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8/7/2019 Seismic Retrofitting - Copy
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8/7/2019 Seismic Retrofitting - Copy
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INTRODUCTION OF SEISMIC
RETROFITTING
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Public Safety Retrofitting StructureSurvivability
Primary structureundamaged
StructureUnaffected
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External Post Tensioning
Base Isolation
Active Control System
Adhoc addition of structure
Connections between buildings and their expansion
additions
Exterior concrete columns
Exterior concrete columns
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Seismic isolation is simple
structural design approach to
mitigate or reduceearthquake damage potential.
The concept of base isolation
is explained through an
example building resting on
frictionless rollers.
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F lexible pads areproperly chosen, theforces induced by ground shaking can be afew times smaller thanthat experienced by thebuilding built directly
on ground, namely afixed base building. Theflexible pads are calledbase-isolators .
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1) L ow-Damping Natural or Synthetic Rubber Bearing.2) High-Damping Natural Rubber Bearing.3) L ead-Rubber Bearing.
1) F lat Sliding Bearing.2) F riction Pendulum System.
A)Elastomeric Bearings
B)Sliding Bearings
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A)L ow Damping Natural and Synthetic
Rubber Bearing:-
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Solid lead cylinder ispress-fitted into centralhole of elastomericbearing.
L ow damping rubbercombined with centralleadcore.
B)L
ead-Rubber Bearings
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The development of a natural rubber compound
with enough inherent damping to eliminate theneed for supplementary damping elements.
The damping is increased by adding extra finecarbon block, oils or resins, and other propriety fillers. The method of vulcanization bounding andconstruction of the isolators are unchanged .
C) High Damping Natural Rubber Systems(HDNR):-
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D)Friction Pendulum System:-The friction PendulumSystem is frictionalisolation system t hatcombines a slidingaction and a restoringforce by geometry.
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BASE ISOL
ATION FOR
BUILDING:-
Seismic isolation is a relatively recent andevolving technology. Base isolation hasnow been used in numerous building indifferent countries Base isolation is alsouseful for retrofitting important building.
In India, base isolation technique was firstdemonstrated after the 1993 Killari(Maharashtra) Earthquake.
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Response of Ba se Isol a ted B uildin g
Experiments and observations of baseisolated buildings in earthquakes have beenshown to reduce building accelerations to aslittle as 1/4 of the acceleration of comparablefixed base buildings.
Experiments and observations of baseisolated buildings in earthquakes have beenshown to reduce building accelerations to aslittle as 1/4 of the acceleration of comparablefixed base buildings.
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BA SE ISOLAT ION FOR B RIDGE:-
Base isolation technique is used forearthquake resistant design and retrofitting
of bridges.
To reduce damage of bridge isolationbearings should be provided like Pad bridgebearing, Pot bridge bearing, High DampingNatural Rubber Systems, and Sphericalbearing.
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CONCLUSION :-
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REF ERENCES:-F arzad Naein & James M. Kelly Design of Seismic isolated structuresPublis hed:-John Willey & Sons, INC.
C.V.R. Murty & A.W. C harleson Eart hq uake design concept prepared underNPEEE & MHRD Govt. of India Publis hed:- NICEE II T Kanpur.
C.V.R. Murty Eart hq uake tips Publis hed:- NICEE II T Kanpur.
W.D. Clark & J.E. Mason volume 38 no.1pp.33-40 Marc h-2005 Earthq uakeengineering practices.
I.S.1893 :1984
In structure criteria for eart hq uake resistant design for structure.
www.bmtpc.org
www.nicee.org
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THANKYOU