1. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print),
ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME
57
INNOVATIVE ISOLATION TECHNIQUES FOR SEISMIC FORCES
Ar.Anurakti Yadav
LNCT College, Bhopal
ABSTRACT
Natural disaster, earthquakes, storms, floods, etc regularly hit the world. Among
these, the most destructive is earthquake since its occurrence is still unpredictable.
Ordinarily the houses are built to withstand only vertical loads and therefore when
they are subjected to horizontal stresses produced by earthquake waves they collapse
resulting in large-scale destruction. Since earthquake are capable of causing severe damage to
environment; physically, ecologically; so it is necessary for an architect or engineers to know
regarding earthquake, their occurrence, its harmful effects and precautionary measures that
can taken to minimize harms and related factors.
Historical evidence tells us that great earthquakes have shaped man’s thinking over
the millennia. While there is no evidence that the numbers of earthquakes are increasing, the
impact in terms of human tragedy and property destroyed is clearly on rise. All this is making
mankind more vulnerable than ever to disasters. In other words earthquakes are not killing
people, but the buildings created by society are it is not fate but plan and design which are
turning destiny’s dark hand.
Earthquakes the hammer of god, as they have been called is beyond human being’s
ability and forecast. It is also true that the intensity of an earthquake makes the condition
worse. But the scale of reduction can be reduced to a large extent by proper planning and
designing of houses and by suitable use of isolation base and seismic dampers.
Conventional seismic design attempts to make buildings that do not collapse under
strong earthquake shaking but may sustain damage to non-structural elements and some
structural members in the building. This may render the building non-functional after the
earthquake, which may be problematic in some structures like hospitals, which need to
remain functional in the aftermath of the earthquake. Special techniques are required to
design buildings such that they remain practically undamaged even in a severe earthquake.
Buildings with such improved seismic performance usually cost more than normal buildings
do. However, this cost is justified through improved earthquake performance.
JOURNAL OF CIVIL ENGINEERING AND TECHNOLOGY
(JCIET)
ISSN 2347 –4203 (Print)
ISSN 2347 –4211 (Online)
Volume 1, Issue 1, July-December (2013), pp. 57-63
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JCIET
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2. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print),
ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME
58
Two basic technologies are used to protect buildings from damaging earthquake effects.
These are Base Isolation Devices and Seismic Dampers.
BASE ISOLATION
If the flexible pads are properly chosen, the forces induced by ground shaking can be
few smaller than that experienced by the building built directly on ground, namely a fixed
base isolation.
The idea behind base isolation is to detach (isolate) the building from the ground in
such a way that earthquake motions are not transmitted up through the building or at least
greatly reduced.

3. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print),
ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME
59
The concept of base isolation is explained through an example building resting on
frictionless rollers. When the ground shakes, the rollers freely roll, but the building above
does not move. Thus, no force is transferred to the building due to the shaking of the ground;
simply, the building does not experience the earthquake.
A base isolated structure is supported by a series of bearing pads, which are placed between
the buildings and building foundation.
The isolators are often designed, to absorb energy and thus add damping to the
system. This helps in further reducing the seismic response of the building. Many of the base
isolators look like large rubber pads, although there are other types that are based on sliding
of one part of the building relative to other. Also, base isolation is not suitable for all
buildings. Mostly low to medium rise buildings rested on hard soil underneath; high-rise
buildings or buildings rested on soft soil are not suitable for base isolation.
Lead-rubber bearings are the frequently-used types of base isolation bearings. A lead
rubber bearing is made from layers of rubber sandwiched together with layers of steel. In the
middle of the solid lead “plug”. On top and bottom, the bearing is fitted with steel plates
which are used to attach the bearing to the building and foundation. The bearing is very stiff
and strong in the vertical direction, but flexible in the horizontal direction.
Response of Base Isolated Buildings
The base-isolated building retains its original, rectangular shape. The base isolated
building itself escapes the deformation and damage-which implies that the inertial forces
acting on the base isolated building have been reduced. Experiments and observations of
base-isolated buildings in earthquakes to as little as. Acceleration is decreased by ¼ of the
acceleration of comparable fixed-base buildings because the base isolation system lengthens
a buildings period of vibration, the time it takes for a building to rock back and forth and then
back again.

4. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print),
ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME
60
Spherical Sliding Base Isolation
Spherical sliding isolation systems are another type of base isolation. The building is
supported by bearing pads that have a curved surface and low friction. During an earthquake
the building is free to slide on the bearings. Since the bearings have a curved surface, the
building slides both horizontally and vertically. The forces needed to move the building
upwards limits the horizontal or lateral forces which would otherwise cause building
deformations. Also by adjusting the radius of the bearings curved surface, this property can
be used to design bearings that also lengthen the buildings period of vibration.
Base Isolation in India
By now, over 1000 buildings across the world have been equipped with seismic base
isolation. In India, base isolation technique was first demonstrated after the 1993 Killari
(Maharashtra) Earthquake [EERI, 1999]. Two single storey buildings (one school building
and another shopping complex building) in newly relocated Killari town were built with
rubber base isolators resting on hard ground. Both were brick masonry buildings with
concrete roof. After the 2001 Bhuj (Gujarat) earthquake, the four-storey Bhuj Hospital
building was built with base isolation technique.
Fig. 1 – view of basement in Bhuj hospital building
SEISMIC DAMPERS

5. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print),
ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME
61
Another approach for controlling seismic damage in buildings and improving their
seismic performance is by installing seismic dampers in place of structural elements, such as
diagonal braces. These damper acts like the hydraulic shock absorbers.
When seismic energy is transmitted through them, dampers absorb part of it, and thus
damp the motion of the building. Dampers were used since 1960s to protect tall buildings
against wind effects. However, it was only since 1990s, that they were used to protect
buildings against earthquake effects.
Seismic dampers are special devices introduced in the buildings to absorb the energy
provided by the ground motion to the building (much like the way shock absorbers in motor
vehicles absorb due to undulations of the road).
Types of seismic dampers
1) Viscous Dampers (energy is absorbed by silicone-based fluid passing between piston
cylinder arrangement),
2) Friction Dampers (energy is absorbed by surfaces with friction between them rubbing
against each other),
3) Yielding Dampers (energy is absorbed by metallic components that yield).
4) Viscoelastic Dampers (energy is absorbed by utilizing the controlled shearing of
solids).

6. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print),
ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME
62
Fig. 2 Viscous Damper
Viscous damper
It consists of a stainless steel piston with bronze orifice head. It is filled with silicone
oil. The piston head utilizes specially shaped passages which alter the flow of the damper
fluid and thus alter the resistance characteristics of the damper. Fluid dampers may be
designed to behave as a pure energy dissipater or a spring or as a combination of the two.
A fluid viscous damper resembles the common shock absorber such as those found in
automobiles. The piston transmits energy entering the system to the fluid in the damper,
causing it to move within the damper. The movement of the fluid within the damper fluid
absorbs this kinetic energy by converting it into heat. In automobiles, this means that a shock
received at the wheel is damped before it reaches the passengers compartment. In buildings
this can mean that the building columns protected by dampers will undergo considerably less
horizontal movement and damage during an earthquake.
Fig. 3 Friction Damper
Friction damper
The novel friction damper device consists of three steel plates rotating against each
other in opposite directions. The steel plates are separated by two shims of friction pad
material producing friction with steel plates.
When an external force excites a frame structure the girder starts to displace
horizontally due to this force. The damper will follow the motion and the central plate

7. Journal of Civil Engineering and Technology (JCIET), ISSN
ISSN 2347 –4211 (Online) Volume 1, Issue 1, July
because of the tensile forces in the bracing elements. When the applied forces are reversed,
the plates will rotate in opposite way. The damper dissipates energy by means of friction
between the sliding surfaces.
Viscoelastic dampers
The latest Friction-Viscoelastic
of pure frictional and viscoelastic mechanisms of energy dissipation.
consists of friction pads and viscoelastic polymer pads
prestressed bolt in combination with disk spring
maintaining the required clamping force on the interfaces as in original FDD concept
Seismic dampers in India
Friction-dampers for seismic control of la gardenia towers
South city, Gurgaon was
towers of eighteen storeys with two levels of basements. In the chosen structural system, Pall
friction-dampers are provided in steel bracing in concrete frames. The use of steel bracing
eliminated the need of expensive concrete shear walls and the uses of friction
eliminate the need of dependence on member ductility. Friction
in partitions, around staircases or elevator shaft. Their use provided greater flexibility in
space planning because unlike shear walls they do not need to be located conti
over the other. Since friction-damped bracing do not carry any gravity load, these do not
need to go down through the basements to the foundation. This allows more open space for
car parking in the basement. At the ground floor level, the la
transferred through the rigid floor diaphragm to the perimeter retaining walls of the basement.
The architects have exposed some friction
appearance. A total of 66 friction
safeguard the structure and its contents from damage.
REFERENCE
1) M.S. Shetty, concrete technology.
2) Concrete engineer’s handbook.
3) Architectural journals.
4) Internet.
5) Earthquakes and buildings
6) Standard book of engineering
Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203
(Online) Volume 1, Issue 1, July-December (2013), © IAEME
63
rces in the bracing elements. When the applied forces are reversed,
the plates will rotate in opposite way. The damper dissipates energy by means of friction
Viscoelastic Damper Device (F-VEDD) combines the advantages
of pure frictional and viscoelastic mechanisms of energy dissipation. This new product
viscoelastic polymer pads separated by steel plates.
prestressed bolt in combination with disk springs and hardened washers is used for
maintaining the required clamping force on the interfaces as in original FDD concept
dampers for seismic control of la gardenia towers
city, Gurgaon was used in India. La Gardenia housing complex consists of 7
with two levels of basements. In the chosen structural system, Pall
dampers are provided in steel bracing in concrete frames. The use of steel bracing
eliminated the need of expensive concrete shear walls and the uses of friction
te the need of dependence on member ductility. Friction-damped bracing are located
in partitions, around staircases or elevator shaft. Their use provided greater flexibility in
space planning because unlike shear walls they do not need to be located conti
damped bracing do not carry any gravity load, these do not
need to go down through the basements to the foundation. This allows more open space for
car parking in the basement. At the ground floor level, the lateral shear from the bracing is
transferred through the rigid floor diaphragm to the perimeter retaining walls of the basement.
The architects have exposed some friction-dampers to view as they add to the aesthetic
appearance. A total of 66 friction-dampers were required to extract sufficient energy to
safeguard the structure and its contents from damage.
M.S. Shetty, concrete technology.
Concrete engineer’s handbook.
Earthquakes and buildings
engineering
4203 (Print),
rces in the bracing elements. When the applied forces are reversed,
the plates will rotate in opposite way. The damper dissipates energy by means of friction
combines the advantages
This new product
separated by steel plates. A
s and hardened washers is used for
maintaining the required clamping force on the interfaces as in original FDD concept.
La Gardenia housing complex consists of 7
with two levels of basements. In the chosen structural system, Pall
dampers are provided in steel bracing in concrete frames. The use of steel bracing
eliminated the need of expensive concrete shear walls and the uses of friction-dampers
damped bracing are located
in partitions, around staircases or elevator shaft. Their use provided greater flexibility in
space planning because unlike shear walls they do not need to be located continuously one
damped bracing do not carry any gravity load, these do not
need to go down through the basements to the foundation. This allows more open space for
teral shear from the bracing is
transferred through the rigid floor diaphragm to the perimeter retaining walls of the basement.
dampers to view as they add to the aesthetic
rs were required to extract sufficient energy to