Flexural Behaviour of Reinforced Concrete Elements Retrofitted Using External Unbonded Superelastic Shape Memory Alloy Bars

i Co-Authorship . iv ACKNOWLEDGEMENT . vii Table of Content . viii List of Tables . xiv List of Figures . xvi List of Abbreviation, Symbols, and Nomenclature . xxii Chapter 1 Introduction . 1 1.1 General . 1 1.2 Research Needs and Motivation . 3 1.3 Specific Research Objectives . 3 1.4 Thesis Outline . 4 1.5 References . 7 Chapter 2 Literature Review . 9 2.1 Introduction . 9 2.2 Canadian Infrastructure Status . 10 2.2.1 Canadian Infrastructure Vulnerability to Damage . 11 2.2.2 Risk to Transportation Systems . 12 2.2.3 Risk to Schools and Hospitals . 13 2.3 Retrofitting RC Structures . 13 2.3.1 Historical Background . 13 2.3.2 External Unbonded Reinforcement . 15 2.4 Failure OF Beam-Column Joints During Past Earthquakes . 16 2.4.1 Introduction . 16 2.4.2 Seismic Deficiencies of the Pre-1970 BCJs . 19 2.4.3 Bond Slip Failure Mode of Unconfined BCJs . 20 2.5 Retrofitting of Seismic Deficient BCJs . 21 2.6 Shape Memory Alloys . 21 ix 2.6.1 Introduction . 21 2.6.2 Mechanical Behaviour of SMAs . 22 2.6. 3 Behaviour of SMAs Under Cyclic Loading . 24 2.6. 4 Modelling of SMAs . 25 2.6. 5 Strain Rate Effect . 26 2.6. 6 Applications of SMA Reinforcing Bars . 28 2.6. 6.1 Reinforcement for concrete elements. 28 2.6. 6.2 Prestressing concrete elements . 32 2.6. 7 SMA in Retrofitting of Existing Structures . 35 2.6. 7.1 SMAs as bracing members . 36 2.6. 7.2 Prestressing . 38 2.6. 7.3 Dampers . 39 2.7 Summary and Conclusions . 41 2.8 References . 42 Chapter 3 Flexural Behaviour of Superelastic Shape Memory Alloys Reinforced Concrete Beams During Loading and Unloading Stages . 53 3.1 Introduction . 53 3.2 Analysis Method . 55 3.2.1 Concrete under Compression . 55 3.2.2 Concrete under Tension . 56 3.2.3 Steel Bars . 56 3.2.4 Superelastic SMA Bars . 58 3.3 Deflection Calculations . 59 3.4 Experimental Validation . 59 3.5 Parametric Study . 63 3.6 Results and Discussion . 66 3.6.1 Reinforcement Ratio (ρSMAs) . 66 3.6.2 Ratio between the Amount of SMA Bars and the Amount of Steel Bars (ASMAs/As) . 69 3.6. 3 Cross-section Height-to-Width Ratio (h/b) . 74 3.6. 4 Beam Span-to-Depth Ratio (L/h) . 77 x 3.6. 5 Concrete Compressive Strength (fc) . 82 3.7 Choice of SMA length . 83 3.8 Conclusions . 91 3.9 References . 93 Chapter 4 Flexural Behaviour of Reinforced Concrete Beams Retrofitted using External Unbonded Superelastic Shape Memory Alloy Bars . 96 4.1 Introduction . 96 4.2 Finite Element Simulation . 97 4.2.1 Concrete under Compression . 97 4.2.2 Concrete under Tension . 98 4.2.3 Steel Bars . 98 4.2.4 Superelastic SMA Bars . 99 4.3 Experimental VALIDATION . 101 4.4 Suggested Retrofitting Technique. 111 4.5 Simplified Analysis Method . 114 4.6 Deflection Calculations . 118 4.7 Program Validation . 118 4.8 Parametric Study . 119 4.9 Results and Discussions . 120 4.9. 1 ASMA/As Parameter . 120 4.9. 2 Load Level Parameter (δmax/δy) . 122 4.9. 3 LSMA/L Parameter . 124 4.10 Choice of SMA Bars . 129 4.11 Conclusions . 136 4.12 References . 137 Chapter 5 Flexural Behaviour of Reinforced Concrete Joints Retrofitted Using External Superelastic Shape Memory Alloy Bars. 139 5.1 Introduction . 139 5.2 Finite Element Simulation . 141 5.3 Experimental Validation . 141 xi 5.4 Proposed Retrofitting Technique . 150 5.5 Retrofitted BCJ .