Page 49 - EQTips_Eng

IITK-BMTPC Earthquake Tip 24

How to reduce Earthquake Effects on Buildings? page 2
Base Isolation in Real Buildings provided in a 18-storey RC frame structure in Gurgaon
Seismic isolation is a relatively recent and evolving (See http://www.palldynamics.com/main.htm).
technology. It has been in increased use since the
1980s, and has been well evaluated and reviewed
internationally. Base isolation has now been used in Viscous
Fluid
numerous buildings in countries like Italy, Japan, New
Zealand, and USA. Base isolation is also useful for
retrofitting important buildings (like hospitals and
historic buildings). By now, over 1000 buildings across Piston
the world have been equipped with seismic base
isolation. In India, base isolation technique was first
demonstrated after the 1993 Killari (Maharashtra) (a) Viscous Damper
Earthquake [EERI, 1999]. Two single storey buildings
(one school building and another shopping complex
building) in newly relocated Killari town were built Steel
with rubber base isolators resting on hard ground. Both Plate
were brick masonry buildings with concrete roof. After the
2001 Bhuj (Gujarat) earthquake, the four-storey Bhuj
Hospital building was built with base isolation Bolt
technique (Figure 2).

Photo Courtesy:
Marjorie Greene, EERI, USA (b) Friction Damper

Yield location
of metal

Basement columns Base Isolator (c) Yielding Dampers

supporting base isolators

Figure 2: View of Basement in Bhuj Hospital Figure 3: Seismic Energy Dissipation Devices –
each device is suitable for a certain building.
building – built with base isolators after the

original District Hospital building at Bhuj Related - Earthquake Tip

collapsed during the 2001 Bhuj earthquake. Tip 5: What are the Seismic Effects on Structures?
Tip 8: What is the Seismic Design Philosophy for Buildings?
Seismic Dampers
Another approach for controlling seismic damage Reading Material
in buildings and improving their seismic performance EERI, (1999), “Lessons Learnt Over Time – Learning from Earthquakes
Series: Volume II Innovative Recovery in India,” Earthquake
is by installing seismic dampers in place of structural Engineering Research Institute, Oakland (CA), USA; also
elements, such as diagonal braces. These dampers act available at http://www.nicee.org/readings/EERI_Report.htm.
like the hydraulic shock absorbers in cars – much of Hanson,R.D., and Soong,T.T., (2001), “Seismic Design with
the sudden jerks are absorbed in the hydraulic fluids Supplemental Energy Dissipation Devices,” Earthquake Engineering
Research Institute, Oakland (CA), USA
and only little is transmitted above to the chassis of the Skinner,R.I., Robinson,W.H., and McVerry,G.H., (1999), “An
car. When seismic energy is transmitted through them, Introduction to Seismic Isolation,” John Wiley & Sons, USA
dampers absorb part of it, and thus damp the motion of
the building. Dampers were used since 1960s to Authored by:
C.V.R.Murty
protect tall buildings against wind effects. However, it
was only since 1990s, that they were used to protect Indian Institute of Technology Kanpur
Kanpur, India
buildings against earthquake effects. Commonly used Sponsored by:
types of seismic dampers include viscous dampers Building Materials and Technology Promotion
(energy is absorbed by silicone-based fluid passing Council, New Delhi, India
between piston-cylinder arrangement), friction dampers
(energy is absorbed by surfaces with friction between This release is a property of IIT Kanpur and BMTPC New
them rubbing against each other), and yielding dampers Delhi. It may be reproduced without changing its contents
(energy is absorbed by metallic components that yield) and with due acknowledgement. Suggestions/comments
may be sent to: nicee@iitk.ac.in Visit www.nicee.org or
(Figure 3). In India, friction dampers have been www.bmtpc.org, to see previous IITK-BMTPC Earthquake Tips.

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