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IIT Kharagpur
CONTENTS
Title Page
Certificate of Approval Declaration
Certificate by the Supervisors Dedication
Acknowledgement
Abstract i
Contents iii
List of Figures vii
List of Tables xi
List of Symbols xiii
List of Abbreviations xvii
Chapter 1 Introduction
1.1 Introduction 1
1.2 Structural Behavior of Concrete Pavement 1
1.3 Motivation for the Work 4
1.4 Objective of the Work 5
1.5 Contributions from the Present Research Work 6
1.6 Organization of the Thesis 6
Chapter 2 Literature Review
2.1 Introduction 9
2.2 Approaches for Design of Jointed Concrete Pavements 9 2.2.1 Portland Cement Association (PCA) Method 9
2.2.2 Indian Roads Congress (IRC) Method 11
2.2.3 Australian Pavement Design (AUSTROADS) Method 11 2.2.4 American Association of State Highway And
Transportation Officials (AASHTO) Method
12
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IIT Kharagpur
2.3.1 Closed-form Solution 14
2.3.2 Finite Element Method 16
2.3.2.1 Two-Dimensional Finite Element Method 17 2.3.2.2 Three-Dimensional Finite Element Method 18 2.3.3 Modeling of different Components of Concrete Pavement 19
2.3.3.1 Concrete Slab 19
2.3.3.2 Foundation 19
2.3.3.3 Interface 22
2.3.3.4 Dowel Bar System 25
2.3.3.5 Aggregate Interlocking System 29
2.4 Fatigue Cracking in Concrete Pavement 32
2.4.1 Fracture Mechanics and Fatigue Fracture – Application in Concrete Pavement
33
2.5 Critical Observations 36
2.6 Scope of the Present Work 37
Chapter 3 Numerical Modeling of Concrete Pavement
3.1 Introduction 39
3.2 Concrete Slab and Base Layers 39
3.3 Subgrade 40
3.4 Interface 41
3.5 Joints 44
3.5.1 Joints with Dowel Bar System 44
3.5.2 Joints with Aggregate Interlocking System 46 3.5.2.1 Guidelines for Selection of Spring Stiffness 47
3.5.2.2 Modulus of Interlocking Joint 49
3.6 Validation of Dowel Bar Model with Experimental Results 52 3.7 Validation of Aggregate Interlocking Model with
Experimental Results
59
3.8 Summary 64
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Chapter 4 Interface Characteristics
4.1 Introduction 65
4.2 Push-off Test 65
4.3 Discussion of Test Results 69
4.3.1 Variation of Friction Coefficient with Sliding Displacement
69
4.3.2 Effective Horizontal Displacement 70
4.3.3 Effect of Slab Thickness on Coefficient of Friction 70 4.3.4 Variation of Coefficient of Friction with type of
Foundation and Interface Condition
70
4.3.5 Coefficient of Friction Values 70
4.3.6 Sliding Plane and Bond Characteristics 74
4.4 Summary 75
Chapter 5 Structural Evaluation of In-Service Concrete Pavement
5.1 Introduction 77
5.2 Details of Test Sections 77
5.3 Falling Weight Deflectometer (FWD) Tests 78
5.3.1 IIT Kharagpur FWD 79
5.3.2 FWD Test Program 80
5.4 Validation of FE Model 83
5.4.1 Finite Element Representation of Test Sections 83 5.4.2 Backcalculation of Pavement Layer Parameters 85
5.4.3 Backcalculation of Joint Parameters 87
5.4.4 Validation of the FE Model with Edge Loading Data 89
5.5 Summary 93
Chapter 6 Fatigue Analysis
6.1 Introduction 95
6.2 Fictitious Crack Model 96
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6.4 Validation of the Fracture model 102
6.5 Fatigue Performance Model 105
6.6 Numerical Analysis using the Proposed Fatigue Performance Model
106
6.7 Summary 111
Chapter 7 Examination of Some Design Issues
7.1 Introduction 113
7.2 Load Transfer Efficiency of Dowelled Joint 113
7.3 Dowel Group Action 118
7.4 Effect of different Interface Conditions on Concrete Pavement Response
124 7.4.1 Numerical Analysis of Concrete Pavement with Different
Interface Conditions
125
7.4.2 Axle Load Configuration 126
7.4.3 Temperature Consideration 127
7.4.4 Critical Load Combinations 127
7.4.5 Results and Discussion 128
7.4.6 Some Observations on the Influence of Interface Conditions
131 7.5 Identification of Critical Stress Combination 131
7.6 Modification of Bradbury’s Coefficient 135
7.7 Summary 135
Chapter 8 Conclusion
8.1 Introduction 137
8.2 Major Conclusions from the Present Work 137
8.3 Scope for Future Works 140
References
List of Publications
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LIST OF FIGURES
Figure No.
Description Page
No.
1.1 Schematic Arrangement of Concrete Pavement Components 2 3.1 FE Representation of Slab-Foundation Pavement System 40
3.2 Geometry of the Contact Element 42
3.3 FE Representation of Interface and Contact Behavior 43 3.4 Typical Finite Element Model for the Pavement System 43 3.5 Dowel Bar with Uniform Gap on the Unloaded Slab 45
3.6 FE Representation of Dowel Bar 46
3.7 Aggregate Interlocking at Crack / Joint 47
3.8 FE Representation of Aggregate Interlocking 47
3.9 Variation of Modulus of Interlocking Joint with Aggregate Size for Different Joint Openings (Slab Thickness = 250 mm)
51 3.10 Variation of Kj with IR for different Joint Openings 51
3.11 Variation of LTE with Kj 52
3.12 Schematic Arrangement of the Test Pavement (Keeton and Bishop,
1957) 54
3.13 Bending Moment Diagram for the Central Dowel Bar (Load case ‘a’) 56 3.14 Shear Force Diagram for the Central Dowel Bar (Load case ‘a’) 58 3.15 Schematic Arrangement of the Test Pavement (Colley and Humphrey,
1967)
60
4.1 Schematic Layout of Test Set-up 67
4.2 Test Slab with Screw Jack, Proving Ring and Dial Gauges 68 4.3 Variation of Coefficient of Friction with Horizontal Displacement for
different Load Cycles for Slab laid over DLC base with Smooth Interface (S2a1)
71
4.4 Variation of Coefficient of Friction with Horizontal Displacement for different Load Cycles for Slab laid over WMM base with Smooth Interface (S1a2)
72
4.5 Variation of Coefficient of Friction with Horizontal Displacement for different Load Cycles for Slab placed directly over WMM (S1b3)
72
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4.7 Variation of Maximum Coefficient of Friction for different Combinations of slabs with both Smooth and Rough Interface Conditions
73
4.8 Bottom Surfaces of Slabs with Smooth and Rough Interface (after testing)
74 5.1 A View of the Pavement Stretch considered for Field Investigation 78
5.2 Schematic Details of Test Sections 79
5.3 Arrangements for the Calibrations of Load Cell and Geophones 80
5.4 Typical Locations selected for FWD Testing 81
5.5 Field Evaluation of Concrete Slabs using FWD 82
5.6 Typical FWD Load Pulse 82
5.7 Finite Element Representation of the Test Section 84 5.8 Comparison between Experimental and Finite Element Deflection
Basins for Interior Loading Condition
87 5.9 Comparison between Experimental and Finite Element Deflection
Basins for Corner Loading Condition
88 5.10 Comparison between Experimental and Finite Element Deflection
Basins for Load Position ‘2’
89 5.11 Comparison between Experimental and Finite Element Deflection
Basins for Load Position ‘4’
90 5.12 Comparison between Experimental and Finite Element Deflection
Basins for Load Position ‘5’
90 5.13 Comparison between Experimental and Finite Element Deflection
Basins for Load Position ‘6’
91 6.1 Typical Stress-Crack Mouth Opening Displacement Relationship (σ-w
curve) for Concrete
97 6.2 Typical Stress-Strain Relationship (σ-ε curve) for Concrete 97 6.3 Discretization of Concrete beam with Potential Crack Path for Finite
Element Analysis
98
6.4 Cohesive Forces at the Fictitious Crack Zone 98
6.5 Superposition Scheme on the basis of Influence Method 99 6.6 Finite Element Mesh for the Three-Point Bending Beam 104
6.7 Load vs. CMOD Curve 105
6.8 Finite Element Model for Pavement with Winkler Foundation 107 6.9 Load vs. CMOD Curve for Beam over Winkler Foundation 108 6.10 Stress vs. Normalized Crack Length curve for Beam over 108
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6.11 Normalized Crack Length vs. Number of Load Cycles Curve for Beam with Load Level 63.06 kN
109 6.12 Load vs. Number of Cycles (log N) Curve for the Beam 110 6.13 Stress Ratio (S) vs. Number of Load Cycles (log N) Curves for Concrete
Beam
111 7.1 Variation of LTE (%) with Dowel Looseness for different K values 118
7.2 Placement of Dual Wheel Load on Pavement 119
7.3 Typical Variation of Shear Force transferred by different Dowels for a 350 mm thick Pavement Slab
120
7.4 Variation of n with l 121
7.5 Schematic Representation of the Three-Panel Concrete Pavement 126 7.6 Axle Load Positions and Critical Stress and Deflection Locations 126 7.7 Nonlinear Temperature Differentials considered for Analysis 127 7.8 Bilinear Variation of Temperature in the Slab 132
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LIST OF TABLES
Table No.
Description Page
No.
2.1 Coefficient of Friction Values obtained by different Researchers 24 3.1 Slab Deflections at different Locations for Load Case ‘a’ 55 3.2 Maximum Bending Moments in different Dowels for Load Case ‘a’ 56
3.3 Joint-Face Shear Forces in different Dowels 57
3.4 Comparison of Results obtained from different Models 58 3.5 Modulus of Interlocking Joint and Spring Stiffness Values for Slabs
with different Joint Openings
61 3.6 Deflection and Joint Effectiveness (E) values for Slabs with different
Joint Openings
62 3.7 Load Transfer Efficiency (LTE) for Slabs with different Joint Openings 63 4.1 Details of Experimental Combinations for Base and Interface 66 4.2 Values of Coefficient of Friction from Push-off Tests 71 5.1 Density and Poisson’s ratio values assigned to Pavement Layers 86
5.2 Backcalculated Joint and Interface Parameters 88
5.3 Comparison of Load Transfer efficiencies obtained from FWD Test and FE Analysis
92 6.1 Properties of Concrete considered for Numerical Analysis 103 7.1 Properties of PCC, DLC, WMM and Subgrade used in the Parametric
study
115 7.2 Properties of PCC, DLC, WMM and Subgrade used in the Parametric
study
125 7.3 Maximum Tensile Stresses in the Slab for different Load Combinations 129 7.4 Slab Deflections at Critical Locations for different Load Combinations 130
