Behavior of Unbounded Post- tensioned Masonry Walls (eBook)

Supervisors’ Foreword 7
Parts of this thesis have been published in the following journal articles: 9
Acknowledgements 10
Contents 11
1 Introduction 15
1.1 Reinforced Masonry 15
1.2 Post-tensioned Masonry 17
1.3 Unbonded Post-tensioned Masonry Walls 18
1.4 Aim of the Research 18
1.5 Research Objectives 19
1.6 Research Questions 20
1.7 Significance of the Research 20
1.8 Thesis Organization 21
References 23
2 Literature Review 24
2.1 Codification of Pre-stressed Masonry 24
2.2 Current State of Research 25
2.2.1 Out-of-Plane Versus In-Plane 25
2.2.2 Research on In-Plane Behavior of Masonry 26
2.3 Gap in Knowledge 32
References 33
3 Strength and Seismic Performance Factors of Post-tensioned Masonry Walls 36
3.1 Introduction 36
3.2 Test Database 38
3.3 Prediction of In-Plane Shear Strength of Unbonded PT-MWs 41
3.4 Prediction of In-Plane Strength of Bonded PT-MWs 46
3.5 Bilinear Idealization of Capacity Curves 46
3.6 Response Modification Factor 50
3.7 Overstrength Factor (Rs) 55
3.8 Seismic Response Factors of PT-MWs 57
3.8.1 Effect of Supplemental Mild Steel 63
3.8.2 Effect of Grouting 64
3.8.3 Effect of Initial to Yield Stress Ratio in the Bar 66
3.8.4 Effect of Confinement Plates 67
3.9 Displacement Amplification Factor 67
3.10 Conclusions 69
References 70
4 Effect of Dimensions on the Compressive Strength of Concrete Masonry Prisms 73
4.1 Introduction 73
4.2 Finite Element Modelling 78
4.2.1 Constitutive Masonry Material Model 79
4.2.2 Damage Function 81
4.2.3 Volumetric Strain 83
4.2.4 Shear Dilation 83
4.3 Calibration of Concrete Masonry Prism 83
4.4 Parametric Study 85
4.4.1 Effect of Length 89
4.5 Discussion and Recommendations for Correction Factor 93
4.6 Conclusion 98
References 99
5 Flexural Strength Prediction of Unbonded Post-tensioned Masonry Walls 101
5.1 Introduction 101
5.2 Stress in Unbonded PT Bars 102
5.3 Finite Element Model 105
5.4 Constitutive Model 106
5.5 Calibration of the Material Model 109
5.6 Validation of the Finite Element Model (FEM) 110
5.7 Parametric Study 117
5.7.1 Parametric Study-Set I 117
5.7.1.1 Effect of Axial Stress Ratio /bf{/hbox{f}}_{{m}} /{/hbox{f}}_{{m}}^{{/prime }} 117
5.7.1.2 Effect of the Initial to Yield Stress Ratio of PT Bars /bf{/hbox{f}}_{{ i}} /{/hbox{f}}_{{py}} 120
5.7.1.3 Effect of the Height 121
5.7.1.4 Effect of the PT Bar Spacing 123
5.7.1.5 Effect of Wall Length 124
5.7.2 Parametric Study-Set II 124
5.8 Proposed Expression to Predict the Flexural Strength of Unbonded Masonry Walls 127
5.9 Validation of the Proposed Design Approach 129
5.9.1 Validation of the Proposed Design Approach Against Experimental Results 129
5.9.2 Validation of the Proposed Design Approach Against Finite Element Results 131
5.10 Design Example 135
5.11 Conclusion 136
References 138
6 Simplified Approach to Predict the Flexural Strength of Unbonded Post-tensioned Masonry Walls 140
6.1 Introduction 140
6.2 Prediction of Nominal Flexural Strength 141
6.2.1 Masonry Standard Joint Committee (MSJC 2013) 142
6.3 Comparison of Flexural Expressions with Experimental Results 145
6.4 Comparison of Flexural Expressions with Finite Element Model Results 147
6.5 Proposed Simplified Method 149
6.5.1 Stress in Unbonded PT Bars 150
6.5.2 Ultimate Masonry Strain, {/varvec /varepsilon}_{{{/varvec mu}}} 153
6.5.3 Plastic Hinge Length 154
6.6 Analytical Procedure to Obtain Force-Displacement Response of PT-MWs 155
6.6.1 Decompression Point 156
6.6.2 Force-Displacement Response Beyond Decompression State 156
6.7 Validation of the Analytical Procedure 158
6.8 Proposed Expression for Compression Zone Length 161
6.9 Validation of the Proposed Simplified Approach 165
6.9.1 Validation of the Proposed Simplified Design Approach Against Experimental Results 168
6.9.2 Validation of the Proposed Simplified Design Approach Against Finite Element Results 170
6.10 Conclusion 171
References 172
7 Experimental Investigation of Unbonded Post-tensioned Masonry Walls 174
7.1 Introduction 174
7.2 Construction Details 176
7.2.1 Wall Specifications 176
7.2.2 Wall Construction 179
7.3 Material Properties 180
7.4 Instrumentation 180
7.5 Test Setup and Test Procedure 180
7.6 Test Results 181
7.6.1 Damage Pattern and Failure Mode 181
7.6.2 Force-Displacement Response 183
7.6.3 Force in the PT Bars 185
7.6.4 Residual PT Force Ratio 188
7.6.5 Residual Drift Ratio 189
7.6.6 Strain in Masonry 190
7.6.7 Compression Zone Length and Wall Rotation 191
7.6.8 Displacement Ductility 195
7.6.9 Wall Stiffness 195
7.6.10 Stiffness Degradation 197
7.6.11 Equivalent Viscous Damping and Energy Dissipation 198
7.7 Response Prediction 199
7.7.1 Force-Displacement Response Prediction 199
7.7.2 Strength Prediction of PT-MWs 200
7.8 Conclusion 204
References 204
8 Summary and Conclusions 206
8.1 Introduction 206
8.2 Summary of the Research Undertaken 207
8.3 Summary of the Research Findings 208
8.4 Contribution to Knowledge 211
8.5 Recommendations for Future Work 211
References 212
Appendix A 213
Appendix B 246
Appendix C 251
About the Author 277