Horizontal diaphragms are
usually floors and roofs. They
are made up from a horizontal
frame covered by a floor or roof
deck.
When a diaphragm is stiff
enough in its horizontal plane, it
can share the sideways
earthquake forces on a building
between the vertical structural
members, e.g. the columns and
walls.
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17. HORIZONTAL TRUSSING
Horizontal trussing is
usually used in roofs where
there is not enough deck to
allow the roof to act as a
stiff horizontal diaphragm.
The trussing transfers the
sideways earthquake forces
on a building to its vertical
structural members e.g. the
columns and walls.
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18. VERTICAL STRUCTURAL
SYSTEMS
Made up from columns,
beams, walls and bracing.
They transfer the sideways
forces on the building to
the ground.
They include:
 Braced frames
 Moment resisting frames
 Shear walls
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 Braced frames use trussing to resist sideways forces
on buildings.
 Trussing, or triangulation, is formed by inserting
diagonal structural members into rectangular areas of
a structural frame.
 It helps stabilise the frame against sideways forces
from earthquakes and strong winds.
BRACED FRAMES
 Single diagonals
 Cross-bracing
 Other ways of bracing frames

20. OTHER WAYS OF BRACING
FRAMES
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Knee Bracing
V Bracing
K Bracing
Knee Bracing

21. MOMENT RESISTING FRAMES
In moment resisting frames,
the joints, or connections,
between columns and beams
are designed to be rigid
This causes the columns and
beams to bend during
earthquakes. So these
structural members are
designed to be strong in
bending.
Moment resisting frames
simply means frames that
resist forces by bending.
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22. SHEAR WALLS
Shear walls are vertical walls
that are used to stiffen the
structural frames of buildings.
They help frames resist
sideways earthquake forces
The earthquake forces are
transferred to the ground
mainly by shear forces in the
walls
It is better to use walls with
no openings in them.
Usually the walls around lift
shafts and stairwells are used
 Walls on the sides of
buildings that have no windows
can be used. GURUVIGNESH N 22

23. Techniques to be Adopt on
Skyscrapers
Base isolation
Rubber bearings
Friction dampers
Metallic dampers
Friction pendulum
Viscous dampers
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24. base isolation -- involves floating a building
above its foundation on a system of
bearings, springs or padded cylinders.
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BASE ISOLATION

25. BASE ISOLATION
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26. RUBBER BEARINGS
Rubber bearings are made from layers of rubber
with thin steel plates between them, and a thick steel
plate on the top and bottom.
The bearings are placed between the bottom of a
building and its foundation .
The bearings are designed to be very stiff and
strong for vertical load, so that they can carry the
weight of the building. However, they are designed to
be much weaker for horizontal loads, so that they can
move sideways during an earthquake.
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27. Rubber attached at foundation 27GURUVIGNESH N

28. METALLIC DAMPERS
Metallic dampers are usually made from steel.
They are designed to deform so much when the
building vibrates during an earthquake that they cannot
return to their original shape.
This permanent deformation is called inelastic
deformation, and it uses some of the earthquake energy
which goes into building.
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X - Plate Metallic Damper

29. FRICTION DAMPERS
Friction dampers are designed to
have moving parts that will slide
over each other during a strong
earthquake.
When the parts slide over each
other, they create friction which
uses some of the energy from the
earthquake that goes into the
building.
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30. FRICTION PENDULUM BEARINGS
Friction pendulum bearings are
made from two horizontal steel
plates that can slide over each
other because of their shape and
an additional articulated slider.
They are designed to be very
stiff and strong for vertical load,
so that they can carry the weight
of the building.
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31. VISCOUS FLUID DAMPERS
Viscous fluid dampers are similar to shock absorbers
in a car. They consist of a closed cylinder containing a
viscous fluid like oil.
A piston rod is connected to a piston head with small
holes in it. The piston can move in and out of the
cylinder. As it does this, the oil is forced to flow
through holes in the piston head causing friction.
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32. San Francisco Airport International Terminal
World’s Largest Isolated Building

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THANK YOU…