Design Procedures for the Use of Composites in Strengthening of Reinforced Concrete Structures (eBook)

Contents 6
RILEM Publications 8
1 Introduction 16
Abstract 16
Introduction 16
2 Design by Testing and Statistical Determination of Capacity Models 20
Abstract 20
Introduction 20
Probabilistic Capacity Models: Analytical Definition 21
Calibration of Partial Safety Factors Based on Testing 23
Application 1---End Debonding 27
Theoretical Formulations of Debonding Load 28
Experimental Database 31
Calibration Procedure 32
Application to the Experimental Database 35
Application 2---Intermediate Debonding 43
Experimental Database 44
Procedure and Application 46
References 50
3 Bond Between EBR FRP and Concrete 54
Abstract 54
General Aspects 54
Mechanism of Debonding Failure 54
Anchorage Length 57
Effect of Surface Preparation 60
Bond as a Fracture Mechanics Process 62
Introduction 62
Direct-Shear Tests 64
Cohesive Material Law 67
Interfacial Fracture Energy 68
Concluding Remarks 70
Cyclic Loads 72
Experimental Analysis of Debonding 75
Existing Experimental Set-Ups 75
Comparison of Experimental Results of Different Set-Ups 78
Intermediate Debonding 81
Bond Law Identification Method 84
Existing Models and Code Formulations 88
Theoretical Models 89
Code Formulations 91
Assessment of Code Formulations Pellegrino 95
Critical Issues of Models and Experimental Procedures 97
Fib Bulletin 14 (New Formulation) 99
References 104
4 Shear Strengthening of RC Elements by Means of EBR FRP Systems 112
Abstract 112
Introduction 113
Current Formulations and Models on Shear Strengthening of RC Elements by Means of EBR FRP Systems 114
fib TG 9.3 (2001) 115
CNR DT-200 (2004) and CNR DT-200R1 (2012) 116
Main Differences Between DT-200R1 and the Previous DT-200 118
FRP Layout 118
Design Shear Capacity 119
Optimal Anchoring Length 119
Specific Fracture Energy 119
Geometric Coefficient Kb 120
Design Value of FRP Debonding Strength 120
ACI 440 (2008) 121
Eurocode 8 122
Chen and Teng (2003a, b) 123
Carolin and Taljsten (2005) 124
Pellegrino and Modena (2008) 125
Bukhari et al. (2010) 127
Modifi and Chaallal (2011) 127
Assessment of Current Formulations and Models on Shear Strengthening of RC Elements by Means of EBR FRP Systems 129
Experimental Validation 129
Design Comparison 133
Lacunae and Proposals of Improvement for Current Formulations and Models on Shear Strengthening of RC Elements by Means of EBR FRP Systems 137
Revised Model for EBR FRP Shear-Strengthening 138
Needs for Future Work 142
References 143
5 Confinement of RC Elements by Means of EBR FRP Systems 146
Abstract 146
General Aspects 147
Database of Published Tests 150
Behaviour of FRP-Jacketed Concrete in Uniaxial Compression 155
Estimation of the FRP Effective Ultimate Strain 161
Reduced Jacket Effectiveness Due to Pore Compaction of Confined Concrete 169
Confinement Models from Design Codes (CNR, ACI, EC8-III, Fib) 171
Confined Strength Formulae for Jacketed Reinforced Concrete Columns---Considering the Interaction with Reinforcement 173
Lacunae and Proposals of Improvement for Current Formulations and Models on Confinement of RC Elements by Means of EBR FRP Systems 179
New Proposals for Predictive Models 179
Strength Models 179
Strain Models 182
Confinement of Wall-like Cross-Sections 188
Confinement of Hollow Sections 189
Bar Buckling in FRP Strengthened RC Columns 193
Assessment of Current Formulations and Models on Confinement of RC Elements by Means of EBR-FRP Systems 195
Performance and Correlation of Models 195
Effectiveness of Confinement in Members Under Moment and Axial Load Combinations 198
Extension of Confinement Models Calibrated to Concentric Compression Tests for the Case of Moment-Axial Load Combination 198
Confinement of Lap Splices 199
Appendix: List of Sources for Database Specimens 203
References 204
6 Special Problems 210
Abstract 210
Serviceability Limit States 211
Introduction 211
Stress Limitation 212
Control of Cracking Phenomena 214
Limitation of Longitudinal Cracks 214
Verification of Bond Interface 219
Limitation of Deflections 220
Fatigue Behaviour 221
Introduction 221
Experimental Tests 222
Bond Stress-Slip Behaviour Under Fatigue Loads 223
Database 225
Codes and Guidelines 233
Effects of Fire and High Temperature 235
Introduction 235
Critical Temperatures for the Mechanical Properties 235
Review of Experimental Studies 236
Numerical Modeling 237
The Effects of High Temperatures in a Practical Application 238
Long Term Properties of FRP Systems 240
Introduction 240
FRP Relaxation 240
Adhesive Shrinkage 242
Adhesive Creep 242
Introduction 242
Standards on Creep Behaviour 244
Research on Creep Behaviour 246
Anchorage Systems for External Strengthening with FRP 250
Special Anchorage for Flexural Strengthening 250
Special Anchorage for Shear Strengthening 255
Special Anchorages for Confinement 256
Special Anchorages for Flexural Strengthening of Columns 257
Mechanically Fastened Systems 258
Description of the MF-FRP System 258
FRP Strips 259
Fasteners 260
Failure Modes of FRP-Fastener-Concrete Connection 261
State of Advancement and Current Research 262
Design Rules 264
References 267
Serviceability Limit States 267
Fatigue Behaviour 269
Effects of Fire and High Temperature 270
Long Term Properties of FRP Systems 272
Anchorage Systems for External Strengthening with FRP 273
Mechanically Fastened Systems 275
7 Prestressed FRP Systems 278
Abstract 278
Introduction 279
Flexural Strengthening 280
General Information 280
Prestressing Systems and Anchorage Techniques 281
Types of Prestressing 281
Commercially Available Prestressing and Anchorage Systems 281
Prototypes at Laboratory Level 285
Beam and Girder Strengthening 286
Influential Parameters 290
Two-Way Slab Strengthening 293
NSM-FRP Prestressed Systems 294
Introduction 294
Flexurally Strengthened Beams and Plates 294
Analytical Models 298
Design Issues 298
Shear Strengthening 299
Prestressed Shear Reinforcement for Concrete 299
FRP Prestressed Shear Strengthening 300
Analysis and Design of Prestressed FRP Shear Strengthening Systems 301
Practical Considerations for Strengthening Applications 301
Confinement 302
Introduction 302
Effect of Prestress on Confined Column Response 303
Residual Strength of Concrete 304
Residual Strength Under Cyclic Loading 305
Eccentric Loading of Confined Columns 306
Technical Aspects of Confinement Prestressing 307
Practical Applications 307
Durability 307
Concluding Remarks 309
Acknowledgments 312
References 312
8 NSM Systems 317
Abstract 317
Introduction 318
Bond 320
Evaluation of the Existing NSM ACI Formulation 323
Predicting Formulae for NSM 324
Flexural Strengthening 328
Beams and Slabs 328
Failure Modes 330
Influence of Different Parameters on the Flexural Strengthening Performance 333
Flexural Strengthening According to ACI 440.2R-08 versus Experimental Results 335
Continuous RC Slabs 336
Columns 340
Test Specimens and Tests Setup 341
Failure Modes and Effective Strain 343
Load-Deflection Response 344
Influence of Different Parameters on the Flexural Strengthening Performance 345
Design of NSM Strengthened Columns Subjected to Biaxial Bending 346
Comparison of the Analytical and Numerical Models with Test Results 350
Shear Strengthening 351
Design Approaches 352
Experimental-Base Model 352
Physical-Mechanical-Base Model 354
Acknowledgments 358
References 359
9 Fiber Reinforced Composites with Cementitious (Inorganic) Matrix 363
Abstract 363
Introduction 364
FRCM Materials 365
Materials by G& P
FRCM Materials by Ruredil 366
Mechanical Characterization of FRCM Systems: Tensile Test 368
Characteristic Behavior of FRCM Materials Under Tension (Politecnico di Milano) 370
Experimental Test to Characterize FRCM Composites (University of Padova) 372
Analysis of the FRCM-Concrete Bond Behaviour 374
Test Set-up and Material Characteristics 375
Experimental Tests 376
Effect of the Bonded Width 377
Strain Measurements 379
Effect of the Bonded Length 381
Final Remarks on the Bond Behaviour for PBO-FRCM Composites 381
Flexural Strengthening 382
Introduction 382
Literature Review 383
Mechanical Effectiveness 383
Failure Modes 385
Design Considerations 389
Confinement 394
Behaviour of TRM-Confined Concrete in Axial Compression 395
Behaviour of TRM-Confined Columns Under Cyclic Loading 397
Deformation Capacity of TRM-Confined RC Members 401
References 403