BASE ISOLATION SYSTEM

BY:SYED JABER

Effects of Earthquake

Seismic

Intuition

Definition:

•Seismic retrofitting is the modification ofexisting structures to make them more resistant to seismicactivity, ground motion, or soil failure due to earthquakes.

The retrofit techniques are also applicable forother natural hazards such as tropical cyclones,tornadoes, and severe winds from thunderstorms.

Column jacketingShear wall

Beam-columns joint jacketing

Strengthening of individual footings

Buildings with foundation base fixed to the super structure are known as Fixed base.

Buildings with rubber or similarisolation between to base foundation andstructure are known as Base isolatedbuildings.

Most widely used method of seismicretrofitting is the technique of Base isolation.

The main concept behind base isolation is allowingslight lateral movement of the base in order toincrease the fundamental time period of thestructure. This increase in the period will cause thestructure to be less attractive to seismic forces andwill result in less structural deformations.

BASE ISOLATION SYSTEM

Base isolation is categorized into two very different yet broad methods.

Flat Sliding Bearing

Lead Rubber Bearing

1.Sliding system.

2.Elastometric isolators

Natural rubber bearingsLow damping rubber bearingsLead plug bearingsHigh damping rubber bearings

Flat sliding systemSpherical sliding isolator

Flat Sliding Bearing

•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.

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

Base Isolation as a Whole

ANY QUERIES???

Thank U