ENHANCEMENT OF SEISMIC RESISTANCE OF STRUCTURES

Disaster is a natural calamity which may be in the

form of :-

Earthquakes

Landslides

Cyclones

Floods

Drought

Volcanic eruptions

Forest fire…..etc

Facts And Figures

In India

60% of Land mass is prone to earthquakes

8% is prone to Cyclone

68% is susceptible to Drought

Over 40 million Hectare is prone to floods

Earthquakes, cyclones and fire needs special consideration in building design and

Construction since they are Frequent, widespread and more disastrous

Losses

1

Seismic zones from I-V are present in INDIA

Over 60% of India’s land is under Seismic Zones III, IV & V

INDIAN SEISMIC ZONE & SOME

DANGEROUS EARTHQUAKE

Do we have any reliable technologies

1

Upgrading of certain building system (existing structures) to make them more resistant to seismic activity such as earthquake resistance

When is it needed:-Structures that are :

-Earthquake damaged

-Earthquake vulnerable

(with no exposure to severe earthquake)

Retrofitting of Column and Beam

Aims at increase in strength and ductility

RETROFITTING

Purpose:-the major purpose of retrofitting is to make the building safer

and less prone to major structural damage during an earthquake

Retrofitting proves to be a better economic consideration and immediate shelter to problems rather than replacement of building

Retrofitting in India

After 2001 earthquake the awareness and need of seismic detailing has increased

In our country there is a notion that Retrofitting is very expensive and is not viable for economy like India. But it is totally wrong because retrofitting an existing structure may cost roughly 15-20% of the total cost of the structure and it has matured in the recent years to a highly reliable technique.

Popular Earthquake resistant Techniques

Earthquake may not be able to damage entire building but it damages

members of it . So special techniques are adopted.

List of some top famous earthquake-proofing techniques in the world:

Shear walls

Braces

Seismic Dampers.

Base Isolation Devices

SHEAR WALLS

Resist;

• Gravity Loads

• Lateral Loads

Shear Wall

March 3, 1985 Earthquake (Chile) Shear Wall performed very well

BRACING

Diagonal Cross Chevron Eccentric

Link

Beams

DAMPERS: special devices - introduced in building – absorb the energy –

produced by seismic waves

Dampers are of:

Viscous Damper

Friction Damper

Yielding Damper

Seismic Dampers: Taipei 101 has the largest TMD sphere in the world and

weighs 660 metric tonnes with a diameter of 5.5 meter and costs US$4 million (total

structure costs US$1.80 billion)

Fig: TMD in Taipei 101

BASE ISOLATION

Base isolation is a passive vibration control system.

The goal of base isolation is to reduce the energy that is transferred from the

ground motion to the structure.

Fig: San-Francisco city hall after seismic retrofit with the help of base isolation

Precautionary measures

• Avoid weak column and strong beam design

• Provide thick slab which will help as a rigid diaphragm

• Provide cross walls which will stiffen the structures

• Provide shear walls in a symmetrical fashion

•Increase in the transverse (Shear) reinforcement.

• Horizontal lintel band should be provided

• Revision/ updation of building code of India

• The building must be regular and symmetrical in shape

• Reinforcing bars should be provided at the corners and the junctions of the

walls

CONCLUSION

We often underestimate the importance of being prepared because we forget that tragedy

strikes when we least expect it to happen ~alan

siegmford

WE ARE HERE ONLY TO PROVIDE SAFETY

TO PUBLIC TO LEAD THEIR LIFE

HAPPILY.

THANK YOU