Assessment of Capacity of Existing Building Through Nonlinear

Static Pusover Analysis A Comparison between Micro and Macro

Modeling

by

Narender Bodige, Raghavender Baroda, Pradeep Kumar Ramancharla

in

Advances inEarth Sciences, Structural, Geotechnical and Earthquake Engineering(AESG2E-2012)

Report No: IIIT/TR/2012/-1

Centre for Earthquake EngineeringInternational Institute of Information Technology

Hyderabad - 500 032, INDIAOctober 2012

Assessment of Capacity of Existing Building

Through Nonlinear Static Pusover Analysis

A Comparison between Micro and Macro Modeling

B Narender, IIIT Hyderabad

B Raghavender, JNTU Anantapur

and

R Pradeep Kumar

Earthquake Engineering Research Centre

International Institute of Inform

ation Technology

Gachibowli, Hyderabad 500 032, India

Slide 2

EERC @ IIIT, Hyderabad

�Introduction

�Case studies

�Applied Element Method

�Nonlinear Pushover Analysis

�Collapse simulation

�Observations

�Conclusions

OVERVIEW

Slide 3

Reason for collapse of structures

-Earthquake loads

-Wind loads

-Explosions

-Other natural and Manmade disasters

-To understand the process of collapse, we need efficient

numerical model

Slide 4

Collapse during earthquakes

Slide 5

More than 60 % area

is earthquake prone.

Zone V

12 %

Zone IV 18 %

Zone III 26 %

Zone II

44 %

IS 1893:2002

Slide 6

Lat( Deg N )

Long( Deg E )

1819 JUN 16

23.60

68.60

KUTCH,GUJARAT

8.0

1869 JAN 10

25.00

93.00

NEAR CACHAR, ASSAM

7.5

1885 MAY 30

34.10

74.60

SOPOR, J&K

7.0

1897 JUN 12

26.00

91.00

SHILLONGPLATEAU

8.7

1905 APR 04

32.30

76.30

KANGRA, H.P

8.0

1918 JUL 08

24.50

91.00

SRIMANGAL, ASSAM

7.6

1930 JUL 02

25.80

90.20

DHUBRI, ASSAM

7.1

1934JAN 15

26.60

86.80

BIHAR-NEPALBORDER

8.3

1941 JUN 26

12.40

92.50

ANDAMAN ISLANDS

8.1

1943 OCT 23

26.80

94.00

ASSAM

7.2

1950 AUG 15

28.50

96.70

ARUNACHAL PRADESH-CHINA BORDER

8.5

1956 JUL 21

23.30

70.00

ANJAR, GUJARAT

7.0

1967 DEC 10

17.37

73.75

KOYNA, MAHARASHTRA

6.5

1975 JAN 19

32.38

78.49

KINNAUR, HP

6.2

1988 AUG 06

25.13

95.15

MANIPUR-M

YANMAR BORDER

6.6

1988 AUG 21

26.72

86.63

BIHAR-NEPAL BORDER

6.4

1991 OCT 20

30.75

78.86

UTTARKASHI, UP HILLS

6.6

1993 SEP 30

18.07

76.62

LATUR-O

SMANABAD, MAHARASHTRA

6.3

1997 MAY 22

23.08

80.06

JABALPUR,M

P

6.0

1999 M

AR 29

30.41

79.42

CHAMOLI DIST, UP

6.8

2001 JAN 26

23.40

70.32

BHUJ, GUJARAT

6.9

DATE

EPICENTRE

LOCATION

MAGNITUDE

List of Significant Earthquakes in India

and its Neighborhood

Slide 7

PERFORMANCE OF BUILDINGS

Common site destruction in meizoseismalarea

Slide 8

Damage in Anjar

situated on hill

Slide 9

Essentials of

Earthquake Resistant Design

�Configuration

�Strength

�Stiffness

�Ductility

Slide 10

Extensive damage occurred in

non-engineered structures

Many casualties occurred in

stone masonry buildings

Slide 11

Large blocks piled

up using weak bond

Out of plane failure of

brick masonry walls

Slide 12

Soft bottom storey

Slide 13

Pan cake collapse

Surprise for common man:

Adjoining buildings with

radically different

performances

Slide 14

Poor reinforcement

detailing

Slide 15

Weak joint

Slide 16

Numerical technique

Slide 17

Continuum M

odeling

Discrete M

odeling

Numerical Techniques

FEM

RBSM

BEM

Disk Element Method

DDA

EDEM

AEM

Slide 18

APPLIED ELEMENT METHOD

(AEM)

Element Form

ulation

�Material is composed of discrete elements.

�Elements are connected to each other by means of

springs.

Norm

al and S

hear Springs

and shea

r sp

rings

by a

pair o

f norm

al

Are

a repre

sente

d

bd

a

d/2 a

d

b

a

Rein

forc

emen

t bar

Structu

re b

oundary

Slide 19

Spring distribution and area of

influence of each pair of

springs

Element shape, contact point

and degrees of freedom

a

td

EKn

**

=

a

td

GKs

**

=

Slide 20

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

()

α+

α

αα

+θ

+

αα

+θ

αα

+θ

−

αα

+θ

αα

+θ

+

αα

+θ

α+

θ+

α+

θ

α+

θα

+θ

+

α+

θα

+θ

−

αα

+θ

−

αα

+θ

α+

θα

+θ

+

α+

θα

+θ

−

α+

θ+

α+

θ

s2

2

n2

2

sn

ns

sn

n2

s2

sn

ns

sn

s2

n2

KSin

L

KC

os

L

LSin

KSin

LC

os

KC

os

LC

os

KSin

LSin

KC

os

LSin

KSin

LC

os

KC

os

KC

os

KSin

Cos

Sin

K

Cos

Sin

K

LC

os

KSin

LSin

KC

os

Cos

Sin

K

Cos

Sin

K

KC

os

KSin

Slide 21

�Each spring represents area of d*t of cross section and

length "a" i.e. the distance between centrelines.

�Three degrees of freedom, rigid body m

otion.

�Global stiffness m

atrix by adding all the m

atrices.

[]{}

{}F

K=

∆�

Load control & Displacement control.

�Reinforcement is also m

odeled.

Slide 22

�Each spring represents distance (D/2n).

�Horizontal and vertical degrees of freedom have no

effect.

Number of springs

Effect of number of connecting springs on rotational stiffness

Slide 23

Analy

sis dom

ain

of A

EM

com

para

ble

to F

EM

Slide 24

Tension, compression and shear models for concrete

Slide 25

Stress strain relation for steel

Slide 26

cB

a

xa

axσ

σσ

)(

2

−+

=

22

12

1)

2(

)2

(τ

σσ

σσ

σ+

−+

+=

p

)2

()

2ta

n(

21

σσ

τβ

+=

Failure Criteria

Slide 27

Rel

ation b

etw

een load a

nd w

all r

ota

tion for

2-s

tori

ed R

C w

all

0

10

20

30

40

50

60

70

00.0

02

0.0

04

0.0

06

0.0

08

0.0

1

Rota

tion, θ

(rad

)

Load, P (tf)

500 incr

emen

ts

(10 springs)

50 incr

emen

ts

(10 springs)

250 incr

emen

ts

(2 springs)

Exper

imen

t250 incr

emen

ts

(10 springs)

(5 springs)

00.0

02

0.0

04

0.0

06

0.0

08

0.0

1

0

10

20

30

40

50

60

70

50 incr

em

ents

(10 spri

ngs) 500 incr

em

ents

(10 spri

ngs)

Load (x 9.81 kN)

Rota

tion (ra

dia

ns)

Slide 28

Deform

ed shape and crack locations of 2-storied RC wall structure

(in case of 500 increments with 10 springs between each two adjacent faces,

Illustration scale factor=30)

Def

orm

ed shape

and c

rack

ed p

atter

ns

460 k

N540 k

N620 k

N

660 k

N700 k

NE

xper

imen

t

Slide 29

(a)Concrete (b) Steel

Material models for steel and concrete

Slide 30

Dim

ensions and reinforcement of a double cantilever subjected tocyclic loading

Slide 31

-80

-60

-40

-200

20

40

60

80

0500

1000

1500

2000

2500

3000

3500

4000

No. of in

crem

ents

Load (tf)

(1)

(2)

(3)

(4)

(5)

(6)

(7)

Load cycles applied to a double cantilever

-60

-40

-200

20

40

60

80

-0.0

15

-0.0

1-0

.005

00.0

05

0.0

10.0

15

0.0

20.0

25

0.0

3

Dis

pla

cem

ent (m

)

Load (tf)

New

model

Exper

imen

t

Load-displacement relation of a double cantilever

Slide 32

Deform

ed shape and crack

patterns of a double cantilever

Slide 33

Finite Element Method (FEM)inSAP-2000

Description of finite element modal at joint

Modeling of a structure

Slide 34

Material model

Kent and park concrete model

IS 456 stress strain curve for steel

Slide 35

Stress blocks at different extreme compression fiber strain

Moment-Curvature

Assumed M-θ

hinge property

Slide 36

Plan of building (All

dimension are in meters)

Elevation of frame along

X-direction

Structural details of Four storey RC building

Column

Beam

C1

360 X 300

C2

C3

C4

360 X 300

360 X 300

360 X 300

B1

300 X 240

B2

300 X 240

B3

300 X 240

B4

300 X 240

Slab thickness: 120

Table.1Schedule of member sizes

Material property of members

Use M20, M25 and M30 grade of

concrete

Fe 250 and Fe 415 for steel

Table.2

material property

Slide 37

S.N

o

Load

Com

bin

atio

nD

LLL

EQ

11.5

DL+1.5

LL

1.5

1.5

-

21.2

(DL+LL

*+EQ

X)

1.2

0.2

5/0

.5*

+1.2

31.2

(DL+LL

*-EQ

X)

1.2

0.2

5/0

.5*

-1.2

41.2

(DL+LL

* +

EQ

Y)

1.2

0.2

5/0

.5*

+1.2

51.2

(DL+LL

* -

EQ

Y)

1.2

0.2

5/0

.5*

-1.2

61.5

(DL+

EQ

X)

1.5

-+1.5

71.5

(DL-EQ

X)

1.5

--1

.5

81.5

(DL+

EQ

Y)

1.5

-1.5

91.5

(DL-EQ

Y)

1.5

--1

.5

10

0.9

DL+1.5

EQ

X0.9

-+1.5

11

0.9

DL-1

.5EQ

X0.9

--1

.5

12

0.9

DL+1.5

EQ

Y0.9

-+1.5

13

0.9

DL-1

.5EQ

Y0.9

--1

.5

Table.3Load combinations for earthquake loading

Loads

Gravity Loads

1. live load : 2 Kn/m

2

2. Floor finishing load: 1 Kn/m

2

3. Brick load : 12.04 Kn/m

Seismic load

1.Zone-II

2.Hard soil

3.Base shear: 26.73 KN

4.Story forces

a.11.25KN at top

b.9.96 KN at Third floor

c. 4.43 KN at second floor

d. 1.11 KN at first floor

Slide 38

EERC @ IIIT, Hyderabad

Load combination of frame along x-direction

Slide 39

3-12mm

8mm@30

0mm c/c

2-8 mm

3-16mm

8mm@30

0mm c/c

2-8 mm

8mm@300

mm c/c

8-20 mm

3-12mm

6mm@10

0 c/c

2-10 mm

4-14mm

6mm@10

0 c/c

2-10 mm

8mm@75

c/c

8-20 mm

IS: 456 design details

IS: 13920 ductile design details

Design details

Slide 40

Steel-Case-1-Column

Steel-Case-2-Column

Non Ductile Ductile

S-M

15, B&C-M

20 S-M

15, B&C-M

20

S-M

15, B-M

20 , C-25 S-M

15, B-M

20, C-25

Non Ductile Ductile

S-M

15, B&C-M

20 S-M

15, B&C-M

20

S-M

15, B-M

20 , C-25 S-M

15, B-M

20, C-25

Structure :

S-M

15, B&C-M

20

S-M

15, B-M

20 & C-M

25

Only Concrete for Beam & Column

Moment-

Curvature

Slide 41

EERC @ IIIT, Hyderabad

Moment Curvature

Moment curvature for M-20 Non-ductile Case-1 Beam

Slide 42

EERC @ IIIT, Hyderabad

Moment curvature for M-20 ductile Case-1 Beam

Slide 43

Moment Curvature

Moment curvature for M-20 Non-ductile Case-1 columns

Slide 44

EERC @ IIIT, Hyderabad

Moment curvature for M-20 Non-ductile Case-2 columns

Slide 45

EERC @ IIIT, Hyderabad

Moment curvature for M-25 Non-ductile Case-1 columns

Slide 46

case-1: Reinforcement details changed in Column-Non

ductile detailing

Pushover curve for 2D RC frame building Non-ductile, S-M

15, B&C-M

20

Comparing Pushover curve from AEM and FEM

Slide 47

case-1: Reinforcement details changed in Column-Non

ductile detailing

Pushover curve for 2D RC frame building Non-ductile, S-M

15, B20 and C-M

25

Slide 48

Case-1: Reinforcement details changed in Column-ductile

detailing

Pushover curve for 2D RC frame building ductile detailing, S-M

15, B & C20

Slide 49

Case-1: Reinforcement details changed in Column-ductile

detailing

Pushover curve for 2D RC frame building Non-ductile, S-M

15, B20 and C-M

25

Slide 50

Case-2: Reinforcement details changed in Column-Non

ductile detailing

Pushover curve for 2D RC frame building Non-ductile, S-M

15, B & C20

Slide 51

Case-2: Reinforcement details changed in Column-ductile

detailing

Pushover curve for 2D RC frame building ductile detailing, S-M

15, B & C20

Slide 52

Pushover curve for four storey concrete structure

Slide 53

Pushover curve for four storey RC Frame for Non-ductile detailing

Slide 54

Pushover curve for four storey RC Frame for Ductile detailing

Slide 55

Pushover curves for Effect of grade of concrete for Non ductiledetailing

Slide 56

Pushover curves for Effect of grade of concrete for ductile detailing

Slide 57

Pushover curves for Change in diameter of bars in column members

non ductile detailing

Slide 58

Pushover Curves change in diameter of bars in column members for

ductile detailing

Slide 59

EERC @ IIIT, Hyderabad

Thank you