Rehabilitation of Concrete Structures with Fiber-Reinforced Polymer

1. Introduction

1.1 Need for Rehabilitation and

Strengthening

1.2 Structural Degradation of Concrete

Structures

1.3 Strengthening of Concrete Structures

Using FRP Composites

1.3.1 Strengthening of RC Members

in Flexure

1.3.2 Strengthening of RC Members

in Shear

1.3.3 Confinement of Axial Members

Using FRP

2. Methods of Structural Rehabilitation

and Strengthening

2.1 Externally Bonded Steel Plates

2.2 External Posttensioning

2.3 Jacketing of Structural Members

2.4 Rehabilitation of Reinforcement

Corrosion

2.5 Crack Injection

2.6 Selection of Appropriate Strengthening

Technique

References

3. Fiber-Reinforced Polymers and Their

Use in Structural Rehabilitation

3.1 Materials and Manufacturing

3.2 Wet Layup Systems

3.3 Prepreg Systems

3.4 Precured Systems

3.5 Near-Surface-Mounted FRP Systems

3.5.1 Bond Behavior

3.5.2 Modes of Failure

3.6 Prestressed FRP

3.6.1 S&P Prestressed FRP Systems

3.6.2 Carbo-Stress System (Stress Head)

References

4. Design Basis for FRP Systems

4.1 Strengthening Limits

4.2 Structural Fire Endurance

4.3 Environmental Considerations

4.3.1 Moisture—Humidity/Chemical

Attack

4.3.2 Hygrothermal Aging of Epoxy Resin

4.3.3 Alkalinity

4.3.4 Thermal Effects and Freeze/Thaw

Conditions

4.3.5 Ultraviolet Radiation

4.3.6 Design Recommendations

References

5. Strengthening Members in Flexure

Using FRP

5.1 General

5.2 Basis of Design

5.3 Rectangular Stress Block

5.4 Failure Modes of FRP Flexurally

Strengthened Members

5.4.1 Concrete Crushing

5.4.2 FRP Rupture

5.4.3 Intermediate Crack-Induced

Debonding

5.4.4 End Debonding

5.4.5 Use of U-Strap Anchors to Mitigate

End Debonding

5.5 Ductility of FRP-Strengthened Members

5.6 FRP Termination and Anchorage

5.7 Serviceability Considerations

5.8 Creep Rupture and Fatigue Stress

Limits

5.9 Design Summary Flow Charts for

Flexurally Strengthened Members

5.9.1 Flexural Strengthening Flow Chart

According to AS 5100.8 (2017)

5.9.2 Flexural Strengthening Flowchart

According to ACI 440.2R (2017)

5.9.3 Flexural Strengthening Flowchart

According to TR 55 (2012)

5.10 Flexural Strengthening Examples

5.10.1 Flexural Strengthening of an RC

T Beam According to AS 5100.5

(2017) and AS 5100.8 (2017)

5.10.2 Flexural Strengthening of a

Prestressed Super-T beam

According to AS 5100.5 (2017)

and AS 5100.8 (2017)

5.10.3 Flexural Strengthening of an

RC T-Beam According to ACI 318

(2014) and ACI 440.2R (2017)

5.10.4 Flexural Strengthening of a

Prestressed Super-T Beam

According to ACI 318 (2014)

and ACI 440.2R (2017)

5.10.5 Flexural Strengthening of an RC

T-Beam According to BS EN

1992–1-1 (24) and Technical

Report No. 55 (2012)

5.10.6 Flexural Strengthening of a

Prestressed Super-T Beam

According to BS EN1992–1:1(24)

and Technical Report No. 55

(2012)

References

Further Reading

6. Strengthening Members in Shear

Using FRP

6.1 Introduction

6.2 Concept of Safety in Design

6.3 Contribution of Concrete to Shear

Capacity of Prestressed Members

6.4 Contribution of Concrete to Shear

Capacity of Prestressed Members

6.5 Shear Contribution of Transverse Shear

Reinforcement

6.6 Design of Concrete Members

Strengthened in Shear Using FRP

6.6.1 Failure Modes

6.6.2 Contribution of FRP to Shear

Capacity

6.7 Design Summary Flowcharts for

Shear-Strengthened Members

6.7.1 Shear-Strengthening Flow Chart

According to AS5100.8 (2017)

6.7.2 Shear-Strengthening Flow Chart

According to TR55 (2012)

6.8 Shear-Strengthening Examples

6.8.1 Shear Strengthening of an RC

T-Beam According to AS5100.5 (2017)

and AS5100.8 (2017)

6.8.2 Shear Strengthening of a Prestressed

Super T-beam According to AS5100.5

(2017) and AS5100.8 (2017)

6.8.3 Shear Strengthening of an RC

T-beam According to ACI Committee

318 (2014) and ACI440.2 (2017)

6.8.4 Shear Strengthening of a Prestressed

Super T-beam According to ACI

Committee 318 (2014) and ACI 440.2

(2017)

6.8.5 Shear Strengthening of a RC

T-beam According to BS EN 1992-1-1

(24) and Technical Report No. 55

6.8.6 Shear Strengthening of a Prestressed

Super T-beam According to BS EN

1992-1-1 (24) and Technical

Report No. 55

References

Further Reading

7. Axial Strengthening of RC Members

Using FRP

7.1 General

7.2 Confinement Under Concentric

Axial Load

7.2.1 ACI and AS 5100 Models for

Confined Circular Columns

7.2.2 ACI and AS 5100 Models for

Confined Rectangular Columns

7.2.3 TR 55 Model for Confined Circular

Columns

7.2.4 TR 55 Model for Confined

Rectangular Columns

7.2.5 Confinement of Slender

Columns

7.2.6 Ultimate Strength in Compression

of a Short Column

7.3 Combined Axial Compression and

Flexure

7.3.1 Diagram of Axial Moment

Interaction for Rectangular and

Circular Sections

7.3.2 Ultimate Strength in Compression

of a Slender Column

7.4 Serviceability Considerations

7.5 Design Summary Flowcharts for Axially

Strengthened Members

7.5.1 Axial Strengthening Flowchart

According to ACI 440.2 (2017)

7.5.2 Axial Strengthening Flowchart

According to AS5100.8 (2017)

7.5.3 Axial Strengthening Flowchart

According to Technical

Report No. 55

7.6 Axial Strengthening Examples

7.6.1 Axial Strengthening of a Circular

Column According to AS5100.5 (2017)

and AS5100.8 (2017)

7.6.2 Axial strengthening of a

rectangular column according to

AS5100.5 (2017) and AS5100.8

(2017)

7.6.3 Axial Strengthening of a Circular

Column According to

ACI 318 (ACI Committee 318, 2014)

and ACI 440.2 (2017)

7.6.4 Axial Strengthening of a

Rectangular Column According to

ACI Committee 318 (2014) and

ACI 440.2 (2017)

7.6.5 Axial Strengthening of a Circular

Column According to BS EN

1992-1-1 (24) and

Technical Report No. 55

7.6.6 Axial Strengthening of a Rectangular

Column According to BS EN

1992-1-1 (24) and

Technical Report No. 55

References

Further Reading

8. FRP Anchorage Systems

8.1 Introduction

8.2 Anchorage Devices for FRP

Reinforcement Used to Strengthen

Members in Flexure

8.2.1 FRP U-jacket Anchors

8.2.2 Inclined U-jacket Orientations

8.2.3 Prestressed U-jackets

8.2.4 Metallic Anchorage Systems

8.2.5 FRP Anchors

8.2.6 p-Anchor

8.2.7 Evaluation of FRP Anchorage

Systems Used to Strengthen

Members in Flexure

8.3 Flexural Anchor Discussion

8.4 Mechanisms of FRP Failure in Shear

Strengthening Applications

8.5 Anchorage Devices for FRP

Reinforcement Used to Strengthen

Members in Shear

8.5.1 Mechanically Fastened Metallic

Anchors in Shear and Torsion

Applications

8.5.2 Anchorage of FRP Through

Concrete Embedment

8.5.3 FRP Spike Anchors in Shear

Applications

8.5.4 Patch Anchors

8.5.5 Hybrid (FRP Anchors+Patch

Anchors)

8.5.6 Substrate Strengthening

8.5.7 NSM Anchors

8.5.8 Evaluation of FRP Anchors

Used to Strengthen Members

in Shear

8.6 Shear Anchor Discussion

8.7 Further Work and Development of

Design Provisions

8.8 Conclusions and Recommendations

References

Further Reading

9. Installation and Testing of FRP

Systems

9.1 General

9.2 Preparation

9.2.1 Concrete Substrate

9.2.2 Concrete Flatness

9.2.3 Leveling of the Substrate

9.2.4 Environmental Conditions

9.2.5 Set Out

9.3 Application of Pultruded FRP Laminate

Systems

9.4 Application of FRP Fabrics

9.5 Quality Control

9.5.1 Testing of Substrate Prior to

Application of FRP

9.5.2 Adhesion and Durability

9.5.3 Visual Inspections

9.6 Repair Techniques

9.7 Cold Weather Application/Accelerated

Curing

9.8 Hot Weather Application

References

Further Reading

10. Field Applications

10.1 West Gate Bridge Project

10.1.1 Modeling

10.1.2 Selection of Material

10.1.3 Detailing

10.1.4 Application and Quality Control

10.2 Strengthening of Posttensioned Slabs

at White City London

10.2.1 Method of Works

10.2.2 Aspects of Construction

10.2.3 Testing and Approval

10.2.4 Summary

Acknowledgments

References

Further Reading