seismic performance evaluation of un-bonded fibre

North East Regional Conference on Earthquake and Landslide Mitigation Building Disaster Mitigation-Building Disaster Resilience in North East India

Seismic Performance Evaluation of Un-bonded Fibre Reinforced Elastomeric Isolator (U-FREI)( )

Anjan DuttaAnjan Dutta

DEPARTMENT OF CIVIL ENGINEERINGIIT GUWAHATI

1

Other Members of the Research Group

1. Prof. S.K. Deb, IITG

2. Dr. Ngo Van Thuyet, Univ. of Hanoi (Former, R/S)

3. Dr. Animesh Das, BHEL, New Delhi (Former R/S)

4. Mr. A. Hazarika, Atkins, B’luru (Former PG Student)

5. Mr. K. Reddy, Former Undergraduate student

Supporting Staffs

1. Dr. Arun C. Borsaikia, SeniorTechnical Officer

2. Mr. Biswajit Debnath, Junior Tech. Supdt.

Industry Partner

2

Outline of the presentation

Basic Concept of Base Isolation

Design issues

FE Simulation of Isolator

Comparison of Experimental and FE Results

Shake Table Testing of unreinforced masonry test model

Prototype Implementationyp p

3

L f C l Limitations of Conventional Design

C ti l fi d b t t t b• Conventional fixed base structures can not berealistically designed to remain elastic in largeseismic events (more so in regions of high seismicity)seismic events (more so in regions of high seismicity)

• Common practice is to design them so that theyexperience damage in a controlled manner andexperience damage in a controlled manner andcan undergo large inelastic displacements

4

Structural control devices: classification

• Base isolation systems• Base isolation systems

• Energy dissipation systemsgy p y

• Tuned Systems

Passive System

• Active control systems• Active control systems

• Semi-active systems Active Systemy

• Hybrid control systems

Active System

5

Seismic Base Isolation

The objective of seismic i l ti t i t d l isolation systems is to decouple the building structure from the damaging components of the damaging components of the earthquake input motion, i.e., to prevent the superstructure of p pthe building from absorbing the earthquake energy.

The entire superstructure must be supported on discrete isolators whose dynamic characteristics are chosen to

uncouple the ground motion6

Suitability of Base Isolation Systems

Earthquake protection of structures using base isolation technique is generally suitable if following conditions are fulfilled:

• The subsoil does not produce a predominance of long periodground motion

• The structure is fairly squat with sufficiently high column load

• The site permits large horizontal displacements at the base

• Lateral loads due to wind are less than approximately 10% of pp ythe weight of the structure

8

Concept of Base IsolationConcept of Base Isolation

Fixed Base

Significantly Increase the Period of the Structure and Period of the Structure and the Damping so that the Response is Significantly Reduced

B I l t dPeriod

Base Isolated

9

Designs of Seismic IsolatorDesigns of Seismic Isolator

Idealized force-displacement hysteretic behavior Idealized force displacement hysteretic behavior of isolation system

Conventional Laminated Rubber Seismic Isolation Bearings

Construction DetailsConstruction Details

12

Estimation of Displacement [ASCE / SEI: 7-10]

13

Constructed base isolated buildings

Non-Isolated IsolatedSponsor of the projectBRNS, DAE, GOI15

x 10-3

Base-Isolated Building: Time histories in X-direction recorded on 10/9/2006

0

2x 10

c(g)

Roof Acceleration; Max = 0.0011g

0 5 10 15 20 25-2

0

acc

0 .5

1 x 1 0-3

First Floor Acceleration; Max = 0.00088862g

time(sec)

-0 .5

0

acc(

g)

2 x 1 0- 3

0 5 1 0 1 5 2 0 2 5-1

tim e (s e c )

- 1

0

1

acc(

g)

0 5 1 0 1 5 2 0 2 5- 3

- 2

t im e (s e c )

Ground Acceleration; PGA = 0.0023g16

Details of peak acceleration response reduction relative to PGA in base-isolated building

(X-direction is longer direction of the building)

E D PGA( ) P R d i

( g g)

Event Date PGA(g) Percentage Reduction

X-direction Y-direction X-direction Y-direction

10 09 2006 0 0023 0 0030 52 7610-09-2006 0.0023 0.0030 52 76

06-11-2006 0.0021 0.0030 20 53

10-11-2006 0.0037 0.0048 49 7310 11 2006 0.0037 0.0048 49 73

Nath, R.J., Deb, S.K. and Dutta, A. (2013), “ Base isolated RC building – performance evaluation and numerical model updating using recorded earthquake response”, Int. Journal of Earthquakes and Structures (Techno Press, Korea), Vol.4 (5), PP. 471-487.

17

q ( , ), ( ),

Fiber Reinforced Elastomeric Isolator Fiber Reinforced Elastomeric Isolator (FREI)FREI)

Use of fiber material reduces the weight

Advantages:

Use of fiber material reduces the weight

Sand blasting, acid cleaning coating not required

Manufacturing of long rectangular strip Manufacturing of long rectangular strip

19

Geometry of model FREI

Description SquareDescription Square

Width (2a) of isolator = 100 mm

Thickness of fiber layer (tf) = 0 55 mmThickness of fiber layer (tf) = 0.55 mm

Number of layer = 18

Thickness of single rubber layer = 5.0 mmThickness of single rubber layer(te)

5.0 mm

Number of rubber layer = 19

Total Height (h) = 104.90 mm20

FE ANALYSIS OF FREI

Using ANSYS v.14.0

El t t Element type: Elastomer: SOLID185; Fibre: SOLID46;

C l CONTA173 TARGE170 Contact element: CONTA173; TARGE170;

Material model: Elastomer: hyper-elastic and

visco-elastic behaviour.Hyper-elastic behaviour: Ogden 3-terms model

μ1 = 1.89x106 (N/m2); μ2 = 3600 (N/m2);

Meshing

μ3 = -30000 (N/m2);

α1 = 1.3; α2 = 5; α3 = -2;Visco-elastic behaviour: PronyVisco-elastic Shear Response

21

Visco elastic behaviour: PronyVisco elastic Shear Response

a1 = 0.3333; t1 = 0.04; a2 = 0.3333; t2 = 100.

Imposed horizontal displacement historyImposed horizontal displacement history

50

70(m

m)

10

30

lace

men

t (

-30

-10

onta

l Dis

pl

-70

-50

Hor

izo

0 3 6 9 12 15 18Time (s)

22

Stress Contour

Square isolator with 00 loading direction

Unbonded square isolator Bonded square isolator

Contour of normal stress S33 (N/m2) in rubber layer of isolator at

Unbonded square isolator Bonded square isolator

33horizontal displacement 60mm and 00 loading direction (Positive value indicate tension)23

H t ti b h i f b d d Hysteretic behaviour of square bonded isolator with 450 loading direction

5

2.5

3.75

5

kN)

-1.25

0

1.25

-80 -60 -40 -20 0 20 40 60 80

ear F

orce

(k

-5

-3.75

-2.5She

Horizontal Displacement (mm)

24

Hysteretic behaviour of square unbondedisolator with 450 loading direction

4

1

2

3

(kN

)

-1

0

1

-80 -60 -40 -20 0 20 40 60 80

hear

For

ce

-4

-3

-2Sh

Horizontal Displacement (mm)

25

Square unbonded 45° Square bonded 45°q qDisplaceme

nt (mm)Damping

(β) (%)Damping

(β) (%)( ) (β) ( ) (β) ( )

10 104.8 12.1 104.0 12.2

20 89.1 12.4 94.3 12.230 74.7 13.0 87.2 12.340 63.7 13.3 79.6 12.450 55.4 13.8 75.4 12.660 48.2 14.3 70.6 13.0

26

Experimental Set-up for Lateral Force-Displacement Behaviour

27

Displaced shape of isolator

28

Comparison of Numerical & Experimental Result

2.73.6

Test ResultAnalysis Result 2.7

3.6Test ResultAnalysis Result

0 90

0.91.8

-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60Forc

e (k

N) Analysis Result

0 90

0.91.8

-75 -60 -45 -30 -15 0 15 30 45 60 75Forc

e (k

N) Analysis Result

3 6-2.7-1.8-0.9-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60

Shea

r F

3 6-2.7-1.8-0.9-75 -60 -45 -30 -15 0 15 30 45 60 75

Shea

r FShear force vs. horizontal displacement Shear force vs. horizontal displacement

-3.6Horizontal Displacement (mm)

-3.6Horizontal Displacement (mm)

pat 50mm displacement

pat 60mm displacement

Das A Dutta A and Deb S K (2015) "Performance of fiber reinforced elastomeric base

29

Das, A., Dutta, A. and Deb, S.K. (2015), "Performance of fiber-reinforced elastomeric base isolators under cyclic excitation", Journal of Structural Control and Health Monitoring,(Wiley Inter-Science), Vol. 22(2), pp.197-220.

Sh k T bl T ti f M d l B ildi S t d FREI Shake Table Testing of Model Building Supported on FREI

Das, A., Deb, S.K. and Dutta, A. (2016), "Shake table testing of unreinforced brick masonry unreinforced brick masonry building test model isolated by U-FREI", Earthquake Engineering and Structural Dynamics (Wiley Inter Science) Vol 45 pp 263

30

Inter-Science), Vol. 45, pp. 263-272.

Acceleration time histories of four different earthquakes

0.6 0.6

-0.2

0

0.2

0.4

0 2 4 6 8 10 12

ratio

n (g)

0

0.2

0.4

0 5 10 15 20 25 30 35 40 45eler

atio

n (g

)

-0.8

-0.6

-0.4

Acc

ele

Time (sec)-0.6

-0.4

-0.2

Acc

e

Time (sec)

(a) Koyna (1967) (b) Parkfield (1966)

0.4 0.4

0

0.2

0 5 10 15 20 25 30 35eler

atio

n (g

)

0 4

-0.2

0

0.2

0 5 10 15 20 25

eler

atio

n (g

)

-0.4

-0.2Acc

e

Time (sec)-0.8

-0.6

-0.4A

cce

Time (sec)

(c) El Centro (1940) (d) Mexico (1980)

Time (sec) ( )

31

Displaced shape of isolator during shake table test for Park-Field input earthquake for Park Field input earthquake

(a) Park-field (for 100% acceleration amplitude of earthquakes along X-axis).

(b) Park-field (for 70% acceleration amplitude of earthquakes along 450 to X-axis.)

Acceleration response at shake table level and base level subjected to four earthquakes

0.8Shake TableBase of bldg

0.8Shake TableBase of bldg

0

0.4

0 1 2 3 4 5

cele

ratio

n (g

)Base of bldg

0

0.4

0 5 10 15 20

cele

ratio

n (g

)

Base of bldg

-0.8

-0.4Acc

Time (sec)-0.8

-0.4Acc

Time (sec)(a) Koyna (1967) (b) Parkfield (1966)

0 2

0.4

)

Shake TableBase of bldg

0 4

0.8

)

Shake TableBase of bldg

0 2

0

0.2

0 3 6 9 12 15

Acc

eler

atio

n (g

)

0 4

0

0.4

0 3 6 9 12

Acc

eler

atio

n (g

)

(c) El Centro (1940) (d) Victoria (1980)

-0.4

-0.2A

Time (sec) -0.8

-0.4A

Time (sec)(c) Ce t o ( 9 0) (d) cto a ( 980)

33

Comparison of acceleration responses at base level, first floor and roof level subjected to four earthquakesj q

0.12Base level

0.3 Base level

0

0.06

0 1 2 3 4 5lera

tion

(g)

ase eveFirst floorRoof level

0

0.15

0 5 10 15 20lera

tion

(g)

First floorRoof level

-0.12

-0.06

0 1 2 3 4 5

Acc

el

Time (sec) -0.3

-0.15

0 5 10 15 20

Acc

el

Time (sec)


( )

0.2Base levelFirst floorR f l l

0.2Base levelFirst floor

0

0.1

0 3 6 9 12 15

ccel

erat

ion

(g) Roof level

0

0.1

0 3 6 9 12cc

eler

atio

n (g

) Roof level

-0.2

-0.1A

Time (sec)-0.2

-0.1Ac

Time (sec)

(c) El Centro (1940) (d) Victoria (1980)

34

Displacement at base level and first floor level subjected to four earthquakesfour earthquakes

10Base level

60Base level

0

5

men

t (m

m)

Base levelFirst floor

0

30

emen

t (m

m)


-10

-5

0 1 2 3 4 5

Dis

plac

em

i ( )-60

-30

0 5 10 15 20

Dis

plac

e

Ti ( )


Time (sec) Time (sec)

22.5Base level

30Base level

0

7.5

15

0 3 6 9 12 15emen

t (m

m)


0

10

20

0 3 6 9 12cem

ent (

mm

)


-22.5

-15

-7.50 3 6 9 12 15

Dis

plac

e

Time (sec)-30

-20

-100 3 6 9 12

Dis

plac

Time (sec)(c) El Centro (1940) (d) Victoria (1980)

Time (sec) Time (sec)

35

Peak acceleration and displacement at different levels of model subjected to four earthquakes along X-axis

Peak

Earthquake

Peak Accelerations (g) Displacement (mm)

At Shake At Base At First At Roof At Base At First At Shake Table

At Base At First Floor

At Roof Level

At Base level

At First Floor

Koyna(1967)

0.632 0.0873 0.0700 0.0867 6.326 7.240

Parkfield 0 476 0 2145 0 2081 0 2463 36 199 39 920Parkfield(1966)

0.476 0.2145 0.2081 0.2463 36.199 39.920

El Centro 0.319 0.1524 0.1601 0.1686 17.789 19.409(1940)Mexico (1980)

0.615 0.1230 0.1310 0.1459 19.452 21.251(1980)

36

EXPERIMENTAL STUDY ON HORIZONTAL-DISPLACEMENT EXPERIMENTAL STUDY ON HORIZONTAL DISPLACEMENT BEHAVIOUR OF PROTOTYPE U-FREIs

Prototype U-FREI

37

EXPERIMENTAL STUDY ON HORIZONTAL FORCE DISPLACEMENT EXPERIMENTAL STUDY ON HORIZONTAL FORCE-DISPLACEMENT BEHAVIOUR OF PROTOTYPE U-FREIs

Details of prototype FREIs: (support of METCO Pvt. Ltd., Details of prototype FREIs: (support of METCO Pvt. Ltd., Kolkata, India)

38

Evaluation of lateral load-displacement behaviour of prototype U FREIsprototype U-FREIs

Experimental set-up

39

Horizontal displacement historyHorizontal displacement history

All isolators are subjected to a constant vertical pressure of 5.6 MPa and cyclic horizontal displacement (f = 0.025 Hz) up to 0.89tr

40

EXPERIMENTAL STUDY ON HORIZONTAL-DISPLACEMENT EXPERIMENTAL STUDY ON HORIZONTAL DISPLACEMENT BEHAVIOUR OF PROTOTYPE U-FREIs

Deformed shapes:

f f fExperimental Deformed shapes of U-FREI at 80 mm amplitude of horizontal displacement

41

EXPERIMENTAL STUDY ON HORIZONTAL-DISPLACEMENT BEHAVIOUR OF PROTOTYPE U-FREIs

Hysteresis loops:

42

EXPERIMENTAL STUDY ON HORIZONTAL-DISPLACEMENT BEHAVIOUR OF PROTOTYPE U-FREIs

Mechanical characteristic properties: max minhff

F FK Mechanical characteristic properties:

The effective horizontal stiffness:[Kelly and Takhirov , 2001]

max mineffK

u u

W The equivalent viscous damping:2max2

dheff

WK

maxeff

43


Effect of loading direction on horizontal response of Effect of loading direction on horizontal response of square U-FREIs:

Most previous studies for square U-FREIs were investigated under cyclic horizontal displacement in 0/90o and 45o directions. Angle of incidence of earthquake to a structure may be from any directions.

However, no experimental study on effect of loading directions on horizontal response of square U-FREIs was performed.

U-FREIs type A1 are investigated under cyclic horizontal displacement at different directions (0o, 15o, 30o and 45o) and a constant vertical load of 350 kN.

44Specimens undergoing tests under horizontal displacement in different directions

(0o, 15o, 30o and 45o)


Experimental results: Experimental results:

Deformed shapes:As the loading direction changes from 0o to 45o, the area of the isolator in contact with the support surfaces increases. Thi lt i i i ff ti h i t l This results in an increase in effective horizontal stiffness.

Deformed shapes of U-FREI type A1 corresponding to 0o, 15o, 30o and 45o loading directions at 80mm amplitude of horizontal displacement

45

directions at 80mm amplitude of horizontal displacement

FINITE ELEMENT SIMULATION OF FREI

Hysteresis loops:y p

Comparison of hysteresis loops of different types of U-FREI as obtained from FE analysis and experimental results

46

Mechanical Properties of Prototype FREIsp yp

47

Horizontal load – displacement relationshipsHorizontal load displacement relationships

48

FINITE ELEMENT SIMULATION OF Prototype FREI

49

AN ANALYTICAL APPROACH FOR PREDICTING THE HORIZONTAL STIFFNESS OF U-FREIs

effb

r

G AK

t eff eff eff

ub ub br

G A AK or K K

t A

r

Deformed configuration of a U-FREI

Effective plan area:

A di N h d [2014] d i l d

effA a a d 25d hAccording to Nezhad [2014], d is evaluated as

α is geometrical parameter which relates d and curved length, s, at a i di l

16d h

given displacement, u.

Relation between u, s and α as proposed by Nezhad [2014] is expressed as

2 225 2 1 4 ln 2 1 464

u h 50

AN ANALYTICAL APPROACH FOR PREDICTING THE HORIZONTAL STIFFNESS OF FREIsHORIZONTAL STIFFNESS OF FREIs

Proposed method 1: 2

2

0

1 11

zeff

crit

p uG Gaup

Proposed method 2:

,0critpa

2

2

,0

1 1 for 0 1.01

zeff r

crit

p uG G u taup

,0

2

critpa

2

,0

1.01 1 for 1.0 1.51.01

z reff r r

rcrit

p tG G t u tatp

a

51 Ngo, T.V., Dutta, A. and Deb, S.K. (2017), “Evaluation of horizontal stiffness of fibre-reinforced elastomeric isolators”, Earthquake Engineering and Structural Dynamics (Wiley Inter-Science), Vol. 46, pp. 1747-1767

ANALYTICAL APPROACH FOR PREDICTING THE HORIZONTAL ANALYTICAL APPROACH FOR PREDICTING THE HORIZONTAL STIFFNESS OF FREIs

For U-FREI: Good agreements are observed between proposed

h d 1 & 2 d i l d FE l i method 1 & 2 and experimental and FE analysis results up to 1.00tr.

1.0tr < u < 1.5tr: Proposed method 2 has agreed b f i l A1 d B1 hil d h d better for isolator A1 and B1, while proposed method 1 is better than proposed method 2 for isolator B2.

The Keff based on Gerhaher, et al. [2011] and Nezhad [2014] h i i ifi t d i ti i h

52

[2014] are having significant deviation with experimental results up to 0.89tr.

ANALYTICAL APPROACH FOR PREDICTING THE HORIZONTAL ANALYTICAL APPROACH FOR PREDICTING THE HORIZONTAL STIFFNESS OF FREIs

For B-FREI:

The rate of decrease in Keff obtained from Gerhaher [2010], Naeim and Kelly [1999] are almost constant and show significant deviation from those obtained from FE analysisobtained from FE analysis.

Both proposed methods have matched very wellwith FE analysis results.

53

y

Stability Analysis

54

Stability Analysis

55

View of UFREI

58

VULNERABILITY ASSESSMENT OF A LOW-RISE MASONRY BUILDING SUPPORTED ON U-FREIsBUILDING SUPPORTED ON U FREIs

Numerical modelling of masonry building:

3D models of fixed-base and base-isolated buildings are simulated by g ySAP2000.

Masonry wall: Nonlinear layered shell element

Isolator: as rubber isolator in link/support type element using bilinearIsolator: as rubber isolator in link/support type element using bilinear

hysteresis loop

59

Identification of Damage States (DS):Identification of Damage States (DS):

Thresholds based on inter-storey drift from Calvi [1999] are employed to define damage states for the masonry building.

For base-isolated building: a damage state is added to evaluate the damage of U-FREIs in base isolation system (DS5). The damage state limit

f h i t l di l t f U FREI i id d t h d i of horizontal displacement of U-FREIs is considered at hardening behaviour with uh = 155 mm (i.e. 1.70tr).

60

Vulnerability assessment of masonry building: - Pushover analysis

( ) FB b ildi ( ) i(a) FB building (b) BI building

(c) Comparison of pushover curves of fixed-base and relative base-isolated buildings

61

Comparison of fragility curves of FB and BI building

Ngo, T.V., Deb, S.K. and Dutta, A. (2017), “Mitigation of seismic vulnerability of a prototype low-rise masonry building using U-FREIs”, accepted for publication in Journal of

62

y g g p pPerformance of Constructed Facilities, ASCE

IITG CAMPUS: SPRING 2017

Thank you for your kind attention63

seismic performance evaluation of un-bonded fibre

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