seismic retrofitting - copy

8/7/2019 Seismic Retrofitting - Copy

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INTRODUCTION OF SEISMIC

RETROFITTING



Public Safety Retrofitting StructureSurvivability

Primary structureundamaged

StructureUnaffected



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



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.



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 .



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



A)L ow Damping Natural and Synthetic

Rubber Bearing:-



Solid lead cylinder ispress-fitted into centralhole of elastomericbearing.

L ow damping rubbercombined with centralleadcore.

B)L

ead-Rubber Bearings



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):-



D)Friction Pendulum System:-The friction PendulumSystem is frictionalisolation system t hatcombines a slidingaction and a restoringforce by geometry.



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.



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.



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.



CONCLUSION :-



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



THANKYOU

seismic retrofitting - copy

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