This seminar report discusses base isolation, which involves installing flexible material between a structure's foundation and superstructure to reduce seismic forces. Base isolation works by lowering the magnitude and frequency of seismic shocks entering the building. It provides both spring-like and energy-absorbing characteristics. Isolated structures experience much smaller forces and movements compared to conventional structures during earthquakes. Common base isolation devices include laminated rubber bearings and lead-rubber bearings. Base isolation is advantageous as it requires minimal maintenance and results in more durable structures, though it is more costly and not suitable for all building types. The report provides examples of large base-isolated structures built worldwide.

1. Presented By
Mr. Akshay S. Raut
Final Year Civil
Guide By
Prof A.P. Pachgade
SEMINAR REPORT
ON
IBSS COLLEGE OF ENGINEERING,
AMRAVATI

2. Ǫ. What is Base Isolation?
 Base isolation is defined as a flexible material which is provided
at base to reduce the seismic forces of any structure.
 Because the base isolation reduces ground motion transmitted
to the superstructure above the isolator, reducing the response
of a typical structure and the corresponding loading. They are
located strategically between the foundation and the building
structure and are designed to lower the magnitude and
frequency of seismic shock permitted to enter the building.
They provide both spring and energy absorbing
characteristics.

4. Isolated Structure Conventional Structure

5. Conventional Structure
 Ground Forces are
amplified by a factor
of 3 to 4 at the roof.

6. Isolated Structure
 Forces reduced by 3
to 6 across the
isolators
 Forces reduced by 8
to 12 at the roof

7. During a Richter 8.0
Earthquake a Seismically Isolated
Building Will Behave as if it Were
Experiencing a 5.5 Earthquake

8. • Behaviour Under Seismic Loads :

9. Ǫ Why should we use Base Isolation ?
 Advantages :-
1) Minimum maintenance
during the lifetime of
structure
2) Less expansive
3) Durable
 Disadvantages :-
1) It is not suitable for high
rise structure
2) It is not suitable for
building rest on soft soil
3) It is more coastally

10. CONSTRUCTION PROCSSES OF FIXING OF
ISOLATION BASE: -
1) First to place a hydraulic jack on basement and
lift the above ground portion or superstructures
.
2) Cut the column at ground floor slab beam level.
3) Fix the isolation devices or pads.

11. TYPES OF ISOLATION DEVICES : -
2) Lead Rubber Bearing
3) Friction Pendulum System 4) Bearings with Tension Device
1) Laminated Rubber Bearing

12. • Seismic Isolator
Cover Rubber
Energy Dissipation Core
Steel Reinforcing Plates
Internal Rubber Layers
Bottom Mounting
Plate
(Top Mounting Plate Not Shown)

13. • Working Of Lead Core Rubber Bearings :
.

14. Fixed Base building Flexible-Isolated devices
building
1) Fixed base building is directly Rest
on Ground
1) Isolated base building is not directly
Rest on Ground
2) Fundamental natural period is less
like bellow 0.1 sec.
2) Fundamental natural periods is
more than 1 sec.
3) Not flexible base 3) Flexible base
4) More movement of building 4) 5 to 6 time smaller movement fixed
base building
 COMPARISION :-

15. • Some famous base Isolated structure -
San Francisco Airport International Terminal (World’s Largest Isolated Building)

16. •1st application in New Zealand in 1974
•1st US application in 1984
•1st Japanese application in 1985
•US - 80 buildings and 150 bridges
•Japan - 1000 buildings and 500 bridges
•Bhuji Hospital, Gujarat Province, India

17.  CONCLUSIONS-
1. Seismic isolation method has been proved to be a
reliable method of earthquake resistant design.
2. Earthquake resistance can be achieved by resisting the
inertia forces on the structure. This can be achieving
by using base isolation techniques in structure.

18. REFRENCE-
I.S. 1893-2002 (res)
IIT Kanpur Earthquake Tips
Earthquake Resistant Design of Structures- S.K.
Duggal

19. THANKYOU FOR LISTENING ME CAREFULLY