Shear Strengthening of Reinforced Concrete Beams Using Fiber-Reinforced Polymer Wraps

Figures and Tables

Figure 1. Joist configuration.

Figure 2. Joist prestressing tendon profile.

Figure 3. HJ-3 and HJ-4 web reinforcement.

Figure 4. FRP joist repair.

Figure 5. High-performance concrete strength versus time.

Figure 6. Prestressing tendon stress versus strain.

Figure 7. Prestressing and casting of hybrid joists.

Figure 8. Completed hybrid joist construction.

Figure 9. FRP application.

Figure 10. Gap in FRP upgrade of HJ-3.

Figure 11. Epoxy injection of voids.

Figure 12. Internal strain gage layout for HJ-3, HJ-4, HJ-6, and HJ-7.

Figure 13. External strain gage layout on HJ-3.

Figure 14. External strain gage layout on HJ-4.

Figure 15. LVDT locations on test specimens.

Figure 16. Potentiometer locations on test specimens.

Figure 17. Block diagram of data recording system.

Figure 18. Test setup.

Figure 19. Load versus deflection for HJ-3, HJ-4, HJ-6, and HJ-7.

Figure 20. Load versus deflection cycles for HJ-4.

Figure 21. Deflected shape for HJ-3.

Figure 22. Deflected shape for HJ-4 before repair (top) and after FRP repair (bottom).

Figure 23. Deflected shape of HJ-6.

Figure 24. Deflected shape for HJ-7.

Figure 25. Strain distribution for HJ-3.

Figure 26. Strain distribution for HJ-4.

Figure 27. Strain distribution for HJ-6.

Figure 28. Strain distribution for HJ-7.

Figure 29. Strain distribution along strand length of HJ-3.

Figure 30. Strain distribution along strand length of HJ-4.

Figure 31. Strain distribution along strand length of HJ-6.

Figure 32. Strain distribution along strand length of HJ-7.

Figure 33. HJ-3 upgrade FRP strains.

Figure 34. HJ-4 repair FRP strains.

Figure 35. Crack patterns for HJ-6.

Figure 36. Failure of HJ-6.

Figure 37. Crack patterns for HJ-7.

Figure 38. Crack patterns for HJ-3.

Figure 39. Failure of HJ-3.

Figure 40. Crack Patterns of HJ-4 prior to FRP repair.

Figure 41. Crack patterns for HJ-4.

Figure 42. Shear repair design procedure.

Figure 43. Simply supported beam.

Figure 44. Shear diagram.

Figure 45. FRP wrap repair.

Table 1. Hybrid Joists Tested

Joist Designation	Configuration	Web Shear Reinforcement	Slab Width (ft)
HJ-3	Upgraded with FRP	Figure 4.6	6
HJ-4	Tested, then repaired with FRP	Figure 4.6	6
HJ-6	Insufficient shear reinforcement	Figure 4.8	4
HJ-7	Proper shear reinforcement	Figure 4.8	4

Table 2. Epoxy Material Properties

Property	Average	Minimum	Test Method
-Tg @ 45% RH	120^OF	100^OF
-Tg @ 95% RH	110^OF	95^OF
-Tg 140OF Postcure (24 Hours)	180^OF	140^OF
Tensile Strength	10,100 psi	9,500 psi	ASTM D 638 Type 1
Tensile Modulus	461,000 psi	425000 psi	ASTM D 638 Type 1
Elongation Percent	5.00%	3.50%	ASTM D 638 Type 1
Flexural Strength	11,500 psi	10,500 psi	ASTM D 790
Flexural Modulus	400,000 psi	375,000 psi	ASTM D 790

Curing Schedule 72 hours post cure at 140^OF

Table 3. Yarn Properties

Property	E-glass	Polyaramid	Test Method
Yield/Denier	1200 and 250 ypp	2160 denier
Density (g/cc)	2.54	1.44	ASTM D 792
Tensile Strength (psi)	440,000	400,000	SIM 13*
Tensile Modulus (psi)	10,500,000	17,000,000	STM 13
Elongation (%)	4.2	2.5	STM 13

* Seguin Test Method - Hexel Manufacturing facility standard methods based on appropriate Standardized testing procedure

Table 4. Fabric Properties

Property	Average Value	Minimum Value	Test Method
Areal Weight (oz/sq. yd.)	27.2	24.4	STM 18
Tensile Strength dry 1" strip (Break Load lb.)	1800	1600	STM 27
Air Permeability (cu. ft./min.)	22	20	STM 26

Table 5. Composite Laminate Specification

Property	Value	ASTM Method
Ultimate Tensile Strength min. (primary fiber direction)*	65,000 psi	D 3039
Elongation at break, min.	2.00%	D 3039
Tensile Modulus	3.0 x 10⁶ psi
Ultimate Tensile Strength min. (90 degrees to primary fiber direction)	4,800 psi	D 3039

* Tensile retained 7 days @ 100% RH, 1,000 hours ozone, 1,000 hours alkali, 1,000 hours salt water, and 1,000 hours at 140^OF
Cured for 48 hours at 140^oF Using Hexcel Sample Preparation

Table 6. Composite Material Properties

Property	Value	Test Method
Tensile Strength at 0^o (ksi)	65	ASTM D3039
Tensile Strength at 90^o (ksi)	6.0	ASTM D3039
Elastic Modulus (ksi)	3,250
Ultimate Strain	0.02	ASTM D3039
Coefficient of Thermal Expansion	4.3 x 10^-6

Table 7. Casting and Release Dates for Each Hybrid Joist Web

Specimen	Casting Date	Release Date
HJ-3	1/29/96	2/5/96
HJ-4	1/29/96	2/5/96
HJ-6	2/12/96	2/16/96
HJ-7	6/20/96	6/24/96

Table 8. Instrumentation for HJ-3 Upgraded With FRP

Hybrid Joist Test

HJ-3

Date:

August 12, 1996

USA Construction Engineering Research Laboratories

Champaign, IL

CERL

CIR

Conversion

Location

Gage

Instrument

Name/

Name

Factor

(X - Dir.)

(Y - Dir.)

Length

Comments

Cable #

(per volt)

(in.)

Cell_N

N / A

5.000 kips

141.000

N / A

Concentrated Load - 50 Kip Actuator

Stroke_N

N / A

0.300 inches

141.000

N / A

Cell_S

N / A

5.000 kips

250.000

N / A

Concentrated Load - 50 Kip Actuator

Stroke_S

N / A

0.300 inches

250.000

N / A

POT_N

N / A

1.994 inches

141.000

N / A

Third span Deflection - Potentiometer

POT_Mid

N / A

1.996 inches

192.000

N / A

Midspan Deflection - Potentiometer

POT_S

N / A

2.000 inches

278.000

N / A

Quarter span Deflection - Potentiometer

Int_1

IS1 / 3

s19

0.00150 in/in

40.000

N / A

Placed by the CIR

Int_2

IS2 / 2

s20

0.00150 in/in

40.000

N / A

Placed by the CIR

Int_3

IS3 / 1

s21

0.00150 in/in

40.000

N / A

Placed by the CIR

Int_4

IS4 / 12

s28

0.00150 in/in

141.000

N / A

Placed by the CIR

Int_5

IS5 / 11

s26

0.00150 in/in

119.000

N / A

Placed by the CIR

Int_6

IS6 / 10

s30

0.00150 in/in

141.000

N / A

Placed by the CIR

Int_7

IS7 / 15

s31

0.00150 in/in

163.000

N / A

Placed by the CIR

Int_8

IS8 / 14

s27

0.00150 in/in

119.000

N / A

Placed by the CIR

Int_9

IS9 / 13

s33

0.00150 in/in

163.000

N / A

Placed by the CIR

Int_10

IS10 / 18

s34

0.00150 in/in

192.000

N / A

Placed by the CIR

Int_11

IS11 / 17

s35

0.00150 in/in

192.000

N / A

Placed by the CIR

Int_12

IS12 / 16

s36

0.00150 in/in

192.000

N / A

Placed by the CIR

LVDT_1

N / A

0.00500 in.

75.500

1.000

7.205

Measured from the Top of the Slab

LVDT_2

N / A

0.00500 in.

74.000

3.000

6.417

Measured from the Bottom Face of the Slab

LVDT_3

N / A

0.00500 in.

73.000

12.250

4.134

Measured from the Bottom Face of the Slab

LVDT_4

N / A

0.00500 in.

145.000

1.000

6.220

Measured from the Top of the Slab

LVDT_5

N / A

0.00500 in.

143.000

3.500

7.480

Measured from the Bottom Face of the Slab

LVDT_6

N / A

0.00500 in.

142.500

11.000

2.677

Measured from the Bottom Face of the Slab

LVDT_7

N / A

0.00500 in.

142.000

22.750

2.756

Measured from the Bottom Face of the Slab

LVDT_8

N / A

0.00500 in.

170.500

1.000

7.520

Measured from the Top of the Slab

LVDT_9

N / A

0.00500 in.

N / A

Not used for this test, Sensor moved to D7

LVDT_10

D10

N / A

0.00500 in.

169.250

22.750

5.630

Measured from the Bottom Face of the Slab

LVDT_11

D11

N / A

0.00500 in.

193.500

1.000

5.276

Measured from the Top of the Slab

LVDT_12

D12

N / A

0.00500 in.

194.000

3.000

5.433

Measured from the Bottom Face of the Slab

LVDT_13

D13

N / A

0.00500 in.

194.000

22.500

5.039

Measured from the Bottom Face of the Slab

LVDT_14

D14

N / A

0.00500 in.

193.500

N / A

5.197

Placed on top of Slab

LVDT_15

D15

N / A

0.00500 in.

243.000

N / A

2.677

Not used for this test

LVDT_16

D16

N / A

0.00500 in.

194.000

N / A

6.850

Placed on bottom side of Web

LVDT_17

D17

N / A

- 0.00500 in.

222.000

2.250

2.677

Measured from the Bottom Face of the Slab

LVDT_18

D18

N / A

0.00500 in.

222.000

22.500

4.803

Measured from the Bottom Face of the Slab

LVDT_19

D19

N / A

- 0.00500 in.

242.000

10.000

3.268

Measured from the Bottom Face of the Slab

LVDT_20

D20

N / A

0.00500 in.

242.000

22.000

2.480

Measured from the Bottom Face of the Slab

Ext. Str._1

ES1

N / A

0.00150 in/in

Ext. Str._2

ES2

N / A

0.00150 in/in

Ext. Str._3

ES3

N / A

0.00150 in/in

See Attached Figure for External

Ext. Str._4

ES4

N / A

0.00150 in/in

Strain Gage Locations

Ext. Str._5

ES5

N / A

0.00150 in/in

Ext. Str._6

ES6

N / A

0.00150 in/in

Ext. Str._7

ES7

N / A

0.00150 in/in

Ext. Str._8

ES8

N / A

0.00150 in/in

*** +X direction is defined as running north to south with north being 0. Measurements taken to the north face of the LVDT blocks.

*** +Y direction is defined as running up to down with 0 being the bottom face of the slab, except where noted that measurement was taken from the top of the slab. Measurement was taken to the middle of the circular opening in the block.

IMPORTANT NOTE: Sensor for D7 was not working. Sensor from D9 was placed in location of D7.

Table 9. Instrumentation for HJ-4 Without FRP Repair

Hybrid Joist Test

HJ-4

Date: June 3, 1996

USA Construction Engineering Research Laboratories

(First Test without FRP)

CERL

CIR

Conversion

Location

Gage

Instrument

Name/

Name

Factor

(X - Dir.)

(Y - Dir.)

Length

Comments

Cable #

(per volt)

(in.)

Cell_N

N / A

5.000 kips

141.000

N / A

Concentrated Load - 50 Kip Actuator

Stroke_N

N / A

0.300 inches

141.000

N / A

Cell_S

N / A

5.000 kips

250.000

N / A

Concentrated Load - 50 Kip Actuator

Stroke_S

N / A

0.300 inches

250.000

N / A

POT_N

N / A

1.994 inches

141.000

N / A

Third span Deflection - Potentiometer

POT_Mid

N / A

1.996 inches

192.000

N / A

Midspan Deflection - Potentiometer

POT_S

N / A

2.000 inches

278.000

N / A

Quarter span Deflection - Potentiometer

Int_1

IS1 / 19

s19

0.00150 in/in

40.000

N / A

Placed by the CIR

Int_2

IS2 / 16

s20

0.00150 in/in

40.000

N / A

Placed by the CIR

Int_3

IS3 / 21

s21

0.00150 in/in

40.000

N / A

Placed by the CIR

Int_4

IS4 / 28

s28

0.00150 in/in

141.000

N / A

Placed by the CIR

Int_5

IS5 / 26

s26

0.00150 in/in

119.000

N / A

Placed by the CIR

Int_6

IS6 / 30

s30

0.00150 in/in

141.000

N / A

Placed by the CIR

Int_7

IS7 / 31

s31

0.00150 in/in

163.000

N / A

Placed by the CIR

Int_8

IS8 / 27

s27

0.00150 in/in

119.000

N / A

Placed by the CIR

Int_9

IS9 / 33

s33

0.00150 in/in

163.000

N / A

Placed by the CIR

Int_10

IS10 / 34

s34

0.00150 in/in

192.000

N / A

Placed by the CIR

Int_11

IS11 / 35

s35

0.00150 in/in

192.000

N / A

Placed by the CIR

Int_12

IS12 / 36

s36

0.00150 in/in

192.000

N / A

Placed by the CIR

LVDT_1

N / A

0.00494 in.

72.750

1.000

7.205

Measured from the Top of the Slab

LVDT_2

N / A

0.00497 in.

71.375

3.000

6.063

Measured from the Bottom Face of the Slab

LVDT_3

N / A

0.00495 in.

69.125

12.250

2.913

Measured from the Bottom Face of the Slab

LVDT_4

N / A

0.00497 in.

145.125

1.000

5.748

Measured from the Top of the Slab

LVDT_5

N / A

0.00496 in.

143.375

3.500

5.197

Measured from the Bottom Face of the Slab

LVDT_6

N / A

0.00496 in.

143.375

11.000

2.559

Measured from the Bottom Face of the Slab

LVDT_7

N / A

0.00496 in.

142.375

22.750

5.236

Measured from the Bottom Face of the Slab

LVDT_8

N / A

0.00495 in.

168.125

1.000

5.236

Measured from the Top of the Slab

LVDT_9

N / A

0.00496 in.

167.375

3.000

2.441

Measured from the Bottom Face of the Slab

LVDT_10

D10

N / A

0.00499 in.

168.375

22.750

2.441

Measured from the Bottom Face of the Slab

LVDT_11

D11

N / A

0.00489 in.

195.000

1.000

6.417

Measured from the Top of the Slab

LVDT_12

D12

N / A

0.00496 in.

193.875

3.000

7.283

Measured from the Bottom Face of the Slab

LVDT_13

D13

N / A

0.00496 in.

195.500

22.500

5.197

Measured from the Bottom Face of the Slab

LVDT_14

D14

N / A

0.00491 in.

194.750

N / A

6.260

Placed on top of Slab

LVDT_15

D15

N / A

0.00496 in.

N / A

Not used for this test, Sensor moved to D13

LVDT_16

D16

N / A

0.00500 in.

195.250

N / A

6.299

Placed on bottom side of Web

LVDT_17

D17

N / A

-0.00503 in.

220.000

2.250

7.638

Measured from the Bottom Face of the Slab

LVDT_18

D18

N / A

0.00487 inches

220.375

22.500

4.055

Measured from the Bottom Face of the Slab

LVDT_19

D19

N / A

-0.00501 in.

244.000

10.000

2.362

Measured from the Bottom Face of the Slab

LVDT_20

D20

N / A

0.00500 in.

244.125

22.000

2.717

Measured from the Bottom Face of the Slab

*** +X direction is defined as running north to south with north being 0. Measurements taken to the north face of the LVDT blocks.

IMPORTANT NOTES: Sensor for D15 was moved into the D13 position. D15 position was not used.

Table 10. Instrumentation for HJ-4 With FRP Repair



Hybrid Joist Test						HJ-4		(2nd Test with FRP)
USA Construction Engineering Research Laboratories
Champaign, IL
Date:	August 2 1996

	CERL	CIR	Conversion	Location	Location	Gage
Instrument	Name	Name	Factor	(X - Dir.)	(Y - Dir.)	Length	Comments
	/ Cable #		(per volt)	(in.)	(in.)	(in.)
Cell_N		N / A	5.000 kips	141.000	N / A	N / A	Concentrated Load - 50 Kip Actuator
Stroke_N		N / A	0.300 inches	141.000	N / A	N / A
Cell_S		N / A	5.000 kips	250.000	N / A	N / A	Concentrated Load - 50 Kip Actuator
Stroke_S		N / A	0.300 inches	250.000	N / A	N / A
POT_N	P1	N / A	2.000 inches	141.000	N / A	N / A	Third span Deflection - Potentiometer
POT_Mid	P2	N / A	2.000 inches	192.000	N / A	N / A	Midspan Deflection - Potentiometer
POT_S	P3	N / A	2.000 inches	278.000	N / A	N / A	Quarter span Deflection - Potentiometer
Int_1	IS1 / 19	s19	0.00150 in/in	40.000	N / A	N / A	Placed by the CIR
Int_2	IS2 / 16	s20	0.00150 in/in	40.000	N / A	N / A	Placed by the CIR
Int_3	IS3 / 21	s21	0.00150 in/in	40.000	N / A	N / A	Placed by the CIR
Int_4	IS4 / 28	s28	0.00150 in/in	141.000	N / A	N / A	Placed by the CIR
Int_5	IS5 / 26	s26	0.00150 in/in	119.000	N / A	N / A	Placed by the CIR
Int_6	IS6 / 30	s30	0.00150 in/in	141.000	N / A	N / A	Placed by the CIR
Int_7	IS7 / 31	s31	0.00150 in/in	163.000	N / A	N / A	Placed by the CIR
Int_8	IS8 / 27	s27	0.00150 in/in	119.000	N / A	N / A	Placed by the CIR
Int_9	IS9 / 33	s33	0.00150 in/in	163.000	N / A	N / A	Placed by the CIR
Int_10	IS10 / 34	s34	0.00150 in/in	192.000	N / A	N / A	Placed by the CIR
Int_11	IS11 / 35	s35	0.00150 in/in	192.000	N / A	N / A	Placed by the CIR
Int_12	IS12 / 36	s36	0.00150 in/in	192.000	N / A	N / A	Placed by the CIR
LVDT_1	D1	N / A	0.00500 inches	72.750	1.000	7.205	Measured from the Top of the Slab
LVDT_2	D2	N / A	0.00500 inches	69.000	3.000	6.000	Measured from the Bottom Face of the Slab
LVDT_3	D3	N / A	0.00500 inches	68.500	12.000	3.125	Measured from the Bottom Face of the Slab
LVDT_4	D4	N / A	0.00500 inches	145.125	1.000	5.748	Measured from the Top of the Slab
LVDT_5	D5	N / A	0.00500 inches	143.375	3.500	5.197	Measured from the Bottom Face of the Slab
LVDT_6	D6	N / A	0.00500 inches	143.375	11.000	2.559	Measured from the Bottom Face of the Slab
LVDT_7	D7	N / A	0.00500 inches	142.375	22.750	5.236	Measured from the Bottom Face of the Slab
LVDT_8	D8	N / A	0.00500 inches	168.125	1.000	5.236	Measured from the Top of the Slab
LVDT_9	D9	N / A	N / A	N / A	N / A	N / A	Not used for this test, Sensor moved to D5
LVDT_10	D10	N / A	0.00500 inches	168.375	22.750	2.441	Measured from the Bottom Face of the Slab
LVDT_11	D11	N / A	0.00500 inches	195.000	1.000	6.417	Measured from the Top of the Slab
LVDT_12	D12	N / A	0.00500 inches	193.875	3.000	7.283	Measured from the Bottom Face of the Slab
LVDT_13	D13	N / A	0.00500 inches	195.500	22.500	5.197	Measured from the Bottom Face of the Slab
LVDT_14	D14	N / A	0.00500 inches	194.750	N / A	6.260	Placed on top of Slab
LVDT_15	D15	N / A	N / A	N / A	N / A	N / A	Not used for this test, Sensor moved to D13
LVDT_16	D16	N / A	0.00500 inches	195.250	N / A	6.299	Placed on bottom side of Web
LVDT_17	D17	N / A	- 0.00500 in.	220.000	2.250	7.638	Measured from the Bottom Face of the Slab
LVDT_18	D18	N / A	0.00500 inches	220.375	22.500	4.055	Measured from the Bottom Face of the Slab
LVDT_19	D19	N / A	- 0.00500 in.	244.000	10.000	2.362	Measured from the Bottom Face of the Slab
LVDT_20	D20	N / A	0.00500 inches	244.125	22.000	2.717	Measured from the Bottom Face of the Slab
Ext. Str._1	ES1	N / A	0.00150 in / in
Ext. Str._2	ES2	N / A	0.00150 in / in
Ext. Str._3	ES3	N / A	0.00150 in / in		See Attached Figure for External Strain Gage Locations
Ext. Str._4	ES4	N / A	0.00150 in / in
Ext. Str._5	ES5	N / A	0.00150 in / in
Ext. Str._6	ES6	N / A	0.00150 in / in
Ext. Str._7	ES7	N / A	0.00150 in / in
Ext. Str._8	ES8	N / A	0.00150 in / in
*** +X direction is defined as running north to south with north being 0. Measurements taken to the north face of the LVDT blocks.
*** +Y direction is defined as running up to down with 0 being the bottom face of the slab, except where noted that measurement was taken from the top of the slab. Measurement was taken to the middle of the circular opening in the block.
IMPORTANT NOTES:
Sensor for D15 was moved into the D13 position. D15 position was not used.
Sensor for D9 was moved into the D5 position. D9 position was not used.

Table 11. Principal Experimental Test Results for Hybrid Joists

Joist designation	Experimental cracking load* (kips)	First Crack Location	Applied *Failure load (kips)**	Total Failure Load (kips)	Equivalent Uniform Load (ksf)	Type of failure
HJ-3		midspan, bottom chord	52.0	53.0	0.62	shear
HJ-4		midspan, bottom chord	56.6	56.6**	0.67	no failure
HJ-6	11.7	midspan, bottom chord	48.0	49.0	0.57	shear
HJ-7	31.5	midspan bottom chord	64.0	65.0	0.76	flexure

* Sum of two actuators.
**No failure occurred.

Table 12. Camber and Deflection for Hybrid Joists (in.)

Joist designation	Camber at release	LL Deflection	SIDL + LL Deflection	Deflection at peak load	Deflection at failure
HJ-3	0.40	.09	.14	5.66	12.58
HJ-4 without FRP	0.45	.10	.16	7.66	7.67*
HJ-4 with FRP repair	NA	.10	.16	8.62	10.06*
HJ-6	0.45	0.03	0.16	3.52	3.52
HJ-7	0.38	0.02	0.14	16.6	16.6

* Deflection at end of test; no failure occurred.

CERL DISTRIBUTION

Chief of Engineers

ATTN: CEHEC-IM-LH (2)
ATTN: CEHEC-IM-LP (2)
ATTN: CECW
ATTN: CECW-O
ATTN: CECW-P
ATTN: CECW-PR
ATTN: CEMP-CE
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ACS(IM) 22060

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