This document discusses seismic retrofitting and base isolation systems. It defines seismic retrofitting as modifying existing structures to make them more resistant to seismic activity. The most widely used retrofitting method is base isolation, which involves inserting rubber or similar isolators between a building's foundation and superstructure. This allows for slight lateral movement during an earthquake to increase the building's natural period and reduce seismic forces. There are two main types of base isolators: sliding systems and elastometric isolators, with lead rubber bearings being a common elastometric isolator that uses lead plugs to dissipate energy and limit displacement. Base isolation has been used worldwide to reinforce historical structures and reduce earthquake damage to buildings and artifacts.

1. BY:SYED JABER

3. Effects of Earthquake

4. Seismic
Intuition

5. Definition:
•Seismic retrofitting is the modification of
existing structures to make them more resistant to seismic
activity, ground motion, or soil failure due to earthquakes.
The retrofit techniques are also applicable for
other natural hazards such as tropical cyclones,
tornadoes, and severe winds from thunderstorms.

7. Column jacketing
Shear wall
Beam-columns joint
jacketing
Strengthening of individual footings

8. Most widely used method of seismic
retrofitting is the technique of Base isolation.
Buildings with foundation base fixed to
the super structure are known as Fixed
base.
Buildings with rubber or similar
isolation between to base foundation and
structure are known as Base isolated
buildings.

9. BASE ISOLATION SYSTEM
The main concept behind base isolation is allowing
slight lateral movement of the base in order to
increase the fundamental time period of the
structure. This increase in the period will cause the
structure to be less attractive to seismic forces and
will result in less structural deformations.

10. Base isolation is categorized into two very different yet
broad methods.
Flat Sliding Bearing
1.Sliding system.
Flat sliding system
Spherical sliding isolator
2.Elastometric isolators
Lead Rubber Bearing
Natural rubber bearings
Low damping rubber bearings
Lead plug bearings
High damping rubber bearings

11. Flat Sliding Bearing

12. •The role of the lead plug is to regulate the lateral displacement of the
infrastructure and dissipate the kinetic energy of the seismic motion. It
converts the energy of motion from the system into heat. By doing so, it does
not allow as much kinetic energy to flow to the infrastructure.
•Internal rubber layers provide lateral flexibility.
•Bottom mounting plate connects to structure above and below isolator. and
•Steel reinforcing plates which provide vertical load capacity and confines lead
core.
•Rubbers cover for protecting steel plates.

13. Traditionally, the application of the system is seen in
larger buildings and bridges. Additionally, engineers have
made an effort to apply the system at a lower cost in
residential areas.
Base isolation techniques have been utilized worldwide in
historical structures and monuments to reduce any possible
destruction. Also on a smaller scale, museums have started
to use the system to ensure the security of artifacts

14. Base Isolation as a Whole

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