T. Anisha ( M.E) Project

7/24/2019 T. Anisha ( M.E) Project

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PUSHOVER ANALYSIS OF TALL BUILDINGS WITH

SOFT STOREY

PHASE-1 REPORT

Submitted by

T.ANISHA

in partial fulfillment for the award of the degree of

MASTER OF ENGINEERING IN

STRUCTURAL ENGINEERING

BETHLAHEM INSTITUTE OF ENGINEERING

DEPARTMENT OF CIVIL ENGINEERING

ANNA UNIVERSITY, CHENNAI

DECEMBER 2015

ANNA UNIVERSITY, CHENNAI

BONAFIDE CERTIFICATE

Certified that this Report titled PUSHOVER ANALYSIS OF TALL

BUILDINGS WITH SOFT STOREY is the bonafide work of T.ANISHA


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(960314413005) who carried out the work under m super!ision" Certified further that

to the best of m knowled#e the work reported herein does not form part of an other

thesis or dissertation on the basis of which a de#ree or award was conferred on an

earlier occasion on this or an other candidate"

M.L.LEEBAN, M.T!"#., M$%%.R.&ENIHA ANCY,M.E.,

$%&' '%*&R+,%-+ &../.+&-+ *R%..R

'epartment of Ci!il %n#ineerin# 'epartment of Ci!il %n#ineerin#

ethlahem /nstitute of %n#ineerin# ethlahem /nstitute of %n#ineerin#

arun#al" arun#al"

.ubmitted to main pro2ect and !i!a eamination held on

/-+%R-& %&,/-%R %+%R-& %&,/-%R

ABSTRACT

pen first store is a tpical feature in the modern multistor constructions in

urban /ndia" .uch features are hi#hl undesirable in buildin#s built in seismicall

acti!e areas7 this has been !erified in numerous eperiences of stron# shakin# durin#

the past earth8uakes" +hou#h multistoried buildin#s with open (soft) #round floor are

inherentl !ulnerable to collapse due to earth8uake load their construction is still

widespread in the de!elopin# nations like /ndia" .ocial and functional need to pro!ide

car parkin# space at #round le!el and for offices open stories at different le!el of

structure" +herefore in addition to #round soft store soft store is re8uired on

different le!els in buildin#"


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/n present stud analsis is carried out to find the best place for soft stories in

hi#h rise buildin#s" /n an attempt to in!esti#ate the effect of soft store for

multistoried reinforced concrete buildin# models (5 10 and 15 store) with both

re#ular and irre#ular buildin# plans were anal:ed" ,asonr walls are pro!ided for

the stories other than soft stories" %arth8uake load was pro!ided at each diaphra#m;s

mass centre as a source of lateral load" +he soft store le!el was altered from #round

floor to top floor for each model and e8ui!alent static analsis was carried awa usin#

%+&.

#'$, 05&" >0& #35 5;D =2 #35 ,- #&F0&@

52+05&$A%" *0$5 $$


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our work successfull"

=e are our heartfelt and obli#ation to our re!ered correspondent M.&ERALD

SELVA RA&A.,for his support etended towards us"

=e are !er much thankful to D.SAMCHANDREN., M.S",(E)**.+ P#.D.

principal for helpin# us in all the aspect to complete this pro2ect"

=e epress our sincere re#ard and deep appreciation to our 'irector

*rof"STPHEN 'INGLSY., M.S",(E)**.+ P#.D., B.G.L., M.B.A. for his

irreplaceable help in pro!idin# all facilities to carr out the work in an effecti!e

manner"

=e are !er thankful to *rof" R.I. RA&IDAP NESHTAR B.T!"#., M.E.,(P#.D+

chief academic Coordinator for helpin# us in all the aspect to complete this pro2ect"

/t;s m #reat pleasure to epress m heartiest thanks to our $ead of the

'epartment P. L.LEEBAN, M.T!"# for his !aluable support in m pro2ect"

=e are !er much thankful to M$%%. &. MERCURY UDHAYAM, M.E. *ro2ect

Coordinator for helpin# us in all the aspect to complete this pro2ect"

/ #reatl indebted to thank m #uide M$%%.R.&ENIHA ANCY,M.E., for his

!aluable #uidance and su##estions which helped us to complete m pro2ect

successfull"

=e thank all the members of the 'epartment of Ci!il %n#ineerin# both

teachin# and non teachin# staff and all our friends"

T. ANISHA /

TABLE OF CONTENTS


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CHAPTER NO. TITLE PAGE NO.

ABSTRACT(ENGLISH+ $$$

ABSTRACT(TAMIL+ $

AC'NOWLEDGEMENT LIST OF TABLES $$$

LIST OF FIGURES $

LIST OF SYMBOLS ABBREVATIONS

1" /NTRODUCTION 1

1"1 >%-%R& 1

1"< '%/-/+/- ,&+%R/& D


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5"< ?+*?+ R > E5 ?/'/-> E15 ?/'/-> E10)


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LIST OF FIGURES

FIGURE TITLE PAGE NO.

4"1 *lan of the buildin# 1

4"< %le!ation (.. at >E5) 1F

4"3 %le!ation (.. at >E10) 1F

4"4 %le!ation (.. at >E15) 19

4"5 3' @iew (.. at >E5) 19

4"6 3' @iew (.. at >E10) raph (.. at >E10)


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5"6 Comparison of soft store 30

LIST OF SYMBOLS, ABBREVATIONS

C Concentricall raced rame

CR Column Retrofit

C., Capacit .pectrum ,ethod

%+&. %tended +hree 'imensional &nalsis of uildin# .stems

> >round e!el

$'C $i#h 'uctilit Class

.. .oft .tore


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CHAPTER 1

INTRODUCTION

1.1 GENERAL

/ndia at present is fast #rowin# econom which brin#s about demands in

increase of infrastructure facilities alon# with the #rowth of population" +he demand

of land in urban re#ions is increasin# da b da" /t is imperati!e that land a!ailable

for farmin# and a#riculture remains intact" +o cater the land demand in these re#ions

!ertical de!elopment is the onl option" +his tpe of de!elopment brin#s challen#es to

counteract additional lateral loads due to wind and earth8uake" +his demands chan#es

in the current structural sstem which needs to be implemented to resist these forces"

,uch research has been carried which describes the suitabilit of !arious lateral load

resistin# sstem a#ainst deformation and shear eerted due to the earth8uake and wind

forces"

.oft store irre#ularit is one of the main reasons of buildin# dama#es durin#

recent earth8uakes in the world as mentioned in almost all reconnaissance reports and

studies" &ccordin# to 'eshmukh and Rahman (


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de!elopin# nations like /ndia" +his is because of the social and functional need to

pro!ide car parkin# space at #round le!el and for offices at different le!el of structure"

+herefore in addition to #round soft store soft store is re8uired on different le!els

of buildin#"

1.2 DEFINITION

& soft stor (..) buildin# is a multistor buildin# with one or more floors

which are GsoftH due to structural desi#n" +hese floors can be especiall dan#erous in

earth8uakes because the cannot cope with the lateral forces caused b the swain#

of the buildin# durin# a 8uake" &s a result the soft stor ma fail causin# what is

known as a soft stor collapse"

.oft stor buildin#s are characteri:ed b ha!in# a stor which has a lot of open

space" *arkin# #ara#es for eample are often soft stories as are lar#e retail spaces or

floors with a lot of windows" =hile the unobstructed space of the soft stor mi#ht be

aestheticall or commerciall desirable it also means that there are fewer

opportunities to install shear walls speciali:ed walls which are desi#ned to distribute

lateral forces so that a buildin# can cope with the swain# characteristic of an

earth8uake"

1.3 PUSHOVER ANALYSIS

*usho!er analsis is a static nonlinear procedure in which the ma#nitude of the

structural loadin# is incrementall increased in accordance with a certain predefined

pattern" =ith the increase in the ma#nitude of the loadin# weak links and failure

modes of the structure are found" &ccordin# to +arta and *intea(


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*usho!er analsis is a performance based analsis" &ccordin# to &+C 40 there

are two ke elements of a performancebased desi#n procedure demand and

capacit" 'emand is the representation of earth8uake #round motion or shakin# that

the buildin# is sub2ected to" /n nonlinear static analsis procedures demand is

represented b an estimation of the displacements or deformations that the structure is

epected to under#o" Capacit is a representation of the structure;s abilit to resist the

seismic demand" +he performance is dependent on the manner that the capacit is able

to handle the demand" /n other words the structure must ha!e the capacit to resist

demands of the earth8uake such that the performance of the structure is compatible

with the ob2ecti!es of the desi#n"

*usho!er analsis is performed b 'isplacement coefficient methodICapacit

spectrum method" +he Capacit .pectrum ,ethod (C.,) a performancebased

seismic analsis techni8ue can be used for a !ariet of purposes such as rapid

e!aluation of a lar#e in!entor of buildin#s desi#n !erification for new construction

of indi!idual buildin#s e!aluation of an eistin# structure to identif dama#e states

and correlation of dama#e states of buildin#s to !arious amplitudes of #round motion"+he procedure correlation of dama#e states of buildin#s to !arious amplitudes of

#round motion" +he procedure compares the capacit of the structure (in the form of a

pusho!er cur!e) with the demands on the structure" +he ob2ecti!e of 'isplacement

coefficient method is to find tar#et displacement which is the maimum displacement

that the structure is likel to be eperienced durin# the desi#n earth8uake" /t pro!ides

a numerical process for estimatin# the displacement demand on the structure b usin#

a bilinear representation of capacit cur!e and a series of modification factors

or coefficients to calculate a tar#et displacement.

1.3.1 APPLICATION

*usho!er analsis ma be applied to !erif the structural performance of newl

desi#ned and the eistin# buildin#s for the followin# purposesJ

1" +o !erif the o!er stren#th ratio !alues"


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4" &s an alternati!e to the desi#n based on linear analsis"

1.4 ETABS

%+&. (%tended +hree 'imensional &nalsis of uildin# .stems)

is a specialpurpose computer pro#ram de!eloped b Computers

and .tructures /nc" specificall for structural analsis and desi#n of

buildin# structures" /t pro!ides the .tructural %n#ineer with all the tools

necessar to create modif anal:e desi#n and optimi:e buildin# models"

+hese features are full inte#rated in a sin#le =indowsbased #raphical

user interface that is unmatched in terms of easeofuse producti!it and

capabilit"

%+&. is a powerful pro#ram that can #reatl enhance an en#ineerKs

analsis and desi#n capabilities for structures" *art of that power lies in

an arra of options and features" +he other part lies in how simple it is to use" +he

basic approach for usin# the pro#ram is !er strai#htforward" +he user

establishes #rid lines places structural ob2ects relati!e to the #ridlines usin#

2oints frames and shells and assi#ns loads and structural properties to those

structural ob2ects (for eample a frame ob2ect can be assi#ned section

properties7 a 2oint ob2ect can be assi#ned sprin# properties7 a shell ob2ect

can be assi#ned slab or deck properties)" &nalsis desi#n and detailin#

are then performed based on the structural ob2ects and their assi#nments" Results

are #enerated in #raphical or tabular form that can be printed to a printer or to a file

for use in other pro#rams"


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1.5 OB&ECTIVE OF THE PRO&ECT

+he ob2ecti!e of the pro2ect is to find thebest place for pro!idin# soft store in

a >E15 store buildin# b pusho!er analsis usin# %+&. software" +he structural

beha!ior of tall buildin#s of both re#ular and irre#ular shapes is to be studied" +he

followin# are the different shapes to be studied to understand the effect of pro!idin#

soft stories at different le!els"

1" Re#ular uildin#

.8uare .haped uildin#


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CHAPTER 2

LITERATURE REVIEW

1" &R/ =/= B$- " =/.- (


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EVALUATION OF SEISMIC STRENGTHENING TECHNI7UES FOR

REINFORCED CONCRETE FRAMES WITH SOFT GROUND STORY

%->/-%%R/-> .+R?C+?R%. *>"56"

+his paper presents a desi#n procedure and analtical e!aluation of two

stren#thenin# techni8ues to impro!e the seismic performance of the eistin# non

ductile RC frames with softstor at the #round stor le!el" +he first techni8ue termed

as column retrofit (CR) uses onl partial steel 2acketin# (or ca#in#) to enhance the

lateral stren#th and plastic rotational capacities of the deficient columns at the #round

stor le!el" +he later techni8ue termed as full retrofit (R) considers the aluminumshear links as supplemental ener# dissipation de!ices in addition to the stren#thened

#round stor columns" .teel collector beams and che!ron braces are used to transfer

the lateral load from the RC frame to these dissipatin# de!ices" *erformancebased

plastic desi#n approach is used to proportion !arious elements of the stren#thenin#

techni8ues" -onlinear static and dnamic analses are carried out to e!aluate the

performance of the eistin# and the stren#thened frames" +he main parameters

in!esti#ated are (a) interstor drift (b) residual drift (c) ield mechanism (d) ener#

dissipation and (e) lateral stren#th" +he R frame effecti!el controlled the drift

response b a!oidin# the softstor collapse because of the si#nificant ener#

dissipation in the shear links" ,oreo!er the R frame achie!ed the desired ield

mechanism without eceedin# the desi#n tar#et drift le!el"

3" >/R'&- " & >?&'&>-? . M(


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4" >/R/.$ '%.$,?$ .$&/$ &'? &/B&B &'? R&$,&- *R" @A&=&$&R%","R "161F5"

/n this paper the seismic !ulnerabilit of buildin# is shown with an %ample of

>E


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force is increasin#" &s the soft store is shifted to hi#her le!el ieldin# is less than

lower le!el soft store and lower intensit hin#es are formin# after maimum number

of pusho!er steps" &s the soft store is shifted to hi#her le!el it can be seen from

pusho!er and capacit spectrum cur!es that +eff" #oes on reducin# from 1"5< .ec" for

3rd floor soft store to 1"/?">


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and collapse due to soft stor are most often obser!ed in buildin#s the can

also be de!eloped in other tpes of structures" +he lower le!el containin#

the concrete columns beha!ed as a soft stor in that the columns were unable

to pro!ide ade8uate shear resistance durin# the earth8uake" & combination

of the two structural components leads to a hi#hl efficient sstem in

which the shear wall resists the ma2orit of the lateral loads in the lower

portion of the buildin# and the frame supports the ma2orit of the

lateral loads in the upper portion of the buildin#" /t was found that location number

and curtailment of shear wall acts as an important factor for the soft stor

structures to displace durin# earth8uake" /t is shown that the use of shearwall has more stable beha!ior and appears to be a no!el approach to reduce

effect of soft stor in seismic response" &lso !ulnerabilit le!el of eistin#

hi#h rise buildin# can be increased b addin# different arran#ement of shear

wall on buildin# and it will help for retrofittin# of structure to resist the

ma2or portion of lateral load induced b an earth8uake"

F" -/@%'/+& -" R&?+ (/-%%R/-> @?,% 13"

& lar#e number of multistore reinforced concrete (RIC) framed buildin#

structures in urban /ndia are constructed with masonr in fills for architectural

aesthetic or economic reasons" +he effect of the laout of masonr infill panels o!er

the ele!ation of masonr in filled RIC frames on the seismic performance and

potential seismic dama#e of the frame under stron# #round motions usin# nonlinear

static pusho!er analsis based on realistic and efficient computational models is

in!esti#ated in this stud" +he ase shear and 'isplacement results obtained from

output nonlinear analsis is compared for bare frame and infill wall frame" /t is seen

that at roof le!el displacement in bare frame is more than the infill wall frame and

displacement at #round floor in weak stor is more" ,ostl hin#es are formed in beam

than in column"

9" *?B" . /C " ' (


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STRUCTURE WITH MASONRY INFILL WALLS %->/-%%R/-> .+R?C+?R%.

*>J311


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seismic performance of the structure under stron# earth8uakes" +he results of this

stud compare well with the dama#e obser!ations after the

&-' +%C$->A @?,% 4"

/n this paper attempt has been made to stud performance of >E" +he nonlinear static

pusho!er analsis is carried out" +his stud hi#hli#hts the poor seismic performance

of the buildin# with soft store at different le!el alon# with soft store at #round le!el"

/t is obser!ed that plastic hin#es are de!eloped in columns of #round le!el soft store

which is not acceptable criteria for safe desi#n" &fter retrofittin# of all the models

with shear walls hin#es are not de!eloped in an of the columns" *ro!ision of shear

walls results in reduction in lateral displacement" 'isplacement reduces when the soft

store is pro!ided at hi#her le!el" &fter retrofittin# the base shear carrin# capacit is

increased b F"45N to 13"


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performance of specimens with and without the brick infill throu#h 8uasistatic cclic

loadin# tests the effects of infill on the o!erall frame performance were 8uantitati!el

e!aluated" ,oreo!er the seismic performance of the earth8uakedama#ed buildin#

was e!aluated numericall considerin# the findin#s of the tests" /n particular the

contributions of nonstructural brick infills to the seismic performance were discussed

throu#h the probabilities of collapse computed under se!eral artificial earth8uake

#round motions"/t was found that nonstructural brick infills si#nificantl decreased the

probabilit of collapse namel increased the seismic performance"

13" +&R+& ">" */-+%&"" & (


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CHAPTER 3

METHODOLOGY

F$* 3.1 F9:"#;< M!

LITERATURE SURVEY

DATA PREPARATION

PUSHOVER ANALYSIS IN

ETABS

RESULT DISCUSSION

CONCLUSION


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+he data re8uired for the analsis of >E15 store buildin# is collected from

different /ndian .tandard codes" +he codes used are as followsJ

1" /. 456 J


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loadin# and analsis parameters for the structures"

)

respecti!el"


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F$* 4.2E9!;


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F$* 4.4 E9!;


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F$* 4. 3D V$!: (SS ;< GL ? 10


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+he seismic properties for the structure is taken from the /ndian .tandard code

/. 1F93 (*&R+ 1)J


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is specified alon# with loads" & selfwei#ht multiplier of 1 means to include the full

selfwei#ht of the structure in the load pattern" & selfwei#ht multiplier of 0"5 means

to include half of the selfwei#ht of the structure in the load pattern" -ormall a self

wei#ht multiplier of 1 is specified in one load pattern onl usuall the dead load

pattern with all other load patterns ha!in# a multiplier of :ero"

+he floor finish load and li!e load are assi#ned to the floor slabs of each store"

&ccordin# to /. 456J


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F$* 4. A%%$*)$)* 9$! 9;=

4.4 ANALYSIS OF THE STRUCTURE

&fter assi#nin# all the loads to the structure the model is checked for an error"

/f an error eists in the model then the model can be modified incorporatin# all the

corrections" +hen the model can be finall anal:ed b runnin# the analsis "&fter

runnin# the analsis the output parameters such as base shear store drift and lateral

displacements are obtained" +he results are #enerated in #raphical or tabular form"

CHAPTER 5

RESULT DISCUSSION

5.1 INTRODUCTION


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&fter runnin# the analsis the results are #enerated in #raphical or tabular form"

+he parameters such as base shear store drift and lateral displacements are obtained"

+he analsis results obtained for the models with soft store at >E5 th >E10thand

>E15thstore are #i!en below"

5.2 OUTPUT FOR SS AT GL?5 BUILDING

F$* 5.2 D$%9;"!!)< *;#

T;@9! 5.2 D$%9;"!!)< ;)= S D$E5 buildin# when compared to >E10 and >E15

buildin#s"

+he stor drift !alue obtained for the three buildin#s (.. at >E5 >E10

>E15) are combined to #et the #raph shown in fi# 5"6


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Story 1 story 5 Story 10 Story 15

0

0.5

1

1.5

2

2.5

3

3.5

GL+5

GL+10

GL+15

.tore

F$* 5. C;$%) S =$< ;9!

rom the #raph it is clear that the stor drift is initiall more for the lower

le!el floors reaches the maimum at intermediate floors and suddenl drops down for

hi#her le!el floors" /t is also clear that the stor drift is more for >E5 buildin# when

compared to >E10 and >E15 buildin#s"

5.6 DISCUSSION

rom the result it is known that the lateral displacement of the structure

increases with increase in hei#ht of the structure "&lso the displacement is more for

soft stor located at lower le!els and it is less for soft stor located at hi#her le!els" /t

is also known that the stor drift is low at lower and hi#her le!els of the structure and

it is hi#h at intermediate le!els" &lso the stor drift is more for soft stor located at

lower le!els and it is less for soft stor located at hi#her le!els" +herefore from theresults obtained it is concluded that ad!isable to pro!ide soft store at hi#her le!els in

addition to one pro!ided at #round for re#ular s8uare shaped buildin#"

REFERENCES

1" &ri =ibowo Bohn " =ilson (


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iordano " & >uada#nuolo " , ( *rof" @awahare","R " *intea"" & (


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rames with .tiffness/rre#ularities ?sin# .tandard and &d!anced *usho!er ,ethodsH

*rocedia %n#ineerin# *#" 445 M 450"

14" /. 456 J

T. Anisha ( M.E) Project

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