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Transcript of enhancement of seismic resistance of structures
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