Experimental study on fiber-reinforced concrete panels subjected to shear, Sommario - Tesi

SUMMARY

1. INTRODUCTION

Italian Presentation................................................................................... 1

1.1 Fiber Reinforced Concrete(FRC)............................................................. 8

1.2 Why Toronto............................................................................................ 9

1.3 Scope and Objectives of the Thesis.......................................................... 10

1.4 Organization of the Thesis....................................................................... 11

1.5

2. LITERATURE SURVEY

2.1 Starting Point.............................................................................................. 13

2.2 Development.............................................................................................. 14

2.3 Modified Compression Field Theory for

Reinforced Concrete Element subjected to shear (MCFT)........................ 15

2.3.1 Theory Assumption........................................................................... 15

2.3.2 Compatibility, Equilibrium and Stress-Strains

Conditions......................................................................................... 17

2.3.3 Experimental Program....................................................................... 22

2.3.4 Conclusions....................................................................................... 31

2.4 Disturbed Stress Field Model for reinforced concrete:

Formulation.............................................................................................. 33

2.4.1 Conceptual Model............................................................................. 34

2.4.2 Equilibrium conditions, Compatibility and i

SUMMARY

Constitutive Relations....................................................................... 36

2.4.3 Slip Model......................................................................................... 46

2.4.4 Conclusions....................................................................................... 47

2.5 Disturbed Stress Field Model for reinforced concrete:

Implementation......................................................................................... 48

2.5.1 Shear Slip Model............................................................................... 50

2.5.2 Conclusions....................................................................................... 52

2.6 Variable Engagement Model.................................................................... 52

2.6.1 Introduction....................................................................................... 53

2.6.2 Stress-COD Model Excluding Fiber Fracture................................... 55

2.6.3 Stress-COD Model Including Fiber Fracture.................................... 57

2.6.4 Conclusions....................................................................................... 57

2.7 Diverse Embedment Model (DEM) for Steel

Fiber-Reinforced concrete in tension: model development..................... 57

2.7.1 Theory Assumption........................................................................... 58

2.7.2 Pullout behavior of a single fiber...................................................... 59

2.7.2.1 Pullout behavior of a single straight fiber embedded

on one side............................................................................... 59

2.7.2.2 Pullout behavior of a single straight fiber embedded

on both sides............................................................................ 61

2.7.2.3 Pullout behavior of a single end-hooked fiber embedded

on both side.............................................................................. 62

2.7.3 Consideration of member dimension and

fiber embedded length....................................................................... 64

2.8 Diverse Embedment Model (DEM) for steel fiber-reinforced

concrete in tension: model verification.................................................... 67

2.8.1 Fiber orientation factor considering member dimension.................. 67

2.8.2 Model Verification............................................................................ 68

2.8.3 Conclusions....................................................................................... 69

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SUMMARY

3. MATERIALS and BEHAVIORS

3.1 Introduction.............................................................................................. 70

3.2 Fiber Reinforced Concrete (FRC) – Material Properties......................... 71

3.2.1 Concrete............................................................................................. 72

3.2.2 Normal Concrete (NC) and High Strength Concrete........................ 74

3.2.3 Reinforcing Steel............................................................................... 86

3.2.4 Fibers................................................................................................. 87

3.2.4.1 Steel Fibers (SF)...................................................................... 91

3.2.4.2 Macro-synthetic Fibers (MSNF).............................................. 92

3.2.4.2.1 Development of Macro-synthetic Fibers........................ 95

3.2.4.2.2 Properties of Macro-synthetic Fibers............................. 96

3.2.4.2.3 Adding Macro-synthetic Fibers in Concrete Matrix...... 96

3.2.4.3 Durability of Fibers in a Concrete Matrix................................. 97

3.3 Studies about Shrinkage........................................................................... 98

3.3.1 Different types of Shrinkage............................................................. 99

3.3.2 Plastic Shrinkage............................................................................... 100

3.3.3 Autogenous Shrinkage...................................................................... 101

3.3.4 Drying Shrinkage.............................................................................. 102

3.4 Adding Fibers in Concrete....................................................................... 105

3.4.1 Bond Concrete-Fibers....................................................................... 111

3.5 Constitutive Models for Concrete in Tension.......................................... 115

3.5.1 Tension Stiffening............................................................................. 119

3.5.2 Tension Softening............................................................................. 120

3.5.3 Tension Splitting............................................................................... 121

3.6 Constitutive Models for Concrete in compression................................... 123

3.6.1 Compression Softening..................................................................... 124

3.7 Structural use of FRC............................................................................... 125

3.8 Experiments on specimens....................................................................... 127

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SUMMARY

4. EXPERIMENT on FRC

4.1 Introduction.............................................................................................. 128

4.2 Panel Element Tester................................................................................ 128

4.3 Displacement measurement (LVDTs)...................................................... 130

4.4 LED Target............................................................................................... 132

4.5 Specimen Description............................................................................... 135

4.5.1 Concrete Mixing Procedures............................................................. 136

4.5.2 Cylinders........................................................................................... 138

4.5.2.1 Casting Procedure...................................................................... 139

4.5.2.2 Test Procedure........................................................................... 141

4.5.3 Dog-Bones......................................................................................... 142

4.5.3.1 Casting Procedure...................................................................... 145

4.5.3.2 Test Procedure........................................................................... 146

4.5.4 Prisms............................................................................................... 150

4.5.4.1 Casting Procedure...................................................................... 152

4.5.4.2 Test Procedure........................................................................... 153

4.5.5 Panels................................................................................................. 154

4.5.5.1 Casting Procedure...................................................................... 157

4.5.5.2 Test Procedure........................................................................... 160

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SUMMARY

5. TEST RESULTS

5.1 Introduction.............................................................................................. 163

5.2 Cylinder Compression Test...................................................................... 163

5.2.1 Previous Tests................................................................................... 166

5.2.2 Data Analysis.................................................................................... 167

5.2.3 Test Observation............................................................................... 169

5.2.4 Comparisons...................................................................................... 172

5.2.5 Conclusions....................................................................................... 178

5.3 Uniaxial Direct Tension Test................................................................... 179

5.3.1 Previous Tests.................................................................................... 181

5.3.2 Test Observation............................................................................... 182

5.3.3 Data Analysis..................................................................................... 189

5.3.4 Results of Data Analysis................................................................... 191

5.3.5 Influence of fiber content, fiber type, loading protocol

and concrete matrix strength.............................................................. 192

5.4 Prisms – Modulus of Rupture Tests......................................................... 194

5.4.1 Previous Tests................................................................................... 194

5.4.2 Test Observation............................................................................... 195

5.4.3 Data Analysis.................................................................................... 198

5.4.4 Results of Data Analysis................................................................... 200

5.5 Panel Test................................................................................................. 201

5.5.1 Previous Tests................................................................................... 201

5.5.2 Test Observation............................................................................... 202<