Progress presentation ISISE, Department of Civil Engineering University of Minho, Guimarães, Portugal

USE OF NSM FRP FOR TORSIONAL STRENGTEHNING OF THIN WALLED TUBULAR RC STRUCTURES CHANDAN GOWDA Prof JOAQUIM BARROS UNIVERSITY OF MINHO

Contract Number MC-ITN-2013-607851

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Contents • • • • •

Introduction Strengthening techniques: Part I (400 x 400) Results Real case application Experimental work – FEM analysis – Activity

• Strengthening techniques: Part II (800 x 800) • Next steps

Contract Number MC-ITN-2013-607851

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Introduction: Beam details Beam: 400 x 400 x 1900 • • •

Compressive strength Tensile strength Modulus of elasticity

: 25 MPa : 2.0 MPa : 29000 MPa

Over strengthened region

Longitudinal Section

Cross Section Note: All dimensions are in mm*

Contract Number MC-ITN-2013-607851

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures Torque - Angle of rotation

Introduction: Parametric analysis • • • •

60 50

LY TY

Torque (kN-m)

Mesh variation Transverse diameter variation Longitudinal diameter variation Concrete compressive strength variation Torque - Angle of rotation

40 30 20 L12S6_100 L12S6_50

10

L12S6_25 0 -0.2

0.3

70

70

70

60

60

60

30

Moment (kN-m)

80

40

50 40

L10S6 L10S8 L10S10

10

30

0.5

1 Angle of rotation (degrees)

Contract Number MC-ITN-2013-607851

1.5

2

0

0.5

1 Angle of rotation (degrees)

1.5

LY TY

40 30 L10S8_C12/15 L10S8_C20/25 L10S8_C25/30 L10S8_C40/50

20 10

0

0 0

L8S8 L10S8 L12S8

10

1.8

50

20

20

1.3

80

80

50

0.8 Angle of rotation (degrees)

Torque - Angle of rotation

LY TY

Torque - Angle of rotation

Moment (kN-m)

Moment (kN-m)

70

2

0 0

0.5

1 1.5 Angle of rotation (degrees)

2

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Strengthening techniques: Part I (400 x 400) • FRP laminates – – – –

FRP_1: 2 in transverse direction & 2 in longitudinal direction FRP_2: 4 in transverse direction & 2 in longitudinal direction FRP_3: 2 in transverse direction & 4 in longitudinal direction FRP_4: 4 in transverse direction & 4 in longitudinal direction

134 mm

134 mm

65 mm

Contract Number MC-ITN-2013-607851

40 mm

80 mm

80 mm

65 mm

40 mm

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Results: Strengthened beams (400 x 400) • Torque - angle of rotation

LY TY

Torque - Angle of rotation

80

LY TY

Torque - Angle of rotation 70

80 70

60

Torque (kN-m)

Torque (kN-m)

60 50 40 30

50 40 L10S8

30

Strengthening 1

20

L10S8

Strengthening 2

20

10

Strengthening 1

Strengthening 3

Strengthening 2

Strengthening 4

0 0

0.5

101

1.5

Strengthening 3

2

Angle of rotation (degrees)

Strengthening 4

0 Contract Number MC-ITN-2013-607851

0

0.5

1

1.5

2

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Results: Strengthened beams (400 x 400) • Maximum angle of rotation and maximum moment Sl. No

Beam

Strengthening type

Max moment (kN∙m)

Max Angle of rotation (degrees)

Moment at rotation of 1.67 degrees (kN∙m)

Moment Increment (%)

1

L10S8

-

62.18

1.67

62.18

-

2

FRP_1

Longitudinal FRP at 134 mm & transverse FRP at 65 mm

69.64

1.87

66.25

6.55

3

FRP_2

Longitudinal FRP at 134 mm & transverse FRP at 40 mm

69.65

1.73

68.50

10.17

4

FRP_3

Longitudinal FRP at 80 mm & transverse FRP at 65 mm

69.44

1.67

69.44

11.68

5

FRP_4

Longitudinal FRP at 80 mm & transverse FRP at 40 mm

74.97

1.81

71.39

14.81

Contract Number MC-ITN-2013-607851

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Results: Strengthened beams (400 x 400) • Crack pattern

FRP_2

FRP_1

L10S8

FRP_3

FRP_4 *Fully opened crack status only

Contract Number MC-ITN-2013-607851

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Results: Strengthened beams (400 x 400) • FRP stress evolution and crack width of concrete LY TY

FRP stress - Angle of rotation 1000

LY TY

Crack width - Angle of rotation 0.25

IV

900 800

0.2 Crack width (mm)

FRP Stress (MPa)

700 600

0.15

III

500 400 300 200

0.05

frp_1 (E=60) II

100

0.1

frp_1 (E=60) frp_1 (E=160) frp_1 (E=240)

frp_1 (E=160)

I

frp_1 (E=240)

0

0 0

0.5

1 1.5 Angle of rotation (degrees)

Contract Number MC-ITN-2013-607851

2

2.5

0

0.5

1 1.5 Angle of rotation (degrees)

2

2.5

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Results: Strengthened Pre-stress beam • Stress evolution and crack width LY

Torque - Angle of rotation

LY

Crack width - Angle of rotation

TY

TY

0.25

80 70

0.2

Crack width (mm)

Torque (kN-m)

60 50 40

48%

30

0.15

0.1

20 0.05

frp_1 10

frp_1

frp_1 (p)

frp_1 (p)

L10S8

0

0 -0.5

0

0.5 1 Angle of rotation (degrees)

Contract Number MC-ITN-2013-607851

1.5

2

0

0.5

1 Angle of rotation (degrees)

1.5

2

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Experimental work: FEM analysis

F FIXED END

LOADING END TESTING BEAM

I-SECTION STEEL SECTION (10 MM) BOLTS (32 MM)

STEEL LOADING SECTION PINNED SUPPORT CIRCULAR ARC BEARING

CONCRETE BASE

TOP STEEL PLATE BOLT BOTTOM STEEL PLATE

Contract Number MC-ITN-2013-607851

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Experimental work: FEM analysis

Deformation Contract Number MC-ITN-2013-607851

Displacement in X-direction

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Experimental work: FEM analysis

Displacement in Y-direction Contract Number MC-ITN-2013-607851

Displacement in Z-direction

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Experimental work: Preparation • Data measuring instruments SG on transverse reinforcement

SG on longitudinal reinforcement

LVDT to measure the elongation/shortening

Fixed end

Loading end

LVDT to measure the rotation

Strain Gauge Digital camera LVDT Transverse reinforcement Longitudinal reinforcement

Contract Number MC-ITN-2013-607851

Digital camera

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Experimental work: Laboratory activity

Contract Number MC-ITN-2013-607851

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Experimental work: Laboratory activity

Contract Number MC-ITN-2013-607851

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Work in Progress: • FEM of 800*800*3600 beams • Effect of prestressing on larger section – Transverse FRP – Longitudinal FRP – Both transverse and longitudinal FRP

• Finite element model

Contract Number MC-ITN-2013-607851

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Work in Progress: Beam: 800 x 800 x 3600 • Compressive strength • Tensile strength • Modulus of elasticity (same reinforcement ratios)

: 43 MPa : 3.2 MPa : 34000 MPa

Note: All dimensions are in mm*

Contract Number MC-ITN-2013-607851

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Strengthening techniques: Part II (800 x 800) • FRP laminates • Strengthening with FRP (longitudinal & transverse) • Strengthening with FRP and pre-stress – Transverse FRP 25% and 50% – Longitudinal FRP 25% and 50%

• Both transverse and longitudinal 25% and 50%

Note: All dimensions are in mm*

Contract Number MC-ITN-2013-607851

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Results: Strengthened beams (800 x 800) • Torque - angle of rotation

LY

Torque - Angle of rotation

TY

700

Torsional moment (kN-m)

600 500

70%

L20S12 L0S0

400

L0S25 L0S50

300

L25S0 L50S0

200

L25S25 L50S50

100 0 0

Contract Number MC-ITN-2013-607851

0.2

0.4

0.8 0.6 Angle of rotation (degrees)

1

1.2

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Preliminary conclusions: • Increase in torsional moment of the section • Similar behavior of smaller and larger section • Pre-stress more effective in larger section – 400 x 400 section: Tcr = +48% – 800 x 800 section: Tcr = +70%

Next Steps: • Analyze results of 800*800*3600 beams • Experimental work – Casting more beams – Strengthening, testing, data analysis

• Final numerical analysis Contract Number MC-ITN-2013-607851

Chandan C Gowda Use of NSM FRP for torsional strengthening of thin walled tubular RC structures

Thank you (http://www.endure-itn.eu)

Contract Number MC-ITN-2013-607851