Major Project-1

DUCTILITY ENHANCEMENT OF R.C. COLUMNS USING FRP COMPOSITES MAJOR PROJECT By, Vijay N. Garchar (06MCL004) Guided by, Prof. U.V.Dave

DEPARTMENT OF CIVIL ENGINEERING Ahmedabad 382481 May 2008

1

INTRODUCTION • Ductility is defined by the ratio of the total imposed displacement Δ at any instant to that at the concept of yield Δy. µ=

∆ 〉1 ∆y

The primary aim of the detailing of composite structures, Produce ductile members, which are capable of meeting the inelastic deformation demands imposed by severe earthquakes. 2

EFFECT OF DUCTILITY ON R.C. COLUMNS

• •

Improve the behavior of the building primarily by reducing the forces in the structure. Serves as a shock absorber in structure and reduces the transmitted force to one that is sustainable 3

FACTORS AFFECTING COLUMN DUCTILITY

Ductility Increases in following cases, 1. Shear Strength 2. Axial Compressive Stress 3. Ultimate Strain of Concrete 4. Axial Compressive Stress 5. Ultimate Strain of Concrete 6. Yield Strength of Steel 7. Transverse Reinforcement

4

RESEARCH SIGNIFICANCE

• Resistance of Structure to sustain forces during earthquakes. • To impart ductility in RC Columns using FRP material along with steel and concrete i.e. Composites Material. • To study Behavior of Different FRP composites & RC Columns under different loadings.

5

DUCTILITY ENHANCEMENT OF R.C. COLUMNS

• Increasing Transverse Reinforcement • Steel Jacket confinement • FRP confinement

6

INCREASING TRANSVERSE REINFORCEMENT

7

STEEL JACKET CONFINEMENT

8

ADVANTAGES OF FRP COMPOSITES

• • • •

Increase Structure Service Life Resistance to Salts and other Corrosive Agents Reduce Field Installation Time and Light Weight Reduce Traffic Delays due to Faster Construction Especially in Bridge • Corrosion Resistance • Allow Greater Vehicular Load due to Weight Reduction

9

ADVANTAGES OF FRP COMPOSITES 1. Light weight, 2. Nonmagnetic, 3. High strength to weight ratio, 4. High impact strength, 5. Directional strength, 6. High dielectric strength insulator 7. Corrosion resistance, 8. Low maintenance, 9. Weather resistance, 10.Long term durability, 11.Dimensional stability, 12.Part consolidation, 13.Low thermal conductivity, 14.Small to large part geometry possible, 15.Low coefficient of thermal expansion, 16.Tailored surface finish, and 17.Radar transparency.

10

SCOPE OF WORK

SCOPE OF WORK

EXPERIMENTAL

ANALYTICAL

11

SCOPE OF WORK

EXPERIMENTAL WORK

CIRCULAR

SQUARE

12

SCOPE OF WORK LOADING CONDITIONS

AXIAL

AXIAL CYCLIC

ECCENTRIC

WRAPPING MATERIAL

GLASS FIBERS

CARBON FIBERS

13

SCOPE OF WORK 36 Columns Shape

Square (18)

Circular (18)

Loading

Cyclic (6)

Axial (6) FRP Material UN Wrapped (2)

GFRP (2)

CFRP (2)

UN Wrapped GFRP (2) (2)

FRP Material UN Wrapped (2)

Eccentric (6)

CFRP (2)

UN Wrapped (2) Loading

GFRP (2)

Axial (6)

GFRP (2)

CFRP (2)

Eccentric (6)

Cyclic (6)

CFRP (2)

UN Wrapped (2)

GFRP (2)

CFRP (2)

UN Wrapped (2)

GFRP (2)

14

CFRP (2)

SCOPE OF WORK Name of Specimen Unwrapped CTA1

Square

Circular

Eccentric

Cyclic

AXIAL

.

.



.



CFRP

GFRP

.

.

.

.

.

.

.

.

.

.

.

.

.

.



.

CTA2



.

.



.

CTE1



.

.



.



.

CTE2



.

.



.



.

CTAC1



.

.



.

.



.

.

.

.

CTAC2



.

.



.

.



.

.

.

.

STE1



.



.

.



.

.

.



.

.

.

.

.

.

.

.

.



.

. .

.

.

STE2



.



.

.

STAC1



.



.

.

.

. 

. .

STAC2



.



.

.

.



.

STA1



.



.

.

.

STA2



.



.

.

.

.



.

.

.

.



.

.

.

Notation of Specimen :

SGFA1

.



.

.

.

.



.

.



.

SGFA2

.



.

.

.

.



.

.



.

CGFA1

.

.



.

.

.



.

.



.

CGFA2

.

.



.

.

.



.

.



.

SGFAC1

.



.

.

.



.

.

.



.

SGFAC2

.



.

.

.



.

.

.



.

CGFAC1

.

.



.

.

.



.

CGFAC2

.

.

SGFE1

.

 

.

.



.

.

 .

.

.

.

.



.

.

.

.

.



.



SGFE2

.

CGFE1

.

CGFE2

.

SCFA1

.



.

.

.

.



.



.

.

SCFA2

.



.

.

.

.



.



.

.

CCFA1

.

.



.

.

.



.



.

.

CCFA2

.

.



.

.

.



.



.

.

SCFAC1

.



.

.

.



.

.



.

.

SCFAC2

.



.

.

.



.

.



.

.

CCFAC1

.

.



.

.



.

.



.

.

CCFAC2

.

.



.

.



.

.



.

.

SCFE1

.



.

.



.

.

.



.

.

SCFE2

.



.

.



.

.

.



.

.

CCFE1

.

.



.



.

.

.



.

.

CCFE2

.

.



.



.

.

.



.

.

.

.

.





.





.

.

.

.



.

.



.

.

.

.



.

.



.

.

.

.

.



C

Circular

S

Square

T

Control specimen

CF

CFRP Wrapped Specimen

GF

GFRP Wrapped Specimen

A

Axially Loaded Column

AC

Axially Cyclic Loaded Column Specimen

E

Eccentrically Loaded Specimen

SGFAC

GFRP wrapped, Axially cyclic Loaded Square Column Specimen

15

MATERIAL USED IN COLUMNS 1. CONCRETE GRADE – M25 Water 0.45

Cement 1

Sand 1.27

Coarse Aggregates 2.26

1. Longitudinal Reinforcement 1. Fe-415 – Square Columns – 4 Nos. 2. Fe-250 – Circular Columns – 8 Nos. 2. Transverse Reinforcement Fe-250 – Square & Circular Columns @ 150 mm c/c 16

GEOMETRY OF SECTION Geometry of section is decided based on extensive literature review 8 – 6 mm Dia bars

100 mm

1000 mm

4 – 10 mm Dia bars

6 mm @ 150 mm c/c

100 mm 6 mm @ 150 mm c/c

1000 mm

17

PARAMETERS MEASURED 1. Ultimate Failure Load of Axially and eccentric loaded columns. Ultimate Failure Load of Axial cyclic loaded columns. 2. Cracking pattern of wrapped and unwrapped columns. 3. Strain measurement at external of surface of FRP. 4. Strain measurement at intermediate height of columns. 5. Ultimate stress carried by confined and unconfined concrete column.

18

PARAMETERS STUDIED 1. Comparative study of axial and eccentric loaded circular and square columns. 2. Efficiency of wrapping material base upon geometry of columns under different loading conditions. 3. Ductility measurement of wrapped and unwrapped columns and comparison of the same under different loading conditions. 4. Comparisons of experimental and analytical results for axially loaded circular and square columns. 5. Measurement of Specific Damping Capacity (SDC), Stiffness Degradation & Energy Dissipation under Axial Cyclic Loading. 19

ANALYTICAL SCOPE OF WORK

• Axial load of column wrapped with CFRP & GFRP composites for Square and Circular columns. • Analytical Pu – Mu curve

20

LITERATURE REVIEW Literature review has been done based on classification of paper according to the following topics. •Parametric study by various Researchers •Eccentrically loaded column •Confinement model •Corner radius effect •Wrapping techniques •Test setup for Eccentrically loaded columns

21

LITERATURE REVIEW Researchers

Size of Specimens

Corner Radius FRP (mm) Type

ff(MPa)

Ef(MPa)

fco (MPa)

Mirmiran et al.[21]

153 x 153 x 305

3.65

GT

524 - 641

37.2 – 40.7

40.6

Mohamed [22]

132 x 132 x 300 102 x 176 x 300 79 x 214 x 300 152 x 305

30 30

CC GS

4364

230 230 230 248 248 230

18.3 15.2

CC GS CC

3500 3500 3500 -

27.58 34.47 31.7 – 52.1

3200 2500 1100

230 74 39

25 170 24

Youssef, et al. [23] Wang, et al. [6]

150 x 150 x 300 150 x 150 x 300 150 x 150 x 300

15 30 45 60 75

Berthet et al. [24]

160 x 320

-

Lau et al. [25]

100 x 200

-

CC GS GS

Labossie[26]

5, 25, 38 5, 25, 38

CC AS

1265 230

82.7 13.6

35.7 -43.9

8.3 30 30 5

CC CC

3022 3654

188.9 207

22.5 20.7 – 41.7

Zhao [30]

152 x 152 x 500 152 x 203 x 500 152 x 152 x 500 108 x 108 x 305 152.5 x 305 200 x 200 x 400 200 x 200 x 600 200 x 200 x 600 100 x 100 x 300

CC HS CC

4433 3972 1800

252 439 221

38 38 26.8 – 35.5

Matthys et al. [31]

400 x 2000

-

CC GS

2600

198

31.8 39.1

Parvin [27] Shahawy et al. [28] Hosotani et al.[29]

22

LITERATURE REVIEW

• It has been revealed from extensive literature review that in following research is needed in following areas 1. Eccentrically Loaded Columns 2. Axial Cyclic Loaded Columns

23

LITERATURE REVIEW Hadi (2007)

Knife Edge Plate System

24

Knife Edge Plate System

25

26

LITERATURE REVIEW

27

Parveen et al.

Knife Edge Plate System 28

LITERATURE REVIEW Mander et al. Shao et al. Sheikh Baris et al. Lin et al. Hoshikuma et al. Hoppel et al. Samaan et al. Xiao et al. Kumutha et al. Youssef et al. Maalej et al.

29

LITERATURE REVIEW

EXPERIMENTATION

30

CASTING OF COLUMNS Formwork Square Columns

31

CASTING OF COLUMNS Reinforcement for Square & Circular Columns

32

CASTING OF COLUMNS Casting of Square Column

33

CASTING OF COLUMNS

Casting of Circular Column

34

WRAPPING OF COLUMNS Following Procedure is used for wrapping of Column using GFRP & CFRP composites. 1.Surface Preparation 2.Application of Putty 3.Application of Primer Coat 4.Cutting of Fibers 5.Application of Saturent 6.Wrapping of Fibers

35

SURFACE PREPARATION

36

WRAPPING TECHNIQUES

Orientation of Fibers in Hoop Direction

Orientation of Fibers in Longitudinal Direction 37

APPLICATION OF PUTTY Columns are washed with water and dried for 24 hours. PREPARATION OF PUTTY APPLICATION OF PUTTY APPLICATION OF PUTTY ON COLUMN FINISHING OF SURFACE

Unevenness of Concrete surface.

38

APPLICATION OF PRIMER COAT 24 hours after application of putty primer coat is applied. PREPARATION OF PRIMER COAT APPLICATION OF PRIMER COAT

Finished Surface

Column Specimen after primer coat application.

39

CUTTING OF FIBERS Fibers are cut according to the size of Square and Circular Column. MEASUREMENT OF FIBERS CUTTING OF FIBERS

40

APPLICATION OF SATURENT 5 hours after application of Primer Coat, Saturent is Applied. APPLICATION OF SATURENT ON COLUMN

Mixing of Goldband base for saturent

Mixing of Goldband hardener with base for saturent.

41

WRAPPING OF COLUMNS

WRAPPING OF SQUARE COLUMN COMPLETE WRAPPING OF SQUARE COLUMN WRAPPING OF CIRCULAR COLUMN CFRP WRAPPING Pressing of GFRP wrap remove entrapped air.

to

42

TESTING SETUP p

Eccentric Loading System

h

h

43

d

d

TESTING OF RC COLUMNS

44

TESTING SETUP Eccentric Loading System

FIX SUPPORT

RCC Column

Knife Edge Plate Hydraulic Jack

Base

45

TESTING SETUP Eccentric Loading System

46

TESTING SETUP AXIAL , AXIAL CYCLIC LOADING

47

TESTING SETUP

150 mm

100 mm 50 mm

50 mm

15 mm

200 mm

200 mm

FIX SUPPORT

48

TESTING SETUP

FIX SUPPORT

49

TESTING SETUP FIX SUPPORT-CIRCULAR COLUMNS

15 mm

200 mm

150 mm

6 mm Thick Plate

150 mm

200 mm

PLAN

100 mm

200 mm

ELEVATION

50

TESTING SETUP KNIFE EDGE PLATE

60 mm

400 mm

400 mm

51

TESTING SETUP ATTACHMENTS 150 mm

50 mm

LVDT resting point

Connection point with Knife Edge Plate

Adjustable Groove

Packing Plate (Square) 150 mm Diameter

50 mm

Vertical Attachment

Packing Plate (Circular)

52

INSTRUMENTATION LVDT (Liner Variable Differential Transducer)

LVDT is attached with column to give total displacement at the time of load application

Digital Displacement Indicator. 53

INSTRUMENTATION HYDRAULIC JACK

Hydraulic jack

MECHANICAL STRAIN GAUGE

Mechanical Strain Gauge (DEMEC) 54

INSTRUMENTATION ELECTRONIC STRAIN GAUGE

Components of Strain Gauges

Strain Indicator 55

TESTING SETUP

Fix Support

Dial Gauge

300 mm Column

30 0 m m

Strain Gauge s

LVDT

30 0 m m Hydraulic

Knife Edge Plate

Jack

56

AXIALLY LOADED COLUMNS

57

TESTING PROCEDURE AXIAL LOADING

Stress Controlled Approach Load is increased on the column at specific intervals and corresponding to every load displacement and strains are measured for the columns Interval for load increment is kept as 10 kN

58

TEST RESULTS-AXIAL LOADINGCIRCULAR COLUMN

CIRCULAR

SQUARE COLUMNS

COLUMNS UN -WRAPPED

UN-WRAPPED

GFRP WRAPPED

GFRP WRAPPED

CFRP WRAPPED

CFRP WRAPPED

59

TEST RESULTS-AXIAL LOADINGCIRCULAR COLUMN 350 300 250

) N (k d a o L

200 CTA

150

CGFA

100

CCFA

50 0 0

2

4 6 Deflection (mm)

8

10

Variation of Load Deflection for CTA, CGFA & CCFA

Column

Load(kN)

Increment in % with respect to CTA

CTA CGFA CCFA

145 230 310

70 113.79

Increment in % with respect to CGFA 23

60

TEST RESULTS-AXIAL LOADINGCIRCULAR COLUMN 50

2)

40 30 CTA

20

/m (N s tre S

CGFA CCFA

10 0 0

0.002

0.004

0.006 Strain

0.008

0.01

0.012

Variation of Stress-Strain for CTA, CGFA & CCFA

Column

Stress N/mm2

Increment in % with respect to CTA

CTA CGFA CCFA

18.46 29.46 39.47

70 113.79

Increment in % with respect to CGFA 23

61

45

40

40

35

35

2)

45

30

30

25

CTA

20

CGFA

20

CGFA

15

CCFA

15

CCFA

10

CTA

25

/m (N s tre S

/m s(N tre S

2)

TEST RESULTS-AXIAL LOADINGCIRCULAR COLUMN

10

5

5

0

0 0

0.0001

0.0002

0.0003 Strain

0.0004

0.0005

0.0006

0

0.0001

0.0002

0.0003

0.0004

0.0005

Strain

Variation of Stress-Strain for CTA, CGFA & CCFA at 1/3rd Variation of Stress-Strain for CTA, CGFA & CCFA at 2/3rd height height 45 40

/m (N s tre S

2)

35 30 25

CTA

20

CGFA

15

CCFA

10 5 0 0

0.00005

0.0001

0.00015 0.0002 Strain

0.00025

0.0003

0.00035

62 Variation of Stress-Strain for CTA, CGFA & CCFA at 1/2

FAILURE MODES – AXIAL LOADING – CIRCULAR COLUMNS

Radial Cracks in CTA

Failure mode for CTA

63

FAILURE MODES – AXIAL LOADING – CIRCULAR COLUMNS

Longitudinal Crack of CTA

Failure of CTA

64

FAILURE MODES – AXIAL LOADING – CIRCULAR COLUMNS

Failure of GFRP in CGFA

Rupture of GFRP in CGFA

65

FAILURE MODES – AXIAL LOADING – CIRCULAR COLUMNS

Failure mode of GFRP in CGFA

Cracking in Fibers in CGFA 66

FAILURE MODES – AXIAL LOADING – CIRCULAR COLUMNS

Buckling of bar in CCFA

Rupture of CFRP in CCFA 67

FAILURE MODES – AXIAL LOADING – CIRCULAR COLUMNS

Buckling of bar & Rupture of CFRP in CCFA

Failure mode of CCFA

68

TEST RESULTS-AXIAL LOADINGSQUARE COLUMN 400 350 300 250

STA

) N (k d a o L

200

SGFA

150

SCFA

100 50 0 0

2

4

6 Deflection (mm)

8

10

12

Variation in Load- Deflection relationship for STA, SGFA & SCFA Column

Load(kN)

Increment in % with respect to STA

Increment in % with respect to SGFA

STA SGFA SCFA

210 330 380

61.90 80.95

12

69

TEST RESULTS-AXIAL LOADINGSQUARE COLUMN 50

2)

40 30 STA

20

/m (N s tre S

SGFA SCFA

10 0 0

0.002

0.004

0.006 0.008 Strain

0.01

0.012

0.014

Variation in Stress-Strain relationship for STA, SGFA & SCFA Column

Stress N/mm2

Increment in % with respect to Unwrapped

Increment in % with respect to GFRP

STA SGFA SCFA

26.73 42.016 48.38

61.90 80.95

12

70

TEST RESULTS-AXIAL LOADINGSQUARE COLUMN 50

40.000

40

2)

2)

50.000

30

SGFA SCFA

20.000

/m (N s tre S

/m (N s tre S

30.000

STA

STA SGFA

20

SCFA

10

10.000

0

0.000 0

0

0.0001 0.0002 0.0003 0.0004 0.0005 0.0006 0.0007 0.0008 Strain

Variation in Stress-strain relationship for STA, SGFA & SCFA at 1/3rd height

0.0001

0.0002

0.0003 Strain

0.0004

0.0005

0.0006

Variation in Stress-strain relationship for STA, SGFA & SCFA at 2/3rd height

50

2 )

40 30

(N s e r t S /m

STA SGFA

20

SCFA

10 0 0

0.0001

0.0002

0.0003 Strain

0.0004

0.0005

0.0006

71 Variation in Stress-strain relationship for STA, SGFA & SCFA at 1/2

FAILURE MODES – AXIAL LOADING – SQUARE COLUMNS

Buckling of Reinforcement bar & failure mode for STA

Buckling of Reinforcement bar for STA 72

FAILURE MODES – AXIAL LOADING – SQUARE COLUMNS

73

Initiation of Crack on STA

Failure of cover concrete for STA

FAILURE MODES – AXIAL LOADING – SQUARE COLUMNS

Cracking pattern in cross sectional area of SGFA

Complete failure of SGFA

74

FAILURE MODES – AXIAL LOADING – SQUARE COLUMNS

75

Failure of GFRP from corner in SGFA

Failure mode of SGFA

FAILURE MODES – AXIAL LOADING – SQUARE COLUMNS

76

Cracked Cross-section of SCFA

Failure from corner for SCFA

FAILURE MODES – AXIAL LOADING – CIRCULAR COLUMNS

Rupture of CFRP from corner for SCFA

Failure of SCFA

77

ECCENTRICALLY LOADED COLUMNS

78

TESTING PROCEDURE ECCENTRIC LOADING

Stress Controlled Approach. Eccentricity of 20 mm is applied over the column and kept constant throughout test Interval for load increment is kept as 10 kN

79

TEST RESULTS - ECCENTRIC LOADINGCIRCULAR COLUMN

CIRCULAR

SQUARE COLUMNS

COLUMNS UN -WRAPPED

UN-WRAPPED

GFRP WRAPPED

GFRP WRAPPED

CFRP WRAPPED

CFRP WRAPPED

80

TEST RESULTS - ECCENTRIC LOADINGCIRCULAR COLUMN 300 250 200 150

) N (k d a o L

CTE CGFE

100

CCFE

50 0 0

2

4 6 Deflection (mm)

8

10

Variation of Load-Deflection for CTE, CGFE & CCFE Column Load(kN) CTE CGFE CCFE

120 200 250

Increment in % with respect to CTE 66.66 108.33

Increment in % with respect to CGFE 25

81

TEST RESULTS - ECCENTRIC LOADINGCIRCULAR COLUMN

2)

30.000

20.000 CTE

/m (N s tre S

CGFE

10.000

CCFE

0.000 0

0.002

0.004

0.006

0.008

0.01

Strain

Variation of Stress-Strain for CTE, CGFE & CCFE Column CTE CGFE CCFE

Stress N/mm2 12 20 25

Increment in % with respect to CTE 66.66 108.33

Increment in % with respect to CGFE 25

82

35.000

35.000

30.000

30.000

25.000

25.000

2)

2)

TEST RESULTS - ECCENTRIC LOADINGCIRCULAR COLUMN

20.000

20.000

CTE

15.000

CTE

10.000

CGFE

5.000

CCFE

/m (N s tre S

tre S /m (N s

15.000

CGFE

10.000

CCFE

5.000 0.000

0.000 0

0.0001

0.0002 0.0003 Strain

0.0004

0

0.0005

Variation of Stress-Strain for CTE, CGFE & CCFE at 1/3rd height

0.00005

0.0001 0.00015 Strain

0.0002

0.00025

Variation of Stress-Strain for CTE, CGFE & CCFE at 2/3rd height

35.000 30.000

2)

25.000 20.000

CTE

15.000

/m (N s tre S

CGFE CCFE

10.000 5.000 0.000 0

0.0001

0.0002 Strain

0.0003

0.0004

83

Variation of Stress-Strain for CTE, CGFE & CCFE at 1/2 height

FAILURE MODES – ECCENTRIC LOADING – CIRCULAR COLUMNS

Failure of CTE

Cracking Pattern of CTE

84

FAILURE MODES – ECCENTRIC LOADING – CIRCULAR COLUMNS

Spalling of cover concrete due to eccentricity effect

Failure pattern for CTE

85

FAILURE MODES – ECCENTRIC LOADING – CIRCULAR COLUMNS

Rupture of GFRP due to eccentric loading

Failure pattern of CGFE

86

FAILURE MODES – ECCENTRIC LOADING – CIRCULAR COLUMNS

Crushing of concrete and rupture of GFRP

Failure modes of GFRP in CGFE

87

FAILURE MODES – ECCENTRIC LOADING – CIRCULAR COLUMNS

Failure of CFRP due to rupture of CFRP

Failure of CCFE

88

FAILURE MODES – ECCENTRIC LOADING – CIRCULAR COLUMNS

89

Rupture of CFRP in CCFE

Failure pattern of CCFE

TEST RESULTS - ECCENTRIC LOADINGSQUARE COLUMN 350 300 250 200 ) N (k d a o L

STE 150

SGFE

100

SCFE

50 0 0

2

4 6 Deflection (mm)

8

10

Variation in Load Deflection for STE, SGFE & SCFE Column Load(kN) STE SGFE SCFE

150 200 300

Increment in % with respect to STE 33.33 100

Increment in % with respect to SGFE 50

90

TEST RESULTS - ECCENTRIC LOADINGSQUARE COLUMN

2)

30.000

20.000

/m (N s tre S

CTE

10.000

CGFE

S

CCFE

S S

0.000 0

0.002

0.004

0.006

0.008

0.01

Strain

Variation Stress-Strain for STE, SGFE & SCFE Column Load(kN) STE SGFE SCFE

15 20 30

Increment in % with respect to STE 33.33 100

Increment in % with respect to SGFE 50

91

35.000

35.000

30.000

30.000

25.000

25.000

2)

2)

TEST RESULTS - ECCENTRIC LOADINGSQUARE COLUMN

20.000

20.000

CTE

15.000

CTE

10.000

CGFE

5.000

CCFE

/m (N s tre S

/m (N s tre S

15.000

CGFE

10.000

CCFE

5.000 0.000

0.000 0

0.0001

0.0002 0.0003 Strain

0.0004

0

0.0005

Variation in Stress-Strain for STE, SGFE & SCFE at 1/3rd height 35.000

0.00005

0.0001 0.00015 Strain

0.0002

0.00025

Variation in Stress-Strain for STE, SGFE & SCFE at 2/3rd height

30.000

2)

25.000 20.000

CTE

15.000

/m (N s tre S

CGFE CCFE

10.000 5.000 0.000 0

0.0001

0.0002 Strain

0.0003

0.0004

92

Variation in Stress-Strain Curve for STE, SGFE & SCFE at 1/2 height

FAILURE MODES – ECCENTRIC LOADING – SQUARE COLUMNS

Crack pattern of column along the line of load applied

Crack pattern in section of STE

93

FAILURE MODES – ECCENTRIC LOADING – SQUARE COLUMNS

Crack pattern along eccentric line for STE

Crack pattern for STE

94

FAILURE MODES – ECCENTRIC LOADING – SQUARE COLUMNS

Cracked section for SGFE

Rupture of GFRP from corner in SGFE

95

FAILURE MODES – ECCENTRIC LOADING – SQUARE COLUMNS

Cracked section and crushing of concrete for SGFE

Cracking of Concrete SGFE

96

FAILURE MODES – ECCENTRIC LOADING – SQUARE COLUMNS

Rupture of CFRP composites from corner for SCFE

Failure Pattern for SCFE

97

FAILURE MODES – ECCENTRIC LOADING – SQUARE COLUMNS

Cracking pattern on section of SCFE

Failure pattern for SCFE

98

COMPARISIONS AXIAL - ECCENTRIC LOADING Decrease in Load Carrying Capacity of Circular Column Column Unwrapped GFRP CFRP

Axial (kN) 145 230 310

Eccentric % Decrease w.r.t. Axial (kN) Load 120 20 200 9.09 250 19.35

Decrease in Load Carrying Capacity of Square Column Column

Axial (kN) Unwrapped 210 GFRP 330 CFRP 380

Eccentric (kN) 150 200 300

% Decrease w.r.t. Axial Load 28.57 39.39 18.42

99

AXIAL CYCLIC LOADED COLUMNS

100

TESTING PROCEDURE AXIAL CYCLIC LOADING Load

Load

Deformation

Deformation

Full cycle hysteresis loop

Half Cycle hysteresis Loop

Strain Controlled Approach. Load is applied in specific interval and corresponding displacement is measure while in this case displacement is having specific interval and corresponding load is measured. 101 Interval for displacement increment is 1 mm

TESTING PROCEDURE AXIAL CYCLIC LOADING Restoring Force ΔL Vertical Displacement

ΔL

A

D

Height of Column

O

E G Vertical Displacement

102

TEST RESULTS– CYCLIC LOADING – CIRCULAR COLUMNS Results as mentioned are average of column1 & Column2

CIRCULAR

SQUARE COLUMNS

COLUMNS UN -WRAPPED

UN-WRAPPED

GFRP WRAPPED

GFRP WRAPPED

CFRP WRAPPED

CFRP WRAPPED 103

TEST RESULTS– CYCLIC LOADING – CIRCULAR COLUMNS 160 CYCLE-1

140

CYCLE-2

120

CYCLE-3

100

CYCLE-4

80

CYCLE-5

) N (k d a o L

CYCLE-6

60 CYCLE-7

40

CYCLE-8 CYCLE-9

20 0 0

2

4 6 Deflection (mm)

8

10

104

Variation of Load Deflection Relationship for Unwrapped Circular Column (CTAC)

TEST RESULTS– CYCLIC LOADING – CIRCULAR COLUMNS 300 CYCLE-1 250

CYCLE-2 CYCLE-3

200

CYCLE-4 CYCLE-5

150

) N (k d a o L

CYCLE-6 CYCLE-7

100

CYCLE-8 CYCLE-9

50

CYCLE-10 CYCLE-11

0 0

2

4

6 8 Deflection (mm)

10

12

CYCLE-12

105

Variation of Load Deflection Relationship for GFRP wrapped Circular Column (CGFAC)

TEST RESULTS– CYCLIC LOADING – CIRCULAR COLUMNS 350 CYCLE-1

300

CYCLE-2 CYCLE-3

250

CYCLE-4 CYCLE-5 CYCLE-6

200

) N (k d a o L

CYCLE-7 CYCLE-8

150

CYCLE-9 CYCLE-10

100

CYCLE-11 CYCLE-12

50

CYCLE-13 CYCLE-14

0 0

2

4

6 8 Deflection (mm)

10

12

14

106

Variation of Load Deflection Relationship for CFRP wrapped Circular Column (CCFAC)

TEST RESULTS– CYCLIC LOADING – CIRCULAR COLUMNS 0.0007

0.0012

CYCLE-1

CYCLE-1

0.0006 CYCLE-2

0.0005

CYCLE-2

0.001

CYCLE-3

CYCLE-3

CYCLE-4

0.0008 0.0004

CYCLE-5

in tra S

CYCLE-4

CYCLE-6

0.0003

train S

CYCLE-5

0.0006

CYCLE-7 CYCLE-8

CYCLE-6

0.0002

0.0004

CYCLE-9 CYCLE-10

CYCLE-7

0.0001

CYCLE-11

0.0002 CYCLE-8

0 1

2

3

4 5 6 Deflection (mm)

7

8

9

CYCLE-13

0

CYCLE-9

10

0

1

2

3

4

5

6 7 8 9 Deflection (mm)

Unwrapped 0.0012

CYCLE-1

10

11

12

13

14

15

CYCLE-14

GFRP Wrapped

CYCLE-2 0.001

CYCLE-3 CYCLE-4 CYCLE-5

0.0008

CYCLE-6 CYCLE-7

train S

0

CYCLE-12

0.0006

CYCLE-8 CYCLE-9

0.0004

CYCLE-10 CYCLE-11

0.0002

CYCLE-12 CYCLE-13

0 0

1

2

3

4

5

6 7 8 9 Deflection (mm)

10

11

12

13

14

15

CYCLE-14

CFRP Wrapped 107

Strain Variation at 1/3rd Height of Columns

TEST RESULTS– CYCLIC LOADING – CIRCULAR COLUMNS 0.0004

0.0004 CYCLE-1 CYCLE-2

0.0003 CYCLE-3

0.00025 CYCLE-4

in tra S

0.0002 CYCLE-5

0.00015 CYCLE-6

0.0001

CYCLE-7

CYCLE-1

0.00035

CYCLE-2 CYCLE-3

0.0003

CYCLE-4 CYCLE-5

0.00025

CYCLE-6

0.0002

CYCLE-7

train S

0.00035

CYCLE-8

0.00015

CYCLE-9 CYCLE-10

0.0001

CYCLE-11

0.00005 0 0

1

2

3

4 5 6 Deflection (mm)

7

Unwrapped

8

9

10

CYCLE-8

0.00005

CYCLE-9

0

CYCLE-12 CYCLE-13

0

4

8 Deflection (mm)

0.0009 CYCLE-1

0.0008

12

16

CYCLE-14

GFRP Wrapped

CYCLE-2

0.0007

CYCLE-3

0.0006

CYCLE-4

train S

CYCLE-5 0.0005

CYCLE-6

0.0004

CYCLE-7 CYCLE-8

0.0003

CYCLE-9

0.0002

CYCLE-10 CYCLE-11

0.0001

CYCLE-12 CYCLE-13

0 0

1

2

3

4

5

6 7 8 9 Deflection (mm)

10 11 12 13 14

15

CYCLE-14

CFRP Wrapped 108

Strain Variation at 2/3rd Height of Columns

TEST RESULTS– CYCLIC LOADING – CIRCULAR COLUMNS 0.0006

0.0008

CYCLE-1

0.0005

CYCLE-1

0.0007

CYCLE-2

in tra S

0.0001

CYCLE-5 CYCLE-6

0.0004

CYCLE-7

train S

CYCLE-5

0.0002

CYCLE-4

0.0005

CYCLE-4

0.0003

CYCLE-3

0.0006

CYCLE-3

0.0004

CYCLE-2

CYCLE-6

0.0003

CYCLE-7

0.0002

CYCLE-8

0.0001

CYCLE-9

0

CYCLE-8 CYCLE-9 CYCLE-10 CYCLE-11

0 0

1

2

3

4 5 6 Deflection (mm)

7

Unwrapped

8

9

10

CYCLE-12 CYCLE-13

0

1

2

3

4

5

6 7 8 9 Deflection (mm)

0.0009 CYCLE-1

0.0008

10

11

12

13

14

15

CYCLE-14

GFRP Wrapped

CYCLE-2

0.0007

CYCLE-3

0.0006

CYCLE-4

train S

CYCLE-5 0.0005

CYCLE-6

0.0004

CYCLE-7 CYCLE-8

0.0003

CYCLE-9

0.0002

CYCLE-10 CYCLE-11

0.0001

CYCLE-12 CYCLE-13

0 0

1

2

3

4

5

6 7 8 9 10 11 12 13 14 15 Deflection (mm)

CYCLE-14

CFRP Wrapped 109

Strain Variation at 1/2 Height of Columns

FAILURE MODES– CYCLIC LOADING – CIRCULAR COLUMNS

Failure modes for CTAC

Buckling of Reinforcement bars for CTAC

110

FAILURE MODES– CYCLIC LOADING – CIRCULAR COLUMNS

Failure modes for CTAC

Cracking Pattern for CTAC

111

FAILURE MODES– CYCLIC LOADING – CIRCULAR COLUMNS

Rupture of GFRP for CGFAC

Failure of CGFAC

112

FAILURE MODES– CYCLIC LOADING – CIRCULAR COLUMNS

Failure Pattern for CGFAC

Cracking Pattern for CGFAC 113

FAILURE MODES– CYCLIC LOADING – CIRCULAR COLUMNS

Fracture of CFRP

Buckling of Reinforcement

114

TEST RESULTS– CYCLIC LOADING – SQUARE COLUMNS 300 CYCLE-1

250

CYCLE-2 CYCLE-3

200

CYCLE-4 CYCLE-5

150

) N (k d a o L

CYCLE-6 CYCLE-7

100

CYCLE-8 CYCLE-9

50

CYCLE-10 CYCLE-11

0 0

2

4

6 8 Deflection (mm)

10

12

CYCLE-12

Variation of Load Deflection for unwrapped Square Column (STAC)

115

TEST RESULTS– CYCLIC LOADING – SQUARE COLUMNS 350 CYCLE-1

300

CYCLE-2 CYCLE-3

250

CYCLE-4

200

CYCLE-5

) N (k oad L

Series6

150

CYCLE-7 CYCLE-8

100

CYCLE-9 CYCLE-10

50

CYCLE-11

0

CYCLE-12

0

2

4

6 8 Deflection (mm)

10

12

CYCLE-13

116

Variation of Load Deflection for GFRP wrapped Square Column (SGFAC)

TEST RESULTS– CYCLIC LOADING – SQUARE COLUMNS 400 CYCLE-1

350

CYCLE-2 CYCLE-3

300

CYCLE-4 CYCLE-5

250

CYCLE-6

200

CYCLE-7

) N (k d a o L

CYCLE-8

150

CYCLE-9 CYCLE-10

100

CYCLE-11

50

CYCLE-12 CYCLE-13

0 0

2

4

6 8 10 Deflection (mm)

12

14

CYCLE-14

117

Variation of Load Deflection for CFRP wrapped Square Column (SCFAC)

TEST RESULTS– CYCLIC LOADING – SQUARE COLUMNS 0.0008

0.0012 CYCLE-1

CYCLE-1

0.0007

CYCLE-2 0.0006

CYCLE-2

0.001

CYCLE-3

CYCLE-3

CYCLE-4

0.0008

CYCLE-4

0.0005

CYCLE-5

CYCLE-5

CYCLE-6

CYCLE-6

0.0006

CYCLE-7

0.0003

CYCLE-7

in tra S

train S

0.0004

CYCLE-8

CYCLE-8

CYCLE-9

0.0004

CYCLE-10

CYCLE-9

0.0002

CYCLE-10 0.0001

CYCLE-11

0.0002

CYCLE-12

CYCLE-11

CYCLE-13

CYCLE-12

0 2

4

6 8 Deflection (mm)

Unwrapped

10

0

12

2

4

6 8 Deflection (mm)

0.0016 CYCLE-1

0.0014

10

12

GFRP Wrapped

CYCLE-2 CYCLE-3

0.0012

CYCLE-4 CYCLE-5

0.001

CYCLE-6 CYCLE-7

0.0008

train S

0

0

CYCLE-8

0.0006

CYCLE-9 CYCLE-10

0.0004

CYCLE-11 CYCLE-12

0.0002

CYCLE-13 CYCLE-15

0 0

4

8 Deflection (mm)

12

16

CYCLE-14

CFRP Wrapped 118

Strain Variation at 1/3rd Height of Columns

TEST RESULTS– CYCLIC LOADING – SQUARE COLUMNS 0.0004

0.0004

CYCLE-1

0.00035

CYCLE-3

0.0003

CYCLE-2 CYCLE-3

0.0003

CYCLE-4 0.00025

CYCLE-1

0.00035

CYCLE-2

CYCLE-4

CYCLE-5

CYCLE-5

0.00025

CYCLE-6

CYCLE-6

in tra S

0.0002

0.0002

CYCLE-7

in tra S

CYCLE-7

0.00015

CYCLE-8

CYCLE-8

0.00015

CYCLE-9

CYCLE-9

0.0001

CYCLE-11

CYCLE-11

0.00005

CYCLE-10

0.0001

CYCLE-10

CYCLE-12

0.00005

CYCLE-12

CYCLE-13

0

0

2

4

6 8 Deflection (mm)

Unwrapped

10

12

0

0.0008

2

4

6 8 Deflection (mm)

CYCLE-1 CYCLE-2

0.0007

10

12

GFRP Wrapped

CYCLE-3

0.0006

CYCLE-4 CYCLE-5

0.0005

CYCLE-6 CYCLE-7

0.0004

train S

0

CYCLE-8 CYCLE-9

0.0003

CYCLE-10

0.0002

CYCLE-11 CYCLE-12

0.0001

CYCLE-13 CYCLE-15

0 0

4

8 Deflection (mm)

12

16

CYCLE-14

CFRP Wrapped 119

Strain Variation at 2/3rd Height of Columns

TEST RESULTS– CYCLIC LOADING – SQUARE COLUMNS 0.0006

0.0008

CYCLE-1 0.0005

CYCLE-1

0.0007

CYCLE-2 CYCLE-3

CYCLE-2 CYCLE-3

0.0006

CYCLE-4

CYCLE-4

0.0004

CYCLE-5

CYCLE-6

CYCLE-6

0.0004

CYCLE-7 CYCLE-8

0.0002

CYCLE-8

0.0003

CYCLE-9

CYCLE-9 CYCLE-10

0.0002

CYCLE-10 0.0001

CYCLE-7

in tra S

train S

0.0003

CYCLE-5

0.0005

CYCLE-11

CYCLE-11 CYCLE-12

0.0001

CYCLE-12

CYCLE-13

0

0

2

4

6 8 Deflection (mm)

Unwrapped

10

0

12

2

4

6 8 Deflection (mm)

0.0012 CYCLE-1 CYCLE-2

0.001

10

12

GFRP Wrapped

CYCLE-3 CYCLE-4

0.0008

CYCLE-5 CYCLE-6 CYCLE-7

0.0006

in tra S

0

CYCLE-8 CYCLE-9

0.0004

CYCLE-10 CYCLE-11

0.0002

CYCLE-12 CYCLE-13 CYCLE-15

0 0

4

8 Deflection (mm)

12

16

CYCLE-14

CFRP Wrapped 120

Strain Variation at 1/2 Height of Columns

FAILURE MODES– CYCLIC LOADING – SQUARE COLUMNS

Failure modes of STAE

Failure modes of STAE

121

FAILURE MODES– CYCLIC LOADING – SQUARE COLUMNS

Failure modes for SGFAC

Cracking Pattern of SGFAC

122

FAILURE MODES– CYCLIC LOADING – SQUARE COLUMNS

Failure modes for SCFAC

Failure modes for SCFAC

123

EVALUATION OF PARAMETERS

Following parameters are evaluated for Cyclic Loaded Columns 1.Ductility 2.Energy Dissipation 3.Specific Damping Capacity 4.Stiffness Degradation

124

DUCTILITY EVALUATION •Area under load deflection curve is correlated as the ductility of RC columns. •Area under load deflection curve is measured in kN mm which directly gives measurement of energy for RC columns •Area of load deflection curve for all three load cases is measured with data interpretation software “Origin 8.0”. 125

DUCTILITY EVALUATION

126

Inserting Data in Origin-8.0

DUCTILITY EVALUATION

127

Integrating Curve to find area

DUCTILITY EVALUATION

Estimation of Area under Load-deflection curve using Origin 8.0 Software

128

DUCTILITY EVALUATION Energy for Axially loaded Circular columns Type of

Energy

Increase in Energy with CTA (%)

Column

(kN-mm)

CTA

583

0

CGFA

680

16.45

CCFA

1493

155.69

Energy for Axially loaded Square columns Type of

Energy

Increase in Energy with

Column

(kN-mm)

STA (%)

STA

895.425

0

SGFA

1198.775

34

SCFA

1848.75

106

129

DUCTILITY EVALUATION Strain Energy for Eccentrically Loaded Circular Columns Type of

Energy

Increase in Energy with CTE (%)

Column

(kN-mm)

CTE

493.275

0

CGFE

695.125

40.92

CCFE

1051.5

113.16

Strain Energy for Eccentrically Loaded Square columns Type of

Energy

Increase in Energy with STE (%)

Column

(kN-mm)

STE

673.875

0

SGFE

758.125

12.50

SCFE

1413.25

109.71 130

ENERGY DISSIPATION & DUCTILITY EVALUATION – CYCLIC LOADING Restoring Force

Eso µo ED

Deformation

ED/Eso is called as Specific Damping Capacity (SDC) Energy Dissipated ED at cycle of harmonic vibration evaluated from experiments 131

ENERGY DISSIPATION & DUCTILITY EVALUATION – CYCLIC LOADING Variation in Parameters at successive cycle for CTAC Cycle

Deflection (mm)

Load (kN)

Energy Dissipated (kN-mm)

1 2 3 4 5 6 7 8 9

1 2 3 4 5 6 7 8 9

27.5 37.5 50 65 83.75 102.5 122.5 130 145

13.075 13.75 26.125 43.375 50.875 80.625 91.625 218.25 95

Energy SDC Applied (kN-mm) 13.75 24.375 45 71.5 100.875 164 214.375 273 253.75

0.95 0.56 0.58 0.61 0.5 0.49 0.43 0.8 0.37

Stiffness (kN/mm)

27.50 18.75 16.67 16.25 16.75 17.08 17.50 16.25 16.11

132

ENERGY DISSIPATION & DUCTILITY EVALUATION – CYCLIC LOADING

Variation in Parameters at successive cycle for CGFAC Cycle 1 2 3 4 5 6 7 8 9 10 11 12 13

Deflection (mm)

Load (kN)

1 2 3 4 5 6 7 8 9 10 11 12 13

30 45 63.75 83.75 100 108.75 131.25 148.75 171.25 187.5 212.5 240 257.5

Energy Dissipated (kN-mm) 9.125 12.375 21.375 39.55 53.3125 59.5 87.865 98.56 132.93 181.75 197.81 229.5 179.93

Energy Dissipated (kN-mm) 15 33.75 76.5 129.8125 185 217.5 301.875 371.875 479.5 562.5 648.125 780 901.25

SDC

Stiffness (kN/mm)

0.6083 0.3667 0.2794 0.3047 0.2882 0.2736 0.2911 0.265 0.2772 0.3231 0.3052 0.2942 0.1996

30.00 22.50 21.25 20.94 20.00 18.13 18.75 18.59 19.03 18.75 19.32 20.00 19.81 133

ENERGY DISSIPATION & DUCTILITY EVALUATION – CYCLIC LOADING Variation in Parameters at successive cycle for CCFAC Cycle Deflection Load (kN) Energy Energy SDC Stiffness (mm) Dissipated Applied (kN/mm) (kN-mm) (kN-mm) 1 1 36.25 4.875 18.125 0.27 36.25 2 2 53.75 20.375 45.68 0.45 26.88 3 3 75 29.5 90 0.33 25.00 4 4 96.25 52.1875 149.1875 0.35 24.06 5 5 110 82.375 203.5 0.4 22.00 6 6 123.75 91.75 247.5 0.37 20.63 7 7 140 122.675 322 0.38 20.00 8 8 160 128.625 400 0.32 20.00 9 9 178.75 164 499.8 0.33 19.86 10 10 192.5 224.31 577.5 0.39 19.25 11 11 215 233.25 645 0.36 19.55 12 12 240 270.75 720 0.38 20.00 13 13 267.5 194 829.25 0.23 20.58 134

ENERGY DISSIPATION & DUCTILITY EVALUATION – CYCLIC LOADING 300 250

-m ) m

200 CTAC

150 N (k y rg e n E

CGFAC 100

CCFAC

50 0 0

1

2

3

4

5

6

7

8

9

10 11 12 13 14

Cycle

Energy Dissipated for CTAC, CGFAC & CCFAC 135

SPECIFIC DAMPING CAPACITY – CYCLIC LOADING 1 0.9 0.8

CTAC

0.7

CGFAC

C D S

0.6

CCFAC

0.5 0.4 0.3 0.2 0.1 0 0

2

4

6

Cycle

8

10

12

Variation in SDC for CTAC, CGFAC & CCFAC

14

136

STIFFNESS DEGRADATION – CYCLIC LOADING 40 35

CTAC CGFAC

-k /m N

25

ts S ifn e

30

20

CCFAC

15 10 0

2

4

6

Cycle

8

10

12

14

Variation in Stiffness for CTAC, CGFAC & CCFAC 137

ENERGY DISSIPATION & DUCTILITY EVALUATION – CYCLIC LOADING Variation in Parameters at successive cycle for STAC Cycle Deflection (mm) 1 2 3 4 5 6 7 8 9 10 11 12

1 2 3 4 5 6 7 8 9 10 11 12

Load (kN)

Energy Dissipated (kN-mm)

25 43.75 56.25 66.25 78.75 95 115 132.5 158.75 185 212.5 235

11.25 21.5 39.1875 47.81 59.31 77.25 99.31 125.36 153.5 214.87 258.37 295.25

Energy Applied SDC Stiffness (kN-mm) (kN/mm) 12.5 28.43 53.43 66.25 98.43 137.75 189.75 251.75 349.25 444 595 669.75

0.9 0.76 0.73 0.72 0.6 0.56 0.52 0.5 0.44 0.48 0.43 0.44

25.00 21.88 18.75 16.56 15.75 15.83 16.43 16.56 17.64 18.50 19.32 19.58 138

ENERGY DISSIPATION & DUCTILITY EVALUATION – CYCLIC LOADING Variation in Parameters at successive cycle for SGFAC Cycle

Deflection (mm)

Load (kN)

1 2 3 4 5 6 7 8 9 10 11 12 13

1 2 3 4 5 6 7 8 9 10 11 12 13

30 50 70 90 115 150 165 190 215 225 250 260 310

Energy Energy Applied Dissipated (kN(kN-mm) mm) 6.5 15 19 45 25.625 87.5 51.75 144 65.25 212.75 125 322.5 136.5 396 185.425 532 209 623.5 235.25 697.5 203.5 812.5 323.625 884 334 2165

SDC

Stiffness (kN/mm)

0.43 0.42 0.29 0.36 0.31 0.39 0.34 0.35 0.34 0.34 0.25 0.37 0.15

30.00 25.00 23.33 22.50 23.00 25.00 23.57 23.75 23.89 22.50 22.73 21.67 23.85 139

ENERGY DISSIPATION & DUCTILITY EVALUATION – CYCLIC LOADING Variation in Parameters at successive cycle for SCFAC Cycle

Deflection (mm)

Load (kN)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

35 53.75 75 105 130 152.5 188.75 210 227.5 252.5 272.5 295 320 325 360

Energy Dissipation Energy Applied SDC Stiffness (kN-mm) (kN-mm) (kN/mm) 4.75 16.75 39.18 37.3125 65.625 126.875 161.3125 128.875 211.875 203.6785 251.8015 376.25 416.125 433.375 368.25

17.75 48.375 93.75 168 240.5 327.875 453 588 659.75 795.375 885.625 1003 1136 942.5 1080

0.27 0.35 0.42 0.22 0.27 0.39 0.36 0.22 0.32 0.26 0.28 0.38 0.37 0.46 0.34

35.00 26.88 25.00 26.25 26.00 25.42 26.96 26.25 25.28 25.25 24.77 24.58 24.62 23.21 24.00

140

ENERGY DISSIPATION & DUCTILITY EVALUATION – CYCLIC LOADING 500 450 400

N (k y rg e n E

-m ) m

350 300 250

STAC

200

SGFAC

150

SCFAC

100 50 0 0

1

2

3

4

5

6

7

8

9 10 11 12 13 14 15 16

Cycle

Energy Dissipated for STAC, SGFAC & SCFAC

141

SPECIFIC DAMPING CAPACITY – CYCLIC LOADING 1 0.9 0.8 0.7

C D S

0.6

STAC

0.5

SGFAC

0.4

SCFAC

0.3 0.2 0.1 0 0

5

10 Cycle

15

Variation in SDC for STAC, SGFAC & SCFAC

20

142

STIFFNESS DEGRADATION – CYCLIC LOADING 40 35

STA SGFAC

-k /m N

25

s e fn ti S

30

20

SCFAC

15 10 0

5

Cycle

10

15

Variation in Stiffness for STAC, SGFAC & SCFAC

143

ANALYTICAL WORK

144

ANALYSIS OF R.C. COLUMN • Analysis of R.C. Column is to be carried out by Confinement model given by Mander et al. • Compressive Strength of Short Column is given by following equations.

Pn = Pcn + Psn • Pcn = Load carried by the concrete. • Psn = Load carried by the steel reinforcement.

145

ANALYSIS OF R.C. COLUMN EVALUATION OF COMPRESSIVE LOAD OF FRC WRAPPED SQUARE COLUMN

P = Pc + Ps

Where, Pc = Load carried by the concrete. Ps = Load carried by the steel reinforcement.

Ps = fs ⋅ As Where, fs = Compressive stress in longitudinal reinforcement. As = Area of longitudinal reinforcement. 146

ANALYSIS OF R.C. COLUMN

fs = ε ⋅ E

Monotonic stress-strain curve

Where, Є= Strain in steel reinforcement. E = modulus of elasticity of steel.

147

ANALYSIS OF R.C. COLUMN

Pc = Pco + Pccj + Pccjs Where, Pco = Load carried by unconfined concrete area. Pccj = Load carried by the area of concrete confined by FRP jacket. Pccjs = Load carried by effective area of concrete confined by both FRP and Steel hoops.

Pco = fco ⋅ Acu

Where, fco = Compressive stress in unconfined concrete (cube strength of the concrete). Acu = Area of unconfined concrete

Pccj = fccj ⋅ Acj Where, fccj = Compressive stress in FRP jacket. Acj = Area of FRP jacket.

148

ANALYSIS OF R.C. COLUMN Pccjs = fccjs ⋅ Acjs Where, fccjs = Effective compressive stress in FRP jacket and steel hoops. Acjs = effective area of concrete confined by FRP and steel hoops.

Areas of confining regions are given by following equations.

Acu = Accj − Aej Acj

=

Acjs

Aej − Aes =

Aes

Where, Accj = Effective area of concrete confined by FRP jacket. Aej = Effective area of concrete effectively confined by FRP jacket. Aes = Effective area of concrete effectively confined by steel hoops.

149

ANALYSIS OF R.C. COLUMN Accj, Aej and Aes can be given by following expressions A ccj = t x ⋅ t y − A s − (4r 2 − ∏ r 2 ) 2

A ej = t x ⋅ t y −

A e, s

w jx + w jy 3

2

tan θ j − A s − (4r 2 − Π r 2 )

2   w s' s   1 − 0.5 = dx ⋅ dy − ∑  6  dx 

 s' 1 − 0.5  dy 

    150

ANALYSIS OF R.C. COLUMN

151

ANALYSIS OF R.C. COLUMN The compressive strength of confined concrete, f’cc is given by f'cc = k c ⋅ f'c kc is the concrete strength enhancement factor

k c = α1 α 2   F1 F1  α1 = 1.25 1.8 1 + 7.94 − 1.6 − 1   f ' f ' c c   2   F   f1 f1 α 2 = 1.4 − 0.6  − 0.8 1 + 1 F1 F1    f 'c   

F1 and f1 are the maximum and minimum confining lateral stresses, respectively. 152

ANALYSIS OF R.C. COLUMN Lateral confining stresses induced by FRP jacket in the x- and y-directions f1, jy = ρ jy 0.005EP f1, jx = ρ jx 0.005EP

Ep is the elastic modulus of the FRP jacket The reinforcement ratios ρjx and ρjy are defined as ρ jx = 2

tj ty

ρ jy = 2

tj tx

tj is the nominal jacket thickness and tx and ty are the overall column cross-section 153

ANALYSIS OF R.C. COLUMN The lateral confining stresses induced by the steel hoops

f1,sx = ρ sx fsyh

f1,sy = ρ sy fsyh

The confinement reinforcement ratios ρsx and ρsy are defined as below

ρ sx = ρ sy =

A t, x sdy A t, y sdx

154

ANALYSIS OF R.C. COLUMN

155

ANALYSIS OF R.C. COLUMN Combined Effects due to both FRP and Steel hoop are summation of transverse stresses exerted by both FRP Jacket and Steel hoops as shown in below equation.

f1, x = f1,sx + f1, jx

f1, y = f1,sy + f1, jy

156

ANALYSIS OF R.C. COLUMN SQUARE SECTION 4 – 10 mm Dia bars

100 mm 6 mm @ 150 mm c/c 1000

mm

100 mm

CIRCULAR SECTION 8 – 6 mm Dia bars

100 mm

1000 mm

6 mm @ 150 mm c/c

157

ANALYSIS OF R.C. COLUMN Properties of Square Section tx :

100mm

ty :

100mm

Steel Grade For Longitudinal Reinforcement :

415N / mm2

Steel Grade For Transverse Reinforcement :

250N / mm2

Concrete Cover :

15mm

No of Layer of FRP :

1.5

Thickness of FRP : No of Longitudinal Bars :

1.27mm 4

Diameter of Longitudinal Bar :

10mm

Concrete Grade:

25N / mm2

EFRP :

20GPa

Diameter of Transverse Bar : Spacing s :

6mm 150mm

158

ANALYSIS OF R.C. COLUMN Properties of Circular Section Diameter Steel Grade For Longitudinal Reinforcement fy : Steel Grade For Transverse Reinforcement fsyh : Concrete Cover : No of Layer of FRP : Thickness of FRP tj: No of Longitudinal Bars : Diameter of Longitudinal Bar : Concrete Grade: EFRP : Diameter of Transverse Bar : Area of Steel : Area of Concrete : Spacing s : d:

100 415 250 15 1.5 1.27 8 6 25 45 6 226.19 7853.98 150 76

mm N/mm2 N/mm2 mm mm mm N/mm2 GPa mm mm2 mm2 mm 159

ANALYSIS OF R.C. COLUMN

Results Section

Type of Strengthening

Circular

Unwrapped GFRP

143.33 232.70

CFRP Unwrapped GFRP

301 199.97 282.082

CFRP

343.51

Square

Failure Load (kN)

160

ANALYSIS OF R.C. COLUMN 400 350 300

) N (k d a o L

250 200

EXPERIMENTAL

150

ANALYTICAL

100 50 0 CTA

CGFA

CCFA

STA

SGFA

SCFA

Comparison of Analytical & Experimental Results 161

PU-MU INTERACTION CURVE

PU-MU INTERACTION CURVE FOR FRP WRAPPED R.C. COLUMNS

An Attempt has been made by only two researchers in United States by , Bank Lawrance C. Mohamed H. Harajli

162

PU-MU INTERACTION CURVE EFFECT OF ECCENTRICITY ON CONFINED CONCRETE

Є1

1 Є2

2 3

fc

Є3

Confined Concrete Column with Strain Gradient 163

PU-MU INTERACTION CURVE CONSTRUCTION OF Pu-Mu INTERACTION DIAGRAM

ЄC d’ h/2

d

c

0.85 fy

a

Cs Cc

N.A.

h

Ts

b Єs

164

PU-MU INTERACTION CURVE Assumption In Pu-Mu Interaction Curve • The FRP confining effect applies to the compressive strength of concrete regardless to the extent of the compression zone. • As per above assumption P-M diagram can be constructed in same manner as for un strengthen column simply by replacing f’c by f’cc. Above assumption have limitation that it stats that compression zone is fully confined by FRP wrap while in real case FRP doesn’t encircle whole section.

165

PU-MU INTERACTION CURVE SQUARE SECTION

4 – 10 mm Dia bars

1 0 0 m m

6 mm @ 150 mm c/c 1000

mm

100 mm

166

PU-MU INTERACTION CURVE

STRENGTHENED COLUMN POINTS

Єs

c(mm)

Pu(kN)

Mu(kNm)

e(mm)

A

-

-

738.22

0

B

-

-

738.22

5.90

B1

0

90

438.52

12.16

B2

0.0011

70

324.98

12.57

C

0.00207

53.25

176.02

11.67

66.30

D

0.005

23.15

99.40

9.43

94.93

E

0.0314

15.18

0

5.54

-

0.01

167

PU-MU INTERACTION CURVE

UNWRAPPED COLUMN POINTS

Єs

c(mm)

Pu(kN)

Mu(kNm)

e(mm)

A

-

-

336.20

0

B

-

-

336.20

2.68

B1

0

90

136054.8

7.25

B2

0.0011

70

89728.43

6.99

C

0.00207

53.25

8399.49

5.61

66.30

D

0.005

23.15

3620.75

5.39

94.93

E

0.0314

15.18

0

4.86

-

0.01

168

PU-MU INTERACTION CURVE 800

A

700

600

500

400

) (kN u P

B

300

A

B

C

200

100

D C

0

0

5

10

15

M u (kNm)

D

E

169

CONCLUDING REMARKS

Benefits of FRP Wrapping Wrapping of fibers are in hoop direction performed very effectively during application of axial load. Overlap of 150 mm provided for circular and square columns proved sufficient. No de-bonding has been observed due to overlap. It also helped to utilize entire tensile strength of fibers and prevented premature failure of wrapped columns. 170

CONCLUDING REMARKS Test Setup Testing setup specially prepared for experiment has been able to function well during axial, eccentric and cyclic loading application. No movement during application of load has been observed during experiment. Unwrapped Columns Axial load carrying capacity of the unwrapped column is higher compared to eccentrically loaded columns. No change in axial load carrying capacity has been observed during axial cyclic loading. Higher ductility in the columns have been observed more for axially loaded columns compared to eccentrically loaded columns.

171

CONCLUDING REMARKS GFRP Wrapped Columns GFRP enhances ductility and load carrying capacity of RC columns. Fibers in GFRP wrapped columns remain in a hoop direction and behave very efficiently during the application of load. Failures observed in wrapped columns are local failure only and the same can be repaired easily in real structures. For eccentrically loaded columns, very less cracking has been observed and failure is due to rupture of GFRP which make concrete in columns undamaged. CFRP Wrapped Columns CFRP wrapped columns behave better compared to unwrapped and GFRP wrapped columns respectively. CFRP enhances ductility, load carrying capacity and energy dissipation 172 of RC columns.

CONCLUDING REMARKS

Energy Dissipation Energy dissipation observed in CFRP wrapped columns is higher compared to other columns. Increase in energy dissipation shows that CFRP enhance the ductility in RC columns. Energy dissipation in GFRP wrapped column is less compared to CFRP wrapped columns and higher than unwrapped columns respectively. It is clear indication of increase in ductility of RC columns due to FRP composites

173

FUTURE SCOPE OF WORK Experimental work can be extended further by selecting different wrapping techniques of GFRP and CFRP materials Investigations on durability of FRP materials and FRP-reinforced concrete subject to environmental loadings of different types Mechanical durability is also a concern for FRP. Fatigue and impact behavior of FRP materials is required to be studied Fire resistance of FRP materials or FRP-reinforced concrete is required to be studied Further investigation of the physical and chemical behavior of the FRP-to-concrete interface is to be carried out Study of failure modes and ductility capacity for lateral load for compression members, is required for using FRP-reinforced concrete in high seismic zones To propose new confinement model from results of experimental work. Development of the confinement model for FRP reinforced concrete subjected to lateral load Study of long-term costs and/or savings associated with use of FRP materials compared to traditional materials

174

ACKNOWLEDGEMENT

This Project has been funded under research grant by Gujarat Council of Science & Technology (GUJCOST)

175

THANKS

176

RESULTS COMPARISION & CONCLUSION Why Circular Section is the Best

177