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Experimental study to investigate compression failures of thin concrete walls Lorzadeh, Amir 2012

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Experimental Study to Investigate Compression Failures of Thin Concrete Walls by Amir Lorzadeh B.A., The University of British Columbia, 2010 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE in THE FACULTY OF GRADUATE STUDIES (Civil Engineering) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver)  October 2012 © Amir Lorzadeh, 2012  Abstract The experimental research was completed to investigate the strain capacity of thin concrete walls. 45 wall elements that were either 24 in. (610 mm) or 36 in. (914 mm) high had 5.5 in. (140 mm) ,6 in. (152 mm), 8 in. (203 mm) or 10 in. (254 mm) thickness and various reinforcement arrangements. The concrete wall elements were subjected to concentric axial compression load. The strain capacity of the wall elements was measured. In many of the tests the strain was kept uniform and in some of the testing no effort was made to keep strain equable. The test results and observations indicated that the strain capacity of thin concrete walls could be as low as 0.0015. Low strain capacity was observed when the slender specimens (with height-to-thickness ratio of 4.5) did not contain lateral confinement. In slender specimens that had straight horizontal reinforcement and no lateral ties, concrete cover tended to separate. Moreover, diagonal cracks were formed through the location of lateral reinforcement. In some cases the cracks coalesced at the middle section of the specimen into a larger crack and split the specimen in the middle. An analytical study was conducted to investigate how the compression strain capacity could influence the axial load capacity of bearing walls. Maximum compression axial load was calculated for various bearing wall lengths of 2 to 60 ft while keeping the strain demand on the bearing walls within certain limits.  ii  Table of Contents  Abstract .................................................................................................................................... ii Table of Contents ................................................................................................................... iii List of Tables .......................................................................................................................... vi List of Figures ....................................................................................................................... viii List of Symbols and Abbreviation .................................................................................... xviii Acknowledgements .............................................................................................................. xix Chapter 1: Introduction ......................................................................................................... 1 Chapter 2: Experimental Study............................................................................................. 5 2.1  Overview of Chapter ............................................................................................................. 5  2.2  Testing Methodology ............................................................................................................ 6  2.3  Test Specimens ..................................................................................................................... 8  2.3.1  Test Specimen Properties ............................................................................................... 17  2.4  Construction of Test Specimens ......................................................................................... 22  2.5  Concrete Properties ............................................................................................................. 25  2.6  Specimen Preparation Prior to Testing ............................................................................... 26  2.7  Instrumentation ................................................................................................................... 31  2.8  Testing Procedure and Protocol .......................................................................................... 34  Chapter 3: Experimental Results ........................................................................................ 37 3.1  Overview of Chapter ........................................................................................................... 37  3.2  Summary of Test Results .................................................................................................... 38  3.3  Shape of Cracks at Failure and Fragility of Specimens ...................................................... 41  3.4  Influence of Lateral Ties on Failure Mode ......................................................................... 56  3.5  Concrete Compression Stress and Strain Capacity ............................................................. 61  3.6  Influence of Different Testing Protocols on Response of Specimen .................................. 67  Chapter 4: Analytical Study ................................................................................................ 70 4.1  Overview of Analytical Work ............................................................................................. 70  4.2  Maximum Axial Load on Bearing Walls in High-Rise building ........................................ 72  4.3  Calculation Methodology .................................................................................................... 74  iii  4.4  Analytical Results ............................................................................................................... 77  Chapter 5: Conclusions ........................................................................................................ 83 Bibliography .......................................................................................................................... 88 Appendices ............................................................................................................................. 89 Appendix A Detail Test Information ............................................................................................... 89 A.1  Specimen A1................................................................................................................... 90  A.2  Specimen A2................................................................................................................... 96  A.3  Specimen A3................................................................................................................. 102  A.4  Specimen B1 ................................................................................................................. 108  A.5  Specimen B2 ................................................................................................................. 114  A.6  Specimen C1 ................................................................................................................. 120  A.7  Specimen C2 ................................................................................................................. 126  A.8  Specimen D................................................................................................................... 131  A.9  Specimen E1 ................................................................................................................. 137  A.10  Specimen E2 ................................................................................................................. 143  A.11  Specimen AA1 .............................................................................................................. 148  A.12  Specimen AA2 .............................................................................................................. 154  A.13  Specimen AB1 .............................................................................................................. 160  A.14  Specimen AB2 .............................................................................................................. 166  A.15  Specimen BA1 .............................................................................................................. 173  A.16  Specimen BA2 .............................................................................................................. 182  A.17  Specimen BB1 .............................................................................................................. 188  A.18  Specimen BB2 .............................................................................................................. 194  A.19  Specimen BC1 .............................................................................................................. 202  A.20  Specimen BC2 .............................................................................................................. 209  A.21  Specimen CA1 .............................................................................................................. 215  A.22  Specimen CA2 .............................................................................................................. 223  A.23  Specimen CA3 .............................................................................................................. 229  A.24  Specimen CA4 .............................................................................................................. 236  A.25  Specimen CB1 .............................................................................................................. 244  A.26  Specimen CB2 .............................................................................................................. 253  A.27  Specimen CB3 .............................................................................................................. 259  A.28  Specimen CB4 .............................................................................................................. 267  iv  A.29  Specimen CC1 .............................................................................................................. 275  A.30  Specimen CC2 .............................................................................................................. 284  A.31  Specimen CD1 .............................................................................................................. 293  A.32  Specimen CD2 .............................................................................................................. 303  A.33  Specimen DA1 .............................................................................................................. 307  A.34  Specimen DA2 .............................................................................................................. 315  A.35  Specimen DA3 .............................................................................................................. 323  A.36  Specimen DA4 .............................................................................................................. 330  A.37  Specimen DB1 .............................................................................................................. 338  A.38  Specimen DB2 .............................................................................................................. 345  A.39  Specimen DB3 .............................................................................................................. 351  A.40  Specimen DB4 .............................................................................................................. 358  A.41  Specimen EA1 .............................................................................................................. 366  A.42  Specimen EA2 .............................................................................................................. 377  A.43  Specimen EB1 .............................................................................................................. 384  A.44  Specimen F1 ................................................................................................................. 394  A.45  Specimen F2 ................................................................................................................. 401  Appendix B Schematic Drawings of Failure Plane ........................................................................ 410 Appendix C Partial Analytical Study ............................................................................................. 421 C.1  Matlab Script ................................................................................................................ 422  v  List of Tables Table 2.1  Specimens Properties .......................................................................................... 18  Table 2.2  28 Days Concrete Strength ................................................................................. 25  Table 2.3  Testing Protocols ................................................................................................ 35  Table 3.1  Summary of Test Results ................................................................................... 38  Table 4.1  Concrete and Steel Properties ............................................................................. 74  Table A.1  Specimen A1 Properties ..................................................................................... 90  Table A.2  Specimen A1 Properties ..................................................................................... 96  Table A.3  Specimen A3 Properties .................................................................................. 102  Table A.4  Specimen B1 Properties ................................................................................... 108  Table A.5  Specimen A4 Properties ................................................................................... 114  Table A.6  Specimen C1 Properties ................................................................................... 120  Table A.7  Specimen C2 Properties ................................................................................... 126  Table A.8  Specimen D Properties ..................................................................................... 131  Table A.9  Specimen E1 Properties ................................................................................... 137  Table A.10  Specimen E2 Properties ................................................................................. 143  Table A.11  Specimen AA1 Properties .............................................................................. 148  Table A.12  Specimen AA2 Properties .............................................................................. 154  Table A.13  Specimen AA2 Properties .............................................................................. 160  Table A.14  Specimen AB2 Properties .............................................................................. 166  Table A.15  Specimen BA1 Properties .............................................................................. 173  Table A.16  Specimen BA2 Properties .............................................................................. 182  Table A.17  Specimen BB1 Properties .............................................................................. 188  Table A.18  Specimen BB2 Properties .............................................................................. 194  Table A.19  Specimen BC Properties ................................................................................ 202  Table A.20  Specimen BC2 Properties .............................................................................. 209  Table A.21  Specimen CA1 Properties .............................................................................. 215  Table A.22  Specimen CA2 Properties .............................................................................. 223  Table A.23  Specimen CA3 Properties .............................................................................. 229  Table A.24  Specimen CA4 Properties .............................................................................. 236 vi  Table A.25  Specimen CB1 Properties .............................................................................. 244  Table A.26  Specimen CB2 Properties .............................................................................. 253  Table A.27  Specimen CB3 Properties .............................................................................. 259  Table A.28  Specimen CB4 Properties .............................................................................. 267  Table A.29  Specimen CC1 Properties .............................................................................. 275  Table A.30  Specimen CC2 Properties .............................................................................. 284  Table A.31  Specimen CD1 Properties .............................................................................. 293  Table A.32  Specimen CD2 Properties .............................................................................. 303  Table A.33  Specimen DA1 Properties .............................................................................. 307  Table A.34  Specimen DA2 Properties .............................................................................. 315  Table A.35  Specimen DA3 Properties .............................................................................. 323  Table A.36  Specimen DA4 Properties .............................................................................. 330  Table A.37  Specimen DB1 Properties .............................................................................. 338  Table A.38  Specimen DB2 Properties .............................................................................. 345  Table A.39  Specimen DB3 Properties .............................................................................. 351  Table A.40  Specimen DB4 Properties .............................................................................. 358  Table A.41  Specimen EA1 Properties .............................................................................. 366  Table A.42  Specimen EA2 Properties .............................................................................. 377  Table A.43  Specimen EB1 Properties .............................................................................. 384  Table A.44  Specimen F1 Properties .................................................................................. 394  Table A.45  Specimen F2 Properties ................................................................................. 401  vii  List of Figures Figure 1.1  Example of Shear Wall and Thin Bearing Wall .................................................. 1  Figure 1.2  An Example of Compression Failure in an 18 Stories Building in Chile  (Sherstobitoff et al. 2012) ......................................................................................................... 2 Figure 1.3  Examples of Compression Failure in Thin Walls in February 2010 Chile  Earthquake ................................................................................................................................ 3 Figure 2.1  Baldwin Universal Testing Machine ................................................................... 6  Figure 2.2  Elevation of Specimen during Test ..................................................................... 7  Figure 2.3  Cross-sections Showing the Arrangement of Horizontal Reinforcement in 7  Types of Specimens .................................................................................................................. 8 Figure 2.4  Cross-sectional Area of Type 1 Specimens ....................................................... 10  Figure 2.5  Cross-Sectional Area of Type 2 Specimens ...................................................... 11  Figure 2.6  Cross-sectional Area of Type 3 Specimens ....................................................... 12  Figure 2.7  Cross-sectional Area of Type 4 Specimens ....................................................... 13  Figure 2.8  Cross-sectional Area of Type 5 Specimens ....................................................... 14  Figure 2.9  Cross-sectional Area of Type 6 Specimens ....................................................... 15  Figure 2.10  Cross-sectional Area of Type 7 Specimens ..................................................... 16  Figure 2.11  AutoCad Drawing of Formwork for Phase 2: Plane View .............................. 22  Figure 2.12  Images of Reinforcement Set and Formwork: (a) Example of Assembly of  Reinforcement Skeleton, (b) Finished Formwork .................................................................. 23 Figure 2.13  Image of Horizontal Reinforcement Attached to Vertical Reinforcing Bar  Using Tie Wire ........................................................................................................................ 24 Figure 2.14  End Confining Cap: (a) 3D Drawing of Specimen Placed in Confining End  Cap, (b) Picture of the Specimen Ready to be Tested. ........................................................... 26 Figure 2.15  Process to Prepare Specimen for Compression Testing: (a) and (b) Show that  the Specimen was Lifted and Placed on Top of the Grout, (c) Specimen was Perpendicular to the Bottom plate, (d) the Gaps were Filled with Grout, (e) Confining End-cap was Placed on the Top of the Specimen ......................................................................................................... 29 Figure 2.16  Defining the Sides of Specimens ..................................................................... 31  viii  Figure 2.17  Universal Testing Machine Baldwin: (a) Control Setting, (b) Testing  Apparatus ................................................................................................................................ 32 Figure 3.1  Failure Images of Type 1 Specimens ................................................................ 43  Figure 3.2  Images of Failure for Type 2 Specimens ........................................................... 48  Figure 3.3  Failure Images of Type 3 Specimens ................................................................ 50  Figure 3.4  Failure Images of Type 4 Specimens ................................................................ 52  Figure 3.5  Failure Images of Type 5 Specimens ................................................................ 53  Figure 3.6  Failure Images of Type 6 Specimens ................................................................ 54  Figure 3.7  Failure Image of Type 7 Specimens .................................................................. 55  Figure 3.8  Hysteretic Response for Specimen with Lateral Ties ........................................ 58  Figure 3.9  Hysteretic Response for Specimens with no Ties ............................................. 60  Figure 3.10  Influence of Specimen Slenderness and Vertical Reinforcement Ratio on  Maximum Concrete Compression Stress ................................................................................ 62 Figure 3.11  (a) Maximum Concrete Stress Variation as a Function of Strain Capacity, (b)  Influence of Specimen Slenderness on Maximum Compression Strain Capacity of Concrete ................................................................................................................................................. 64 Figure 3.12  Comparison of Maximum Concrete Stress with Respect to Age at Testing ... 65  Figure 3.13  Influence of Reduction in Number of Loading Cycles from 5 to 3: Specimen  AB1 and AB2 were tested according to protocol Type 2 and 3 respectively ......................... 68 Figure 3.14  Influence of Reduction in Number of Loading Cycle from 5 to 3: Specimen  BC1 and BC2 were Tested According to Protocol Type 2 and 3 Respectively ..................... 69 Figure 4.1  Curvature Demand on Bearing Wall is a Function of Shear Wall Length ......... 73  Figure 4.2  Calculation of Strain for each Fiber along the Wall Section ............................. 75  Figure 4.3  Relationship between Maximum Axial Load and Bearing Wall Length given ϕd  of 0.0035 ................................................................................................................................ 76 Figure 4.4  Influence of Curvature Demand Change from 0.003 to 0.004 on Maximum  Compression Axial Load of Bearing Walls ............................................................................ 77 Figure 4.5  Ratio of Maximum Axial Load to Nominal Strength vs. Wall Length (ρ: 0.003)  ................................................................................................................................................. 78 Figure 4.6  Ratio of Maximum Axial Load to Nominal Strength vs. Wall Length (ρ:  0.0015) .................................................................................................................................... 79 ix  Figure 4.7  Ratio of Axial Load to Nominal Strength vs. Wall Length ............................... 80  Figure 4.8  Maximum Axial Load vs. Wall Length (фd = 0.0035)...................................... 81  Figure 4.9  Maximum Strain (Top Strain) at Maximum Axial Load vs. Wall Length (фd =  0.0035) .................................................................................................................................... 82 Figure A.1  Stress-Strain Response of A1: Average of Two Measurements  91  Figure A.2  Stress-Strain Response of A1: Two Position Transducers ............................... 91  Figure A.3  Images of A1 up to Strain of 0.00275 .............................................................. 93  Figure A.4  Images of Specimen A1 after Failure: (a) Right Side, (b) Left Side ................ 94  Figure A.5  Stress-Strain Response of A2: Average of Two Measurements....................... 97  Figure A.6  Stress-Strain Response of A2: Two Position Transducers ............................... 97  Figure A.7  Images of A2 up to Strain of 0.004 .................................................................. 99  Figure A.8  Images of Specimen A2 after Failure: (a) Left Side, (b) Back Side ............... 100  Figure A.9  Stress-Strain Response of A3: Average of Two Measurements..................... 103  Figure A.10  Stress-Strain Response of A3: Two Position Transducers ........................... 103  Figure A.11  Images of A3 up to Strain of 0.004 .............................................................. 105  Figure A.12  Images of Specimen A3 after Failure: (a) Right Side, (b) Back Side .......... 106  Figure A.13  Stress-Strain Response of B1: Average of Two Measurements ................... 109  Figure A.14  Stress-Strain Response of B1: Two Position Transducers ........................... 109  Figure A.15  Images of B1 up to Strain of 0.0325 ............................................................. 111  Figure A.16  Images of Specimen B1 after Failure: (a) Left Side, (b) Back Side ............. 112  Figure A.17  Stress-Strain Response of B2: Average of Two Measurements ................... 115  Figure A.18  Stress-Strain Response of B2: Three Position Transducers ......................... 115  Figure A.19  Images of B2 up to First Cycle at Strain of 0.0035 ...................................... 117  Figure A.20  Images of Specimen B2 after Failure: (a) Right Side, (b) Back Side ........... 118  Figure A.21  Stress-Strain Response of C1: Average of Two Measurements ................... 121  Figure A.22  Stress-Strain Response of C1: Two Position Transducers ........................... 121  Figure A.23  Images of First Detected Damage on Specimen C1 ..................................... 122  Figure A.24  Images of Specimen C1 after Failure: (a) Right Side, (b) Front Side, (c) Back  Side, (d) Left Side ................................................................................................................. 124 Figure A.25  Stress-Strain Response of C2: Average of Two Measurements ................... 127  Figure A.26  Stress-Strain Response of C2: Two Position Transducers ........................... 127  x  Figure A.27  Images of Specimen C1 after Failure: (a) Left side, (b) front side, (c) back  side, (d) right side ................................................................................................................. 129 Figure A.28  Stress-Strain Response of D: Average of Two Measurements..................... 132  Figure A.29  Stress-Strain Response of D: Three Position Transducers ........................... 132  Figure A.30  Images of Specimen D Prior to Failure ........................................................ 134  Figure A.31  Images of Specimen D after Failure: (a) Right Side, (b) Left Side .............. 135  Figure A.32  Stress-Strain Response of E1: Average of Two Measurements ................... 138  Figure A.33  Stress-Strain Response of E1: Two Position Transducers............................ 138  Figure A.34  Images of Specimen E1 Prior to Failure ....................................................... 140  Figure A.35  Images of Specimen E1 after Failure: (a) Right Side, (b) Left Side ............ 141  Figure A.36  Stress-Strain Response of E2: Average of Two Measurements ................... 144  Figure A.37  Stress-Strain Response of E2: Two Position Transducers............................ 144  Figure A.38  Images of Specimen E2 Prior to Failure ....................................................... 145  Figure A.39  Images of Specimen E2 after Failure: (a) Right Side, (b) Left side ............. 146  Figure A.40  Stress-Strain Response of AA1: Average of Four Measurements ............... 149  Figure A.41  Stress-Strain Response of AA1: Four Position Transducers ........................ 149  Figure A.42  Images of AA1 up to Strain of 0.00275........................................................ 151  Figure A.43  Images of Specimen AA1 after Failure: (a) Plane of Failure on Right, (b) Left  Side ....................................................................................................................................... 152 Figure A.44  Stress-Strain Response of AA2: Average of Four Measurements ............... 155  Figure A.45  Stress-Strain Response of AA2: Four Position Transducers ......................... 155  Figure A.46  Specimen’s Condition up to Strain of 0.002................................................. 157  Figure A.47  Images of Specimen AA1 after Failure: (a) Back Side, (b) Left Side .......... 158  Figure A.48  Stress-Strain Response of AB1: Average of Four Measurements ................. 161  Figure A.49  Stress-Strain Response of AB1: Four Position Transducers ........................ 161  Figure A.50  Specimen’s Condition up to Strain of 0.003................................................. 163  Figure A.51  Images of Specimen AA1 after Failure: (a) Right Side, (b) Left Side ......... 164  Figure A.52  Stress-Strain Response of AB2: Average of Four Measurements ................ 167  Figure A.53  Stress-Strain Response of AB2: Four Position Transducers ........................ 167  Figure A.54  Specimen’s Condition up to Strain of 0.00225............................................. 169  xi  Figure A.55  Images of Specimen AB2 after Failure: (a) Left Side, (b) Front Side, (c) Right  Side ....................................................................................................................................... 171 Figure A.56  Stress-Strain Response of BA1: Average of Four Measurements ................ 174  Figure A.57  Stress-Strain Response of BA1: Four Position Transducers ........................ 174  Figure A.58  Images of Specimen BA1 up to Strain of 0.00225 ....................................... 176  Figure A.59  Images of Specimen Showing Damage Progress before Failure ................... 179  Figure A.60  Images of Specimen BA1 at Failure: (a) Front Side, (b) Right Side of  Specimen ............................................................................................................................... 180 Figure A.61  Stress-Strain Response of BA2: Average of Four Measurements ................ 183  Figure A.62  Stress-Strain Response of BA2: Four Position Transducers ........................ 183  Figure A.63  Images of Specimen up to Strain of 0.000225.............................................. 185  Figure A.64  Images of Specimen BA2 after Failure: (a) Right Side (b) Left Side .......... 186  Figure A.65  Stress-Strain Response of BB1: Average of Four Measurements ................ 189  Figure A.66  Stress-Strain Response of BB1: Four Position Transducers ........................ 189  Figure A.67  Specimen’s Condition up to Strain of 0.00225............................................. 191  Figure A.68  Images of Specimen BB1 after Failure: (a) Right Side (b) Left Side of  Specimen ............................................................................................................................... 192 Figure A.69  Stress-Strain Response of BB2: Average of Four Measurements ............... 195  Figure A.70  Stress-Strain Response of BB2: Four Position Transducers ........................ 195  Figure A.71  Specimen’s Condition up to Strain of 0.00325............................................. 198  Figure A.72  Images of Specimen BB2 at Failure: (a) Right Side (b) Left Side, (c) Front  Face of Specimen .................................................................................................................. 200 Figure A.73  Stress-Strain Response of BC1: Average of Four Measurements ................ 203  Figure A.74  Stress-Strain Response of BC1: Four Position Transducers ........................ 203  Figure A.75  Images of Specimen up to Strain of 0.00275................................................. 206  Figure A.76  Images of Specimen BC1 at Failure: (a) Right Side (b) Left Side ............... 207  Figure A.77  Stress-Strain Response of BC2: Average of Four Measurements ................ 210  Figure A.78  Stress-Strain Response of BC2: Four Position Transducers ........................ 210  Figure A.79  Images of Specimen up to Strain of 0.002.................................................... 212  Figure A. 80  Images of Specimen BC1 at Failure: (a) Right Side (b) Left Side .............. 213  Figure A.81  Stress-Strain Response of CA1: Average of Four Measurements ................ 216  xii  Figure A.82  Stress-Strain Response of CA1: Four Position Transducers ........................ 216  Figure A.83  Images of Specimen up to Strain of 0.002.................................................... 218  Figure A.84  Images Specimen CA1 Showing the Increase in Damage at Higher Strain  Levels .................................................................................................................................... 220 Figure A.85  Images of Specimen CA1 after Failure: (a) Right Side (b) Left Side .......... 221  Figure A.86  Stress-Strain Response of CA2: Average of Four Measurements ................ 224  Figure A.87  Stress-Strain Response of CA2: Four Position Transducers ........................ 224  Figure A.88  Images Specimen CA2 Showing Specimen’s Condition up to Strain of 0.0025  ............................................................................................................................................... 226 Figure A.89  Images of Specimen CA2 after Failure: (a) Right Side (b) Left Side .......... 227  Figure A.90  Stress-Strain Response of CA3: Average of Four Measurements ................ 230  Figure A.91  Stress-Strain Response of CA3: Four Position Transducers ........................ 230  Figure A.92  Images Specimen CA3 Showing Specimen’s Condition up to Strain of  0.00175.................................................................................................................................. 233 Figure A.93  Images of Specimen CA3 after Failure: (a) Right Side (b) Left SIde .......... 234  Figure A.94  Stress-Strain Response of CA4: Average of Four Measurements ................ 237  Figure A.95  Stress-Strain Response of CA4: Four Position Transducers ........................ 237  Figure A. 96  Images Specimen CA4 Showing Specimen’s Condition up to Failure ....... 240  Figure A.97  Images of Specimen CA4 after Failure: (a) and (b) Right Side (c) Left Side of  Specimen ............................................................................................................................... 242 Figure A.98  Stress-Strain Response of CB1: Average of Four Measurements ................. 245  Figure A.99  Stress-Strain Response of CB1: Four Position Transducers ........................ 245  Figure A.100  Images Specimen CB1 Showing Specimen’s Condition up to Strain of 0.002  ............................................................................................................................................... 247 Figure A.101  Images Specimen CB1 Showing Specimen’s Condition up to Strain of  0.0025.................................................................................................................................... 249 Figure A.102  Images of Specimen CB1 after Failure: (a) Right Side, (b) Front Side, (c)  Left Side of the Specimen ..................................................................................................... 251 Figure A.103  Stress-Strain Response of CB2: Average of Four Measurements .............. 254  Figure A.104  Stress-Strain Response of CB2: Four Position Transducers ...................... 254  xiii  Figure A.105  Images Specimen CB2 Showing Specimen’s Condition up to Strain of 0.002  ............................................................................................................................................... 256 Figure A.106  Images of Specimen CB2 after Failure: (a) Right Side, (b) Left Side  Specimen ............................................................................................................................... 257 Figure A.107  Stress-Strain Response of CB3: Average of Four Measurements .............. 260  Figure A.108  Stress-Strain Response of CB3: Four Position Transducers ...................... 260  Figure A. 109  Images Specimen CB3 Showing Specimen’s Condition up to Strain of 0.002  ............................................................................................................................................... 263 Figure A.110  Images of Specimen CB3 at Strain of 0.00225: (a) Right Side, (b) Left Side  ............................................................................................................................................... 264 Figure A.111  Images of Specimen CB3 after Failure: (a) Right Side, (b) Left Side  Specimen ............................................................................................................................... 265 Figure A.112  Stress-Strain Response of CB4: Average of Four Measurements .............. 268  Figure A.113  Stress-Strain Response of CB4: Four Position Transducers ...................... 268  Figure A.114  Images Specimen CB4 Showing Specimen’s Condition up to Strain of 0.002  ............................................................................................................................................... 272 Figure A.115  Images of Specimen CB4 after Failure: (a) Right side, (b) Left Side  Specimen ............................................................................................................................... 273 Figure A.116  Stress-Strain Response of CC1: Average of Four Measurements ............... 276  Figure A.117  Stress-Strain Response of CC1:Four Position Transducers ....................... 276  Figure A.118  Images Specimen CC1 Showing Specimen’s Condition prior to Failure .. 281  Figure A.119  Images of Specimen CC1 after Failure: (a) Right Side (b) left Side Specimen  ............................................................................................................................................... 282 Figure A.120  Stress-Strain Response of CC2: Average of Four Measurements .............. 285  Figure A.121  Stress-Strain Response of CC2:Four Position Transducers ....................... 285  Figure A.122  Images Specimen CC2 Showing Specimen’s Condition prior to Failure .. 289  Figure A.123  Images of Specimen CC2 after Failure: (a) Right Side, (b) Left Side, (c)  Back Side, (d) Front Side of the Specimen ........................................................................... 291 Figure A.124  Stress-Strain Response of CD1: Average of Four Measurements .............. 294  Figure A.125  Stress-Strain Response of CD1: Four Position Transducers ...................... 294  Figure A.126  Images Specimen CD1 Showing Specimen’s Condition prior to Failure .. 297  xiv  Figure A.127  Images of Specimen CD1 after Failure: (a) Right Side, (b) Left Side  Specimen ............................................................................................................................... 298 Figure A. 128  Images of Specimen CD1 before Failure: The Specimen was Loaded 33  Cycles at a Constant Load of 1778 kN before Failure .......................................................... 300 Figure A.129  Images of Specimen CD1 after Failure: (a) Front Side, (b) Left Side........ 301  Figure A.130  Stress-Strain Response of CD2: Average of Four Measurements .............. 304  Figure A.131  Stress-Strain Response of CD2: Four Position Transducers ...................... 304  Figure A. 132  Images of Specimen CD1 after Failure: (a) Front Side, (b) Right Side .... 305  Figure A.133  Stress-Strain Response of DA1: Average of Four Measurements ............. 308  Figure A.134  Stress-Strain Response of DA1: Four Position Transducers ...................... 308  Figure A.135  Images Specimen DA1 Showing Specimen’s Condition up to Strain of 0.002  ............................................................................................................................................... 310 Figure A.136  Images of Specimen DA1 after Failure: (a) Right Side, (b) Left Side  Specimen ............................................................................................................................... 311 Figure A.137  Images of Specimen DA1 at Failure: (a) Front Side, (b) Back Side, (c) Right  Side of Specimen .................................................................................................................. 313 Figure A.138  Stress-Strain Response of DA2: Average of Four Measurements ............. 316  Figure A. 139  Stress-Strain Response of DA2: Four Position Transducers ..................... 316  Figure A.140  Images Specimen DA2 Showing Specimen’s Condition prior to Failure .. 318  Figure A.141  Images of Specimen DA2 Showing the Damage Progression ................... 320  Figure A.142  Images of Specimen DA2 at Failure: (a) Front Side, (b) Back Side ......... 321  Figure A.143  Envelope of Average Stress-Strain Response of DA3 ............................... 324  Figure A.144  Images Specimen DA3 Showing Specimen’s Condition prior to Failure .. 327  Figure A.145  Images of Specimen DA3 at Failure: (a) Front Side, (b) Back Side .......... 328  Figure A.146  Stress-Strain Response of DA4: Average of Four Measurements ............. 331  Figure A.147  Stress-Strain Response of DA4: Four Position Transducers ...................... 331  Figure A.148  Images Specimen DA4 Showing Specimen’s Condition prior to Failure .. 335  Figure A.149  Images of Specimen DA4 at Failure: (a) Front Side, (b) Back Side .......... 336  Figure A.150  Stress-Strain Response of DB1: Average of Four Measurements .............. 339  Figure A.151  Stress-Strain Response of DB1: Four Position Transducers ...................... 339  Figure A.152  Images Specimen DB1 Showing Specimen’s Condition prior to Failure .. 342  xv  Figure A.153  Images of Specimen DB1 at Failure: (a) Front Side, (b) Back Side .......... 343  Figure A.154  Stress-Strain Response of DB2: Average of Four Measurements .............. 346  Figure A.155  Stress-Strain Response of DB2: Four Position Transducers ...................... 346  Figure A.156  Images Specimen DB2 Showing Specimen’s Condition prior to Failure .. 348  Figure A.157  Images of Specimen DB2 at Failure: (a) Right Side, (b) Back Side .......... 349  Figure A.158  Stress-Strain Response of DB3: Average of Four Measurements .............. 352  Figure A.159  Stress-Strain Response of DB3: Four Position Transducers ...................... 352  Figure A.160  Images Specimen DB3 Showing Specimen’s Condition prior to Failure .. 355  Figure A.161  Images of Specimen DB3 at Failure: (a) Front Side, (b) Back Side .......... 356  Figure A.162  Stress-Strain Response of DB4: Average of Four Measurements .............. 359  Figure A.163  Stress-Strain Response of DB4: Four Position Transducers ...................... 359  Figure A.164  Images Specimen DB4 Showing Specimen’s Condition prior to Failure .. 363  Figure A.165  Images of Specimen DB4 at Failure: (a) Front Side, (b) Back Side .......... 364  Figure A.166  Stress-Strain Response of EA1: Average of Four Measurements .............. 367  Figure A.167  Stress-Strain Response of EA1: Four Position Transducers ...................... 367  Figure A.168  Images Specimen EA1 Showing Specimen’s Condition prior to Failure .. 374  Figure A.169  Images of Specimen EA1 at Failure: (a) Front Side, (b) Back Side ........... 375  Figure A.170  Stress-Strain Response of EA2: Average of Four Measurements .............. 378  Figure A.171  Stress-Strain Response of EA2: Four Position Transducers ...................... 378  Figure A.172  Images Specimen EA2 Showing Specimen’s Condition prior to Failure .. 381  Figure A.173  Images of Specimen EA2 at Failure: (a) Front Side, (b) Back Side ........... 382  Figure A.174  Stress-Strain Response of EB1: Average of Four Measurements .............. 385  Figure A.175  Stress-Strain Response of EB1: Four Position Transducers ....................... 385  Figure A.176  Images Specimen EB1 Showing Specimen’s Condition prior to Failure ... 391  Figure A.177  Images of Specimen EB1 at Failure: (a) Front Side, (b) Back Side ........... 392  Figure A.178  Stress-Strain Response of F1: Average of Four Measurements ................. 395  Figure A.179  Stress-Strain Response of F1: Four Position Transducers.......................... 395  Figure A.180  Images Specimen F1 Showing Specimen’s Condition prior to Failure ...... 398  Figure A.181  Images of Specimen F1 at Failure: (a) Front Side, (b) Back Side .............. 399  Figure A.182  Stress-Strain Response of F2: Average of Four Measurements ................. 402  Figure A.183  Stress-Strain Response of F2: Four Position Transducers.......................... 402  xvi  Figure A.184  Images Specimen F2 Showing Specimen’s Condition prior to Failure ...... 406  Figure A.185  Images of Specimen F2 at Failure: (a) Front Side, (b) Left Side, (c) Back  Side ....................................................................................................................................... 408 Figure B. 1  Schematic Drawings of Failure Plane for 45 Wall Elements ………………..…420  xvii  List of Symbols and Abbreviation ACI  american concrete institute  Aci  area of concrete layer  Asi  area of steel layer  Ag  gross area of section  c  compression depth  d  effective depth of section  E  modulus of elasticity  Ec  modulus of elasticity for concrete  Es  modulus of elasticity for steel  f’c  compressive strength of concrete  fc-max  maximum compression strength of concrete element  f’cr  concrete tensile strength  fy  yielding strength of steel reinforcement  Lb  length of bearing wall  Lsw  length of shear wall  P  compression axial load  ρ  reinforcement ratio  ϕd  curvature demand  xviii  Acknowledgements I would like to offer my sincere gratitude to my supervisor, Dr. Perry Adebar, for his invaluable advice and guidance. He has supported me throughout the research with his patience and unsurpassed knowledge. I attribute the level of my Master Degree to his endless encouragement and effort. This dissertation would have never been completed without him. Besides, I am very grateful to my parents for their unending love and support throughout my education.  xix  To my Parents  xx  Chapter 1: Introduction Figure 1.1 illustrates the plan view of a typical Vancouver high-rise building. The thick shear walls are design to resist all of the lateral loads due to an earthquake and wind. The thin bearing walls are designed to resist axial compression and out-of-plane bending due to the gravity loads (loads on slabs plus weight of slabs and wall self-weight). The bearing walls may experience unintentional strong-axis bending due to the deformation of the shear walls.  Figure 1.1  Example of Shear Wall and Thin Bearing Wall  A significant number of compression failures of thin concrete walls were observed in recent earthquakes. During the Chile Earthquake that struck in February 2010, many buildings suffered significant damage due to the compression failure of shear walls. The shear walls typically had two layers of horizontal reinforcements and were between 120 and 200 mm thick (Adebar, Lorzadeh, 2012). Observations indicate that failed buildings were composed of few shear walls with relatively smaller wall thickness in comparison to the buildings with insignificant damage (Yanev, 2010). An example of a building that failed in Chile is provided in Figure 1.2 (Sherstobitoff et al. 2012). The structure contained two long (corridor) shear walls in one direction and many shorter shear walls perpendicular to the corridor walls. The thickness of most of these 1  shear walls was 6 in. (152 mm). The compression failure occurred in the shear walls at the first level below the grade (see Figure 1.2). As shown in the Figure 1.2, the building had no support at the step designed at the bottom of the building.  Figure 1.2  An Example of Compression Failure in an 18 Stories Building in Chile (Sherstobitoff et al. 2012)  Figure 1.2 illustrates some examples of compression failures in thin concrete walls during the Chile Earthquake.  2  Figure 1.3  Examples of Compression Failure in Thin Walls in February 2010 Chile Earthquake  The five-story Pyne Gould Building collapsed during the earthquake that occurred in City of Christchurch, New Zealand in February 2011. The cause of failure was reported as the compression failure in the east core wall. The wall thickness was 203 mm and it had a single layer of horizontal and vertical reinforcement with a diameter of 16 mm. The horizontal reinforcing bars were spaced at 380 mm which is acceptable according to current Canadian Concrete Code requirements (horizontal reinforcement shall be spaced at the smaller of three times the wall thickness or 500 mm). Another example was the compression failure of a concrete wall in 26-story Grand Chancellor Hotel, one of the tallest buildings in Christchurch. The wall that failed supported significant load from a large transfer girder that cantilevered over the wall (Elwood, 2012). The current experimental study was undertaken to better understand the compression failure of thin concrete walls. The reason for undertaking the current study was the many compression failures of thin concrete walls observed in recent earthquake as mentioned  3  above. The study involved an extensive experimental program, as well as a brief analytical study. The methodology used in the experimental study was to test small full-scale segments of thin concrete walls subjected to cyclic axial compression load. The impetus for the current study was the surprising result obtained from a pilot study that was completed in 2010. The pilot study included testing 10 thin concrete wall elements that were 5.5 in. (140 mm) thick and 24 in. high. Some of the wall elements failed suddenly at very low compression strains. Therefore, in 2011 a more extensive study was undertaken to investigate strain capacity of other wall thicknesses and reinforcement arrangements. The thickness of the wall elements varied from 6 in. (152 mm) to 10 in. (254 mm) and the height of the wall element specimens varied from 24 in. (610 mm) to 36 in. (914 mm). In addition to the wall thickness, the main parameters that were investigated included the amount and arrangement of wall reinforcement; in particular, the presence of out-of-plane reinforcement, i.e., column ties within the walls. An analytical study was undertaken to investigate the influence of compression strain capacity of thin concrete walls on the maximum compression axial load if the wall is subjected to unexpected strong bending. The objective was to investigate the influence of the compression strain capacity on the maximum axial load resisted by thin bearing walls. Overview of Thesis Chapter 2 provides details of the testing methodology, specimen properties, construction of specimens, concrete properties, the instrumentation, and the loading protocols used to apply the concentric axial compression load. A detailed summary of all experimental results are presented in Appendix A. Chapter 3 summarizes the test results and provides a discussion of the failure mode of the seven types of specimens. In addition, Chapter 3 contains a discussion of the influence of confining ties on the failure response of thin concrete walls. Chapter 4 presents a summary of analytical work that was performed to understand how the reduced strain capacity of thin bearing walls influences the maximum compression axial load resisted by the bearing walls. Chapter 5 presents a summary of the experimental and analytical conclusions and provides a briefing of lessons learned. 4  Chapter 2: Experimental Study 2.1  Overview of Chapter  All the specimens were tested under concentric cyclic axial compression force in Baldwin, a universal machine. Figure 2.1 shows a specimen placed in Baldwin. The objective was to test a large number of wall elements under concentric cyclic axial load to study and better understand the strain response of the wall elements. The specimens were grouped in seven types according to their lateral reinforcement arrangement. In order to make it possible to have a variety of lateral reinforcement profiles, 45 specimens with relatively small dimensions had been constructed and tested. The specimens represented different segments of a thin concrete wall. The specimens were either 24 in. (610 mm) or 36 in. (914 mm) high with cross-sectional dimensions of 5.5 10 in2 (203  254 mm2), or 10  12 in2 (140  8 in2 (203  305 mm2), 6  12 (152  305 mm2), 8  254 mm2). Section 2.2 describes the testing  methodology used to axially compress the wall elements. The individual specimen properties are available in section 2.3. Section 2.4 provides details on the method of construction of the concrete wall elements. Concrete was cast at two different stages. Concrete properties for both stages are given in section 2.5. The compression strain was measured on four sides of the majority of the specimens using position transducers. The instrumentations were described in section 2.7. Three different loading protocols were used to apply concentric cyclic axial load and compress the specimens. Detail on protocol types is provided in section 2.8.  5  2.2  Testing Methodology  The objective was to maximize the numbers of specimens; therefore, a larger number of specimens which had a variety of reinforcement configurations was made possible. The testing setup had to be simple to empower the duration of the test setup procedure and to minimize possible errors during the setup. Figure 2.1 shows a specimen placed in the universal machine, Baldwin. In addition, Figure 2.2 illustrates the schematic drawing of a specimen after setup.  Figure 2.1  Baldwin Universal Testing Machine  6  Figure 2.2  Elevation of Specimen during Test  The wall elements were subjected to concentric axial compression in the universal testing machine.  7  2.3  Test Specimens  The wall elements tested were either 24 in. (610 mm) or 36 in. (914 mm) high. Figure 2.3 includes the schematic diagram of seven different types of specimen cross-sections, while the detail of each specimen is provided in Table 2.1. All the specimens contained vertical reinforcements which had a nominal diameter of 10 mm; therefore, the nominal cross-section area was 100 mm2. As shown in Figure 2.3, numbers of the vertical reinforcements varied among the specimen types (one, two, or four vertical bars depending on the configuration of lateral reinforcements). Horizontal reinforcing bars had a diameter of 9.5, 10, 15 or 20 mm (nominal cross-section area of 70, 100, 200, or 300 mm2). The clear cover to the horizontal reinforcement for each specimen is provided in Table 2.1.  Figure 2.3  Cross-sections Showing the Arrangement of Horizontal Reinforcement in 7 Types of Specimens  8  The wall elements were categorized based on their cross-sectional dimensions and their horizontal reinforcing bars configuration. Each type of specimen contained different sets of elements. The details of properties of each element, such as height, cross-sectional dimension, reinforcement properties, are provided in Table 2.1. The clear cover was measured to the horizontal reinforcement in all specimens except for specimens D, F1 and F2, for which the cover was measured to vertical reinforcements because these specimens did not contain horizontal reinforcing bars. The horizontal reinforcement spacing was set to be equal to the smallest dimension of the specimens’ cross-sections. However, the horizontal reinforcing bars were placed at 305 mm apart for specimens CA3, CA4, CB3, CB4, DA3, DA4, DB3 and DB4 (Type 2 specimens with a cross-section of either 254 by 203 or 203 by 254 mm2).  9  Type 1 specimens had a single layer of horizontal reinforcement with no hooks on the ends and had a single vertical reinforcing bar placed adjacent to the horizontal reinforcing bars at the middle of the specimens along the longest side. Type 1 specimens included six sets that contained a pair of wall elements with cross-sections of 5.5 mm2), 8  10 in2 (203  12 in2 (140  305  254 mm2). The covers within each set varied to investigate the  effect of different clear covers. The clear cover dimensions are reported in Table 1. The schematic drawing of Type 1 specimens are provided in Figure 2.4. The diameter of horizantal reinforceing bars was 15 mm for AA1-2 and AB1-2 and the diameter was 20 mm for BA1-2, BB1-2, BC1-2. The spacing of horiznatal reinforcements for all Type 1 specimens was 152 mm.  Figure 2.4  Cross-sectional Area of Type 1 Specimens  10  Type 2 specimens had two layers of horizontal reinforcing bars with no hooks on the ends and had two or four vertical reinforcing bars placed adjacent to the horizontal bars within the core section. Type 2 specimens included four sets that each contained a pair of wall elements with cross-sections of 5.5 mm2), or 10  8 in2 (254  12 in2 (140  305 mm2), 8  10 in2 (203  254  203 mm2). The clear cover to the horizontal reinforcing bars and  horizontal reinforcement spacing are given in Table 1. Figure 2.5 contains the drawings of all Type 2 specimens’ cross-sections. The diameter of horizantal reinforcing bars was 10 mm for C elements and was 15 mm for the rest of Type 2 elements. The spacing of horiznotal reinforcement for 24 in. (610 mm) and 36 in. (914 mm) high specimens was 152 and 305 mm respectively. However, the specing of horiznotal reinforcements in C specimens was 140 mm.  Figure 2.5  Cross-Sectional Area of Type 2 Specimens  11  As shown in Figure 2.6, the wall elements with U-shaped horizontal reinforcements formed Type 3 specimens. The reinforcing bar went along the three sides of the specimen to simulate an end segment of reinforced concrete walls. The ends of the U-shaped reinforcing bars were extended such that they were visible on the fourth side of the specimens. The diameter of the lateral ties with a single cross-tie was 10 mm. The specimens’ cross-section was either 8  10 in2 (203  254 mm2), or 10  8 in2 (254  203 mm2).The ties were spaced  at 203 mm for 203 mm wide specimens (CC), and the ties were spaced at 254 mm for 254 mm wide specimen (EA).  Figure 2.6  Cross-sectional Area of Type 3 Specimens  12  Type 4 specimens that contained column ties with 135o hooks had four vertical reinforcing bars; one of each was placed in every corner of ties (see Figure 2.7). These type specimens included three sets that each contained a pair of wall elements with cross-sections of 5.5  12 in2 (140  305 mm2), 8  10 in2 (203  254 mm2), or 10  8 in2 (254  203  mm2). Schematic drawings of cross-sections of Type 4 specimens are provided in Figure 2.7.The diameter of lateral ties was 10 mm. The lateral ties were spaced at the smallest dimension of cross-section of specimens. The lateral ties were spaced at 203 mm for CD1-2 and the lateral ties were spaced at 254 mm for EB1. Also, the lateral ties were 140 mm apart for the specimens A1-4  Figure 2.7  Cross-sectional Area of Type 4 Specimens  13  Specimen B1 and B2 had 90o hooks in the cover; as shown in Figure 2.8, the confinement was provided by placing two U-shaped reinforcing bars on top of each other. These specimens are Type 5. After forming 90 hooks, the horizontal reinforcement was extended out 60 mm parallel to the other side. The clear cover to horizontal reinforcement was 20 mm. Type 5 specimens had one cross-section area of 5.5  12 in2 (140  305 mm2).  The diameter of ties was 10 mm and they were spaced at 140 mm, the smallest dimension of cross-section of elements.  Figure 2.8  Cross-sectional Area of Type 5 Specimens  14  The specimens that contained no horizontal reinforcement and had four vertical reinforcing bars were called Type 6. For this type of specimens, the cover was measured to the vertical reinforcing bars. The cross-sections associated to Type 5 specimens were as follows: 5.5  12 in2 (140  305 mm2), 8  10 in2 (203  254 mm2). Figure 2.9 shows the  two different cross-sections for this type.  Figure 2.9  Cross-sectional Area of Type 6 Specimens  15  Finally, Type 7 specimens that were very similar to Type 1 contained a single layer of horizontal reinforcing bars at the middle of the wall element with 180o hooks on the two ends. Moreover, each hook formed around two vertical reinforcing bars as shown in the figure below. The horizontal reinforcing bars were extended 60 mm out parallel to the other side after forming 180o hooks (see Figure 2.10). Type 7 specimens had one cross-section area of 5.5  12 in2 (140  305 mm2).  Figure 2.10  Cross-sectional Area of Type 7 Specimens  16  2.3.1  Test Specimen Properties  45 specimens that were either 24 or 36 in. (610 or 914mm) high were constructed to investigate the strain capacity of walls. The detail of each specimen is provided in Table 2.1. The experimental program included the study of influence of clear cover, horizontal bar dimension and spacing, different numbers of horizontal reinforcing layers, and horizontal reinforcement configurations. These parameters were considered to model all possible segments of a thin wall: segments with confining ties, segments without confining reinforcement, and the end portion of a thin concrete wall. The specimens were given two sets of names. The first name was to identify each specimen and the second name was to determine the properties of each specimen: height, width, horizontal reinforcement diameter and the numbers of horizontal reinforcing layers.  17  Table 2.1  Specimens Properties  Single Layer Reinforcment Plan View  Hight (ft)  2  2  2  2  2  2  Thickness (in.)  Specimen Code  Name  Type  Cover (mm)  Horiz. Bar Diameter  Horiz. Bar Spacing (in.)  T6"-SL-15M-C20  AA1  1  20  15 M  6  6  Layer  3 T6"-SL-15M-C20  AA2  1  20  15 M  6  T6"-SL-15M-C60  AB1  1  60  15 M  6  6  3 T6"-SL-15M-C60  AB2  1  60  15 M  6  T8"-SL-15M-C20  BA1  1  20  20 M  6  8  3 T8"-SL-15M-C20  BA2  1  20  20 M  6  T8"-SL-20M-C50  BB1  1  50  20 M  6  8  3 T8"-SL-20M-C50  BB2  1  50  20 M  6  T8"-SL-20M-C80  BC1  1  80  20 M  6  8  3 T8"-SL-20M-C80  BC2  1  80  20 M  6  T5.5"-10M-C35  E1  6  20  10M  5.5  5.5  5 T5.5"-10M-C35  E2  6  20  10M  5.5  18  Double Layer Reinforcment Plan View  Height Thickness (ft) (in.) 2  Specimen Code  Name Type  Cover (mm)  Horiz. Bar Diameter  Horiz. Bar Spacing (in.)  Layer  CA1  2  20  15 M  6  CA2  2  20  15 M  6  CA3  2  20  15 M  12  CA4  2  20  15 M  12  CB1  2  40  15 M  6  CB2  2  40  15 M  6  CB3  2  40  15 M  12  CB4  2  40  15 M  12  DA1  2  20  15 M  6  DA2  2  20  15 M  6  DA3  2  20  15 M  12  DA4  2  20  15 M  12  DB1  2  40  15 M  6  DB2  2  40  15 M  6  DB3  2  40  15 M  12  DB4  2  40  15 M  12  T5.5"-DL-15M-C20  C1  2  20  10M  5.5  5  T5.5"-DL-15M-C21  C2  2  20  10M  5.5  5  T8"-DL-15M-C20  3  8 3  T8"-DL-15M-C20  2  3  T8"-DL-15M-C40  3  8 3  T8"-DL-15M-C40  2  3  T10"-DL-15M-C20  3  10 3  T10"-DL-15M-C20  2  3  T10"-DL-15M-C40  3  10 3  2  T10"-DL-15M-C40  3  5.5  19  Single and Double Cross-Tie(s) Plan View  Height (ft)  Thickness (in.)  3  Specimen Code  Name Type  Cover (mm)  Horiz. Bar Diameter  Horiz. Bar Spacing (im.)  Layer  T10"-DL-10M-C20(WE)  EA1  3  20  10M  10  3  T10"-DL-10M-C20(WE)  EA2  3  20  10M  10  3  T8"-DL-10M-C20(WE)  CC1  3  20  10M  8  10 3  3  3  3  2  2  8  5 T8"-DL-10M-C20(WE)  CC2  3  20  10M  8  T8"-Col. Tie-10M-C20  CD1  4  20  10M  8  8  5 T8"-Col. Tie-10M-C20  CD2  4  20  10M  8  T10"-Col. Tie-10M-C20  EB1  4  20  10M  10  3  T10"-Col. Tie-10M-C20  EB2  4  20  10M  10  3  T5.5"-Col. Tie-10M-C20  A1  4  20  10M  5.5  T5.5"-Col. Tie-10M-C20  A2  4  20  10M  5.5  T5.5"-Col. Tie-10M-C20  A3  4  20  10M  5.5  T5.5"-Col. Tie-10M-C20  A4  4  20  10M  5.5  T5.5"-10M-C20  B1  5  20  10M  5.5  5  T5.5"-10M-C20  B2  5  20  10M  5.5  5  10  5.5  5  10  20  Without Horizantal Reinforcment Plan View  Height (ft)  3  2  Thickness (in.)  Specimen Code  Name  Type  Cover (mm)  T10"-P-C20  F1  7  35  T10"-P-C20  F2  7  35  T5.5"-P-C20  D  7  30  Horiz. Bar diameter  Horiz. Bar Spacing (im.)  Layer  10 or 8  5.5  21  2.4  Construction of Test Specimens  The specimens were cast in two phases. Phase 1 consisted of all specimens with a 5.5 in2 (140  12  305 mm2) cross-section. Phase 2 consisted of the rest of the specimens with cross-  sections of 6  12 in2 (152  305 mm2), 8  10 in2 (203  254 mm2), and 10  8 in2 (254  203 mm2). In both phases, wooden forms were constructed and were used to cast the specimens in a vertical direction. The formwork for the concrete specimens consisted of wooden sets of rectangular slots. The dimensions of slots that were 24 or 36 in. high were constructed to have cross-sections of 5.5  12 in2, 6  12 in2, 8  10 in2, and 10  8 in2.  Sawn lumbers were cut and adjusted to be equal to the width of the specimens. The slots were assembled by nailing the sawn lumbers to the sides of ½ in plywood sheets that were 24 or 36 in. high depending on the height of the specimens. Figure 2.11 illustrates the AutoCad drawings for the formwork for phase 2.  Figure 2.11  AutoCad Drawing of Formwork for Phase 2: Plane View  22  To ensure that the bottom section of the formwork was able to stand the pressure due to wet fresh mixed concrete, a wooden collar was built around the formwork. The collar provided additional confinement to prevent breakage at the bottom of the slots where the pressure would be at its maximum (see Figure2.11 and 2.12). In addition, the bottom plywood sheet was attached to the formwork using screws. Assembly sheets, ½ in plywood sheets, were cut to match the widths and heights of the specimens in order to facilitate the horizontal reinforcement bars in their exact locations. Then, the locations of the reinforcement bars were marked and drilled on the sheets such that the reinforcing bar was held in position by placing the free ends inside the holes made in plywood sheets (see Figure 2.12 (a)). Another objective of using the assembly sheet was to prevent the horizontal reinforcement bars from moving from their specific location and to minimize disturbance during the vibration process. The reinforcement skeleton for each specimen was assembled outside, then the bar cage was installed inside the specified slotted formwork (see Figure 2.12).  (a) Figure 2.12  (b)  Images of Reinforcement Set and Formwork: (a) Example of Assembly of Reinforcement Skeleton, (b) Finished Formwork  23  As shown in Figure 2.12 (a), the vertical reinforcement bars were welded to ¼ in steel flat bars on both top and bottom. The flat bars were used to hold the vertical reinforcement in place and prevent the vertical reinforcement from taking the direct axial load. The horizontal reinforcement bars were held against the vertical reinforcement using tie wire (see Figure 2.13).  Figure 2.13  Image of Horizontal Reinforcement Attached to Vertical Reinforcing Bar Using Tie Wire  Column ties were held to the vertical reinforcement bars only by tie wire. The specimens were cast in vertical position. While casting the specimens, an electrical vibrator was used to insure a uniform distribution of aggregate and to minimize air void in the mixed concrete for each element. The vibrator was simply inserted inside a concrete mix for a few seconds and immediately was removed to prevent segregation of course aggregates. The specimens were cast and cured inside the Structures Lab at University of British Columbia.  24  2.5  Concrete Properties  The specimens were cast in two different phases. 10 specimens, all with 5.5 in. (140 mm) thickness, were cast on June 9, 2010, and 35 specimens with thickness of 6 in. (152 mm), 8 in. (203mm), or 10 in. (254 mm) were cast on August 12, 2011. The 28 days concrete strength of each phase is presented in Table 2.2. Standard compression cylinder tests were conducted for both field and moist-cured cylinders that were 200 mm high and had a diameter of100 mm  Table 2.2  28 Days Concrete Strength  Phase 1 (Casting Date: June 9) Cylinder 1 2 3  Field Cured Moist Cured Load Stress (MPa) Load (kN) Stress (MPa) 170.0 21.6 206.7 26.3 180.2 22.9 235.2 29.9 187.3 23.9 240.3 30.6 Ave (2 and 3) 22.8 Ave: 30.3  Phase 2 (Casting Date: August 12) Field Cured Moist Cured Load Stress (MPa) Load (kN) Stress (MPa) 219.9 27.1 245.9 30.3 215.7 26.6 249.1 30.7 217.5 26.8 247.1 30.5 Ave 26.9 Ave: 30.5  As presented in Table 2.2, the concrete strength for both phases was about the same: 30 MPa. The specimen age on the test day is provided in Table 3.1. The specimen was tested between 30 days up to 322 days. In phase 1, the standard cylinder compression test was repeated 6 months after casting. Moist cured strength and field cured strength were 32 and 26 MPa respectively. There had been 14% and 5% increase in concrete strength for field and moist-cured cylinders respectively.  25  2.6  Specimen Preparation Prior to Testing  To prevent failure of the ends of the specimens and to ensure uniform stress, the concrete wall elements were grouted within confining steel caps. The caps for 5.5 mm2) and 6  12 in2 (152  1 in. thickness and four 2.5  305 mm2) specimens were made of 16 2.5  2.5  305  12 in.2 steel plates with  in.3 angles that were cut in 16 and 12 in. length. The  angles were bolted to a 1 in. bottom plate. Moreover, the end caps for 8 mm2) specimens were made of 12  12 in2 (152  10 in2 (203  254  14 in.2 steel plates with a thickness of 1 in. and four 2.5  in.3 angles, two of which were 12 in. long and the other two of which were 14 in.  long. Figure 2.14 illustrates the schematic shape of the end caps.  (a) Figure 2.14  (b)  End Confining Cap: (a) 3D Drawing of Specimen Placed in Confining End Cap, (b) Picture of the Specimen Ready to be Tested.  26  Prior to testing, a specimen was placed inside the confining angles, which is filled up to the height of 0.5 in. with soft mixed grout (with strength of 30 MPa). Then the spacing between the angles and four sides of the specimen was filled with the same high-strength, fast-setting grout. It was critical to insure that the specimen was perpendicular to the level surface of the 1 in. thick plate. Therefore, three steel posts that were 18 in. long were used to correct the possible inclination angle. The steel posts, each of which had an adjustable rectangular flat bar on top, were designed such that they could be attached to three sides of the bottom 1 in. thick steel plate using existing bolt holes (see Figure 2.14). The flat bars were designed to move forward and backward as the screws attached to them rotate clockwise and counter-clockwise respectively. With the aid of a 36 in. long high-precision level, the angle of inclination along the height of the specimen was detected and the specimen was pushed by the flat bars to the direction that created a near-perfect leveled surface. Then, the grout was squeezed inside the gap between the angles and the surface of the specimen. Moreover, the rest of the void volume was captivated with the same mix. Next, the top of the specimen was evenly covered with a soft mix of the same grout. Then, the top plate was placed on the top of the grout. A 24 in. long high-precision level was used to insure the plate was leveled. Also, the weight of the steel plate assisted in providing a perpendicular plane on the top section. Once the top plate was placed and the grout was set, the gap between the angles and the concrete surface was filled with the same high-strength grout. The process of preparation of the specimen took about 5 hours to complete. The time period included the grout-setting time for each stage in addition to the actual steps involved to prepare the specimen for testing. Figure 2.15 shows steps in the setup process prior to testing.  27  (b)  (a)  28  (c)  (d)  (e) Figure 2.15  Process to Prepare Specimen for Compression Testing: (a) and (b) Show that the Specimen was Lifted and Placed on Top of the Grout, (c) Specimen was Perpendicular to the Bottom plate, (d) the Gaps were Filled with Grout, (e) Confining End-cap was Placed on the Top of the Specimen  29  A 1 in. thick plate was used to insure that an applied load was evenly distributed to the cross-section area of the specimen. The angles were used to identify the confined zone and testing region. The confinement provided by the angles was to prevent possible failure in the top and bottom end of the specimen. Therefore, the position transducers attached to the rods (which were located adjacent to the confining angles) were less vulnerable to any type of damage. As a result, less chance of disturbance in displacement measurement was expected. The confined section outside the testing region was 2.5 inches from the top and bottom of the specimen. Moreover, the gauge length over which a strain was measured was 457 and 762 mm for the 24 in. (610 mm) and 36 in. (914 mm) tall specimens respectfully.  30  2.7  Instrumentation  Four position transducers (PTs), LP18, LP19, LP20, and LP21, were used to measure the average strain over the gauge length of 457 mm on the 24 in. (610 mm) high specimens and 762 mm on the 36 in. (914 mm) high specimens. The strain was measured on four sides of most of the specimens. Average strain was measured by monitoring the displacement on two sides that were 12 in. across from each other for specimens A1, A2, A3, B1, C1, C2, D, and E1. The PTs were mounted on the steel rods that were placed at 457 and 762 mm apart for 24 in. and 36 in. tall specimens. The locations of PTs were defined by front, back, right and left side as shown in Figure 2.16.  Figure 2.16  Defining the Sides of Specimens  The rods were about 3 in. long, and they were installed inside the holes using highstrength epoxy that is used for the same purpose in the industry: to attach anchor bolts or rods to concrete elements. The holes were made first by drilling a 1.5 in. (38 mm) long chasm 31  with a diameter of in. (9.5 mm), and then, the diameter of the holes was expanded to in. (13mm) with the depth of  in. from the surface of the specimens. The holes were drilled one  month after casting the specimens. The objective was to measure the displacement with an accuracy of 0.01 mm; therefore, Novotechnik Position Transducers were selected. PTs had repeatability of 0.002 mm and a resolution of 0.01 mm which was appropriate for the current experimental purpose. Baldwin was the universal testing machine that was used at the Structures Lab at University of British Columbia to cyclically compress the specimens. The machine was capable of applying 400,000 lb (1778 kN) of axial compression load. As shown in Figure 2.17, Baldwin is composed of a control system, two head shafts, posts and a loading table which was operated hydraulically.  (a) Figure 2.17  (b)  Universal Testing Machine Baldwin: (a) Control Setting, (b) Testing Apparatus  32  The control consisted of a load dial gauge as well as a digital load reader. The load was applied by allowing the oil inside the cylinder which was underneath the table. Since the top head was fixed in place, the specimen located in the machine was subjected to compression load as the table was pushed up. During the test, the top head and the posts were subjected to tension force. They were held together by specially-designed steel rings. The load was controlled using two valves on the control system. While the test was in progress, the average displacement was monitored. Once the target strain was reached, the load was manually dropped. Moreover, the stress was gradually reduced to zero at the end of one cycle.  33  2.8  Testing Procedure and Protocol  The specimens were loaded under pseudo strain control, i.e., the load was increased until the target average strain was reached. Table 2.3 includes details on the protocol types that were used to load specimens and the exact number of loading cycles at corresponding target strains. The standard protocol, Type-1, involved five cycles to each strain level. The first target strain level was 0.0005 and the subsequent strain target was 0.00025 higher than the previous one. Thus, a specimen loaded using the standard protocol to a maximum strain of 0.0035 was loaded a total of 65 cycles – five cycles to each of 13 strain levels: 0.0005, 0.00075, 0.001, 0.00125 … 0.0035. Type-2 protocol involved five cycles to each strain level. The test commenced at the first target strain level of 0.0005 and the subsequent target strains were increased by 0.0005 up to the target strain of 0.0015. Then, the increment was changed to 0.00025 up to a strain level of 0.0035 similar to protocol Type-1. Therefore, a specimen loaded according to Type 2 protocol and was loaded to a maximum strain of 0.0035 was subjected to 55 cycles. The specimens AA1, AB1, BA1, BB2, BC1, CA1, CA4, CB3, DA1, DA3, DB1, CD1, CC1, and F1 were subjected to Type 2 protocol to investigate the influence of reduction in target strains at an early stage of testing on the strain capacity of the specimens. In addition, specimens AA2, AB2, BA2, BB1, BC2, CA2, CB2, and DB2 were subjected to the last type of testing protocol, Type-3. This protocol was similar to Type-2 with the exception that the protocol involved 3 loading cycles instead of five cycles. Moreover, the strain variation was slightly different than testing protocol Type-2. In Type-3 protocol, the specimen was loaded at a strain of 0.0005 and the subsequent target strains were increased by 0.0005 up to a strain level of 0.0035. Therefore, a specimen loaded according to Type 3 was subjected to 21 cycles if loaded up to a strain of 0.0035. Protocol Type 3 was used to study the effect of reducing the loading cycles from five to three gyrations on the test results. The protocol type that each specimen was tested with accordingly is shown in Table 2.3.  34  Table 2.3  Testing Protocols Target Strain  Specimen  Loading Protocol  0.0005  0.00075  0.001  0.00125  0.0015  0.00175  A1 A2 A3 B1 B2 C1 C2 D E1 E2 AA1 AA2 AB1 AB2 BA1 BA2 BB1 BB2 BC1 BC2 CA1 CA2 CA3 CA4 CB1 CB2 CB3 CB4 CC1 CC2 CD1 CD2 DA1 DA2 DA3 DA4 DB1 DB2 DB3 DB4 EA1 EA2 EB1 F1 F2  1 1 1 1 1 1 1 1 1 1 2 3 2 3 2 3 3 2 2 3 2 3 1 2 2 3 2 1 2 1 2 1 2 1 2 1 2 3 2 1 1 1 1 2 1  5 5 5 5 5 5 5 5 5 5 5 3 5 3 5 3 3 5 5 3 5 3 5 5 5 3 5 5 5 5 5 5 5 5 5 5 5 3 5 5 5 5 5 5 5  5 5 5 5 5 5 5 5 5 5  5 5 5 5 5 5 5 5 5 5 5 3 5 3 5 3 3 5 5 3 5 3 5 5 5 3 5 5 5 5 5 5 5 5 5 5 5 3 5 5 5 5 5 5 5  5 5 5 5 5 5 1 5 5 5  5 5 5 5 5 5  5 5 5 5 5 1  5 5 5 5 3 5 3 5 3 3 5 5 3 5 3 5 5 5 3 5 5 5 5 5 5 5 5 5 5 5 3 5 5 5 5 5 5 5  5 5 5 5  5  5  5 5 5 5 5  5 5 5 5 5  5  5 5 5 5 5  5 5 5 5 5  5  5 5 5 5 1 5 10 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 1 5  0.002  0.00225  Number of Cycles 31 11 5 5 5 5 5 5 5 5  5 5 5 5 3 5 3 5 3 3 5 5 3 5 3 5  5 5 5 5  5 3 22 5 5 5 5 5 5 5 2 5 5 3 5 5 5 5 5  5  5  1  5 6  5 8 5 5  5 5 5 5 5 5 5 5 5  1 5 1 5  0.0025  0.00275  0.003  0.00325  0.0035  11 5 5 5 5  5 5 5 5 5  5 5 5 5 5  5 5 5 5 5  5 5 5 5 5  5 5 3 5 1 5 1 5 3 1 5 7 2 10 3 1  5 5  5 5  5 2  5  5  1  5  5  1  5  5 1  5  5  5 5  5 1  5  1  5 1  5  5  5  5 3 5 5 5 5  1 1  16 cycle at constant 400,000lb load 5 5 5 5 5 5 5 5 34 cycle at constant 400,000lb load 5 5 5 5 5 5 5 5 1 5 5 5 5 5 1 5 3  5  5 1  5  5  5  5  5  5  5  5  5  5  5  5  In all three types of testing protocol, the rate of loading was kept constant. At each strain level the rate of loading was selected such that the period it took for each cycle was a ratio of 3 minutes, the standard time for a compression cylinder test. The time it took to complete one cycle at strain of 0.0005 was equivalent to 45 seconds which was ¼ of 3 minutes ( . At the end of each cycle, the specimen was visually examined to keep record of the changes and damage that appeared while the test was in progress. A typical wall element test 35  took up to eight hours to complete because of large number of loading cycles and documentation of damage imposed on the specimen. Details regarding the performance of specimens for individual specimens are provided in Appendix 1. In some tests, no effort was made to ensure the specimen was subjected to uniform strain; however, the strain gradient was recorded. During most tests, the compression strains were maintained uniform by shifting the specimens in the loading frame to change the point of applied-load application. The offset formed in the point of applied load application caused the side that experienced less deformation to deform more and created a uniform strain response. This approach allowed maintaining a relative uniform compression strain on all four sides of the specimen during the tests.  36  Chapter 3: Experimental Results 3.1  Overview of Chapter  Details of the 45 wall element tests is provided in Appendix A. Test detail includes stressstrain curve response, detail observations during the test including report of damage progression at every target strain level, observation of failure, and summary of test observations. In addition, Appendix B contains schematic drawings of failure planes for the specimens. The stress values in the stress-strain curves were the net concrete stress that was calculated by subtracting the vertical reinforcement stress from the measured stress values. The steel was assumed to yield at a strain of 0.002. The modulus of elasticity of 200 MPa was considered for vertical reinforcement. The experimental results are summarized in Table 3.1 and a summary of the test results is provided in section 3.2. Different modes of failure planes, such as a single diagonal crack or a cone-shape failure, were observed in 45 tests. Section 3.3 includes the images of individual specimens at failure along with a description of the failure planes. The strain capacity, with respect to height-to-thickness ratio, significantly varied between 36 in. high specimens with lateral tie, and ones with no ties. Moreover, section 3.4 includes a discussion of influence of lateral ties on the failure modes of the specimens. Section 3.5 includes Figure 3.9 and 10 that present the relationship of maximum concrete stress and strain capacity with specimen height-to-thickness ratio.  37  3.2  Summary of Test Results  The test results are summarized in Table 3.1 and are discussed briefly below.  Table 3.1 Thickness Name Type (mm) A1 4 140 A2 4 140 A3 4 140 A4 4 140 B1 5 140 B2 5 140 C1 2 140 C2 2 140 D 6 140 E1 7 140 E2 7 140 AA1 1 152 AA2 1 152 AB1 1 152 AB2 1 152 BA1 1 203 BA2 1 203 BB1 1 203 BB2 1 203 BC1 1 203 BC2 1 203 CA1 2 203 CA2 2 203 CA3 2 203 CA4 2 203 CB1 2 203 CB2 2 203 CB3 2 203 CB4 2 203 CC1 3 203 CC2 3 203 CD1 4 203 CD2 4 203 DA1 2 254 DA2 2 254 DA3 2 254 DA4 2 254 DB1 2 254 DB2 2 254 DB3 2 254 DB4 2 254 EA1 3 254 EA2 3 254 EB1 3 254 F1 6 254 F2 6 254  Properties of Wall Elements Horizantal Bars Cover No.Vertical Size Spacing (mm) (mm) Bars 9.5 mm 140 20 4 9.5 mm 140 20 4 9.5 mm 140 20 4 9.5 mm 140 20 4 9.5 mm 140 20 4 9.5 mm 140 20 4 10M 140 20 4 10M 140 20 4 10M 140 30 4 10M 140 60 4 10M 140 60 4 15M 152 20 1 15M 152 20 1 15M 152 60 1 15M 152 60 1 20M 152 20 1 20M 152 20 1 20M 152 50 1 20M 152 50 1 20M 152 80 1 20M 152 80 1 15M 152 20 2 15M 152 20 2 15M 305 20 2 15M 305 20 2 15M 152 40 2 15M 152 40 2 15M 305 40 2 15M 305 40 2 10M 203 20 2 10M 203 20 2 10M 203 20 4 10M 203 20 4 15M 152 20 2 15M 152 20 2 15M 305 20 2 15M 305 20 2 40 15M 152 2 40 15M 152 2 15M 305 40 2 15M 305 40 2 10M 254 20 2 10M 254 20 2 10M 254 20 4 35 ----4 35 ----4  Summary of Test Results ρ (As/Ag) 0.0094 0.0094 0.0094 0.0094 0.0094 0.0094 0.0094 0.0094 0.0094 0.0094 0.0094 0.0022 0.0022 0.0022 0.0022 0.0019 0.0019 0.0019 0.0019 0.0019 0.0019 0.0039 0.0039 0.0039 0.0039 0.0039 0.0039 0.0039 0.0039 0.0039 0.0039 0.0078 0.0078 0.0039 0.0039 0.0039 0.0039 0.0039 0.0039 0.0039 0.0039 0.0039 0.0039 0.0078 0.0078 0.0078  Height Age at (mm) Testing (day) 610 34 610 56 610 61 610 196 610 43 610 191 610 37 610 65 610 122 610 48 610 106 610 91 610 260 610 72 610 100 610 98 610 260 610 252 610 126 610 132 610 258 610 89 610 268 914 290 914 135 610 115 610 262 914 139 914 295 914 182 914 297 914 170 914 322 610 191 610 280 914 141 914 283 196 610 269 610 914 160 914 287 914 301 914 310 914 303 148 914 308 914  f c-max, (MPa) 31.7 33.4 31.3 30.0 32.2 30.8 28.1 28.3 29.6 32.1 32.3 33.6 30.5 33.8 34.2 33.5 33.0 31.5 33.7 33.9 33.6 33.2 33.1 33.1 30.0 31.8 33.0 33.1 33.0 30.1 31.0 31.6 31.6 32.9 31.3 31.6 33.0 32.4 32.4 33.1 31.9 29.2 32.6 30.2 27.8 31.6  Summary of Test Results f c-max, Peak Strain Strain at /f' c Strain Capacity Failure 1.05 0.0020 0.0030 0.0033 1.10 0.0020 0.0035 0.0043 1.03 0.0023 0.0035 0.0044 0.99 0.0022 0.0035 0.0046 1.06 0.0022 0.0035 0.0039 1.02 0.0018 0.0035 0.0039 0.93 0.0017 0.0015 0.0017 0.93 0.0013 0.0010 0.0013 0.98 0.0025 0.0033 0.0033 1.06 0.0023 0.0035 0.0037 1.07 0.0023 0.0020 0.0023 1.10 0.0023 0.0028 0.0029 1.00 0.0023 0.0020 0.0024 1.11 0.0020 0.0030 0.0031 1.12 0.0024 0.0020 0.0024 1.10 0.0020 0.0035 0.0039 1.08 0.0023 0.0025 0.0027 1.03 0.0019 0.0020 0.0023 1.11 0.0025 0.0033 0.0034 1.11 0.0025 0.0028 0.0030 1.10 0.0023 0.0020 0.0025 1.09 0.0022 0.0035 0.0039 1.08 0.0023 0.0025 0.0028 1.09 0.0020 0.0023 0.0024 0.98 0.0015 0.0015 0.0016 1.04 0.0022 0.0025 0.0026 1.08 0.0023 0.0025 0.0028 1.09 0.0022 0.0023 0.0026 1.08 0.0019 0.0020 0.0023 0.99 0.0018 0.0035 0.0038 1.02 0.0020 0.0025 0.0026 1.04 0.0020 0.0030 0.0031 1.04 0.0020 0.0035 0.0038 1.08 0.0023 0.0030 0.0032 1.03 0.0022 0.0035 0.0039 1.04 0.0020 0.0018 0.002 1.08 0.0020 0.0023 0.0025 0.0038 1.06 0.0025 0.0035 0.0028 1.06 0.0023 0.0025 1.08 0.0020 0.0020 0.0023 1.05 0.0020 0.0023 0.0025 0.96 0.0020 0.0035 0.0043 1.07 0.0020 0.0020 0.0022 0.99 0.0020 0.0035 0.0040 0.0017 0.91 0.0015 0.0015 0.0024 1.04 0.0019 0.0023  38  The specimens were divided into seven types as described in section 2.3. In Table 3.1, the specimen type is provided in the second column, adjacent to the specimen names. The third column indicates the wall thickness for each element. The fourth and fifth columns describe the diameter and the spacing of lateral reinforcement. Each specimen had a different number of vertical reinforcing bars; the number of vertical reinforcement bars is given in the seventh column. The ratio of area of vertical reinforcement to gross area is defined as “ρ” and is provided in column eight. The specimens were 24 or 36 in. high. Column nine contains wall element height. The age of a specimen on the testing day is given in column 10. The first 10 specimens, A1-E2, were cast on June 9, 2010, and the rest of the specimens were cast on August 12, 2011. The stress resisted by the vertical reinforcement for each element was obtained using the measured average compression strain during the tests. The net compression force that was resisted by concrete and the area of the concrete element were used to calculate the maximum stress: fc-max. The properties of steel reinforcement were not measured and the values for strength and modulus of elasticity were assumed to be 400 and 200,000 MPa respectively. The magnitude of error in selecting steel strength is very small because “ρ” is very small compared to the gross area for each specimen. Consider specimen F2: if fs was selected as 500 MPa (the upper-bound value for steel strength), the reduction in fc-max would have been by 2.5 % which would be a minor change. Peak strain was defined as the average strain at which the maximum concrete strength was achieved. Strain capacity was defined as the largest strain level to which the specimen was compressed over five or three cycles, depending in the loading protocol type, without failure. In addition, Table 3.1 contains the strain failure which was the maximum strain measured at failure. The results indicated that the strain capacity varies between 0.001 to a value greater than 0.0035 depending on the specimen height, clear cover, configuration of horizontal reinforcement, and confinement if provided (column ties). It was observed that the specimen which experienced a strain gradient had a strain capacity as high as 0.0035. Strain gradient happened in specimens that experienced damage on one side while the other side remained relatively stiffer. The specimen (C1-2, CA1-4, CB1-4, DA1-4, DB1-4) that had horizontal reinforcement bars with free ends showed that the lateral reinforcement bars were high-stress concentration points. Schematic drawings of the failure plane (see Appendix B) for these 39  specimens indicated that the failure cracks formed through the lateral reinforcement bars resulting in either separation of the concrete cover or formation of diagonal cracks through the section. The stress-strain curve for every specimen is provided in Appendix A. The stress was obtained using the net compression force that was resisted by concrete and the strain is the average of four strains measured during the test for all the specimens except the first 10 wall elements (A1-E2). The average strain was obtained using two or three position transducers for specimens A1-E2 (exact number of position transducers that were used to measure the strain for these specimens is provided in Table A1-10 in Appendix A)  40  3.3  Shape of Cracks at Failure and Fragility of Specimens  Figure 3.1 illustrates the shape of failure for all Type 1 specimens. The horizontal steel arrangement varied with respect to the clear cover selected for the specimen. Type 1 specimen widths were 152 or 203 mm. The covers were 20, 50, 60 and 80 mm. The specimens exhibited relatively similar behavior under the same testing protocol. As shown in Figure 3.1, the crack formation was similar in all Type 1 specimens. The crack at failure propagated though cover from the top to the bottom of the section passing through the location of the horizontal reinforcement bars.  41  Specimen AA1  Specimen AA2  Specimen AB1  Specimen BA2  42  Specimen BB1  Specimen BC1 Figure 3.1  Specimen BB2  Specimen BC2 Failure Images of Type 1 Specimens  43  Type 2 specimens included wall elements with 610 and 914 mm heights. The specimen widths were 140, 203, and 254 mm. The longer specimens had failed at earlier strain levels, relatively. In addition, type 2 specimens (C1 and C2) with widths of 140 mm had the smallest strain capacity among all the specimens. Modifying the width from 140 to 203 and 254 mm significantly increased the strain capacity of wall element (see the test results in Table 3.1). Images of Type 2 specimens at failure are shown in Figure 3.2.  Specimen C1  Specimen C2  44  Specimen CA1  Specimen CA3  Specimen CA2  Specimen CA4  45  Specimen CB1  Specimen CB2  Specimen CB3  Specimen CB4  46  Specimen DA1  Specimen DA2  Specimen DA3  Specimen DA4  47  Specimen DB1  Specimen DB2  Specimen DB3  Specimen DA4  Figure 3.2  Images of Failure for Type 2 Specimens  48  As shown in the pictures above, all the specimens with 610 mm heights had similar failure modes. Two main diagonal cracks formed such that they coincided at the middle segment of the specimens and propagated through the concrete cover zone. Specimen CA3 and CA4, which had clear covers of 20 mm, had similar failures. The diagonal crack met at about the midsection (closer to the top segment of the specimens) and a large crack coalesced on the 203 mm side of the specimens, splitting the elements. CB3 and CB4 were different from CA3 and CA4 with respect to the clear cover. The horizontal reinforcement bars were placed 40 mm from the concrete surface. These two specimens failed in a very similar manner. The plane of failure was almost identical in both images (see Appendix B for schematic drawing of failure plane). A large diagonal crack was formed from the top left side down to the left bottom corner of the elements. Planes of failure in DA3, DA4, DB3 and DB4 were very similar to CA3, and CA4. Specimens DA3, DA4 were 254 mm wide and had similar planes of failure to CA3 and CA4. The cover was 20 mm for all four specimens. DB3 and DB4 were 254 mm wide and had concrete covers of 40 mm. These specimens failed similarly to CB3 and CB4. Except specimens CA1, DA1, DA2 and DB1, all Type 2 specimens had a brittle failure that involved extensive load sound. Their strain capacity ranged between 0.001 and 0.0025. Type 3 specimen simulated the end segment of a wall. Figure 3.3 illustrates the failure images for this type of the specimens.  49  Specimen CC1 Figure 3.3  Specimen CC2 Failure Images of Type 3 Specimens  Specimens CC1 and CC2 had similar failure modes. Cracks were formed through the top reinforcement on the side that contained no cross-ties. The cracks propagated in the cover zone. The side with no cross-ties experienced significant damage because the absence of confinement allowed opening of reinforcement, making the wall element more vulnerable. CC1 had a strain capacity of 0.0035 and CC2 had a strain capacity of 0.0025. Comparing the stress-strain response of both elements indicates that CC1 had a significant decrease in loadcarrying capacity after a strain of 0.002. The stress-strain curves are provided in Appendix 1 and 2. Type 4 specimens contained column ties that provided the necessary confinement for the wall elements. These specimens had a strain capacity greater than 0.0035 as expected. Figure 3.4 contains the images of failure.  50  Specimen A1  Specimen A2  Specimen A3  51  Specimen CD1  Specimen CD2  Specimen EB1 Figure 3.4  Failure Images of Type 4 Specimens  52  Type 5 specimens contained 90o hooks for confinement reinforcement. They performed similar to the specimens that had regular column ties with 135o hooks. This may indicates that even with a small width, if adequate confinement was provided, the thin concrete wall elements would reach a strain capacity as high as 0.0035. The figure below contains the images at failure for Type 5 specimens.  Specimen B1 Figure 3.5  Specimen B2 Failure Images of Type 5 Specimens  53  Type 6 specimens, E1 and E2, contained a single layer of reinforcement with 180o hooks on the ends. Failure images of E1 and E2 are shown in Figure 3.6. The plane of failure was slightly different for E1 and E2. This discrepancy was due to the testing procedure. E1 was not loaded uniformly; therefore, the strain measurement between the two position transducers varied significantly. One side experienced significant damage and was less rigid, thus experiencing larger deformation relative to the stiffer side of the specimen. However, for specimen E2, the strain was maintained uniform by the method that is described in section 2.8.  Specimen E1 Figure 3.6  Specimen E2 Failure Images of Type 6 Specimens  Finally, the failure images of Type 7 specimens are shown in Figure 3.7. Specimens F1 and F2 had similar planes of failure. F1 and F2 were very brittle and had low-strain capacity. However, specimen D behaved similarly to a typical cylinder compression test. Specimen D was 24 in. (610 mm) tall and F1 and F2 were 36 in. (914 mm) tall. The specimen slenderness ratio played a significant role in strain capacity and stress-strain response of the wall elements. 54  Specimen F1  Specimen F2  Specimen D Figure 3.7  Failure Image of Type 7 Specimens  55  3.4  Influence of Lateral Ties on Failure Mode  Consideration of lateral ties is one of the essences of column design because lateral ties in a column provide shear resistance, prevent buckling of longitudinal reinforcement, and confine concrete. However, lateral ties are used in concrete walls only in rare cases. According to ACI Code, column ties are provided in concrete walls when the ratio of the area of vertical reinforcements to gross area of concrete exceeds 1%, or when the reinforcement bars are designed as compression elements. Similarly, Canadian Concrete Code indicates that vertical reinforcement bars are not required to be enclosed with lateral ties unless the vertical reinforcement ratio exceed 0.5% or the reinforcing bar diameter is larger than 20M (As of 400 mm). Moreover, if the vertical reinforcement bars are not required as compression reinforcement, lateral ties are not supplicated. ACI Code requires that column ties spaced at a distance not larger than the smallest of 16 times the smallest vertical bar diameter, smallest dimension of a section, or 48 times the tie diameter. Pfister had completed research on how ties would influence the behavior of concrete columns to assist in development of 1963 ACI code (Pfister, 1964). His test results indicated that the difference in ultimate strength of columns between a fully-tied column and column with no tie was insignificant. However, he observed significantly different failure modes. The column with ties failed gradually and with noticeable signs of damage such as crushing of concrete cover prior to failure. However, the columns with no ties were brittle and failed suddenly. As he indicated, the concrete crushing happened prior to buckling of vertical reinforcement. Pfister’s observations were very similar to observations of concrete wall specimens tested in this experimental research. Minimum ties were provided in specimens A1-A3, CD1, CD2 and EB1 (ties were spaced at distance equal to the smallest dimensions of specimens (see Table 3.1)).The wall elements failed gradually and their strain capacity reached a value greater than 0.0035 under cyclic axial compression loading. Specimens C1, C2, CA2-CA4, CB1-CB4, DA3, DA4 and DB2-DB4 had strain a capacity of less than 0.00275. These specimens contained double layers of horizontal reinforcement with free ends that were exposed 10 to 15 mm. The specimens failed very suddenly with no visible or very insignificant sign of damage prior to failure. The failure was very quick and sudden such that a high quality video camera was used to film the failure of the specimens. Reviewing the failure on the film indicated (or suggested) that concrete 56  crushing happened before buckling of vertical reinforcement, similar to Pfister’s observations. Splitting cracks were formed in different shapes because of the geometry of the elements and the layout of the parallel horizontal reinforcement bars. The straight horizontal reinforcement bars seemed to be high stress points in the wall elements. Descriptions and images of failure for all specimens are provided in section 3.3. The detailed test observations for individual elements are provided in Appendix A. Hysteretic response for specimens with ties and without ties are presented in Figure 3.8 and Figure 3.9. Only one example for each cross-section is presented here. The hysteretic stress-strain curves for all the wall elements are available in Appendix A. The measured net compression axial load and concrete area were used to calculate stress, and strain on the x-axis was the average value of four position transducers in most of the indicated elements.  57  30  25  s  c  Compression Stress, (P - P )/A (MPa)  35  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  4  4.5 -3  Strain  x 10  Stress-Strain Response of A2 (Cross-section: 5.5  12 in.2)  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Stress-Strain Response of CD2 (Cross-section: 8 Figure 3.8  4 -3  Strain  x 10  10 in.2)  Hysteretic Response for Specimen with Lateral Ties  58  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5 -3  Strain  x 10  Stress-Strain Response of C2 (Cross-section: 5.5  12 in.2)  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Stress-Strain Response of CA3 (Cross-section: 8  4 -3  Compression Strain  x 10  10 in.2)  59  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Stress-Strain Response of DA4 (Cross-section: 10 Figure 3.9  4 -3  Strain  x 10  8 in.2)  Hysteretic Response for Specimens with no Ties  As shown in Figure 3.8, the specimens that contained lateral column ties had a minimum strain capacity of 0.0035. Concrete crushing did not happen suddenly for the specimen with column ties. The specimen gradually experienced damage. However, the specimens with no confining ties had a brittle failure, regardless of their strain capacities (See section 3.2 for the failure images). Type 2 specimens contained double layers of horizontal reinforcement with free ends. These specimens were either 24 in. or 36 in. high. The 24 in. tall specimen showed greater strain capacity in comparison to 36 in. tall specimen. However, in all the tests the failure happened with explosive load sound and very suddenly. The absence of confinement in such specimens might have caused brittle failure.  60  3.5  Concrete Compression Stress and Strain Capacity  The maximum concrete stress, fc-max, varied between 88 and 112 % of 28-day-cylindercompression strength. Figure 3.10 (a) compares the ratio of concrete compression strength to the ratio of height-to-thickness of the specimen. The height-to-thickness ratio of wall elements varies between 2.4 and 4.5. Type 2 specimens with height-to-thickness ratios of 3.6, 4.3, and 4.5 had brittle and sudden failure. The maximum concrete compression stress measured for these specimens was between 93 and 109 % of f’c. The vertical reinforcement ratio, ρ, varies from 0.2 to 0.9. Figure 3.10 (b) shows the influence that different percentages of vertical reinforcements have on maximum concrete stress.  61  1.2  Ratio Max. Conc. Comp. Stress to fc'  1.1 1.0 0.9 0.8  0.7 0.6 0.5 2  2.5  3  3.5  4  4.5  5  5.5  6  Height-to-Thickness Ratio (a)  Ratio Max. Conc. Comp. Stress to fc'  1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0.000  0.002  0.004  0.006  0.008  0.010  Vertical Reinforcement Ratio (b) Figure 3.10  Influence of Specimen Slenderness and Vertical Reinforcement Ratio on Maximum Concrete Compression Stress  62  Figure 3.11(a) illustrates the correlation between maximum concrete stress and the compression strain capacity of wall elements. The specimen with lower strain capacity resisted smaller maximum compression stress in comparison to specimens with greater strain capacity. The specimen that contained lateral ties with 135o hooks had a strain capacity greater than 0.0035. Moreover, the specimen with lateral ties with 90o hooks also had a high strain capacity (minimum of 0.003). Height-to-thickness ration had significant influence on the strain capacity of wall elements. Some of the wall elements with no ties had a strain capacity as high as 0.00325 such as BA1, BB2 and CA1. These elements were 24 in. (610 mm) high with 203 mm thickness. However, 36 in. (914 mm) tall specimens with similar lateral reinforcement layout had failed at much smaller strain levels. Figure 3.11(b) illustrates the relationship between the compression strain capacity and the height-to-thickness ratio. The 36 in. tall specimens that contained no lateral ties had failed at much smaller strains; therefore, they had a smaller strain capacity. However, the 36 in. tall specimens with lateral ties had a minimum strain capacity of 0.003. Considering the results presented in Figures 3.10 and 11, the slender specimens with no confinements had a smaller strain capacity among all specimens tested.  63  Ratio Max. Conc. Comp. Stress to fc'  40.5 35.5 30.5 25.5 20.5 15.5 10.5 5.5 0.5 0  0.0005  0.001  0.0015  0.002  0.0025  0.003  0.0035  4.5  5  Compression Strain Capacity (a) 0.0035  Compression Strain Capacity  0.0030 0.0025 0.0020 0.0015 0.0010 0.0005 0.0000 2  2.5  3  3.5  4  Height-to-Thickness Ratio (b) Figure 3.11  (a) Maximum Concrete Stress Variation as a Function of Strain Capacity, (b) Influence of Specimen Slenderness on Maximum Compression Strain Capacity of Concrete  64  As shown in the Figure 3.13, maximum compression stress and the age of the specimens at testing had no specific correlation. The specimens were tested at different ages from 34 to 322 days after casting.  Ratio Max. Conc. Comp. Stress to fc'  1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5 0  50  100  150  200  Age (days) Figure 3.12  Comparison of Maximum Concrete Stress with Respect to Age at Testing  The experimental results can be summarized in a few points:   Strain capacity of unreinforced concrete wall is less than 0.0035    Strain gradient has significantly influence the strain capacity of walls.    Lateral reinforcements with free ends acted as a point of high stress concentration    In 6 in. wide wall elements, change in the clear cover had minor influence on the strain capacity of wall elements    In a single layer 24 in. tall wall element (Type 1), an increase in cover reduced the strain capacity    Strain capacity decreased from 24 in. tall specimens to 36 in. tall specimens  65    36 in. tall specimens with a 20 mm cover and one cross-tie performed better compared to the specimens with no cross-tie (strain capacity 0.0015)    In 24 in. tall double layer elements, increase in cover reduced the maximum cyclic strain    In 36 in. tall double layer elements, an increase in cover increased the strain capacity    Specimens with regular column tie had a strain capacity greater than 0.0035)    Confinement had significant influence on the strain capacity of the wall elements    Providing any types of ties (with 90o or 135o hooks) increased the strain capacity of wall elements (minimum of 0.003)  66  3.6  Influence of Different Testing Protocols on Response of Specimen  Three testing protocol were selected as discussed in section 2.8 to test the specimens under cyclic compression load. Wall elements tested according to protocol Type 1and 2 were loaded in compression for five cycles starting at 0.0005 strain target. In Type 1 protocol, the subsequent strain target was 0.00025 higher than the previous one. However, in Type 2 protocol, the strain targets increased by 0.0005 up to a strain of 0.002 then the subsequent target strain increases by 0.00025. Due to a large number of loading cycles, the specimen subjected to protocol Type 1and 2 softened earlier than those subjected to Type 3. Strain variation in Type 3 was very similar to Type 2 with exception that the number of loading cycles was 3 at each strain target and the increment was 0.0005 for the subsequent target strain (details of Type 3 protocol is provided in section 2.7). Decrease in number of cycle from five to three cycles resulted in occurrence of failure at a smaller target strain level (see Figure 3.12 and 13). Figure 3.12 and 13 illustrate the influence of reduction loading cycles from five to three. Examples of similar specimens tested under different loading protocol are provided in Figure 3.12 and 13.  67  Compression Stress (P - Ps )/Ag (MPa)  35  30  25  20  15  10  5  0 0  0.5  1  1.5 2 2.5 Average Strain  3  3.5  4 -3  x 10  Image of AB1 at failure  Specimen AB1  Compression Stress, (P - Ps )/Ag (MPa)  35  30  25  20  15  10  5  0 0  0.5  1  1.5  2  2.5  Average Strain  3  3.5  4 -3  x 10  Image of AB2 at failure  Specimen AB2 Figure 3.13  Influence of Reduction in Number of Loading Cycles from 5 to 3: Specimen AB1 and AB2 were tested according to protocol Type 2 and 3 respectively  68  Compression Stress, (P - Ps )/Ag (MPa)  35  30  25  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  4  Image of BC1 at failure  -3  Average Strain  x 10  Specimen BC1  Compression Stress, (P - Ps )/Ag (MPa)  35 30 25 20 15 10 5  0 0  0.5  1  1.5  2  2.5  Average Strain  3  3.5  4 -3  x 10  Image of BC2 at failure  Specimen BC2 Figure 3.14  Influence of Reduction in Number of Loading Cycle from 5 to 3: Specimen BC1 and BC2 were Tested According to Protocol Type 2 and 3 Respectively  69  Chapter 4: Analytical Study 4.1  Overview of Analytical Work  In the experimental study thin walls were investigated. Thin walls normally occur as bearing walls. Also, there are thin conventional shear walls that are only meant to resist lateral load due to wind. However, a more common case of thin walls with potential problem is bearing walls which are very common in western Canada. Bearing walls support an axial vertical load and a moment about the horizontal axis in the plane of the wall. When a high-rise building is subjected to lateral load due to an earthquake or even wind load, there will be unintentional moment that causes bearing walls in the building to experience additional compression strain. The magnitude of the compression strain imposed on the bearing walls is essentially considered strain demand on bearing walls. One important observation in the experimental study was that when strain gradient existed, the wall element exhibited a much higher strain capacity. The problem arose when there was no variation in strain and uniform strain profile was maintained at high stress. At this point, wall elements with no lateral cross reinforcement had failed suddenly and at a much smaller strain level than the design value, 0.0035. A potential problem with bearing walls, that are not meant to resist high in-plane bending, may occur if the walls are subjected to high axial load. The bearing wall would be subjected to strong bending when the building is subjected to earthquake. The purpose of the analytical work was to investigate the maximum axial load on bearing walls to keep strain demand within a certain level, and to understand the relationship between the wall length and the maximum applied axial load on the wall given the curvature demand. In the current study, the building was assumed to have a shear wall. In addition, the curvature demand was assumed to be a function of the shear wall length. Equation 1 in section 4.1 presents the relationship ascertained for the curvature demand on the bearing walls. Three curvature demands were considered to calculate the maximum axial load for the range of bearing walls. The length of bearing walls varied from 2 to 60 ft. The first principle approach was used to calculate the maximum axial load on the bearing wall. The section of bearing wall was broken into layers. Each layer (depending on the strain profile) resisted tensile or compression force. The compression depth was calculated using trial-anderror method by satisfying equilibrium between tension and compression forces along the 70  cross-section to find the maximum compression load on the bearing wall. Section 4.3 includes the methodology used to obtain the maximum compression axial load. Comparison of the results of the upper and lower curvature demand limits showed that increase in curvature demand caused significant reduction on the maximum compression axial load of a bearing wall. Section 4.4 includes the discussions on the effect of variation in curvature demand. In addition, the influence of steel quantity was examined by looking at two different steel densities, ρ of 0.0015 and 0.003, for the range of bearing walls. Section 4.4 includes the result for the two steel ratios.  71  4.2  Maximum Axial Load on Bearing Walls in High-Rise building  The bearing walls in high-rise building induce unintentional bending due to a lateral load such as an earthquake or wind. The bearing walls generally are not designed to resist bending about the strong axis of the wall, and they are prevented from bending by a shear wall in the tall building; however, the bearing walls are subjected to some moments as the shear wall in the structure bends. In this current study, the curvature demand on the bearing walls in a high-rise building was assumed to be a function of shear wall length. Curvature demand of the shear wall was estimated using Eq.1:  Eq. 1  where Lsw is the length of a shear wall in the high-rise building. Three different curvature demands were considered in the analytical work. In Equation 1, axial strain along the length of the shear wall and  was the difference in  was chosen to be 0.003, 0.0035, or  0.004 (see Figure 4.1). It was assumed that the curvature demand on the bearing walls (that were located close to the shear wall) was influenced by the curvature of the shear wall. However, the bearing walls located at a distance from the shear wall might experience higher curvature demand. Figure 4.1 shows the schematic drawing of a shear wall and a bearing wall and illustrates the curvature relationship assumed for the walls. The numerical examples provided are just three possible examples that the difference in compression and tension strains equals 0.003, 0.0035, and 0.004.  72  Figure 4.1  Curvature Demand on Bearing Wall is a Function of Shear Wall Length  The shear wall length was assumed to be 30 ft and the bearing wall lengths varied from two 60 ft with an increment of two ft. Matlab Program was used to complete the iteration process required to calculate the maximum compression axial load demand for the range of bearing walls stated above. First principle approach was used to calculate the maximum compression axial load on the bearing wall sections. The methodology is described in section 4.3. Given the axial load and curvature demand, the compression depth on the bearing wall section is calculated; therefore, the strain compression demand is obtained.  73  4.3  Calculation Methodology  The sections were assumed to have an imposed compression axial load of 3000 kN. Given the curvature demand, the objective was to estimate the maximum axial load that can be exerted on the bearing walls. The curvature demand was equal to the ratio of 0.003, 0.0035, or 0.004 to the length of the shear wall, 30 ft (9144 m). The lengths of the bearing walls varied from 2 ft (610 mm) to 60 ft (18 m) with 2 ft (610 mm) increments. The thickness of the bearing wall was assumed 20 cm and was constant for all the wall lengths. Table 4.1 contains the numerical values assumed for concrete and steel properties.  Table 4.1  Concrete and Steel Properties  P, Imposed Axial Load (kN)  3000  f’c (MPa)  30  Ec-tan (MPa)  27400  f’s (MPa)  400  Es (MPa)  200000  The concrete tensile strength, f’c, was considered as a function of square root of f’c. Knowing the curvature, maximum axial load and the corresponding maximum compression strain were calculated. The maximum compression axial load was obtained by a large number of iteration in which the first principle approach was implemented. The bearing wall cross-section area was divided into small fibers. Matlab Program was used to generate these layers. The number of reinforcement layers was kept constant at 10 layers. However, the program could be modified to increase the number of layers of steel along the length of the wall section. Maximum compression load happened at specific maximum compression strain (strain at top). Therefore, maximum compression strain varied from 0 to Maximum Strain Limit when calculating maximum load for each wall length. Based on the selection of maximum compression strain and the given curvature, the strain at the centre of the section was defined and the strain profile was shaped for the section accordingly. After defining the strain value for each fiber (see Figure 4.2), the corresponding axial load, compression or tension, was calculated. Some of the concrete and steel fibers would be in tension and others 74  would be in tension. The concrete tension stiffening was certainly considered in the calculation of net axial load.  Where fci is the stress at concrete layer and Aci is the layer area. Also fsi is the stress in steel layer and Asi is the layer’s cross-sectional area.  Figure 4.2  Calculation of Strain for each Fiber along the Wall Section  If the equilibrium between compression and tension forces was satisfied, the maximum compression load was recorded. Otherwise, the strain at the center of the section was increased by the length of the bearing wall multiplied by the curvature; then, the process of calculating the strain profile was repeated. The iteration process continued until equilibrium of forces was met for the selected maximum compression strain. After satisfying the equilibrium, the next value of maximum compression strain was selected and the entire process explained above repeated itself. This loop repeated until the maximum compression exceeded the Maximum Strain Limit. At this stage, the compression forces and the corresponding compression strains were analyzed and the maximum compression force and the corresponding strain were defined.  75  Maximum Strain Limit was selected to investigate the influence of limiting compression strain on the maximum axial load of the bearing walls. The strain limit varied from 0.0015 to 0.0035 with increments of 0.0005. The calculation methodology explained above is summarized in the following points. An algorithm was formulated to take the following steps to obtain the desired objective: 1. Axial load that could be applied to the section for a range of maximum compression strain (0.00 to Maximum Strain Limit) was calculated in a cycle. 2. The Maximum Strain Limit (top strain) was set to the following values: -0.001, 0.002, -0.0025, -0.003, -0.0035 in each cycle 3. Maximum axial load and the corresponding compression strain-top was recorded for each limit 4. The process was repeated for the range of wall length from 2 (609.6mm) ft to 60 ft (with a length increment of 2 ft) Figure 4.3 presents the maximum axial load calculated for the range of wall lengths mentioned above.  Figure 4.3  Relationship between Maximum Axial Load and Bearing Wall Length given ϕd of 0.0035  76  4.4  Analytical Results  Figure 4.3 illustrates the change in maximum axial load for two different curvature demands of 0.003 and 0.004.  Figure 4.4  Influence of Curvature Demand Change from 0.003 to 0.004 on Maximum Compression Axial Load of Bearing Walls  As shown in the above figure, the maximum compression axial load carrying capacity of bearing walls reduces as curvature demand increases. Tension stiffening is accounted for in obtaining the data points in the Figure 4.4. Figure 4.5 and 4.6 present the ratio of the maximum axial load to nominal strength versus the ratio of bearing wall length to a 30 ft (9144 mm) long shear wall for two different steel densities of 0.0015 and 0.003 respectively. In addition, the broken lines indicate that tension stiffening was considered in the maximum load calculation. As shown below, tension stiffening causes discernible reduction in maximum axial load. Moreover, the effect of 77  tension stiffening on calculating maximum axial load is greater when the steel quantity, ρ, is  Max Axial Load/(fc.Lbw.b + fy.b.Lbw.ρ) (kN/kN)  0.0015.  1  0.8  0.6  0.4  0.2  0 0  0.5  1  1.5  2  Bearing Wall Length/Shear Wall Length (m/m) Strain Limit:0.0035-with tension stiff  Strain Limit:0.003-with tension stiff  Strain Limit:0.0025-with tension stiff  Strain Limit:0.002-with tension stiff  Strain Limit:0.0015-with tension stiff  Shear Wall Length Limit  Strain Limit:0.0035-without tension stiff  Strain Limit:0.003-without tension stiff  Strain Limit:0.0025-without tension stiff  Strain Limit:0.002-without tension stiff  Strain Limit:0.0015-without tension stiff Figure 4.5  Ratio of Maximum Axial Load to Nominal Strength vs. Wall Length (ρ: 0.003)  78  Max Axial Load/(fc.Lbw.b + fy.b.Lbw.ρ) (kN/kN)  1  0.8  0.6  0.4  0.2  0 0  0.5  1  1.5  2  Bearing Wall Length/Shear Wall Length (m/m) Strain Limit:0.0035-with tension stiff  Strain Limit:0.003-with tension stiff  Strain Limit:0.0025-with tension stiff  Strain Limit:0.002-with tension stiff  Strain Limit:0.0015-with tension stiff  Shear Wall Length Limit  Strain Limit:0.0035-without tension stiff  Strain Limit:0.003-without tension stiff  Strain Limit:0.0025-without tension stiff  Strain Limit:0.002-without tension stiff  Strain Limit:0.0015-without tension stiff Figure 4.6  Ratio of Maximum Axial Load to Nominal Strength vs. Wall Length (ρ: 0.0015)  79  Figure 4.7 provides a comparison of calculated compression axial load versus  Max Axial Load/(fc.Lbw.b + fy.b.Lbw.ρ) (kN/kN)  allowable axial load.  1  0.8  0.6  0.4  0.2  0 0  0.1  0.2  0.3  0.4  0.5  0.6  0.7  0.8  0.9  1  Bearing Wall Length/Shear Wall Length (m/m) Strain Limit:0.0035-with tension stiff  Strain Limit:0.003-with tension stiff  Strain Limit:0.0025-with tension stiff  Strain Limit:0.002-with tension stiff  Strain Limit:0.0015-with tension stiff  Shear Wall Length Limit  Strain Limit:0.0035-without tension stiff  Strain Limit:0.003-without tension stiff  Strain Limit:0.0025-without tension stiff  Strain Limit:0.002-without tension stiff  Strain Limit:0.0015-without tension stiff  Code Method  Figure 4.7  Ratio of Axial Load to Nominal Strength vs. Wall Length  The straight horizontal line in figure 4.6 indicates the allowable compression axial force obtained using Eq. 14-1 in Canadian Concrete Design Hand Book: , where hu is 3 m, k is 0.8 and f’c is 30 MPa and width (b) is 0.2 m (CSA-A23.3-04, 80  2004). Considering the experimental results that indicates the strain capacity of wall is less than 0.0035, it is arguable that the prediction using the code method over-estimate bearing walls’ compression load capacity for a wide range of strain limits (from 0.0025 to 0.0015).The experimental results indicated that the maximum strain for a bearing wall was less than 0.0035. In addition, in wall elements with no confining reinforcement, failure occurred over the strain range of 0.0015 to 0.0025 which again is an indicator of lesser strain capacity for bearing walls and, therefore, smaller loads bearing capacity. Implementing tension stiffening in the calculation reduces the axial compressive capacity of the wall. This is illustrated in Figure 4.6 and 4.7. Moreover, increasing the reinforcement ratio also reduces the axial load capacity due to increase in tensile force along the section of concrete bearing walls. Figure 4.8 provides an insight on the relationship of the maximum axial load of the different range of wall lengths, as well as, the different limits imposed on maximum compression strain given a curvature demand of 0.0035. Moreover, Figure 4.9 shows the relationship between the maximum compression strain at which maximum compression axial load was obtained and the wall length for the same curvature demand. 45000  Max Axial Load (kN)  40000 35000 30000 25000 20000 15000 10000 5000 0 0  2  4  6  8  10  12  14  16  18  20  Wall Length (m) Strain Limit:0.0035-with tension stiff.  Strain Limit:0.003-with tension stiff.  Strain Limit:0.0025-2ith tension stiff.  Strain Limit:0.002-with tension stiff.  Figure 4.8  Maximum Axial Load vs. Wall Length (фd = 0.0035)  81  0  2  4  6  8  10  12  14  16  18  20  Strain Correspond to Max Axial Load  -0.0015  -0.002  -0.0025  -0.003  -0.0035  -0.004  Wall Length (m) Strain Limit:0.0035-with tension stiff Strain Limit:0.0025-with tension stiff  Figure 4.9  Strain Limit:0.003-with tension stiff Strain Limit:0.0015-with tension stiff  Maximum Strain (Top Strain) at Maximum Axial Load vs. Wall Length (фd = 0.0035)  82  Chapter 5: Conclusions An experimental study was conducted to investigate the maximum compression strain capacity of thin walls and better understand the compression failures of thin walls in recent earthquake such as Chile in 2010 and Christchurch in 2011. Forty-five wall elements that were either 24 or 36 in. (610 or 914 mm) high were tested under cyclic axial compression load. The main parameters that were considered in the current study included the wall thickness and the arrangement of reinforcement within the wall elements (amount and type of horizontal reinforcement and minimum cover to the horizontal reinforcement). The wall elements were divided into seven basic types. Each type represented a different segment of a thin wall with specific arrangements of lateral reinforcement. Type 1 specimens contained a single layer of straight horizontal reinforcement spaced at either 6 in. (152 mm) or 12 in (305 mm). Type 2 specimens contained two layers of horizontal reinforcement. Type 3 specimens contained two layers of horizontal reinforcement with one cross-tie at one end. Wall elements with complete column ties were called Type 4. Type 5 specimens were similar to Type 4 except that the lateral ties had 90 hooks instead of 135° hooks. Type 6 specimens had no horizontal reinforcement. Finally, Type 7 specimens contained a single layer of reinforcement with 180o hooks at the two ends. The cylinder compression strength of the concrete used to construct all specimens was about 30 MPa. The strain measurement was achieved by using four position transducers for most of the specimens; however, the average compression strain was measured using only two position transducers for a few of the wall elements. The gauge length over which the strain was measured was either 16.5 in. (419 mm) or 18 in. (457 mm) for 24 in. high specimens and was 30 in. (762 mm) for 36 in. tall specimens. In order to prevent failure at the very top and bottom of the specimens outside the testing region, the top and bottom of the wall elements were restrained with confining steel angles attached to the 1 in. thick steel plate. In addition the 1 in. thick plate was used to ensure that the stress imposed on the wall elements was uniformly distributed on the section. The specimens were subjected to cyclic axial compression load. The load was applied until a target strain was reached and then the load was released to zero. About the same strain rate was used to load and unload for the wall elements as is normally used for cylinder compression tests (strain of 0.0007 per minute). Thus the duration of one cycle (loading and 83  unloading) varied from a minimum of 45 seconds (for the smallest strain target) to 5 minutes and 15 seconds (for the largest strain target). Three different loading protocols were used with the difference being the number of repeated loading cycles and the increment of the target strains. A typical test took up to eight hours to complete due to the large number of cycles and documentation of damaged imposed on the specimen. Most of the specimens were loaded such that compression strains measured by position transducers were uniform. This was achieved by simply shifting the specimen in the loading frame to move the point of applied load. A review of test results indicates that the horizontal reinforcement arrangement, element height, strain gradient, and wall thickness significantly influenced the compression strain capacity of thin concrete wall elements. The following are the conclusions of the experimental study:   Experimental results of the wall tests showed that the strain capacity of thin concrete walls with no confining reinforcement is less than 0.0035 and compression strain capacity of thin concrete walls can be as low as 0.0015    Specimen with strain gradient had higher strain capacities than the similar specimens with uniform strain response    Failure of thin concrete wall elements was influenced by the location of reinforcing horizontal bars (size of clear cover) with free ends    Providing minimum confinement (lateral ties spaced at distance equal the thickness of the specimen) significantly increased the strain capacity (larger than 0.0035) of the thin wall elements    An increase in width of the thin wall elements lead to increase in strain capacity of the elements    Unconfined specimens that had height-to-thickness ratio of 4.5 had low strain capacity (0.001-0.002) Strain gradient was observed in the tests in which the specimens experienced severe  damage on one side and no or relatively minor damage on the other side. Such specimens had strain capacity as high as 0.0035 (Specimens E1 and E2 were two example that illustrated the effect of strain gradient on the specimens compression strain capacity.) 84  The lateral reinforcements that had free ends were high stress concentration points and they had influenced the failure mode of the specimens. The cover did not have consistent effect on the strain capacity of the wall elements. For example in the 24 in. high specimens that had a single layer of horizontal reinforcement (Type 1) and the 24 in. high specimens that had double layers of horizontal reinforcement (Type 2), an increase in the clear cover seemed to reduce the strain capacity of the specimens. In addition, in the specimens that were 36 in. high and had double layers of reinforcements (Type 2), an increase in the clear cover from 20 to 40 mm seemed to have relatively no effect on the compression capacity of the specimens; moreover, the height of the elements seemed to be the governing parameter. The comparison between 24 and 36 in. high elements that did not have any confining ties indicated that the strain capacity of 36 in. tall specimens was relatively lower. The failure observations of the elements that had confining column ties implies that the providing confinement would enable the wall elements to have compression strain capacity larger than 0.0035. Therefore, column ties would eliminate the problem of having strain capacity less than design value (0.0035). For example 8 or 10 in. thick specimens (that had double layers of straight horizontal reinforcement and were 36 in. high) had strain capacity of about 0.002. The test results indicated that the slender wall elements with heightto-thickness ratio of 4.5 that had no confining tie failed very suddenly and had strain resistance as low as 0.001. No significant damage was observed prior to failure of the slender specimens without confining reinforcements. The strain was uniform and no strain gradient was observed. However, the same structured specimens (that had height-to-thickness ratio of 4.5) with minimum confining ties (spaced at distance equal to the lesser of cross-sectional dimension) failed gradually and had a strain capacity greater than 0.0035. A previous study (Pfister, 1964) had been conducted on similar specimens to the wall elements with exception of large density of reinforcement. The results indicated that the specimen with no ties had sudden failure whereas specimens with column ties gradually failed. Type 3 specimens (CC1 and CC2) that had horizontal reinforcement which contained one cross-tie on one end had strain capacity of 0.0025 and 0.003. Reviewing the test result for Type 2 specimens that were 36 in. high, Type 3 specimens, and Type 4 specimens (which contained ties with 135o hooks) indicated that confinement significantly increased the strain capacity of the specimens and influenced failure mode. Type 5 specimens (that contained 90o ties) had a strain capacity as 85  low as 0.003. Type 5 specimens had gradual failure. The result showed that providing confinement of any kind would increase the compression strain capacity of thin concrete walls. Failure mode varied among the specimen types. In general the failure of the specimens was sudden and involved loud sound when no reinforcing ties were provided. Failure of Type 1 specimens included formation of cracks through the straight horizontal reinforcements and the breakage of concrete cover. A typical failure of Type 2 specimens was formation of diagonal cracks through the straight horizontal reinforcements that had free ends. Moreover, the diagonal cracks coalesced into a single crack at the middle of the 36 in. high specimens. Type 3 specimens’ failure involved breakage of the concrete cover. Type 4 and 5 specimens that had confining reinforcements typically failed gradually and the lateral ties were exposed at the middle section due to lose of the concrete cover. A typical failure in type 6 was a diagonal crack through the section. The lateral reinforcement was exposed due to lose of large portion of concrete on the sides. The failure of Type 7 specimen included large diagonal crack through the concrete elements. A review of the data indicates that there is a correlation between maximum concrete compression stress and compression strain capacity of concrete wall elements. The specimen that failed suddenly resisted lower maximum compression stress relative to those that failed gradually. Moreover, no correlation exists between the maximum compression stress and the specimen age at testing. In the design of bearing walls, column ties are not usually provided and the section is designed for a maximum axial load given by Eq. 14-1 in CSA A23.3-04 or by Clause 10 of CSA A23.3-04. Bearing walls are designed to resist axial compression and bending about the weak axis. When a shear wall in a high-rise building is subjected to bending due to lateral load such as earthquake and wind load, the bearing walls may also experience significant strong-axis bending. Analytical work was done to investigate how much the strong axis bending reduces the axial compression capacity of the bearing walls accounting for the reduced compression strain capacity of thin walls. In the analytical study, the curvature demand on the bearing walls was assumed to be a function of the length of the shear wall controlling the lateral displacements of the building. It was found that the curvature demand had significant influence on the maximum axial load that could be resisted by the bearing 86  wall. An increase in the curvature demand reduced the maximum axial load resisted by the bearing walls. Tension stiffening and the amount of vertical reinforcement ratio were found to have a minor effect on the compression axial load resisted by the bearing walls. In concrete structures, the important walls that support large amount force such as the wall in the Grand Chancellor Hotel in Christchurch should contain minimum column ties to prevent sudden and fragile failures; therefore, avoiding collapse of the structure and perhaps preventing irreparable damage. Recommendations for further studies include to experimentally examine a larger portion of a slender wall under the cyclic compression and tension axial load. Two sets of specimen maybe constructed; one with confinement provided along the length of slender wall, and one with confinement provided only at the end of the slender wall. In addition, analytical work should be completed to verify the result for current and possible future experimental research.  87  Bibliography ACI Committee 318., & American Concrete Institute. (2005). Building Code Requirement for Structural Concrete (ACI 318-05) Farmington Hill, MI: American Concrete Institute CSA A23.3-04. (2004). Standard CSA A23.3-04, Canadian Standards Association. In Concrete Design Hand (pp. 96-100). Mississauga, Ont. Dr. Adebar P., Lorzadeh A. (2012, June 12). Compression Failure of Concrete Walls. 15 WCEE. Lisbon. Elwood, K. (2012, February 14). Christchurch Earthquake(s): One Year Later. Department of Civil Engineering Faculty Seminar. J. Sherstobitoff, P. Cajiao, P. Adebar. (2012). Analysis and Repair of an EarthquakeDamaaged High-rise Building in Santigo, Chile. 15 WCEE. Lisboa. Peter I. Yanev, Francisco Medina,Alexander P. Yanev. (2010). Preliminary Summary of Damage and Engineering Recommendations. Pfister, J. F. (1964). Influence of Ties on the Behavior of Reinforced Concrete Columns. ACI JOURNAL, 521-537.  88  Appendices Appendix A Detail Test Information  89  A.1  Specimen A1 Table A.1  Specimen A1 Properties  Specimen Name  A1  Specimen Code  T5.5-H2-Tie-10M-C20  Specimen Type  Type 4  Cross-section Layout  Wall Thickness (in./mm)  5.5/140  Length (in./mm)  12.0/305  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  9.5  Minimum Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  5.5/140  Age at Testing (days)  34  Loading Protocol  Type 1  Number of Sides Strain Measured  2  Gauge Length (in./mm)  16.5/419  Axial Strain Profile  Non-uniform 90  35  25  s  c  Compression Stress, (P - P )/(A ) (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.1  4 -3  Strain  x 10  Stress-Strain Response of A1: Average of Two Measurements  35 LP18 LP19  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.2  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of A1: Two Position Transducers  91  Observations during Testing Specimen A1 contained lateral ties which were spaced at 5.5 in. The confinement provided by lateral ties significantly influenced the specimen strain capacity. Figure A.3 contains images of the specimen with a strain of up 0.00275. The specimen was subjected to bending and no effort was made to achieve uniform strain measurement.  Right side  Left side  92  Left side  Right side  Back side  Front side  Figure A.3  Images of A1 up to Strain of 0.00275  . 93  Observations of Failure The specimen failure was brittle, and the failure involved loud noise. The specimen failed upon loading at a strain of 0.003. Figure A.4 shows the images of the specimen after failure.  (a) Figure A.4  (b) Images of Specimen A1 after Failure: (a) Right Side, (b) Left Side  94  Summary of Test Observations   Strain was not kept uniform    Significant strain difference between position transducers    Strain was measured on two 5.5 in. wide phases of the specimen    Crack formation at the bottom section of the front side of the specimen    Cracks were made in the cover section at the location of the lateral ties    Specimen was subjected to compression load 5 cycles up to a strain of 0.00175    Compression load cycle varied after 0.00175 (see Table. 2.3)    Maximum concrete stress: 31.7 MPa    The specimen failed upon loading at the first cycle at a strain of 0.003.    Strain at failure: 0.003    Failure included loud sound  95  A.2  Specimen A2 Table A.2  Specimen A1 Properties  Specimen Name  A2  Specimen Code  T5.5-H2-Tie-10M-C20  Specimen Type  Type 4  Cross-section Layout  Wall Thickness (in./mm)  5.5/140  Length (in./mm)  12.0/305  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  9.5  Minimum Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  5.5/140  Age at Testing (days)  56  Loading Protocol  Type 1  Number of Sides Strain Measured  2  Gauge Length (in./mm)  16.5/419  Axial Strain Profile  Non-uniform 96  30  25  s  c  Compression Stress, (P - P )/A (MPa)  35  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  4  Figure A.5  4.5 -3  Strain  x 10  Stress-Strain Response of A2: Average of Two Measurements  35 LP18 LP19  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  1  2  3  Strain  Figure A.6  4  5 -3  x 10  Stress-Strain Response of A2: Two Position Transducers  97  Observations during the Testing Specimen A2 contained lateral ties which were spaced at 5.5 in. The confinement provided by lateral ties significantly influenced the specimen strain capacity. Figure A.7 contains images of the specimen with a strain of up to 0.004. The specimen was subjected to bending and no effort was made to achieve uniform strain measurement.  Back side  Left side  98  Left side  Back side  Right side  Front side  Figure A.7  Images of A2 up to Strain of 0.004  . 99  Observations of Failure The specimen failure was not brittle, and the failure did not involve loud noise. The specimen was pushed to failure after the fifth cycle at a strain of 0.004. The strain capacity of the specimen was greater than 0.0035. Figure A.4 shows the images of the specimen after failure  (a) Figure A.8  (b) Images of Specimen A2 after Failure: (a) Left Side, (b) Back Side  100  Summary of Test Observations   Strain was not kept uniform    Significant strain difference between position transducers    Strain was measured on two 5.5 in wide phases of the specimen    Crack formation at the bottom section of the front side of the specimen    Cracks were made in the cover section at the location of the lateral ties    Specimen was subjected to compression load for 5 cycles at each strain level    Maximum concrete stress: 33.4 MPa    Strain at failure: 0.0043    The specimen was pushed to failure after the fifth cycle at a strain of 0.004    Failure did not include loud sound  101  A.3  Specimen A3 Table A.3  Specimen A3 Properties  Specimen Name  A3  Specimen Code  T5.5-H2-Tie-10M-C20  Specimen Type  Type 4  Cross-section Layout  Wall Thickness (in./mm)  5.5/140  Length (in./mm)  12.0/305  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  9.5  Minimum Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  5.5/140  Age at Testing (days)  61  Loading Protocol  Type 1  Number of Sides Strain Measured  2  Gauge Length (in./mm)  16.5/419  Axial Strain Profile  Non-uniform 102  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  4 -3  Strain  Figure A.9  x 10  Stress-Strain Response of A3: Average of Two Measurements  35 LP18 LP19  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  Strain  Figure A.10  3  3.5  4  4.5 -3  x 10  Stress-Strain Response of A3: Two Position Transducers  103  Observations during Testing Specimen A3 contained lateral ties which were spaced at 5.5 in. The confinement provided by lateral tie significantly influenced the specimen strain capacity. Figure A.11 contains images of the specimen with a strain of up to 0.004. The strain measurement was kept uniform during the test.  Right side  Left side  104  Right side  Back side  Back side  Front side  Figure A.11  Images of A3 up to Strain of 0.004  . 105  Observations of Failure The specimen failure was not brittle, and the failure did not involve loud noise. The specimen was pushed to failure after the fifth cycle at a strain of 0.004. The strain capacity of the specimen was greater than 0.0035. Figure A.4 shows the images of the specimen after failure  (a) Figure A.12  (b) Images of Specimen A3 after Failure: (a) Right Side, (b) Back Side  106  Summary of Test Observations   Uniform strain    No significant strain difference between position transducers    Strain was measured on two 5.5 in. wide phases of the specimen    Crack formation at the middle section of the front side of the specimen    Cracks were made in the cover section at the location of the lateral ties    Specimen was subjected to compression load for 5 cycles at each strain level    Maximum concrete stress: 31.3 MPa    Strain at failure: 0.0043    The specimen was pushed to failure after the fifth cycle at strain of 0.004    Failure did not include loud sound  107  A.4  Specimen B1 Table A.4  Specimen B1 Properties  Specimen Name  B1  Specimen Code  T5.5-H2-10M-C20  Specimen Type  Type 4  Cross-section Layout  Wall Thickness (in./mm)  5.5/140  Length (in./mm)  12.0/305  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  9.5  Minimum Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  5.5/140  Age at Testing (days)  43  Loading Protocol  Type 1  Number of Sides Strain Measured  2  Gauge Length (in./mm)  16.5/419  Axial Strain Profile  Non-uniform 108  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.13  4 -3  Strain  x 10  Stress-Strain Response of B1: Average of Two Measurements  35 LP18 LP19  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  1  2  3  4  Strain  Figure A.14  5  6  7 -3  x 10  Stress-Strain Response of B1: Two Position Transducers  109  Observations during Testing Specimen B1 contained lateral ties which were spaced at 5.5 in. The confinement provided by lateral tie significantly influenced the specimen strain capacity. First damage was detected at the end of the fifth cycle at a strain of 0.002 (see photo below). Figure A.15 contains images of the specimen with a strain of up to 0.00325. The strain measurement was not kept uniform during the test.  Left side  First visible damage  110  Right side  Back side  Right side  Front side  Figure A.15  Images of B1 up to Strain of 0.0325  . 111  Observations of Failure The specimen failure was not brittle, and the failure did not involve loud noise. The specimen failed upon loading at the first cycle at a strain of 0.0035. The strain capacity of the specimen was greater than 0.00325. Figure A.16 shows the images of the specimen after failure  (a) Figure A.16  (b) Images of Specimen B1 after Failure: (a) Left Side, (b) Back Side  112  Summary of Test Observations:   Non-uniform strain    Significant strain difference between position transducers    Strain was measured on two 5.5 in. wide phases of the specimen    Crack formation at the middle section of the back side of the specimen    Cracks were made in the cover section at the location of the lateral ties    Specimen was subjected to compression load 5 cycles at each strain level    Maximum concrete stress: 32.2 MPa    Strain at failure:0.0039    Specimen failed upon loading at the first cycle at a strain of 0.0035    Failure did not include loud sound  113  A.5  Specimen B2 Table A.5  Specimen A4 Properties  Specimen Name  B2  Specimen Code  T5.5-H2-10M-C20  Specimen Type  Type 4  Cross-section Layout  Wall Thickness (in./mm)  5.5/140  Length (in./mm)  12.0/305  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  9.5  Minimum Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  5.5/140  Age at Testing (days)  191  Loading Protocol  Type 1  Number of Sides Strain Measured  3  Gauge Length (in./mm)  16.5/419  Axial Strain Profile  uniform 114  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.17  4 -3  Strain  x 10  Stress-Strain Response of B2: Average of Two Measurements  35 LP18 LP19 LP20  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.18  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of B2: Three Position Transducers  115  Observations during Testing Specimen B2 contained lateral ties with 90o hooks. Ties were spaced at 5.5 in. The confinement provided by lateral tie significantly influenced the specimen’s strain capacity. Figure A.19 contains images of the specimen up to the first cycle at a strain of 0.0035. The strain measurement was kept uniform during the test.  Strain: 0.00225  Strain: 0.0025  116  Strain: 0.00275  Strain: 0.003  Strain: 0.00325  Strain: 0.0035 (first cycle)  Figure A.19  Images of B2 up to First Cycle at Strain of 0.0035  . 117  Observations of Failure The specimen failure was not brittle, and the failure did not involve loud noise. The specimen failed upon loading at the second cycle at a strain of 0.0035. The strain capacity of the specimen was 0.00325. Figure A.20 shows the images of the specimen after failure  (a) Figure A.20  (b) Images of Specimen B2 after Failure: (a) Right Side, (b) Back Side  118  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    Strain monitored on three phases of the specimen, two of which were 5.5 in. wide and one of which was 12 in. wide    The average strain was obtained from LP18 and L19 (on two opposite faces)    Crack formation at the middle section of the front side of the specimen    Cracks were made in the cover section at the location of the lateral ties    Specimen was subjected to compression load 5 cycles at each strain level    Maximum concrete stress: 31.2 MPa    Strain at failure: 0.0039    The specimen failed upon loading at the second cycle at a strain of 0.0035    Failure included loud sound  119  A.6  Specimen C1 Table A.6  Specimen C1 Properties  Specimen Name  C1  Specimen Code  T5.5-H2-DL-10M-C20  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  5.5/140  Length (in./mm)  12.0/305  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  10  Minimum Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  5.5/140  Age at Testing (days)  37  Loading Protocol  Type 1  Number of Sides Strain Measured  2  Gauge Length (in./mm)  16.5/419  Axial Strain Profile  Non-uniform 120  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.21  4 -3  Strain  x 10  Stress-Strain Response of C1: Average of Two Measurements  35 LP18 LP19  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.22  2.5  3  3.5 -3  x 10  Stress-Strain Response of C1: Two Position Transducers  121  Observations during Testing No damaged was observed before the fifth cycle at a strain of 0.0015. Figure A.23 shows the first damage on the specimen.  Strain: 0.0015 Figure A.23  Strain: 0.0015 Images of First Detected Damage on Specimen C1  .  122  Observations of Failure The specimen C1 failed upon loading at the first cycle at a strain of 0.00175. The failure was very sudden and brittle. The specimen failure involved load sound. Figure A.24 shows the images of the specimen after failure.  123  Figure A.24  (a)  (b)  (c)  (d)  Images of Specimen C1 after Failure: (a) Right Side, (b) Front Side, (c) Back Side, (d) Left Side  124  Summary of Test Observations:   Non-uniform strain    Significant strain difference between position transducers    Strain was measured on two 5.5 in. wide phases of the specimen    First crack was formed on the right side at the middle section    Specimen was subjected to compression load for 5 cycles at each strain level    Maximum concrete stress: 27.3 MPa    Strain at failure: 0.0018    The specimen failed upon loading at the second cycle at a strain of 0.00175    Failure included loud sound and was extremely brittle  125  A.7  Specimen C2 Table A.7  Specimen C2 Properties  Specimen Name  C2  Specimen Code  T5.5-H2-DL-10M-C20  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  5.5/140  Length (in./mm)  12.0/305  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  10  Minimum Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  5.5/140  Age at Testing (days)  65  Loading Protocol  Type 1  Number of Sides Strain Measured  2  Gauge Length (in./mm)  16.5/419  Axial Strain Profile  Uniform 126  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  Figure A.25  3.5 -3  Strain  x 10  Stress-Strain Response of C2: Average of Two Measurements  35 LP18 LP19  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.26  2.5  3  3.5 -3  x 10  Stress-Strain Response of C2: Two Position Transducers  127  Observations during Testing and Failure No damage was detected prior to failure. Specimen C2 failed suddenly upon loading at the first cycle at a strain of 0.00125. The strain was kept relatively uniform. Figure A27 contains the images of the specimen after failure.  128  (a)  (b)  (c)  (d)  Figure A.27 Images of Specimen C1 after Failure: (a) Left side, (b) front side, (c) back side, (d) right side 129  Test Observations Summary:   Uniform strain    No significant strain difference between position transducers    Strain was measured on two 5.5 in. wide phases of the specimen    No visible damage prior to failure    Specimen was subjected to compression load for 5 cycles at each strain level    Maximum concrete stress: 28.3MPa    Strain at failure: 0.0012    The specimen failed upon loading at the second cycle at a strain of 0.00125    Failure was extremely brittle    Failure included loud sound  130  A.8  Specimen D Table A.8  Specimen D Properties  Specimen Name  D  Specimen Code  T5.5-H2-DL-10M-C20  Specimen Type  Type 6  Cross-section Layout  Wall Thickness (in./mm)  5.5/140  Length (in./mm)  12.0/305  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  ----  Minimum Clear Cover (mm)  30  Spacing of Horiz. Reinf. (in./mm)  ----  Age at Testing (days)  122  Loading Protocol  Type 1  Number of Sides Strain Measured  3  Gauge Length (in./mm)  16.5/419  Axial Strain Profile  Relatively uniform 131  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.28  4 -3  Strain  x 10  Stress-Strain Response of D: Average of Two Measurements  35 LP18 LP19 LP20  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.29  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of D: Three Position Transducers  132  Observations during Testing Specimen D experienced noticeable damage prior to failure. Figure A.30 shows the images of the specimen prior to failure.  133  Right side  Left side  Right side  Left side  Figure A.30  Images of Specimen D Prior to Failure  134  Observations of Failure Specimen D failed upon loading at the first cycle at a strain of 0.0035. The failure did not include load sound and it was not brittle. Figure A.31 illustrates images of the specimen after failure.  (a) Figure A.31  (b) Images of Specimen D after Failure: (a) Right Side, (b) Left Side  135  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    Strain was monitored on three phases of the specimen, two of which were 5.5 in. wide and one which was 12 in. wide    The average strain was obtained from LP18 and L19 (on two opposite faces)    Significant damage prior to failure    Specimen was subjected to compression load for 5 cycles at each strain level    Maximum concrete stress: 29.9 MPa    Strain at failure: 0.0034    The specimen failed upon loading at the second cycle at a strain of 0.0035    Failure did not include loud sound  136  A.9  Specimen E1 Table A.9  Specimen E1 Properties  Specimen Name  E1  Specimen Code  T5.5-H2-SL-10M-C20  Specimen Type  Type 7  Cross-section Layout  Wall Thickness (in./mm)  5.5/140  Length (in./mm)  12.0/305  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  10  Minimum Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  5.5/140  Age at Testing (days)  48  Loading Protocol  Type 1  Number of Sides Strain Measured  2  Gauge Length (in./mm)  16.5/419  Axial Strain Profile  Non-uniform 137  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  4 -3  Strain  Figure A.32  x 10  Stress-Strain Response of E1: Average of Two Measurements  35 LP18 LP19  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  1  2  3  Strain  Figure A.33  4  5  6 -3  x 10  Stress-Strain Response of E1: Two Position Transducers  138  Observations during Testing Specimen E1 experienced noticeable damage prior to failure. Figure A.34 shows the images of the specimen prior to failure. The specimen experienced excessive bending (see Figure A.33). The right side of the specimen took all the deformation while the left side remained rigid and experienced relatively minor damage.  139  Right side  Right side  Right side Figure A.34  Images of Specimen E1 Prior to Failure  140  Observations of Failure The average strain at failure was 0.0037. The failure included load sound and it was brittle. Figure A.35 illustrates images of the specimen after failure.  (a) Figure A.35  (b) Images of Specimen E1 after Failure: (a) Right Side, (b) Left Side  141  Summary of Test Observations:   Non-uniform strain    Significant strain difference between position transducers    Strain was measured on two 5.5 in. wide phases of the specimen    Significant damage prior to failure    Specimen was subjected to compression load for 5 cycles at each strain level    Maximum concrete stress: 32.4 MPa    Strain at failure: 0.0037    The specimen failed upon loading at the second cycle at a strain of 0.00325    Failure included loud sound  142  A.10  Specimen E2 Table A.10  Specimen E2 Properties  Specimen Name  E2  Specimen Code  T5.5-H2-SL-10M-C20  Specimen Type  Type 7  Cross-section Layout  Wall Thickness (in./mm)  5.5/140  Length (in./mm)  12.0/305  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  10  Minimum Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  5.5/140  Age at Testing (days)  106  Loading Protocol  Type 1  Number of Sides Strain Measured  3  Gauge Length (in./mm)  16.5/419  Axial Strain Profile  Uniform 143  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  Figure A.36  3.5 -3  Strain  x 10  Stress-Strain Response of E2: Average of Two Measurements  35 LP18 LP19  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.37  2.5  3  3.5 -3  x 10  Stress-Strain Response of E2: Two Position Transducers  144  Observations during Testing No significant damage was applied to the specimen prior to failure. Figure A.38 shows the images of the specimen prior to failure.  Right side Figure A.38  Right side Images of Specimen E2 Prior to Failure  145  Observations of Failure The average strain at failure was 0.0023. The failure included load sound and it was brittle. Figure A.39 illustrate images of the specimen after failure.  (a) Figure A.39  (b) Images of Specimen E2 after Failure: (a) Right Side, (b) Left side  146  Summary of Test Observations:   Uniform strain    No Significant strain difference between position transducers    Strain was monitored on three phases of the specimen, two of which were 5.5 in. wide and one which was 12 in. wide    The average strain was obtain from LP18 and L19 (on two opposite faces)    No significant damage prior to failure    Specimen was subjected to compression load for 5 cycles at each strain level    Maximum concrete stress: 32.3 MPa    The specimen was failed upon loading at the third cycle at a strain of 0.00225    Strain at failure: 0.0023    Failure included loud sound  147  A.11  Specimen AA1 Table A.11  Specimen AA1 Properties  Specimen Name  AA1  Specimen Code  T6-H2-SL-15M-C20  Specimen Type  Type 1  Cross-section Layout  Wall Thickness (in./mm)  6.0/152  Length (in./mm)  12.0/305  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  15  Minimum Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  91  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Uniform 148  30  Compression Stress, (P  measured  s  c  - P )/A (MPa)  35  25  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  Figure A.40  3.5 -3  Strain  x 10  Stress-Strain Response of AA1: Average of Four Measurements  LP18 LP19 LP20 LP21  30  Compression Stress, (P  measured  s  c  - P )/A (MPa)  35  25  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.41  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of AA1: Four Position Transducers  149  Observations during Testing No damage was observed before the first cycle at a strain of 0.0015. Small cracks were formed and spalling was detected at the bottom edge corner of the specimen at the end of the first loading cycle at a strain of 0.0025. Figure A.42 shows the specimen’s condition up to a strain level of 0.00275. A few cracks and slight spalling at the surface of the concrete were observed prior to failure. Pictures in Figure A.3 demonstrate the cracks propagation, and broken up concrete on the surface of the specimen before failure. The cracks were detected on the middle and bottom sections of the back and front faces of the specimen.  Strain: 0.001  Strain: 0.0015  150  Strain: 0.00174  Strain: 0.002  Strain: 0.0025  Strain: 0.0027  Figure A.42  Images of AA1 up to Strain of 0.00275  . 151  Observations of Failure The specimen failure was very brittle, and the failure involved loud noise and sudden fracture of the specimen. Upon loading to a strain of 0.003, the specimen failed suddenly at a strain of 0.00288. Moreover, the specimen’s load carrying capacity attenuated and dropped to zero immediately. As illustrated in Figure A.43, the crack propagated from the bottom section, away from the bottom reinforcement, through the location of the top horizontal reinforcements that were placed 20 mm from the edge of the concrete wall.  (a) Figure A.43  (b)  Images of Specimen AA1 after Failure: (a) Plane of Failure on Right, (b) Left Side  152  Summary Test Observations:   Uniform strain    No significant strain difference between position transducers    First cracks and spalling were detected at a strain level of 0.0015    Crack formation at the bottom section of the back side of the specimen at the end of the fifth cycle at a strain level of 0.0015    Specimen was subjected to compression load for 5 cycles at each strain level    Maximum concrete stress: 33.6 MPa    Crack propagation at a strain level of 0.00275 on the right face of the specimen at the bottom section    Sudden fracture at a strain of 0.00288    Failure occurred with loud noise and brittle fracture of specimen  153  A.12  Specimen AA2 Table A.12  Specimen AA2 Properties  Specimen Name  AA2  Specimen Code  T6-H2-SL-15M-C20  Specimen Type  Type 1  Cross-section Layout  Wall Thickness (in./mm)  6.0/152  Length (in./mm)  12.0/305  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  15  Minimum Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  260  Loading Protocol  Type 3  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  axial Strain Profile  Uniform 154  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  Figure A.44  3.5 -3  Strain  x 10  Stress-Strain Response of AA2: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.45  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of AA2: Four Position Transducers  155  Observations during Testing No damage was observed before the third cycle at a strain of 0.002. Figure A.46 shows the specimen’s condition with strain of up to 0.002. Very small damage was detected prior to failure. First cracks were detected on the 8 in. wide surface of the specimen on the top segment near the location of the position transducer.  156  Strain: 0.001  Strain: 0.0015  Strain: 0.00174  Strain: 0.002  Figure A.46  Specimen’s Condition up to Strain of 0.002  157  Observations of Failure The specimen failure was very brittle, and the failure involved loud noise and sudden fracture of the specimen. Upon loading to a strain of 0.0.0025, the specimen failed suddenly at a strain of 0.0024. Moreover, the specimen’s load carrying capacity attenuated and dropped to zero immediately. As illustrated in Figure A.47, the middle section containing a horizontal reinforcement was lost. A large crack propagated from the top on the 6 in. wide side down to near the bottom horizontal reinforcement.  (a) Figure A.47  (b)  Images of Specimen AA1 after Failure: (a) Back Side, (b) Left Side  158  Summary of Test Observations:   Uniform Strain    No significant strain difference between position transducers    First cracks and spalling were detected at a strain level of 0.0015    Crack formation at the bottom section of the back side of the specimen at the end of third cycle at a strain level of 0.002    Specimen was subjected to compression load for 3 cycles at each strain level    Sudden fracture upon loading at the first cycle at a strain of 0.0025    Strain at failure was 0.0024    Failure occurred with loud noise and brittle fracture of the specimen  159  A.13  Specimen AB1 Table A.13  Specimen AA2 Properties  Specimen Name  AB1  Specimen Code  T8-H2-SL-15M-C60  Specimen Type  Type 1  Cross-section Layout  Wall Thickness (in./mm)  6.0/152  Length (in./mm)  12.0/305  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  60  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  72  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Relatively uniform 160  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.48  4 -3  Strain  x 10  Stress-Strain Response of AB1: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.49  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of AB1: Four Position Transducers  161  Observations during Testing No damage was observed before the third cycle at a strain of 0.0025. Figure A.50 shows the specimen’s condition up to strain of 0.003. Very small damage was detected prior to failure. First cracks were detected on the 12 in wide surface of the specimen on the bottom segment near the location of the rod.  Strain: 0.001  Strain: 0.0015  162  Strain: 0.0025  Strain: 0.00275  Strain: 0.003 Figure A.50  Specimen’s Condition up to Strain of 0.003  163  Observations of Failure The specimen failure was very brittle, and the failure involved loud noise and sudden fracture of the specimen. Upon loading to a strain of 0.0.00325, the specimen failed suddenly at strain of 0.0031. Moreover, the specimen’s load carrying capacity attenuated and dropped to zero immediately. As illustrated in Figure A.51, a large crack propagated from the top on the 6 in wide side down to near the bottom horizontal reinforcement.  (a) Figure A.51  (b)  Images of Specimen AA1 after Failure: (a) Right Side, (b) Left Side  164  Summary of Test Observations:   Uniform behavior    Slight difference between position transducers after strain level of 0.002    First cracks and spalling were detected at a strain level of 0.0025    Crack formation at the bottom section of the back side of the specimen at the end of the fifth cycle at strain level of 0.0025    Specimen was subjected to compression load for 5 cycles at each strain level    Maximum concrete stress: 33.8 MPa    Sudden fracture upon loading at the first cycle at a strain of 0.00323    Average strain at failure was 0.0031    Failure occurred with loud noise and brittle fracture of specimen  165  A.14  Specimen AB2 Table A.14  Specimen AB2 Properties  Specimen Name  AB2  Specimen Code  T8-H2-SL-15M-C60  Specimen Type  Type 1  Cross-section Layout  Wall Thickness (in./mm)  6.0/152  Length (in./mm)  12.0/305  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  60  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  100  Loading Protocol  Type 3  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Uniform 166  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.52  4 -3  Averge Strain  x 10  Stress-Strain Response of AB2: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Averge Strain  Figure A.53  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of AB2: Four Position Transducers  167  Observations during Testing No visible damage was observed before the third cycle at a strain of 0.0015. First crack was detected at the end of the third loading cycle at a strain of 0.002. Cracks were formed at the middle region on 8 in. and 10 in. sides. Figure A.54 shows the specimen’s condition up to a strain level of 0.002.  168  Strain: 0.001  Strain: 0.0015  Strain: 0.002  Strain: 0.002  Figure A.54  Specimen’s Condition up to Strain of 0.00225  169  Observations of Failure The specimen failure was very sudden and brittle. The images of the specimen at failure are provided in Figure 55. The plane of failure was formed through the location of the top horizontal reinforcement and extended diagonally toward the bottom of the specimen.  170  (a)  (b)  (c) Figure A.55  Images of Specimen AB2 after Failure: (a) Left Side, (b) Front Side, (c) Right Side  171  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First cracks were detected at the end of the third cycle at a strain level of 0.002 at the top section of the left 8 in. side near the horizontal reinforcement    Spalling and crack formation on the edge and at the mid section of the right 8 in. side of the specimen at a strain of 0.002    Crack on the two 8 in. wide sides of the specimen    Specimen was subjected to compression load for 3 cycles at each strain level    Maximum concrete stress: 34.2MPa    Cracks and spalling was detected prior to failure    Specimen did not show ductile behavior prior to failure    The specimen failed suddenly upon loading at the first cycle at a strain level of 0.0025    Strain at failure was 0.0024    Failure occurred suddenly and included loud noise.  172  A.15  Specimen BA1 Table A.15  Specimen BA1 Properties  Specimen Name  BA1  Specimen Code  T8-H2-SL-20M-C20  Specimen Type  Type 1  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10.0/254  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  20  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  98  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Uniform 173  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.56  4 -3  Strain  x 10  Stress-Strain Response of BA1: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.57  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of BA1: Four Position Transducers  174  Observations during Testing No visible damage was observed before the second cycle at a strain of 0.00225. Small cracks formed and spalling was detected at the middle edge corner of the specimen, at the end of the second loading cycle at a strain of 0.0025. Figure A.58 shows the specimen’s condition up to a strain level of 0.00225. Specimen BA1 (T8-SL-15M-C60) showed significant deformation and evidence of damage before failure. Therefore, ductile behavior was considered for this type of specimen. Apparent cracks and significant spalling at the surface of the concrete were observed prior to failure.  175  Strain: 0.001  Strain: 0.0015  Strain: 0.00225 Strain: 0.002 Figure A.58  Images of Specimen BA1 up to Strain of 0.00225  176  FigureA.59 demonstrates the cracks propagation, and broken up concrete on the surface of the specimen before failure. The first crack was detected at the end of the second loading cycle at a strain of 0.00225.  177  Strain: 0.00225  Strain: 0.0025  Strain: 0.00275  Strain: 0.003  178  Strain: 0.00325 Figure A.59  Strain: 0.0035  Images of Specimen Showing Damage Progress before Failure  As shown in the pictures above, visible damage was detected prior to a strain of 0.0035. The cracks were detected on all four sides of the specimen; the middle section of the right face and the bottom portion of the back face of the specimen experienced the most damage during the test. The specimen behavior was highly ductile, and the failure involved slight loud noise and fracture of the specimen. The specimen’s load carrying capacity attenuated and dropped gradually when the specimen was loaded at a strain higher than 0.002.  179  Observations of Failure After loading the specimen for the fifth cycle at a strain of 0.0035, the specimen was compressed until failure occurred. At failure, the crack propagated through the location of the horizontal reinforcements located 20 mm from the edge of the concrete wall. However, the formation of the earlier damage was not around the zone containing the horizontal reinforcing bars. Figure A.60 contains the images of the specimen after failure.  (a) Figure A.60  (b)  Images of Specimen BA1 at Failure: (a) Front Side, (b) Right Side of Specimen  180  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First cracks and spalling were detected at a strain level of 0.00225    Crack formation on the edge at the middle section of the right side of the specimen at the end of the second cycle at a strain level of 0.00225    Crack on three edges of the specimen at mid-height    Specimen was subjected to compression load for 5 cycles at each strain level    Maximum concrete stress: 33.5 MPa    Crack propagation at a strain level of 0.0025 on the right face of the specimen    Significant damage was observed from a strain of 0.0025 to 0.0035    Specimen showed ductile behavior prior to failure    After the fifth cycle loading at a strain of 0.0035, the specimen was pushed until failure occurred with relatively loud noise and fracture of specimen  181  A.16  Specimen BA2 Table A.16  Specimen BA2 Properties  Specimen Name  BA2  Specimen Code  T8-H2-SL-20M-C20  Specimen Type  Type 1  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10.0/254  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  20  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  260  Loading Protocol  Type 3  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Uniform 182  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.61  4 -3  Strain  x 10  Stress-Strain Response of BA2: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.62  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of BA2: Four Position Transducers  183  Observations during Testing No visible damage was observed before the third cycle at a strain of 0.0025. Small cracks were formed on the top corners of the specimen. Figure A.63 shows the specimen’s condition up to a strain level of 0.00225. Specimen BA2 did not show significant deformation and evidence of damage before failure. Unlike specimen BA1, this specimen was subjected to axial compression for three cycles at each strain level. Moreover, the strain increment was larger compare to the testing protocol used for BA1  184  Strain: 0.001  Strain: 0.0015  Strain: 0.002  Strain: 0.00225  Figure A.63  Images of Specimen up to Strain of 0.000225  185  Observations of Failure The specimen failed upon loading at the first cycle at a strain of 0.003.The Figure A.64 contains the images of the specimen after failure  (a) Figure A.64  (b)  Images of Specimen BA2 after Failure: (a) Right Side (b) Left Side  186  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First cracks and spalling were detected at a strain level of 0.0025    Crack formation on the edge at the top corners    Crack on three edges of the specimen at mid-height    Specimen was subjected to compression load for 3 cycles at each strain level    Maximum concrete stress: 33 MPa    Significant damage was observed from a strain of 0.0025 to 0.0035    Sudden failure upon loading at the first cycle at a strain of 0.003    Failure was very brittle and included loud noise  187  A.17  Specimen BB1 Table A.17  Specimen BB1 Properties  Specimen Name  BB1  Specimen Code  T8-H2-SL-20M-C50  Specimen Type  Type 1  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10.0/254  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  20  Clear Cover (mm)  50  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  252  Loading Protocol  Type 3  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Relatively uniform 188  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.65  4 -3  Averge Strain  x 10  Stress-Strain Response of BB1: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Averge Strain  Figure A.66  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of BB1: Four Position Transducers  189  Observations during Testing No visible damage was observed before the second cycle at a strain of 0.002. At the end of the second cycle at a strain of 0.002, a crack formed on the left 8 in. side at the top of the specimen close to the top horizontal reinforcement. In addition, spalling and visible cracks were detected on the right 8 in. side near the horizontal reinforcement. Figure A.67 includes the images of the specimen up to a strain level of 0.00225.  190  Strain: 0.001  Strain: 0.0015  Strain: 0.002  Strain: 0.00225  Figure A.67  Specimen’s Condition up to Strain of 0.00225  191  Observations of Failure Specimen BB1 (T8-SL-15M-C50) experienced relatively small spalling or damage before failure. Therefore, the specimen did not exhibit ductile failure. The specimen failure was highly brittle, and the failure involved loud noise and a large diagonal fracture through the top and bottom of the 8 in. sides of the specimen. Figure A.68 shows the specimen’s condition at failure.  (a) Figure A.68  (b)  Images of Specimen BB1 after Failure: (a) Right Side (b) Left Side of Specimen  192  Summary of Test Observations:   Uniform strain    Slight variation between the average of the paired position transducers    First cracks were detected at the end of the second cycle at a strain level of 0.002 at the top section of the left 8 in. side near the horizontal reinforcement    Spalling and crack formation on the edge and at the mid section of the right 8 “side of the specimen at a strain of 0.002    Crack on the 8 in. long sides of the specimen    Specimen was subjected to compression load for 3 cycles at each strain level    Maximum concrete stress: 31.5 MPa    Specimen did not show ductile behavior prior to failure    The specimen failed suddenly upon loading at the first cycle at a strain level of 0.0025.    Strain at failure: 0.0023    Failure occurred suddenly and included loud noise.  193  A.18  Specimen BB2 Table A.18  Specimen BB2 Properties  Specimen Name  BB2  Specimen Code  T8-H2-SL-20M-C50  Specimen Type  Type 1  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10.0/254  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  20  Clear Cover (mm)  50  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  126  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Relatively uniform 194  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.69  4 -3  Averge Strain  x 10  Stress-Strain Response of BB2: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Averge Strain  Figure A.70  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of BB2: Four Position Transducers  195  Observations during Testing No visible damage was observed before the fifth cycle at a strain of 0.0025. Small cracks formed on both 8 in. sides around the bottom reinforcements. The first crack was detected on the front side at the top corner of the specimen at the end of the fifth loading cycle at a strain of 0.0025. Figure A.71 shows the specimen’s condition up to a strain level of 0.003. As shown in the pictures, some visible damage was detected prior to failure. The cracks were detected in the zone around the top reinforcement on four sides of the specimen. The cover and the zone around the top and bottom horizontal bars experienced the most damage.  196  Strain: 0.001  Strain: 0.0015  Strain: 0.002  Strain: 0.00225  197  Strain: 0.00225  Strain: 0.0025  Strain: 0.00275  Strain: 0.00325  Figure A.71  Specimen’s Condition up to Strain of 0.00325  198  Observations of Failure The specimen failure was highly brittle, and the failure involved loud noise and a large diagonal fracture through the top and bottom of 8 in. sides of the specimen, as shown in Figure A.72. The specimen’s load carrying capacity attenuated and dropped suddenly when the specimen was loaded at 0.0035 strain level. The sudden failure occurred upon loading at the first cycle at a strain of 0.0035.  199  (a)  (b)  (c) Figure A.72  Images of Specimen BB2 at Failure: (a) Right Side (b) Left Side, (c) Front Face of Specimen  200  Summary of Test Observations:   Uniform behavior    No significant strain difference between position transducers    First cracks detected at the end of the fifth cycle at a strain level of 0.0025    Crack formation on the edge at the top section of the right side of the specimen between 0.0275 and 0.00325 strain levels    Cracks on the 8 in. long sides of the specimen    Large crack formation at the middle section of 10 in. long sides at end of the fifth a cycle at strain of 0.00325    Specimen was subjected to compression load for 5 cycles at each strain level    Maximum concrete stress: 33.7    Relatively small damage prior to failure    The specimen failed suddenly upon loading at the first cycle at a strain level of 0.0035    Strain at failure: 0.0034    Failure occurred suddenly and included loud noise.  201  A.19  Specimen BC1 Table A.19  Specimen BC Properties  Specimen Name  BC1  Specimen Code  T8-H2-SL-20M-C80  Specimen Type  Type 1  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10.0/254  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  20  Clear Cover (mm)  80  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  132  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Uniform 202  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.73  4 -3  Averge Strain  x 10  Stress-Strain Response of BC1: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Averge Strain  Figure A.74  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of BC1: Four Position Transducers  203  Observations during Testing No visible damage was observed before the fifth cycle at a strain of 0.00225. At the end of the fifth loading cycle at a strain of 0.0025, cracks formed on the right and left side (8 in. wide) at the top segment of the specimen. Figure A.75 shows the specimen’s condition up to a strain level of 0.00275.  204  Strain: 0.001  Strain: 0.0015  Strain: 0.00175  Strain: 0.002  205  Strain: 0.00225  Strain: 0.0025  Strain: 0.0025  Strain: 0.00275  Figure A.75  Images of Specimen up to Strain of 0.00275  206  Observations of Failure Specimen BC1 experienced small spalling or damage before failure. The specimen behavior was highly brittle, and the failure involved loud noise and was in the shape of a cone. Large diagonal cracks at the top coalesced into a single crack at the middle of the specimen and continued down to the bottom reinforcements, as shown in Figure A.76. The specimen’s load carrying capacity dropped suddenly when the specimen was loaded at strain of 0.003. The sudden failure occurred upon loading at the first cycle at a strain of 0.003.  (a) Figure A.76  (b)  Images of Specimen BC1 at Failure: (a) Right Side (b) Left Side  207  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First cracks were detected at the end of the seventh cycle at a strain level of 0.0025    Crack formation at the top section of the right and left sides, around the top reinforcements of the specimen at the end of the seventh cycle at a strain level of 0.0025    Crack on the 8 in. long sides of the specimen    Target displacement was not reached at the first cycle of a strain of 0.0025    The specimen was subjected to 8 and 7 cycles at strains of 0.00225 and 0.0025 respectively    Specimen was subjected to compression load for 5 cycles at the strain levels    Maximum concrete stress: 33.9 MPa    Crack propagation at a strain level of 0.0025 on 8 in. sides of the specimen    No significant damage prior to failure    The specimen failed suddenly upon loading at the first cycle at a strain level of 0.003 at the moment that the average strain was 0.003    Failure occurred suddenly and included loud noise.  208  A.20  Specimen BC2 Table A.20  Specimen BC2 Properties  Specimen Name  BC2  Specimen Code  T8-H2-SL-20M-C80  Specimen Type  Type 1  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10.0/254  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  20  Clear Cover (mm)  80  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  258  Loading Protocol  Type 3  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Uniform 209  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.77  4 -3  Averge Strain  x 10  Stress-Strain Response of BC2: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Average Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Averge Strain  Figure A.78  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of BC2: Four Position Transducers  210  Observations during Testing No visible damage was observed before the third cycle at a strain of 0.002. At the end of the third loading cycle at a strain of 0.002, cracks formed on the back side (10 in. wide) at the top segment of the specimen. The target strain of 0.0025 was not reached for the first cycle; at this stage the specimen was loaded up to the capacity of the universal machine. FigureA.79 shows the specimen’s condition up to a strain level of 0.002.  211  Strain: 0.001  Strain: 0.0015  Strain: 0.002 Figure A.79  Images of Specimen up to Strain of 0.002  212  Observations of Failure Specimen BC2 experienced very minor damage before failure. The specimen behavior was highly brittle, and the failure involved loud noise. Large diagonal cracks at the top coalesced into a single crack at the middle of the specimen and continued down to the bottom reinforcements, as shown in Figure A.80. The specimen’s load carrying capacity dropped suddenly when the specimen was loaded at a strain of 0.0025. The sudden failure occurred upon loading at the second cycle at a strain of 0.0025.  (a) Figure A. 80  (b) Images of Specimen BC1 at Failure: (a) Right Side (b) Left Side  213  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First cracks were detected at the end of the third cycle at a strain level of 0.002    Cracks on the 10 in. long sides of the specimen    Target displacement was not reached at the first cycle at a strain of 0.0025    Specimen was subjected to compression load for 3 cycles at the strain levels    Maximum concrete stress: 33.6    No significant damage prior to failure    The specimen failed suddenly upon loading at the second cycle at a strain level of 0.0025.    Strain at failure was just under 0.0025    Failure occurred suddenly and included loud noise.  214  A.21  Specimen CA1 Table A.21  Specimen CA1 Properties  Specimen Name  CA1  Specimen Code  T8-H2-DL-15M-C20  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10.0/254  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  89  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Uniform 215  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.81  4 -3  Strain  x 10  Stress-Strain Response of CA1: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  Strain  Figure A.82  3  3.5  4  4.5 -3  x 10  Stress-Strain Response of CA1: Four Position Transducers  216  Observations during Testing No visible damage was observed before the fifth cycle at a strain of 0.00175. At the end of the fifth loading cycle at a strain of 0.002, cracks formed near the bottom reinforcement on the right face of the specimen. Figure A.83 shows the specimen’s condition up to a strain level of 0.002.  217  Strain: 0.001  Strain: 0.0015  Strain: 0.00175  Strain: 0.002  Figure A.83  Images of Specimen up to Strain of 0.002  218  Specimen CA1 experienced significant damage and spalling before failure. Therefore, the specimen exhibited very ductile behavior. Figure A.84 demonstrates the crack’s propagation, and broken-up concrete on the surface of the specimen before failure. The first crack was detected at the end of the fifth loading cycle at a strain of 0.002.  Strain: 0.0025  Strain: 0.003  219  Strain: 0.00325  Strain: 0.0035 Figure A.84  Images Specimen CA1 Showing the Increase in Damage at Higher Strain Levels  220  Observations of Failure The cracks and damage were detected on all four faces of the specimen at the end of the fifth cycle at a strain of 0.0035. The damage was mostly distributed between the location of the middle and bottom reinforcements. Failure cracks formed in the shape of a cone. Large diagonal cracks articulated through the top and bottom reinforcements. The specimen’s load carrying capacity attenuated gradually when the specimen was loaded at strains higher than 0.00225. After loading the specimen for five times at a strain of 0.0035, the load was applied until failure occurred. The Figure A.85 presents the specimen after failure:  (a) Figure A.85  (b)  Images of Specimen CA1 after Failure: (a) Right Side (b) Left Side  221  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First cracks were detected at the end of the fifth cycle at a strain level of 0.002 Crack propagation at the bottom segment on 8 in. sides of specimen at the end of the fifth cycle at a strain of 0.00225.    The specimen was loaded 10 cycles at a strain of 0.0025 – additional 5 cycles was to reduce the resistance in order to be able to load the specimen to the next target displacement    Crack propagation at a strain level of 0.0025 on 8 in. sides of the specimen    Specimen was subjected to compression load for 5 cycles at the strain levels    Maximum concrete stress: 33.6    significant damage prior to failure    The specimen was loaded until load carrying capacity dropped to zero after the fifth cycle at a strain of 0.0035    Strain at failure: 0.0039    Failure did not include loud noise.  222  A.22  Specimen CA2 Table A.22  Specimen CA2 Properties  Specimen Name  CA2  Specimen Code  T8-H2-DL-15M-C20  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10.0/254  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  268  Loading Protocol  Type 3  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Uniform 223  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.86  4 -3  Strain  x 10  Stress-Strain Response of CA2: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.87  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of CA2: Four Position Transducers  224  Observations during Testing No visible damage was observed before the third cycle at a strain of 0.0025. At the end of the third loading cycle at a strain of 0.0025, the first visible cracks formed near the top reinforcement on the right face of the specimen. Figure A.88 shows the specimen’s condition up to strain level of 0.0025.  225  Strain: 0.0015  Strain: 0.002  Strain: 0.0025  Strain: 0.0025  Figure A.88  Images Specimen CA2 Showing Specimen’s Condition up to Strain of 0.0025  226  Observations of Failure Specimen CA2 did not experience significant damage before failure. Failure cracks formed in a shape similar to a cone. Large diagonal cracks articulated through the top and bottom horizontal reinforcements and a segment of concrete was completely separated. Figure A.89 presents the specimen after failure:  (a) Figure A.89  (b)  Images of Specimen CA2 after Failure: (a) Right Side (b) Left Side  227  Summary of Test Observations:   Strain measured was relatively uniform on four sides of the specimen    No significant strain difference between position transducers    First cracks were detected at the end of the third cycle at a strain level of 0.0025    No significant damage prior to failure    Specimen was subjected to compression load for 3 cycles at the strain levels    Maximum concrete stress: 33.1 MPa    Strain at failure: 0.0028    Brittle failure    Failure included loud noise.  228  A.23  Specimen CA3 Table A.23  Specimen CA3 Properties  Specimen Name  CA3  Specimen Code  T8-H3-DL-15M-C20  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10.0/254  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  12.0/305  Age at Testing (days)  290  Loading Protocol  Type 1  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform 229  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.90  4 -3  Compression Strain  x 10  Stress-Strain Response of CA3: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.91  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of CA3: Four Position Transducers  230  Observations during Testing No visible damage was observed before the fifth cycle at a strain of 0.002. At the end of the fifth loading cycle at a strain of 0.002, cracks were formed on the top corner in the region of the clear cover. Figure A.92 shows the specimen’s condition up to a strain level of 0.00225. Specimen CA3 experienced very small damage before failure. The first crack was detected at the end of the fifth loading cycle at a strain of 0.002.  231  Strain: 0.001  Strain: 0.00125  232  Strain: 0.0015  Strain: 0.002 Figure A.92  Strain: 0.00175  Strain: 0.00225  Images Specimen CA3 Showing Specimen’s Condition up to Strain of 0.00175  233  Observations of Failure Failure cracks formed in a V-shape. Two large diagonal cracks articulated through the top and coalesced into a larger single crack above the location of the middle horizontal reinforcing bars. The Figure A.93 presents the specimen after failure.  (a) Figure A.93  (b)  Images of Specimen CA3 after Failure: (a) Right Side (b) Left SIde  234  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First cracks were detected at the end of the fifth cycle at a strain level of 0.002 Crack propagation at the bottom segment on 8 in. sides of specimen at the end of the fifth cycle at a strain of 0.00225.    Crack propagation at a strain level of 0.0025 on 8 in. sides of the specimen    No significant damage prior to failure    Specimen was subjected to compression load for 3 cycles at the strain levels    Maximum concrete stress: 33.1 MPa    Strain at failure: 0.0024    Failure included loud noise    Brittle Failure  235  A.24  Specimen CA4 Table A.24  Specimen CA4 Properties  Specimen Name  CA4  Specimen Code  T8-H3-DL-15M-C20  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10.0/254  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  12.0/305  Age at Testing (days)  135  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform 236  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.94  4 -3  Compression Strain  x 10  Stress-Strain Response of CA4: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.95  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of CA4: Four Position Transducers  237  Observations during Testing No visible damage was observed prior to failure. The specimen failure was brittle and involved loud noise. Figure A.96 shows specimen’s condition up to failure. The specimen did not take any visible damage prior to failure.  238  Strain: 0.001  Strain: 0.001  239  Strain: 0.00175 Figure A. 96  Strain: 0.002  Images Specimen CA4 Showing Specimen’s Condition up to Failure  240  Observations of Failure The brittle failure was evident. As shown in the pictures above, no visible damage was detected prior to failure. The failure occurred at a strain of 0.0016. The failure cracks formed in the shape of a cone at the top of the specimen. The cracks were generated through the top horizontal reinforcement and continued down to the bottom. At the mid section, the cracks converged into a single crack at the center of the section. The failure pattern is illustrated in Figure A.97.  (a)  (b)  241  (c) Figure A.97  Images of Specimen CA4 after Failure: (a) and (b) Right Side (c) Left Side of Specimen  242  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    No visible damage prior to failure    Specimen was subjected to compression load for 5 cycles at the strain levels    Maximum concrete stress: 30 MPa    Strain at failure: 0.0016    Specimen had brittle failure    At failure, a crack formed through the horizontal reinforcement on top.    Cone shape was formed on top and at the mid section    The cracks coalesced into a single crack at the center of the specimen.    Failure involved loud noise.  243  A.25  Specimen CB1 Table A.25  Specimen CB1 Properties  Specimen Name  CB1  Specimen Code  T8-H2-DL-15M-C40  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10.0/254  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  40  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  115  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Relatively uniform  244  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.98  4 -3  Compression Strain  x 10  Stress-Strain Response of CB1: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.99  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of CB1: Four Position Transducers  245  Observations during Testing No visible damage was observed before the fifth cycle at a strain of 0.00225. Figure A.100 shows the specimen up to a strain of 0.002. The first crack was detected at the end of the fifth loading cycle at a strain of 0.00225. Small cracks formed on the top region in the cover zone, 40 mm form the surface of the concrete.  246  Strain: 0.001  Strain: 0.0015  Strain: 0.00175  Strain: 0.002  Figure A.100  Images Specimen CB1 Showing Specimen’s Condition up to Strain of 0.002  247  Specimen CB1 experienced small spalling and damage before failure. Figure A.1001 demonstrates the cracks’ propagation, and broken up concrete on the surface of the specimen before failure. As shown in the pictures in Figure A.101, some visible damage detected at the end of the fifth cycle loading at a strain of 0.0025. The cracks and damage were detected on both 8 in. sides of specimen. The cover and the zone around the top and bottom horizontal bars experienced the most damage.  248  Strain: 0.00225  Strain: 0.0025  Strain: 0.0025 Figure A.101  Images Specimen CB1 Showing Specimen’s Condition up to Strain of 0.0025  . 249  Observations of Failure The specimen behavior was highly brittle, and the failure involved loud sound. As shown in Figure A.102, fracture in the shape of a cone and large diagonal cracks through the top and bottom reinforcements formed at failure. The specimen’s load carrying capacity dropped suddenly upon loading at the first cycle at a strain level 0.00275 and the specimen failed at this point. Failure included loud explosive sound.  250  (a)  (b)  (c) Figure A.102  Images of Specimen CB1 after Failure: (a) Right Side, (b) Front Side, (c) Left Side of the Specimen  251  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First cracks and spalling were detected at the end of the fifth cycle at a strain level of 0.00225    Crack formation on the edge at the top section of the right side of the specimen at the end of the second cycle at a strain level of 0.00225    Crack on the 8 in. long sides of the specimen    Specimen was subjected to compression load for 5 cycles at each strain level    Maximum concrete stress: 31.8 MPa    Crack propagation at a strain level of 0.0025 on all the faces of the specimen    No significant damage prior to failure    Specimen failed suddenly upon loading at the first cycle at a strain level of 0.00275    Strain at failure: 0.0026    Failure occurred suddenly and included loud noise.  252  A.26  Specimen CB2 Table A.26  Specimen CB2 Properties  Specimen Name  CB2  Specimen Code  T8-H2-DL-15M-C40  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10.0/254  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  40  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  262  Loading Protocol  Type 3  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Relatively uniform 253  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.103  4 -3  Compression Strain  x 10  Stress-Strain Response of CB2: Average of Four Measurements  35 LP18 LP20 LP19 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.104  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of CB2: Four Position Transducers  254  Observations during Testing No visible damage was observed before the third cycle at a strain of 0.0025. Figure A.105 shows the specimen up to a strain of 0.0025. A very small crack, hardly visible, was detected around the top reinforcing horizontal bar on the right and left sides.  255  Strain: 0.001  Strain: 0.002 Figure A.105  Strain: 0.0015  Strain: 0.002  Images Specimen CB2 Showing Specimen’s Condition up to Strain of 0.002  256  Observations of Failure The specimen behavior was highly brittle, and the failure involved loud sound. As shown in Figure A.106, a large diagonal crack through the top and bottom reinforcements formed at failure. The middle reinforcement along with the portion of the cover was separated from the specimen. The specimen’s load carrying capacity dropped suddenly upon loading at the first cycle at a strain level 0.003.  (a) Figure A.106  (b)  Images of Specimen CB2 after Failure: (a) Right Side, (b) Left Side Specimen  257  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First cracks and spalling were detected at the end of the third cycle at a strain level of 0.0025    Small crack around the top reinforcing bar on both right and left sides    Specimen was subjected to compression load 3 cycles at each strain level    Maximum concrete stress: 33 MPa    No significant damage prior to failure    Specimen failed suddenly upon loading at the first cycle at a strain level of 0.00275    Strain at failure: 0.003    Failure occurred suddenly and included loud noise.  258  A.27  Specimen CB3 Table A.27  Specimen CB3 Properties  Specimen Name  CB3  Specimen Code  T8-H3-DL-15M-C40  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10.0/254  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  40  Spacing of Horiz. Reinf. (in./mm)  12.0/305  Age at Testing (days)  139  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform 259  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.107  4 -3  Compression Strain  x 10  Stress-Strain Response of CB3: Average of Four Measurements  35 LP18 LP20 LP19 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.108  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of CB3: Four Position Transducers  260  Observations during Testing No visible damage was observed before the first cycle at a strain of 0.0015. Spalling on top corner of left 8 in. side was detected at the end of the first cycle at strain of 0.0015. At the end of the fifth cycle at a strain of 0.00175 no change in the damaged segment was observed. At this stage the specimen was loaded to reach the target strain of 0.002; however, despite the fact that the load on the specimen was 1778 kN (capacity of the universal testing machine), the target displacement was not reached. Therefore, the specimen was loaded at the strain of 0.00175 for one additional cycle. Then, the specimen was loaded again to reach 0.002, yet, the strain was not reached for the second time. The decision was made to load the specimen for an additional of 4 more cycle at strain of 0.00175 before loading at the target strain of 0.002. The specimen was also loaded for 22 cycles at a strain of 0.002 before increasing the strain level to 0.00225. Figure A.109 shows the specimen’s condition up to a strain of 0.002.  261  Strain: 0.001  Strain: 0.0015  262  Strain: 0.002 Figure A. 109  Strain: 0.002  Images Specimen CB3 Showing Specimen’s Condition up to Strain of 0.002  After the fifth cycle at a strain of 0.00225, visible cracks were detected at the bottom region around the horizontal reinforcement of 8 in. right side. In addition, damage was detected on the opposite side at the middle region of the specimen. Damage to the left and right side is shown in Figure A.110  263  (a) Figure A.110  (b)  Images of Specimen CB3 at Strain of 0.00225: (a) Right Side, (b) Left Side  264  Observations of Failure At this stage, the specimen was loaded to the capacity of the machine for five cycles. The specimen failed upon loading at the fifth cycle. Figure A.111 shows the specimen after failure.  (a) Figure A.111  (b)  Images of Specimen CB3 after Failure: (a) Right Side, (b) Left Side Specimen  265  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First damage and spalling were detected at the end of the fifth cycle at a strain level of 0.0015    Crack formation on the bottom section of the right and left 8 in. sides, around the horizontal reinforcement at the end of the fifth cycle at a strain of 0.00225    Cracks on the 8 in. long sides of the specimen    Maximum concrete stress: 33.1 MPa    Specimen was subjected to compression load for 5 cycles at each strain level except 0.00175 and 0.002    Specimen was subjected to 10 cycles at 0.00175 and 22 cycles at 0.002    No significant damage prior to failure    The specimen failed suddenly upon loading at the fifth cycle at the loading capacity of machine (1778kN).    Strain at failure: 0.0026    Failure occurred suddenly and included loud noise.  266  A.28  Specimen CB4 Table A.28  Specimen CB4 Properties  Specimen Name  CB4  Specimen Code  T8-H3-DL-15M-C40  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10.0/254  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  40  Spacing of Horiz. Reinf. (in./mm)  12.0/305  Age at Testing (days)  295  Loading Protocol  Type 1  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform 267  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.112  4 -3  Compression Strain  x 10  Stress-Strain Response of CB4: Average of Four Measurements  35 LP18 LP20 LP19 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.113  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of CB4: Four Position Transducers  268  Observations during Testing No visible damage was observed before the first cycle at a strain of 0.00175. Figure A.114 shows the specimen’s Condition before failure. At this stage, specimen was loaded to reach the target strain of 0.002; however, despite the fact that the load on the specimen was 1778 kN (capacity of the universal testing machine), the target displacement was not reached. Specimen CB4 was loaded at maximum load of 1778 kN for 15 cycles.  269  Strain: 0.001  Strain: 0.00125  270  Strain: 0.0015  Strain: 0.00175  271  10th cycle at 1778 kN Figure A.114  15th cycle at 1778 kN  Images Specimen CB4 Showing Specimen’s Condition up to Strain of 0.002  272  Observations of Failure The failure occurred upon loading at 16th cycle. Figure A.115 shows specimen after failure  (a) Figure A.115  (b)  Images of Specimen CB4 after Failure: (a) Right side, (b) Left Side Specimen  273  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First damage and spalling were detected at the end of the 10th cycle under a constant load of 1778 kN    Crack formation on the bottom section of the right and left 8 in. sides, around the horizontal reinforcement    Maximum concrete stress: 33 MPa    Specimen was subjected to compression load for 5 cycles at each strain level    No significant damage prior to failure    The specimen failed suddenly upon loading at the 16th cycle at a loading capacity of the machine (1778kN).    Strain at failure: 0.0023    Failure occurred suddenly and included loud noise.  274  A.29  Specimen CC1 Table A.29  Specimen CC1 Properties  Specimen Name  CC1  Specimen Code  T8-H3-DL-10M-C20(WE)  Specimen Type  Type 3  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10/254  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  10  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  8.0/203  Age at Testing (days)  182  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Relatively uniform 275  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.116  4 -3  Compression Strain  x 10  Stress-Strain Response of CC1: Average of Four Measurements  35 LP18 LP20 LP19 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.117  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of CC1:Four Position Transducers  276  Observations during Testing No visible damage was observed before the first cycle at a strain of 0.00175. Figure A.118 shows the specimen’s Condition before failure. Images provided in Figure A.118 show how the damage was applied to the specimen. Due to confinement provided on the 8 in. left side the specimen was subjected to bending. One side behaved much stiffer than the other side which had no cross-tie. The specimen experienced crack propagation and spalling before failure.  277  Strain: 0.0015  Strain: 0.00175  278  Strain: 0.002  Strain: 0.00225  279  Strain: 0.0025  Strain:0.003  280  Strain: 0.00325 Figure A.118  Strain: 0.0035  Images Specimen CC1 Showing Specimen’s Condition prior to Failure  281  Observations of Failure The specimen was pushed to failure after the fifth cycle at strain of 0.0035. Figure A.119 shows specimen after failure  (a) Figure A.119  (b)  Images of Specimen CC1 after Failure: (a) Right Side (b) left Side Specimen  282  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    Crack formation around top horizontal reinforcement on the right and left 8 in. sides    Maximum concrete stress: 30.1 MPa    Specimen was subjected to compression load for 5 cycles at each strain level    Significant damage prior to failure    The specimen was pushed to failure after the fifth cycle at a strain of 0.    Failure did not include loud noise    Strain at failure: 0.0038  283  A.30  Specimen CC2 Table A.30  Specimen CC2 Properties  Specimen Name  CC2  Specimen Code  T8-H3-DL-10M-C20(WE)  Specimen Type  Type 3  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10/254  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  10  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  8.0/203  Age at Testing (days)  297  Loading Protocol  Type 1  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform 284  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.120  4 -3  Strain  x 10  Stress-Strain Response of CC2: Average of Four Measurements  35 LP18 LP20 LP19 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.121  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of CC2:Four Position Transducers  285  Observations during Testing No visible damage was observed before the first cycle at a strain of 0.002. Figure A.122 shows the specimen’s condition before failure. Images provided in Figure A.122 show how the damage was applied to the specimen. Unlike specimen CC1, CC2 experienced severe damage as a result of the U-shape ties opening on the ends that did not have cross-ties. Significant drop in strength was observed after the first cycle at a strain of 0.002.  286  Strain: 0.001  Strain: 0.0015  287  Strain: 0.00175  Strain: 0.002  288  Strain: 0.00225 Figure A.122  Strain:0.0025  Images Specimen CC2 Showing Specimen’s Condition prior to Failure  289  Observations of Failure The specimen experienced crack propagation and spalling before failure. The specimen failed upon loading at the first cycle at a strain of 0.00275. Figure A.123 shows specimen after failure. As shown in the pictures, the horizontal reinforcement with single cross-ties pushed the cover outward, causing the clear cover to separate. In addition, this configuration of horizontal reinforcement did not provide adequate confinement for the core section of the specimen.  (a)  (b)  290  (c) Figure A.123  (d)  Images of Specimen CC2 after Failure: (a) Right Side, (b) Left Side, (c) Back Side, (d) Front Side of the Specimen  291  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First damage was detected at the end of the first cycle at a strain of 0.002    Crack formation around top horizontal reinforcement on the right and left 8 in. sides    Maximum concrete stress: 31 MPa    Significant drop in strength was observed after the first cycle at a strain of 0.002    Specimen was subjected to compression load for 5 cycles at each strain level    Significant damage prior to failure    The specimen failed upon loading at the first cycle at a strain of 0.00274    Strain at failure: 0.0026    Failure was very brittle and loud  292  A.31  Specimen CD1 Table A.31  Specimen CD1 Properties  Specimen Name  CD1  Specimen Code  T8-H3-Col. Tie-10M-C20  Specimen Type  Type 4  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10/254  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  10  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  8.0/203  Age at Testing (days)  170  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform 293  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.124  4 -3  Strain  x 10  Stress-Strain Response of CD1: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.125  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of CD1: Four Position Transducers  294  Observations during Testing No visible damage was observed before the first cycle at a strain of 0.002. Figure A.126 shows the specimen’s condition up to a strain of 0.002. Target strain at a higher strain level was not reached; therefore, the specimen was loaded for 34 cycles at a maximum constant load of 1778 kN, the loading capacity of the universal machine.  295  Strain: 0.001  Strain: 0.0015  296  Strain: 0.00175 Figure A.126  Strain: 0.002  Images Specimen CD1 Showing Specimen’s Condition prior to Failure  The first damage was detected at the 9th cycle. Small cracks were detected at the edges of two 8in. wide sides around the mid segment. Figure A.8127 shows the damage.  297  (a) Figure A.127  (b)  Images of Specimen CD1 after Failure: (a) Right Side, (b) Left Side Specimen  The specimen experienced a few cracks before failure. Figure A.128 provides images of the specimen before failure.  298  Cycle 17  cycle 22  299  Cycle 27 Figure A. 128  Cycle 32  Images of Specimen CD1 before Failure: The Specimen was Loaded 33 Cycles at a  Constant Load of 1778 kN before Failure  300  Observations of Failure The specimen failed upon loading at the 34th cycle under a load of 1750 kN. The failure involved extremely loud sound and it was very explosive. The cover and concrete layers within the cover zone around the vertical reinforcement and ties were separated. Relatively significant damage was observed before failure. Figure A.129 shows the specimen after failure.  (a) Figure A.129  (b)  Images of Specimen CD1 after Failure: (a) Front Side, (b) Left Side  301  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    Crack formation around top horizontal reinforcement on the 8 in. right and left sides    Maximum concrete stress: 31.6 MPa    Specimen was subjected to compression load for 5 cycles at up to strain of 0.002    The specimen was compressed under a load control approached after fifth cycle at strain of 0.002    Significant damage prior to failure    The specimen CD1 failed upon loading at the 34th cycle    Strain at failure: 0.0031    Failure sudden and involved loud sound  302  A.32  Specimen CD2 Table A.32  Specimen CD2 Properties  Specimen Name  CD2  Specimen Code  T8-H3-Col. Tie-10M-C20  Specimen Type  Type 4  Cross-section Layout  Wall Thickness (in./mm)  8.0/203  Length (in./mm)  10/254  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  10  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  8.0/203  Age at Testing (days)  322  Loading Protocol  Type 1  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform  303  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.130  4 -3  Strain  x 10  Stress-Strain Response of CD2: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.131  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of CD2: Four Position Transducers  304  Observations during Testing and of Failure No visible damage was observed before the fifth cycle at a strain of 0.00225. The loading protocol Type 1 was used to load the specimen CD2. Relatively to testing procedure for specimen CD1, specimen CD2 was subjected to more cycles at a smaller strain level in order to soften the specimen and attempt to reach the desired target strain levels. First cracks were detected at the end of the fifth cycle at a strain of 0.00225. The cracks were on the top edge of the left side of the specimen. The specimen load carrying capacity attenuated after a strain of 0.00225. The specimen experienced significant damage. Crack propagation and spalling happened as the specimen was loaded at the higher target strain level. Due to confinement provided by lateral ties, the specimen was able to exhibit a strain capacity greater than 0.0035. Figure A.94 contains images of the specimen after failure.  (a) Figure A. 132  (b) Images of Specimen CD1 after Failure: (a) Front Side, (b) Right Side  305  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    Crack formation at the top corner of left 8 in. side    Maximum concrete stress: 31.6 MPa    Specimen was subjected to compression load for 5 cycles at each strain level    Significant damage prior to failure    Specimen C2 was pushed to failure after the fifth cycle at a strain of 0.0035    Strain at failure: 0.0038    Failure did not include loud sound and the specimen gradually failed  306  A.33  Specimen DA1 Table A.33  Specimen DA1 Properties  Specimen Name  DA1  Specimen Code  T10-H2-DL-15M-C20  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  10./254  Length (in./mm)  8.0/203  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  191  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Uniform  307  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.133  4 -3  Strain  x 10  Stress-Strain Response of DA1: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.134  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of DA1: Four Position Transducers  308  Observations during Testing No visible damage was observed before the fifth cycle at a strain of 0.00225. Figure A.135 shows the specimen’s condition up to a strain of 0.002. First crack was detected around the top reinforcement on the front and right sides of specimen. Figure A.136 shows the specimen’s condition before failure.  309  Strain: 0.001  Strain: 0.0015  Strain: 0.00175  Strain: 0.002  Figure A.135  Images Specimen DA1 Showing Specimen’s Condition up to Strain of 0.002  310  Strain: 0.00225  Strain: 0.0025  Strain:0.00275  Strain: 0.003  Figure A.136  Images of Specimen DA1 after Failure: (a) Right Side, (b) Left Side Specimen  311  Observations of Failure The specimen experienced severe damage before failure. The specimen failed upon loading at the first cycle at a strain of 0.00323. Figure A.137 provides images of the specimen before failure. Diagonal cracks in an X-shape formed on the front and back of the specimen through the horizontal reinforcement.  312  (a)  (b)  (c) Figure A.137  Images of Specimen DA1 at Failure: (a) Front Side, (b) Back Side, (c) Right Side of Specimen  313  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First visible damage occurred at the end of the fifth cycle at a strain of 0.00225    Crack formation around the top horizontal reinforcement on the front and right sides    Maximum concrete stress: 32.9MPa    Specimen was subjected to compression load for 5 cycles at a strain of up to 0.002    Significant damage prior to failure    Specimen DA1 failed upon loading at the first cycle at a strain of 0.00325    Strain at failure: 0.0033    Failure was sudden and involved loud sound  314  A.34  Specimen DA2 Table A.34  Specimen DA2 Properties  Specimen Name  DA2  Specimen Code  T10-H2-DL-15M-C20  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  10.0/254  Length (in./mm)  8.0/203  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  6.0/152  Age at Testing (days)  280  Loading Protocol  Type 1  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Relatively uniform  315  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  4 -3  Strain  Figure A.138  x 10  Stress-Strain Response of DA2: Average of Four Measurements  35 LP18 LP20 LP19 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A. 139  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of DA2: Four Position Transducers  316  Observations during Testing No visible damage was observed before the fifth cycle at a strain of 0.00225. Figure A.140 shows the specimen’s condition up to a strain of 0.002. The first crack was detected around the top reinforcement on the front side of the specimen. Figure A.141 shows the specimen’s condition before failure.  317  Strain: 0.00125  Strain: 0.0015  Strain: 0.00175  Strain: 0.002  Figure A.140  Images Specimen DA2 Showing Specimen’s Condition prior to Failure  318  Strain: 0.00225  Strain: 0.0025  Strain:0.00275  Strain: 0.003  319  Strain:0.00325 Figure A.141  Strain:0.0035  Images of Specimen DA2 Showing the Damage Progression  320  Observations of Failure The specimen experienced severe damage before failure. Specimen DA2 had a strain capacity greater than 0.0035. The specimen was pushed to failure after the fifth cycle at a strain of 0.0035. Figure A.142 provides images of specimen before failure. Diagonal cracks in an X-shape formed on the front and back of the specimen through the horizontal reinforcement.  (a) Figure A.142  (b)  Images of Specimen DA2 at Failure: (a) Front Side, (b) Back Side  321  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First visible damage occurred at the end of the fifth cycle at a strain of 0.00225    Crack formation around the top horizontal reinforcement on the front side    Maximum concrete stress: 31.3 MPa    Specimen was subjected to compression load for 5 cycles at each strain level    Significant damage prior to failure    The specimen DA2 was pushed to failure after the fifth cycle at a strain of 0.0035    Strain at failure: 0.0039    Failure did not involved loud sound  322  A.35  Specimen DA3 Table A.35  Specimen DA3 Properties  Specimen Name  DA3  Specimen Code  T10-H2-DL-15M-C20  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  10.0/254  Length (in./mm)  8.0/203  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  12.0/305  Age at Testing (days)  141  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform 323  35  Average Stress(P - Ps)/Ac, MPa)  30 25 20  C1 C2  15  C3 C4  10  C5 5 0 0  0.0005  -5  0.001  0.0015  0.002  0.0025  Strain Figure A.143  Envelope of Average Stress-Strain Response of DA3  324  Observations during Testing No visible damage was observed before the fifth cycle at a strain of 0.00175. Figure A.144 shows the specimen’s condition up to the end of first cycle at a strain of 0.002. The first crack was detected around the top reinforcement on the front side of the specimen. The specimen failed upon loading at the second cycle at a strain of 0.002. Due to a problem during testing, the recorded data was lost and the only data available is the maximum load at each cycle. The envelope of average stress-strain response of the specimen is provided in Figure A.143.  325  Strain: 0.001  Strain: 0.0015  326  Strain: 0.00175  Strain: 0.002 Figure A.144  Images Specimen DA3 Showing Specimen’s Condition prior to Failure  327  Observations of Failure The specimen’s failure was very sudden and loud. Figure 145 includes the images of the specimen after failure. The specimen experienced very small damage before failure. The specimen DA3 had a strain capacity of 0.00175. Diagonal cracks formed around the top lateral reinforcement and coalesced into a single crack at the middle specimen.  (a) Figure A.145  (b) Images of Specimen DA3 at Failure: (a) Front Side, (b) Back Side  328  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First visible damage occurred at the end of the fifth cycle at a strain of 0.00175    Crack formation around the top horizontal reinforcement on the front side    Maximum concrete stress: 31.6 MPa    Specimen was subjected to compression load for 5 cycles at each strain level    No significant damage prior to failure    The specimen DA3 failed upon loading at the second cycle at a strain of 0.002    Strain at failure: 0.002    Failure was sudden and involved loud sound  329  A.36  Specimen DA4 Table A.36  Specimen DA4 Properties  Specimen Name  DA4  Specimen Code  T10-H2-DL-15M-C20  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  10.0/254  Length (in./mm)  8.0/203  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  12.0/305  Age at Testing (days)  283  Loading Protocol  Type 1  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform 330  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  4 -3  Strain  Figure A.146  x 10  Stress-Strain Response of DA4: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  Strain  Figure A.147  2.5  3  3.5  4 -3  x 10  Stress-Strain Response of DA4: Four Position Transducers  331  Observations during Testing No visible damage was observed before the fifth cycle at a strain of 0.00225. Figure A.148 shows the specimen’s condition up to the end of the first cycle at a strain of 0.0025. The first crack was detected at the end of the fifth cycle around the top reinforcement on the front side of the specimen.  332  Strain: 0.001  Strain: 0.00125  333  Strain: 0.00175  Strain: 0.002  334  Strain: 0.00225 Figure A.148  Images Specimen DA4 Showing Specimen’s Condition prior to Failure  335  Observations of Failure The specimen failed upon loading at the second cycle at a strain of 0.0025. The specimen’s failure was very sudden and loud. Figure A.149 includes the images of the specimen after failure. The specimen experienced very small damage before failure. The specimen DA4 had a strain capacity larger than 0.00225. A diagonal crack formed through the top and bottom lateral reinforcements.  (a)  (b) Figure A.149  Images of Specimen DA4 at Failure: (a) Front Side, (b) Back Side  336  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First visible damage occurred at the end of the fifth cycle at a strain of 0.00175    Crack formation around the top horizontal reinforcement on the front side    Maximum concrete stress: 33 MPa    Specimen was subjected to compression load for 5 cycles at each strain level    No significant damage prior to failure    The specimen DA4 failed upon loading at the first cycle at a strain of 0.0025    Strain at failure: 0.0025    Failure was sudden and involved loud sound  337  A.37  Specimen DB1 Table A.37  Specimen DB1 Properties  Specimen Name  DB1  Specimen Code  T10-H2-DL-15M-C40  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  10.0/254  Length (in./mm)  8.0/203  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  40  Spacing of Horiz. Reinf. (in./mm)  6.0/154  Age at Testing (days)  196  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Relatively uniform 338  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.150  4 -3  Strain  x 10  Stress-Strain Response of DB1: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  Strain  Figure A.151  3  3.5  4  4.5  5 -3  x 10  Stress-Strain Response of DB1: Four Position Transducers  339  Observations during Testing No visible damage was observed before the fifth cycle at a strain of 0.002. Figure A.152 shows the specimen’s condition up to the end of the first cycle at a strain of 0.0025. The first crack was detected at the end of the fifth cycle at strain of 0.002 around the top reinforcement on the front side of the specimen.  340  Strain: 0.001  Strain: 0.0015  Strain: 0.00175  Strain: 0.002  341  Strain: 0.00275  Strain: 0.003  Strain: 0.0035 (front side)  Strain: 0.0035 (back side)  Figure A.152  Images Specimen DB1 Showing Specimen’s Condition prior to Failure  342  Observations of Failure The specimen had a strain capacity greater than 0.0035. The specimen was pushed to failure after the fifth cycle at a strain of 0.0035. Figure A.153 includes the images of the specimen after failure. The specimen experienced significant damage before failure  (a) Figure A.153  (b) Images of Specimen DB1 at Failure: (a) Front Side, (b) Back Side  343  Summary of Test Observations:   Significant strain difference between position transducers    First visible damage occurred at the end of the fifth cycle at a strain of 0.002    Crack formation around the top horizontal reinforcement on the front side    Maximum concrete stress: 32.4 MPa    Specimen was subjected to compression load for 5 cycles at each strain level    Significant damage prior to failure    Strain at failure: 0.0038    Failure did not involve loud sound  344  A.38  Specimen DB2 Table A.38  Specimen DB2 Properties  Specimen Name  DB2  Specimen Code  T10-H2-DL-15M-C40  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  10.0/254  Length (in./mm)  8.0/203  Element Height (ft/mm)  2.0/610  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  40  Spacing of Horiz. Reinf. (in./mm)  6.0/154  Age at Testing (days)  269  Loading Protocol  Type 3  Number of Sides Strain Measured  4  Gauge Length (in./mm)  18.0/457  Axial Strain Profile  Uniform 345  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.154  4 -3  Strain  x 10  Stress-Strain Response of DB2: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  Strain  Figure A.155  3  3.5  4  4.5  5 -3  x 10  Stress-Strain Response of DB2: Four Position Transducers  346  Observations during Testing No visible damage was observed before the third cycle at a strain of 0.002. Figure A.156 shows the specimen’s condition before failure. The first crack was detected at the end of the third cycle at a strain of 0.002 at the top corner on the right side.  347  Strain: 0.001  Strain: 0.0015  Strain: 0.002  Strain: 0.0025  Figure A.156  Images Specimen DB2 Showing Specimen’s Condition prior to Failure  348  Observations of Failure The specimen had a strain capacity larger than 0.0025. The specimen failed upon loading at the first cycle at strain of 0.003. Figure A.157 includes the images of the specimen after failure. The specimen experienced damage before failure.  (a) Figure A.157  (b) Images of Specimen DB2 at Failure: (a) Right Side, (b) Back Side  349  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First visible damage occurred at the end of the third cycle at a strain of 0.002    Crack formation around the top horizontal reinforcement on the back side    Maximum concrete stress: 32.4 MPa    Specimen was subjected to compression load for 3 cycles at each strain level    Damage was observed prior to failure    Strain at failure: 0.0028    Failure involved loud sound    Failure happened suddenly  350  A.39  Specimen DB3 Table A.39  Specimen DB3 Properties  Specimen Name  DB3  Specimen Code  T10-H3-DL-15M-C40  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  10.0/254  Length (in./mm)  8.0/203  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  40  Spacing of Horiz. Reinf. (in./mm)  12.0/305  Age at Testing (days)  160  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform  351  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.158  4 -3  Strain  x 10  Stress-Strain Response of DB3: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  Strain  Figure A.159  3  3.5  4  4.5  5 -3  x 10  Stress-Strain Response of DB3: Four Position Transducers  352  Observations during Testing No visible damage was observed before the fifth cycle at a strain of 0.002. Figure A.160 shows the specimen’s condition before failure. The first crack was detected at the end of the fifth cycle at a strain of 0.002 at top corner on the right side.  353  Strain: 0.001  Strain: 0.0015  354  Strain: 0.00175 Figure A.160  Strain: 0.002  Images Specimen DB3 Showing Specimen’s Condition prior to Failure  355  Observations of Failure The specimen had a strain capacity of 0.002.The specimen failed upon loading at the fifth cycle at strain of 0.0025. Figure A.161 includes the images of the specimen after failure. The specimen did not experience damage before failure.  (a) Figure A.161  (b) Images of Specimen DB3 at Failure: (a) Front Side, (b) Back Side  356  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First visible damage occurred at the end of the third cycle at a strain of 0.002    Crack formation around the top horizontal reinforcement on the back side    Target strain was not met at the first cycle at a strain of 0.002 and 0.0025    Maximum concrete stress: 33.1 MPa    Specimen was subjected to compression load for 5 cycles at each strain level    Damage was observed prior to failure    Strain at failure: 0.0023    Failure involved loud sound  357  A.40  Specimen DB4 Table A.40  Specimen DB4 Properties  Specimen Name  DB4  Specimen Code  T10-H3-DL-15M-C40  Specimen Type  Type 2  Cross-section Layout  Wall Thickness (in./mm)  10.0/254  Length (in./mm)  8.0/203  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  40  Spacing of Horiz. Reinf. (in./mm)  12.0/305  Age at Testing (days)  287  Loading Protocol  Type 2  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform  358  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.162  4 -3  Strain  x 10  Stress-Strain Response of DB4: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  Strain  Figure A.163  3  3.5  4  4.5  5 -3  x 10  Stress-Strain Response of DB4: Four Position Transducers  359  Observations during Testing No visible damage was observed before the fifth cycle at a strain of 0.00175. Figure A.164 shows the specimen’s condition before failure. The first crack was detected at the end of the fifth cycle at a strain of 0.00175 at the top corners on the back side.  360  Strain: 0.001  Strain: 0.00125  361  Strain: 0.0015  Strain: 0.00175  362  Strain: 0.002 Figure A.164  Strain: 0.00225  Images Specimen DB4 Showing Specimen’s Condition prior to Failure  363  Observations of Failure The specimen had a strain capacity of 0.00225. The specimen failed upon loading at the first cycle at a strain of 0.0025. Figure A.165 includes images of the specimen after failure. The specimen experienced small cracks and spalling in the cover zone close to the reinforcement at the top section of the specimen.  (a) Figure A.165  (b) Images of Specimen DB4 at Failure: (a) Front Side, (b) Back Side  364  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First visible damage occurred at the end of the third cycle at a strain of 0.00175    Crack formation around the top horizontal reinforcement on the back side    Maximum concrete stress: 31.9 MPa    Specimen was subjected to compression load for 5 cycles at each strain level    Damage was observed prior to failure    Strain at failure: 0.00246    Failure involved loud sound  365  A.41  Specimen EA1  Table A.41  Specimen EA1 Properties  Specimen Name  EA1  Specimen Code  T10-H3- DL-10M-C20(WE)  Specimen Type  Type 3  Cross-section Layout  Wall Thickness (in./mm)  10.0/254  Length (in./mm)  8.0/203  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  10.0/254  Age at Testing (days)  301  Loading Protocol  Type 1  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform  366  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  4  Figure A.166  4.5 -3  Strain  x 10  Stress-Strain Response of EA1: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  Strain  Figure A.167  3  3.5  4  4.5  5 -3  x 10  Stress-Strain Response of EA1: Four Position Transducers  367  Observations during Testing Specimen EA1 contained lateral horizontal reinforcement with one cross-tie. No visible damage was observed before the fifth cycle at a strain of 0.00175. The crack formed behind the mount which held LP19, the position transducer. Figure A.168 shows the specimen’s condition before failure. The specimen experienced significant damage at the end of the first cycle at a strain of 0.002. As shown in Figure A.166, the specimen strength reduces significantly after the first cycle at a strain of 0.002.  368  Strain: 0.001  Strain: 0.0015  369  Strain: 0.00175  Strain: 0.002 (cycle 1)  370  Strain: 0.002 (cycle 5)  Strain: 0.00225  371  Strain: 0.00225  Strain: 0.0025  372  Strain: 0.00275  Strain: 0.003  373  Strain: 0.00325 Figure A.168  Strain: 0.0035  Images Specimen EA1 Showing Specimen’s Condition prior to Failure  374  Observations of Failure Figure A.169 includes the images of the specimen after failure. The specimen experienced severe damage before failure.  (a) Figure A.169  (b) Images of Specimen EA1 at Failure: (a) Front Side, (b) Back Side  375  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First visible damage occurred at the end of the third cycle at a strain of 0.00175    Crack formation around the top horizontal reinforcement on the back side, in the concrete cover (see Figure A.168)    Maximum concrete stress: 29.2 MPa    Specimen was subjected to compression load for 5 cycles at each strain level    Damage was observed prior to failure    Strain at failure: 0.0043    Failure did not involve loud sound  376  A.42  Specimen EA2 Table A.42  Specimen EA2 Properties  Specimen Name  EA2  Specimen Code  T10-H3- DL-10M-C20(WE)  Specimen Type  Type 3  Cross-section Layout  Wall Thickness (in./mm)  10.0/254  Length (in./mm)  8.0/203  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  15  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  10.0/254  Age at Testing (days)  310  Loading Protocol  Type 1  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform  377  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.170  4 -3  Strain  x 10  Stress-Strain Response of EA2: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  Strain  Figure A.171  3  3.5  4  4.5  5 -3  x 10  Stress-Strain Response of EA2: Four Position Transducers  378  Observations during Testing Specimen EA2 contained lateral horizontal reinforcement with one cross-tie. No visible damage was observed before the fifth cycle at a strain of 0.00175. A crack formed at the top corner of the back side of the specimen. Figure A.172 shows the specimen’s condition before failure. Cracks were detected at the end of the fifth cycle at a strain of 0.002 at three corners in the concrete cover (see pictures below).  379  Strain: 0.001  Strain: 0.0015  Strain: 0.00175  Strain: 0.002  380  Strain: 0.002 Figure A.172  Strain: 0.002  Images Specimen EA2 Showing Specimen’s Condition prior to Failure  381  Observations of Failure The specimen had a strain capacity of 0.002.The specimen failed upon loading at the first cycle at a strain of 0.00225. Figure A.173 includes the images of the specimen after failure. The specimen failure was very brittle and happened suddenly.  (a) Figure A.173  (b) Images of Specimen EA2 at Failure: (a) Front Side, (b) Back Side  382  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First visible damage occurred at the end of third cycle at strain of 0.00175    Crack formation around the top horizontal reinforcement on the corner of the back side, in the concrete cover    Maximum concrete stress: 32.6 MPa    Specimen was subjected to compression load for 5 cycles at each strain level    Damage was observed prior to failure    Strain at failure: 0.0022    Failure involved loud sound and happened suddenly    Brittle failure  383  A.43  Specimen EB1 Table A.43  Specimen EB1 Properties  Specimen Name  EB1  Specimen Code  T10-H3-Col. Tie-10M-C40  Specimen Type  Type 4  Cross-section Layout  Wall Thickness (in./mm)  10.0/254  Length (in./mm)  8.0/203  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  10  Clear Cover (mm)  20  Spacing of Horiz. Reinf. (in./mm)  10.0/254  Age at Testing (days)  303  Loading Protocol  Type 1  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform  384  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.174  4 -3  Strain  x 10  Stress-Strain Response of EB1: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  Strain  Figure A.175  3  3.5  4  4.5 -3  x 10  Stress-Strain Response of EB1: Four Position Transducers  385  Observations during Testing Specimen EB1 contained lateral column ties. No visible damage was observed before the fifth cycle at a strain of 0.002. A crack was formed at the top corner of the right side of the specimen. Figure A.176 shows the specimen’s condition before failure (see pictures below).  386  Strain: 0.001  Strain: 0.0015  387  Strain: 0.00175  Strain: 0.002  388  Strain: 0.00225  Strain: 0.0025  389  Strain: 0.00275  Strain: 0.003  390  Strain: 0.00325 Figure A.176  Strain: 0.0035  Images Specimen EB1 Showing Specimen’s Condition prior to Failure  391  Observations of Failure The specimen had a strain capacity greater than 0.0035. The specimen was subjected to axial load for five cycles at an additional target strain of 0.00375.The specimen was pushed to failure after the fifth cycle at strain of 0.00375. Figure A.177 includes the images of the specimen after failure. The specimen failure occurred very gradually. The failure did not include loud noise.  (a) Figure A.177  (b) Images of Specimen EB1 at Failure: (a) Front Side, (b) Back Side  392  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First visible damage occurred at the end of the third cycle at a strain of 0.002    Crack formation around the top horizontal reinforcement on the corner of the right side, in the concrete cover    Maximum concrete stress: 30.2 MPa    Specimen was subjected to compression load for 5 cycles at each strain level    Damage was observed prior to failure    Strain at failure: 0.0039    Failure happened very gradually    Failure did not include loud sound  393  A.44  Specimen F1 Table A.44  Specimen F1 Properties  Specimen Name  F1  Specimen Code  T10"-P-C20  Specimen Type  Type 3  Cross-section Layout  Wall Thickness (in./mm)  10.0/254  Length (in./mm)  8.0/203  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  ----  Clear Cover (mm)  35  Spacing of Horiz. Reinf. (in./mm)  ----  Age at Testing (days)  148  Loading Protocol  Type 3  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform  394  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.178  4 -3  Strain  x 10  Stress-Strain Response of F1: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  Strain  Figure A.179  3  3.5  4  4.5  5 -3  x 10  Stress-Strain Response of F1: Four Position Transducers  395  Observations during Testing Specimen F1 contained no lateral reinforcements. The first damage was detected at the first cycle at a strain of 0.0015. A fine crack was detected at the center of the front face of the specimen, close to the location of position transducer LP18 (see pictures below). Figure A.180 shows the specimen’s condition before failure.  396  Strain: 0.001  Strain: 0.0015 (cycle 1)  397  Strain: 0.0015 (cycle 5) Figure A.180  Images Specimen F1 Showing Specimen’s Condition prior to Failure  398  Observations of Failure The specimen had a strain capacity of 0.0015.The specimen failed upon loading at the first cycle at a strain of 0.00175. Figure A.181 includes the images of the specimen after failure. The specimen failure was very brittle and happened suddenly.  (a) Figure A.181  (b) Images of Specimen F1 at Failure: (a) Front Side, (b) Back Side  399  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First visible damage occurred at the end of the first cycle at a strain of 0.0015    Crack formation in a vertical direction at the center of the front and back side of the specimen    Maximum concrete stress: 27.6 MPa    Specimen was subjected to compression load for 3 cycles at each strain level    Damage was observed prior to failure    Strain at failure: 0.0017    Failure involved loud sound and happened suddenly    Brittle failure  400  A.45  Specimen F2 Table A.45  Specimen F2 Properties  Specimen Name  F2  Specimen Code  T10"-P-C20  Specimen Type  Type 3  Cross-section Layout  Wall Thickness (in./mm)  10.0/254  Length (in./mm)  8.0/203  Element Height (ft/mm)  3.0/914  Diameter of Horizontal Reinforcement (mm)  ----  Clear Cover (mm)  35  Spacing of Horiz. Reinf. (in./mm)  ----  Age at Testing (days)  308  Loading Protocol  Type 1  Number of Sides Strain Measured  4  Gauge Length (in./mm)  30.0/762  Axial Strain Profile  Uniform  401  35  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  3  3.5  Figure A.182  4 -3  Strain  x 10  Stress-Strain Response of F2: Average of Four Measurements  35 LP18 LP19 LP20 LP21  25  s  c  Compression Stress, (P - P )/A (MPa)  30  20  15  10  5  0 0  0.5  1  1.5  2  2.5  Strain  Figure A.183  3  3.5  4  4.5  5 -3  x 10  Stress-Strain Response of F2: Four Position Transducers  402  Observations during Testing Specimen F2 contained no lateral reinforcements. The first crack was detected after the fifth cycle at a strain of 0.002. No visible damage was detected before the fifth cycle at a strain of 0.002. Similar to F1, a fine crack was detected at the center of the front and back face of the specimen close to the location of position transducer LP18 and LP20 (see pictures below). The specimen was loaded for five cycle at maximum load of 400,000 lb after the fifth cycle at a strain of 0.002. Figure A.184 shows the specimen’s condition before failure.  403  Strain: 0.001  Strain: 0.0015  404  Strain: 0.00175  Strain: 0.002 (LP18  405  Strain: 0.002 (LP20)  Fifth cycle at constant load (400 klb) Figure A.184  Images Specimen F2 Showing Specimen’s Condition prior to Failure  406  Observations of Failure The specimen had a strain capacity of 0.002 and the failure happened upon loading at the first cycle at a strain of 0.0025. The specimen was loaded for five cycles at a constant load of 400 klb. The target strain of 0.00225 was never reached. Figure A.185 includes images of the specimen after failure. The specimen failure was very brittle and happened suddenly.  (a)  (b)  407  (c) Figure A.185  Images of Specimen F2 at Failure: (a) Front Side, (b) Left Side, (c) Back Side  408  Summary of Test Observations:   Uniform strain    No significant strain difference between position transducers    First visible damage occurred at the end of the fifth cycle at a strain of 0.002    Crack formation in a vertical direction at the center of the front and back side of the specimen    Maximum concrete stress: 31.6 MPa    Specimen was subjected to compression load for 5 cycles at each strain level    Damage was observed prior to failure    Strain at failure: 0.0024    Failure involved loud sound and happened suddenly    Brittle failure  409  Appendix B Schematic Drawings of Failure Plane  410  411  412  413  414  415  416  417  418  419  Figure B. 1  Schematic Drawings of Failure Plane for 45 Wall Elements  420  Appendix C Partial Analytical Study  421  C.1  Matlab Script  function [max,Strain_Correspond] = axial_load_vs_strain format long; % Load Condition and Specimen Properties % ------------------------------------P_app = -3000 * 1000; %-3000 * 1000; % 1000 is multiplied because P_app is in unit of "N" fc = 30; %[MPa] fcr = 0.33*sqrt(abs(fc)); C_density = 2300; Ec_tan = 5000*sqrt(fc);%[MPa] eps_prime = 2*fc/Ec_tan; if abs(fc) <= 40 Ec = 4500*sqrt(abs(fc));%[MPa] else Ec = (3300*sqrt(abs(fc))+ 6900)*(C_density/2300)^1.5;%[MPa] end eps_cr = fcr/Ec_tan; Es = 200000; %[MPa] fs_y = 400; %[MPa] eps_s_max = 0.08; eps_y = fs_y/Es; a=1; b = 0.2;%[m] h = 12.192; %[m] Ag = b*h; %[m^2] L_bw = h*1000; %[mm] note L_bw is the same as h defined above L_sw = 9144*10^-6; %[km] % -----------------------------------eps_cent = 0; ro = 0.0015; [Layer_Properties]=Layer_ Generator (b,h,ro); curv = 0.0035/L_sw; %unit is in [rad/km] i = 1; %counter for eps_t = (-0.00):(-0.00001):(-0.0035) eps = zeros(length(Layer_Properties),1); type = zeros(length(Layer_Properties),1); force = zeros(length(Layer_Properties),1); M = zeros(length(Layer_Properties),1); eps_cent = eps_t + (L_bw/2)*curv*10^-6; p = 0; m = 0; for j = 1:length(Layer_Properties) %strain is defined as eps type(j) = Layer_Properties(j,1); A = Layer_Properties(j,4); y = Layer_Properties(j,2); eps(j) = eps_cent - curv*(10^-6) * y;  422  if type(j) == 1 if eps(j) < 0 %indicates that the layer is in compression f_layer = Stress_G(eps(j),fc); %f_layer = sign(eps)*fc*abs((2*(abs(eps)/eps_prime)(abs(eps)/eps_prime)^2)); force(j) = f_layer*A; M(j) = force(j)*y; elseif eps(j) >= 0 % force(j) = 0; %________________________TENSION STIFFENING____________________________% if eps(j) <= eps_cr f_layer = Ec_tan*eps(j); force(j) = f_layer*A; M(j) = force(j)*y; else f_layer = fcr/(1+sqrt(500*(eps(j)-eps_cr))); fs = eps(j) * Es; %steel force in the layer if fs > fs_y fs = fs_y; end if f_layer <= ((fs_y - fs)*ro) force(j) = f_layer*A; else force(j) = (fs_y - fs)*ro*A; end %outputforce(j,a)=force(j); M(j) = force(j)*y; end %______________________________________________________________________% end elseif type (j) == 2 if eps(j) >= -eps_y || eps(j) <= eps_y fs = Es * eps(j) ; force(j) = fs *A; M(j) = force(j)*y; end if eps(j) > eps_y && eps(j) < eps_s_max %---Strain Hardening---% %eps_strain_hardening = log(1+eps); %fs = K*eps_strain_hardening^n; %---No Strain hardening---% fs = fs_y; force(j) = fs *A; M(j) = force(j)*y; end if eps(j) <= -eps_y && eps(j) >= -eps_s_max %---Strain Hardening---% %eps_strain_hardening = -1*log(1+abs(eps)); %fs = K*eps_strain_hardening^n; %---No Strain hardening---% fs = -fs_y; force(j) = fs *A; M(j) = force(j)*y; end if abs(eps(j))>eps_s_max fs = 0; force(j) = fs *A;  423  M(j) = force(j)*y; end end p=p+force(j); m=m+M(j); end Force(i,1) = p; Strain(i,1) = eps_t; i = i +1; %i end  424  

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