connection of precast shear wall panels using carbon fiber

Connection of precast shear wall panels using carbon fiber composites and adhesive anchor boltsUSING CARBON FIBER COMPOSITES
AND ADHESIVE ANCHOR BOLTS
Paul W. McMullin
A thesis submitted to the faculty of The University of Utah
in partial fulfillment of the requirements for the degree of
Master of Science
The University of Utah
USING CARBON FIBER COMPOSITES
AND ADHESIVE ANCHOR BOLTS
Paul W. McMullin
A thesis submitted to the faculty of The University of Utah
in partial fulfillment of the requirements for the degree of
Master of Science
The University of Utah
All Rights Reserved
All Rights Reserved
SUPERVISORY COMMITTEE APPROVAL
Paul W. McMullin
This thesis has been read by each member of the following supervisory committee and by majority vote has been found to be satisfactory.
3/2$(21)00
FINAL READING APPROVAL
To the Graduate Council of the University of Utah:
I have read the thesis of Paul W. McMullin in its final form and have found that (1) its format, citations, and bibliographic style are consistent and acceptable; (2) i ts illustrative materials including figures,
tables, and charts are in place; and (3) the final manuscript is satisfactory to the supervisor committee and is ready for submission to The Graduate School.
Date Chris P. Pantelides Chair: Supervisory Committee
Approved for the Major Department
Lawrence D. Reavely Chair
David S. Chapman Dean of The Graduate School
ABSTRACT
A fiber reinforced plastic (FRP) composite connection and the design methodology for the
composite coimection were developed through the testing of nine precast wall panel assemblies. The
final connection design consists of an 18x24 inch composite lay-up, epoxy bonded to the concrete wall
surface. Four Hilti epoxy anchors were placed in strategic locations to prestress the concrete to resist
shear cracking in the concrete just below the connection surface. A design value for the connection of
50 kips was determined from the data and finite element analyses. Correlations between the design
methodology and test data indicate that the design methodology equations accurately predict the
connection capacity. The coimection is an economical solution for retrofitting precast concrete wall
connections and other precast concrete elements which require in-plane shear transfer strengthening.
The composite coimection will become a viable option for new construction as material cost decreases
and the interaction between FRP composites and concrete is better understood.
ABSTRACT
A fiber reinforced plastic (FRP) composite connection and the design methodology for the
composite connection were developed through the testing of nine precast wall panel assemblies. The
final connection design consists of an 18x24 inch composite lay-up, epoxy bonded to the concrete wall
surface. Four Hilti epoxy anchors were placed in strategic locations to prestress the concrete to resist
shear cracking in the concrete just below the connection surface. A design value for the connection of
50 kips was determined from the data and finite element analyses. Correlations between the design
methodology and test data indicate that the design methodology equations accurately predict the
connection capacity. The connection is an economical solution for retrofitting precast concrete wall
connections and other precast concrete elements which require in-plane shear transfer strengthening.
The composite connection will become a viable option for new construction as material cost decreases
and the interaction between FRP composites and concrete is better understood.
This thesis is dedicated to my parents Joy and Phil without whose motivation and support I would not have gone to college or graduate school and to my wife Kari
who shared me with the Structures Lab.
This thesis is dedicated to my parents Joy and Phil without whose motivation and support I would not have gone to college or graduate school and to my wife Kari
who shared me with the Structures Lab.
TABLE OF CONTENTS
1. E JTRODUCTION 1
1.1 Literature Review 5 1.2 Objectives and Scope of Research 7 1.3 Overview of Tests 7
1.3.1 Triple Wall Panel Assembly 10 1.3.2 Double Wall Panel Assembly 10
1.4 Analysis Overview 12
2. TEST SETUP 14
2.1 Hollow-Core Wall Panel Description 14 2.2 Composite Connection 14
2.2.1 Material Properties 14 2.2.1.1 Composite 15 2.2.1.2 Adhesive 16 2.2.1.3 Anchors 16
2.2.2 Concrete Surface Preparation 16 2.2.3 Composite Installation Procedure 18 2.2.4 Anchor Installation Procedure 18
2.3 Specimen Installation and Instrumentation Layout 19 2.3.1 Fixture Material Properties 19 2.3.2 Triple Wall Panel Assembly 29
2.3.2.1 Fixture Layout 19 2.3.2.2 Test3C#l 25 2.3.2.3 Test3C#2 29 2.3.2.4 Resistance Test 29
2.3.3 Double Wall Panel Assembly 32 2.3.3.1 Fixture Layout 32 2.3.3.2 Test 2C#1 32 2.3.3.3 Test 2C#2 32 2.3.3.4 Test 2C#3 42 2.3.3.5 Test 2C#4 40 2.3.3.6 Test 2C#5 40
TABLE OF CONTENTS
I. INTRODUCTION ... .... ...... .. .. ...................................... .. ... ................... .......... ..... .................. ....... I
1.1 Literature Review .................... ............................. ... .. .............. ......... ... ................................ 5 1.2 Objectives and Scope of Research .. .................................. ...... .......... ................. ................. 7 1.3 Overview of Tests .. ....... ... ........ .......... ...... ...... ........ .... ............... ......... ............... ... ............... 7
1.3.1 Triple Wall Panel Assembly ........ ................ ........... ............................................... 10 1.3.2 Double Wall Panel Assembly ..................................................... ... ........................ 1 0
1.4 Analysis Overview ............ ................. ....... .......... ............................ .................... .............. 12
2. TEST SETUP ........ ........ .. .......... ................................................. ............ .......... ......................... 14
2.1 Hollow-Core Wall Panel Description .... ....... ...... ............. ... .. ........ ..... .... ....... .................... 14 2.2 Composite Connection ................................. ................................. .................... ...... .. ........ 14
2.2.1 Material Properties .................................................. ........... ............ .. ...................... 14 2.2.1.1 Composite ............................................................. ... ....... ... ........................ 15 2.2.1.2 Adhesive .. ....... .... .................................. .... .... .. ....... ................ .... ................ 16 2.2.1 .3 Anchors ... ........ ............................... .... ......... .............................................. 16
2.2.2 Concrete Surface Preparation ........ ... ..................... .. .... ........... ..... ...... ..... .... ............ 16 2.2.3 Composite Installation Procedure .... ... .. ... .. ....... ............................................. ... ..... 18 2.2.4 Anchor Installation Procedure .................................................. ........... ..... .............. 18
2.3 Specimen Installation and Instrumentation Layout... ............... ......... ... ............ ................. 19 2.3.1 Fixture Material Properties .. .... ...................... ....... ................................................. 19 2.3.2 Triple Wall Panel Assembly ..... ..................... .... .... .... ...... ......... ....... .. .... .............. .. 29
2.3.2.1 Fixture Layout .................. .. .... .................................. ......... .... ............ .... .. .. 19 2.3 .2.2 Test 3C#1 ............................. ..... ............ ........ .... ............... ......................... 25 2.3.2.3 Test 3C#2 ......... ........... ......... .......... .. ... ..... ....................................... ........ .. 29 2.3.2.4 Resistance Test ... ......... ............. ............ ................. ......... ......... ................. . 29
2.3.3 Double Wall Panel Assembly .... ....................... .. ............................... .................... 32 2.3.3.1 Fixture Layout. ...... ......... ................................................. ........ .... ... ............ 32 2.3.3.2 Test 2C#I ...... .... .... ......... .. ..... .......... .............................. .. ........................... 32 2.3 .3.3 Test 2C#2 .................................. ..... .. ............. .. ........................................... 32 2.3.3.4 Test 2C#3 ...................................................................................... ........ ..... 42 2.3 .3.5 Test 2C#4 .. ..................................... ......... .... ........................................... .... 40 2.3 .3.6 Test 2C#5 ......... ......... ............................................................... .......... ....... .40
2.3.3.7 Test 2C#6 49 2.3.3.8 Test 2C#7 49 2.3.3.9 Resistance Test 52
2.4 Sensors, Instrumentation and Data Acquisition System 49 2.5 Loading Sequence 53
2.5.1 Triple Wall Panel Assembly 53 2.5.2 Double Wall Panel Assembly 53 2.5.3 Resistance Tests 53
2.6 Anchor Tests 53
3. EXPERIMENTAL RESULTS 55
3.1 Resistance Test 55 3.2 Generalized Connection Test Results 55
3.2.1 Failure Modes 55 3.2.2 Generalized Observations 62
3.3 Individual Connection Test Results 72 3.3.1 Test3C#l 72 3.3.2 Test3C#2 72 3.3.3 Test2C#l 72
3.3.3.1 Strain Distribution 72 3.3.4 Test2C#2 78
3.3.4.1 Strain Distribution 78 3.3.5 Test2C#3 78 3.3.6 Test 2C#4 through Test 2C#7 88 3.3.7 Test Results Summary 89
3.4 Individual Anchor Tests 101
4. ANALYTICAL RESULTS 102
4.1 Static Analysis 103 4.1.1 Double Wall Panel 103 4.1.2 Out of Plane Bending 103 4.1.3 Strut Model 104
4.2 SAP2000 Analysis 108 4.2.1 Triple Wall Panel Assembly 110 4.2.2 Double Wall Panel Assembly 110 4.2.3 SAP2000 Results 111
4.3 Composite Analysis Il l 4.3.1 Composite Analysis Results HI
5. CARBON FIBER CONNECTION DESIGN AND CONSTRUCTION 117
5.1 Design Methodology 117 5.2 Design Example 121 5.3 Construction Considerations 123
5.3.1 Installation Time 124 5.3.2 Material Costs 124
6. CONCLUSIONS 126
6.1 Correlation ofTest Data to Analytical Model 127 6.2 Validity of Design Methodology 129 6.3 Effect of Anchorage 130
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2.3.3.7 Test 2C#6 ................. .................... ........... .......... ... .................. .................... 49 2.3 .3.8 Test 2C#7 .. ..... ........ ..... ........ ........... ............ .. .............................................. 49 2.3.3.9 Resistance Test .................. .. .......... .... ........... ................ ......... ..... ............... 52
2.4 Sensors, Instrumentation and Data Acquisition System .............. .. .................................. .49 2.5 Loading Sequence ... ... ........ ....... .... ............... ...................... .............. ............... .......... ...... .. 53
2.5.1 Triple Wall Panel Assembly .. .................................... .. .......................................... 53 2.5.2 Double Wall Panel Assembly ........................ .. ...................................................... 53 2.5.3 Resistance Tests ..... ... ................. ......... ................ .................................... ............... 53
2.6 Anchor Tests .................................... .... .................................... ........................... .. ... .... ..... 53
3. EXPERIMENTAL RESULTS ...... ...... ....................... .. .............. .. ........ .. .............................. .. .. . 55
3. 1 Resistance Test .................... .............................. ... .... ........... .......... ................................... 55 3.2 Generalized Connection Test Results .. .. .. .. ........................ .. ........................... .. .. .. ............ 55
3.2. 1 Failure Modes ............. ... ... ......... ............................................. .... ......... ...... ............ 55 3.2.2 Generalized Observations ........ .. ..... ....................... ..... ................................... ........ 62
3.3 Individual Connection Test Results ....................... .... .......................... .. .................. .. ....... 72 3.3. 1 Test 3C# I .................... .... ......... ...... ........................................................................ 72 3.3.2 Test 3C#2 ..... ....... ......................... .... ........... ................................ ... .................. ...... 72 3.3.3 Test 2C# I ..................... .. .... ...... ..... ........................ .......... .. .......... .................... ..... .. 72
3.3.3.1 Strain Distribution .............................. .... .. .. ....... .. ...................................... 72 3.3.4 Test 2C#2 .......... .......... ....... ........ ..... ... ............... .......................... ............... ......... ... 78
3.3.4. 1 Strain Distribution ................................... .. .......... .. ........... .... ................... .. 78 3.3.5 Test 2C#3 .. ..... .................................. ................ .. ..... ....... .... .................................... 78 3.3.6 Test 2C#4 through Test 2C#7 .......... .. .................................................................... 88 3.3.7 Test Results Summary ........................................................ ............ ....................... 89
3.4 Individual Anchor Tests .. ........... ................. .. .. .. .. .. ......... .......... ....... .. ......... .... .. ............... 101
4. ANALYTICAL RESULTS ..................................................................................................... 102
4.1 Static Analysis .... .. .. .. ...... ......... .... ....... .......... .... ..... ................ ........................ ............ ..... 103 4. 1.1 Double Wall Panel .................................... .. ................. .. .. .... ........ .............. .......... 103 4. 1.2 Out of Plane Bending .. .. ....................................................................................... 103 4.1.3 Strut Model ............ .... ................................ .... ...................................................... 104
4.2 SAP2000 Analysis ....... ......... .. ............................................................ .................... .. ...... 108 4.2.1 Triple Wall Panel Assembly ........ .. .......... .... ...... .................................................. 11 0 4.2 .2 Double Wall Panel Assembly ... .. .............................. ...... .. .. .... ........ .............. .. .. ... 11 0 4.2.3 SAP2000 Results .. ...... .......... ....... .. ....................................................................... III
4.3 Composite Analysis ... ..... ........ ................. .............. .. ................ ...................................... . 111 4.3.1 Composite Analysis Results .. ...... .. .. .. ................. .... ..... ...... ........ .. ......................... I II
5. CARBON FIBER CONNECTION DESIGN AND CONSTRUCTION ..... .. ......................... 117
5. 1 Design Methodology ..................... .... ................................................... .. ................ ......... 11 7 5.2 Design Example ........ ........... ............ ....................... ................. ......... .............................. 121 5.3 Construction Considerations ...................... ...... ......... ....... ...... ...................... ................. .. 123
5.3.1 Installation Time .................... ... ..................... ............... ....... .... ..... ....................... 124 5.3.2 Material Costs ........................ .... .................... ..................... ........ ......................... 124
6. CONCLUSIONS .............................. ......... .. .. ............................................... ........................... 126
6.1 Correlation of Test Data to Analytical Model.. ........ .. ...... .. ..................................... .. ...... 127 6.2 Validity of Design Methodology ........ .... ................ .. .................... ........... .... ................... 129 6.3 Effect of Anchorage ................... .. ........................ ... .. ...................................................... 130
VII
6.4 Economic Considerations 130 6.5 Final Connection Design 130 6.6 Future Research 130
Appendices
B SAP2000 ANALYSIS 199
C COMPOSITE ANALYSIS 239
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6.4 Economic Considerations .................................... .......... ..... ........ ........ .. ...... .... .............. . 130 6.5 Final Connection Design .................. ........ ..... .... ................ ... ...... ....................... . . ..... 130 6.6 Future Research ... ......... ......................... ...................... .................... ....................... ... 130
Appendices
B SAP2000 ANALYSIS .... ........... ..................... ...... .............. ... ... ......... ..... ........ ............. ............. 199
C COMPOSITE ANALySIS .......... ................ ........ ..... ................. ...... ............................. .. .......... 239
1.4. Direction of fiber layout in CFRP connection 8
1.5. Typical coimection. Note anchors and strain gages 9
1.6. Triple wall panel assembly conceptual setup 11
1.7. Triple wall panel assembly setup 11
1.8. Double wall panel assembly conceptual setup 12
1.9. Double wall panel assembly setup 12
2.1. Typical wall panel cross-section 15
2.2. High pressure waterjet of wall panel 17
2.3. Installed HAS anchor after testing 20
2.4. Cross-section at anchor 21
2.5. Triple wall panel assembly test setup 22
2.6. Pin support for triple wall panel tests 23
2.7. Wall yoke. Shown without front wide flange 23
2.8. Hydro-line 150 kip hydraulic actuator (foreground) 24
2.9. Test 3C#1 left connection 26
2.10. Test 3C#1 right connection 27
2.11. Test3C#l left connection details 28
2.12. Test 3C#1 right connection details 29
2.13. Test 3C#2 connection 30
LIST OF FIGURES
104. Direction of fiber layout in CFRP connection .......... .... .............................................................. 8
l.5 . Typical connection. Note anchors and strain gages ....................... ...... ........ ........ ..................... 9
l.6. Triple wall panel assembly conceptual setup ........................................................................... II
l.7. Triple wall panel assembly setup .......................................................... .... .................. ............. II
1.8. Double wall panel assembly conceptual setup ......................................................................... 12
l.9. Double wall panel assembly setup .......................................................................................... . 12
2. 1. Typical wall panel cross-section ................... .. .......................... .... ............ .... ........................... 15
2.2. High pressure waterjet of wall panel. ............... ........ .................................... .... ........................ 17
2.3 . Installed HAS anchor after testing ....................... .. ....................... ...... ............ .... ..................... 20
204. Cross-section at anchor ............................................................................................................ 21
2.5. Triple wall panel assembly test setup ...................................................................................... 22
2.6. Pin support for triple wall panel tests . ..................................................................................... 23
2.7. Wall yoke. Shown without front wide flange .................................................................... ...... 23
2.8. Hydro-line 150 kip hydraulic actuator (foreground) ................................... ...... ....................... 24
2.9. Test 3C#1 left connection ........................................................................................................ 26
2.10. Test 3C#1 right connection ............................... ........ .................................................. ........... 27
2.11. Test 3C#1 left connection detai ls ........................................................................................... 28
2. 12. Test 3C#1 right connection details .................. ............ ........ .......... ........................................ 29
2.13. Test 3C#2 connection ............................................................................................................. 30
2.14. Test3C#2 connection details 31
2.15. General two wall panel set-up and test 2C#1 DT locations 33
2.16. Double wall panel assembly yoke 34
2.17. Double wall panel assembly yoke and actuator 34
2.18. Double wall panel assemlby supports and threaded rods 35
2.19. Double wall panel assembly support 35
2.20. Test2C#l connection 36
2.21. Test2C#l connection details 37
2.22. Test 2C#2 through 2C#4 connection and displacement transducer layout 38
2.24. Test 2C#2 connection details 41
2.28. Tests 2C#4 and 2C#6 connection details 45
2.29. CEDTs formeasurementof out of plane movement 46
2.30. Test 2C#5 through 2C#7 connection and displacement transducer layout 47
2.32. Test2C#5 connection details 50
2.35. Load sequence for triple wall panel tests 54
3.1. Hysteresis loops for resistance tests 2C#6res. Average value of two kips used 57
3.2. Maximum principal strain versus scan number for middle rosette (test 2C#2) 58
3.3. Backbone curves for triple wall panel tests (per FEMA 273 section 2.13.3) 59
3.4. Backbone curves for double wall panel tests (per FEMA 273 section 2.13.3) 60
3.5. Backbone curve and generalized hysteresis loops at 25, 50, 75 and 100% of total drift (test 2C#6) 61
2.14. Test 3C#2 connection detai ls ........ ... ......... ...... ... ....... ........ ................ ............ ......... ........ .... .... 31
2. 15. General two wall panel set-up and test 2C#1 DT locations ......................................... .......... 33
2. 16. Double wall panel assembly yoke ...... .... ............................... ............. .. .................................. 34
2. 17. Double wall panel assembly yoke and actuator. ......................... .............. ............ ................. 34
2.1 8. Double wall panel assemlby supports and threaded rods ........................... .... ......... ... ............ 35
2. 19. Double wall panel assembly support .... ..... ................ ........ ... ...... ........... ................. ................ 35
2.20. Test 2C#1 connection .... ............ ............. ......... ... ...... .. .......... ... ..... ...... .................................... 36
2.21. Test 2C#1 connection details ........... ..... ........ .. ........ ...................................... .... ..................... 37
2.22. Test 2C#2 through 2C#4 connection and displacement transducer layou!... ........................... 38
2.23. Test 2C#2 connection .. ................ .... ........ ....................... .... ....... ....... ................. .. .. ................. 39
2.24. Test 2C#2 connection details .... .... .. ....... ........................ ... .... ........... ........... ... .............. .. ........ 41
2.25. Test 2C#3 connection .... .... .............. .......................... ..... ....... ............. ... ................................. 42
2.26. Test 2C#3 connection details .............. ............... .. ... ... ................... ... ............. ............... ... .. ..... 43
2.27. Test 2C#4 connection ......... .............. ............. ......... ........... ... .... ... ............ ...... ... ..................... 44
2.28. Tests 2C#4 and 2C#6 connection details ......................... ...... ......... ...... .. ............................... 45
2.29. CEDTs for measurement of out of plane movement. ....... ...... ................................................ 46
2.30. Test 2C#5 through 2C#7 connection and displacement transducer layou!... ..................... ... .. 47
2.31. Test 2C#5 connection ........................................................... ..... .... ....... .... ........ ...... ........ ........ 48
2.32. Test 2C#5 connection details ................................................................................................. 50
2.33. Test 2C#6 connection .......... .................................. ................... ............. ................... ...... ....... . 51
2.34. Test 2C#7 connection details . .......... ....... ................................ .. ............ ................. ..... ........... 52
2.35. Load sequence for niple wall panel tests ............. .. ........................... ............. ..... ................... 54
3.1. Hysteresis loops for resistance tests 2C#6res. Average value of two kips used ..... .... ............. 57
3.2. Maximum principal strain versus scan number for middle rosette (test 2C#2) ........................ 58
3.3 . Backbone curves for niple wall panel tests (per FEMA 273 section 2. 13.3) .......................... 59
3.4. Backbone curves for double wall panel tests (per FEMA 273 section 2.13.3) ..... ... .... ............ 60
3.5 . Backbone curve and generalized hysteresis loops at 25,50, 75 and 100% of total drift (test 2C#6) ..... ... ..... .. ..... .... ........... .. .... ......... ..................... ....... .. ... ....... ............................... ... .................... 61
x
3.6. Concrete pullout after connection shear failure 62
3.7. Shear and interlaminar failure in the concrete and CFRP (test 3C#2) 63
3.8. Concrete shear failure (test 2C#1) 64
3.9. CFRP failure during test 2C#2 66
3.10. CFRP failure and subsequent connection delamination and buckling 67
3.11. Unsymmetrical delamination pattern 68
3.12. Crack termination near anchors due to prestressing of the concrete (test 3C#1) 68
3. 13. Crack growth minimization (test 3C#l) 69
3. 14. Crack growth reduction (test 2C#3) 69
3.15. Delamination patterns at varying loads oftest2C#7 70
3.16. Force versus strain 71
3. 17. Test3C#l hysteresis loops and backbone curve 73
3.18. Development strain distribution for test 3C#1 at varying loads (push direction) 74
3.19. Test 3C#2 hysteresis loops and backbone curve 75
3.20. Concrete shear and CFRP interlaminar failure in test 3C#2 76
3.21. Test2C#l hysteresis loops and backbone curve 77
3.22. CFRP vertical centerline strain distribution at various locations (test 2C#1) 79
3.23. CFRP vertical centerline strain distribution 80
3.24. CFRP vertical strain distribution 81
3. 26. CFRP vertical strain distribution 83
3.30. Development strain distribution for test 2C#1 at varying loads (pull direction) 87
XI
3.6. Concrete pullout after connection shear failure ..................... ...................... ............................. 62
3.7. Shear and interlaminar failure in the concrete and CFRP (test 3C#2) . ..... .. ..... .......... .......... .... 63
3.8. Concrete shear failure (test 2C#I) ........... .. ....... .. ............ ......................................... ...... .... ...... . 64
3.9. CFRP failure during test 2C#2 .... ..... ..... ................................. .... .... .. ..... ............... ... .... ... .......... 66
3.10. CFRP failure and subsequent connection delamination and buckling ............. .. .................... 67
3.11. Unsymmetrical delamination pattern .. ... ... ...... ...... ............ .... ..... .......... ............... ................... 68
3.12. Crack termination near anchors due to prestressing of the concrete (test 3C#I) ................... 68
3.13. Crack growth minimization (test 3C#I) ..... ............... ... ............... .. .... ..... ............................. 69
3. 14. Crack growth reduction (test 2C#3) .... .................................... ... ... ... ........ .......... ............. ..... 69
3.15. Delamination patterns at varying loads of test 2C#7 .. ........ ..... .... ... ... ..... ... .. .. ....... ... ...... ... ..... 70
3.16. Force versus strain ...... ............................. .. .. ........ ......... ...................... ................................... 71
3. 17. Test 3C#1 hysteresis loops and backbone curve ....... .... ....... .. .............................. . .. ......... 73
3.18. Development strain distribution for test 3C#1 at varying loads (push direction) .............. ..... 74
3.19. Test 3C#2 hysteresis loops and backbone curve ........... ........ .... ........ ................. ...... .. ........... . 75
3.20. Concrete shear and CFRP interlaminar fai lure in test 3C#2 ...................... ................ ... ..... .... . 76
3.21. Test 2C#1 hysteresis loops and backbone curve . ........... ... ... ....... ..... ............. .. ..... .......... ... ..... 77
3.22 . CFRP vertical centerline strain distribution at various locations (test 2C#I) ......................... 79
3.23. CFRP vertical centerline strain distribution. .. ........... .. .. ............ ... ..... .... ... ................... . .. . 80
3. 24. CFRP vertical strain distribution ........ ..................... ... .... ..... .. ............... ........... ... ........ .. .... .... 81
3.25. CFRP vertical strain distribution ... .......... .. ................... ... ... ............ ....................................... 82
3.26. CFRP vertical strain distribution .......................................................................... ..... ... .... .... 83
3.27. CFRP vertical strain distribution ..................... ........................................... .. .. .......... .......... ... 84
3.28. CFRP vertical strain distribution ... ..... ....... ........... ....... .... ............ .. ........ ............ .......... ...... ..... 85
3.29. CFRP vertical strain distribution .. ... ..... .......... ........ ......... ...... .. .. ... ....... .. ...... ..... ......... .... ......... 86
3.30. Development strain distribution for test 2C#1 at varying loads (pull direction) ....... .... ... .. .. .. 87
3.31. Test 2C#2 hysteresis loops and backbone curve ......................................... ........... ......... ....... 88
3.32. Test 2C#3 hysteresis loops and backbone curve ..................... ..... ............................ ............. 90
3.33. Test 2C#4 hysteresis loops and backbone curve . ....... ..... ... ...... ....... .. .... ... ...... .... ......... .......... 91
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3.37. Maximum principal strain versus scan number (test 2C#4) 95
3.38. Maximum principal strain angle versus scan number (test 2C#4) 96
3.39. Maximum principal strain versus actuator displacement showing permanent strain deformation (test 2C#7) 97
3.40. Single strain gage strain versus displacement showing permanent strain deformation (gage 1, test2C#7) 98
4.1. Double wall panel assembly load, reactions and forces 103
4.2. Out of plane bending (plan view) 105
4.3. Out of plane moment versus horizontal load for four and five layer CFRP connection 106
4.4. Strut model 107
4.5. Equivalent NLLINK element strips 109
4.6. Analysis 3SAP#1 finite element mesh, link locations, supports and loads 112
4.7. Analysis 2SAP# 1 finite element mesh, link locations, supports and loads 113
4.8. Analysis 2SAP#2 and 2SAP#6 finite element mesh, link locations, supports and loads 113
4.9. Analysis 2SAP#3 and 2SAP#5 finite element mesh, link locations, supports and loads 114
4.10. Analysis 2SAP#4 fmite element mesh, link locations, supports and loads 114
5.1. CFRP composite precast wall connection design methodology flowchart 118
6.1. Final connection design 131
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3.34. Test 2C#5 hysteresis loops and backbone curve ................................................ ................. 92
3.35. Test 2C#6 hysteresis loops and backbone curve ......... . .. .......................................... 93
3.36. Test 2C#7 hysteresis loops and backbone curve ..... ........ . ....... ....... ................. . .. .................. 94
3.37. Maximum principal strain versus scan number (test 2C#4) ................................................... 95
3.38. Maximum principal strain angle versus scan number (test 2C#4) ....................................... 96
3.39. Maximum principal strain versus actuator displacement showing permanent strain deformation (test 2C#7) . .. .......... .... ............. ................................................................................... 97
3.40. Single strain gage strain versus displacement showing permanent strain deformation (gage I, test 2C#7) .... ................................. ................................ .. ... .... ........................................................... 98
3.41. Single strain gage strain versus displacement showing permanent strain deformation (gage 2, test 2C#7) ........................ ......... ... ..... .... ..................................... ....................................................... 99
3.42. Single strain gage strain versus displacement showing permanent strain deformation (gage 3, test 2C#7) .............. .. ..................... ... ... ...... ..................................................................................... 100
4.1. Double wall panel assembly load, reactions and forces ................... .............. ....................... 103
4.2. Out of plane bending (plan view) .... ...................................................................................... 105
4.3. Out of plane moment versus horizontal load for four and five layer CFRP connection .......... 106
4.4. Strut model. .. ......................................................................................................................... 107
4.5. Equivalent NLLINK element strips . .............................. ........................................................ 109
4.6. Analysis 3SAP#1 finite element mesh, link locations, supports and loads ............................ 112
4.7. Analysis 2SAP#1 finite element mesh, link locations, supports and loads ............................ 113
4.8. Analysis 2SAP#2 and 2SAP#6 finite element mesh, link locations, supports and loads ....... 113
4.9. Analysis 2SAP#3 and 2SAP#5 finite element mesh, link locations, supports and loads . ...... 114
4.10. Analysis 2SAP#4 finite element mesh, link locations, supports and loads .......................... 114
5.1. CFRP composite precast wall connection design methodology flowchart ............ ................. 118
6.1. Final connection design ..... ... ....................................... .... ...................................... ................ 131
XII
2.2. Waterjet specifications and observations 18
3.1. Wall panel connection test results 56
3.2. Individual anchor tests results and safety factors 101
4.1. SAP2000 analyses parameters 109
4.2. SAP2000 finite element analysis results 115
4.3. ABD composite analysis parameters 115
4.4. ABD composite analysis summary 116
5.1. CFRP installation time 125
5.2. Material and labor cost summary 125
6.1. Test and analytical results comparison 128
LIST OF TABLES
2.2. Water jet specifications and observations ............................ .................................................... 18
3.1. Wall panel connection test results ............... .. ............................................... .... .... ... ................. 56
3.2. Individual anchor tests results and safety factors ....................................................... ... ......... 101
4.1 . SAP2000 analyses parameters ......... .............. ........................................................................ 109
4.2. SAP2000 finite element analysis results ................... ................................... ......... .... .... .. ....... 115
4.3. ABD composite analysis parameters ............ ........ ..... .... ......................................................... 115
4.4. ABD composite analysis summary ............................... ................................... ........... ........... 116
5.1. CFRP installation time .. ..................................................................... .. ... ........... ........... ......... 125
5.2. Material and labor cost summary ...................................... .................... ...... ... ....................... . 125
6.1. Test and analytical results comparison .............................................. ................... .. .. .... .......... 128
LIST OF ABBREVIATIONS
FRP CFRP GFRP HAS HDPE CEDT DT NLLINK KIP CTE
Fiber Reinforced Plastic Carbon Fiber Reinforced Plastic Glass Fiber Reinforced Plastic Hilti Adhesive Anchor High Density Poly Ethylene Cable Extension Displacement Transducers Displacement Transducer Nonlinear link 1000 pounds Coefficient of thermal expansion
FRP CFRP GFRP HAS HDPE CEDT DT NLLfNK KIP CTE
LIST OF ABBREVIATIONS
Fiber Reinforced Plastic Carbon Fiber Reinforced Plastic Glass Fiber Reinforced Plastic Hilti Adhesive Anchor High Density Poly Ethylene Cable Extension Displacement Transducers Displacement Transducer Nonlinear link 1000 pounds Coefficient of thermal expansion
ACKNOWLEDGMENTS
I want to thank Dr. Chris P. Pantelides and Dr. Lawrence D. Reavely for the countless hours
spent discussing the design and layout of the tests, being present during the tests, finding literature and
giving direction for this thesis.
I particularly want to thank Chandra Clyde and the other students, graduate and undergraduate,
for their help in setting up and testing the specimens.
I additionally want to thank Eagle Precast, Sika Corporation and Hilti for their contributions of
time and materials.
ACKNOWLEDGMENTS
I want to thank Dr. Chris P. Pantelides and Dr. Lawrence D. Reavely for the countless hours
spent discussing the design and layout of the tests, being present during the tests, finding literature and
giving direction for this thesis.
I particularly want to thank Chandra Clyde and the other students, graduate and undergraduate,
for their help in setting up and testing the specimens.
I additionally want to thank Eagle Precast, Sika Corporation and Hilti for their contributions of
time and materials.
INTRODUCTION
As shear walls have gained acceptance (1) in seismic zones, the use of precast wall elements
has increased. During the 1980s, seismic resistance of precast concrete structural systems began to
receive a great deal of attention (2). Due to this interest, code recommendations (3) and design aids in
the form of books (4) and technical papers (5, 6, 7, 8, 9) have been developed for precast walls.
However, limited testing has been done on precast walls and their connections. Many precast wall
connection designs are based solely on theory that does not adequately model the complex interaction
between the concrete and connection material. These connections have been proved to be brittle (10),
and because of their low strength, do not sufficiently absorb earthquake energy. Typical brittle failures
are shown in Figure 1.1 and Figure 1.2. Additionally, steel connectors are subject to extreme levels of
corrosion, as seen in Figure 1.3. This corrosion results in significantly decreased strength. Therefore, a
reliable connection is needed for new and retrofit construction that will absorb earthquake energy and
last the design life of the structure.
Recent developments in the composites industry have brought the use of fiber-reinforced plastics (FRP)
into the construction market. Several advantages associated with the use of FRP composites are:
Light weight (their use does not increase inertial loads).
Resistance to corrosion.
Directional material properties.
CHAPTER I
INTRODUCTION
As shear walls have gained acceptance (I) in seismic zones, the use of precast wall elements
has increased. During the 1980s, seismic resistance of precast concrete structural systems began to
receive a great deal of attention (2). Due to this interest, code recommendations (3) and design aids in
the form of books (4) and technical papers (5, 6, 7, 8, 9) have been developed for precast walls.
However, limited testing has been done on precast walls and their connections. Many precast wall
connection designs are based solely on theory that does not adequately model the complex interaction
between the concrete and connection material. These connections have been proved to be brittle (10),
and because of their low strength, do not sufficiently absorb earthquake energy. Typical brittle failures
are shown in Figure I. I and Figure 1.2. Additionally, steel connectors are subject to extreme levels of
corrosion, as seen in Figure 1.3. This corrosion results in significantly decreased strength. Therefore, a
reliable connection is needed for new and retrofit construction that will absorb earthquake energy and
last the design life of the structure.
Recent developments in the composites industry have brought the use of fiber-reinforced plastics (FRP)
into the construction market. Several advantages associated with the use of FRP composites are:
• Light weight (their use does not increase inertial loads).
• Resistance to corrosion.
• Directional material properties.
• High stiffness to weight ratios.
• Speed and ease of application.
.'_.
" ..... ' ..
of steel connector, Note large concrete
Figure 1.2. Brittle failure of steel connector. Note failure of weld and cracked concrete.
3
Figure 1.3. Corrosion of typical steel connector. Note concrete spalling.
4
Figure 1.3. Corrosion of typical steel connector. Note concrete spalling.
• Low labor skill for installation.
• Ability to conform to irregular surfaces.
• Wet lay-up capabilities.
This research addresses the problems associated with precast concrete connections and has
developed a viable connection for new construction and the retrofit of existing buildings using CFRP
composites.
1.1 Literature Review
Limited testing on precast wall connectors has been carried out. This is particularly true of
carbon fiber reinforced plastic (CFRP) composites.
Vertical shear key connections in precast walls were studied in (11). The research developed
equations to predict the ultimate shear load the joint could withstand. These equations depend on the
strength of the infill concrete, amount of reinforcement in the joint, the shear key area and effects due to
shrinkage and creep.
Horizontal grouted, shear key and prestressed precast wall connections were tested in (12, 13).
Through these tests, the behavior and capacity of horizontal grouted and shear key connections have
been quantified and design recommendations for prestressed connections were proposed.
Hoftieins, et al. (10, 14) conducted tests to quantify the performance and assess the ductile
capabilities of welded loose plate connectors. From this research it was found that the connector
exhibits little ductile capability. Lack of ductility is acceptable when a code based 'R' value of one is
used. However, this is generally not the case in current design practice. Additionally, it was found that
the truss analogy for the design of the embed plates is invalid.
Ten precast wall assemblies with CFRP connections were tested in (15). Variations in lay-up,
shear area and surface preparation were evaluated. The results indicated that the CFRP connection is
feasible. In particular, it was found that:
• The stress distribution in the CFRP composite can be approximated as linear, going from the
vertical centerline to the vertical edge of the connection.
• Low labor skill for installation,
• Ability to conform to irregular surfaces,
• Wet lay-up capabilities,
This research addresses the problems associated with precast concrete connections and has
developed a viable connection for new construction and the retrofit of existing buildings using CFRP
composites,
I, I Literature Review
Limited testing on precast wall connectors has been carried out. This is particularly true of
carbon fiber reinforced plastic (CFRP) composites,
5
Vertical shear key connections in precast walls were studied in (II), The research developed
equations to predict the ultimate shear load the joint could withstand, These equations depend on the
strength of the infill concrete, amount of reinforcement in the joint, the shear key area and effects due to
shrinkage and creep,
Horizontal grouted, shear key and prestressed precast wall connections were tested in (12, 13),
Through these tests, the behavior and capacity of horizontal grouted and shear key connections have
been quantified and design recommendations for prestressed connections were proposed,
Hofheins, et aL (10, 14) conducted tests to quantify the performance and assess tbe ductile
capabilities of welded loose plate connectors, From this research it was found tbat the connector
exhibits little ductile capability, Lack of ductility is acceptable when a code based 'R' value of one is
used, However, this is generally not the case in current design practice, Additionally, it was found that
the truss analogy for tbe design of the embed plates is invalid,
Ten precast wall assemblies witb CFRP connections were tested in (IS), Variations in lay-up,
shear area and surface preparation were evaluated, Tbe results indicated tbat the CFRP connection is
feasible, In particular, it was found tbat:
• The stress distribution in tbe CFRP composite can be approximated as linear, going from tbe
vertical centerline to the vertical edge of the connection,
• The development length of the CFRP depends upon the geometry and stiffness of the
connection.
• Surface preparation of the connection significantly influences the connection performance.
An equation for effective bond development length is presented in (16). It was derived using
fracture mechanics and depends upon the maximum tensile strain (cn) in the carbon, fiber direction
modulus (Ell), composite total thickness and peel-off shear strength of the concrete (fctk,s).
In addition to research done on structural subsystems, experimental investigations have been
carried out on individual connection components. The peel-off strength of FRP composites from
concrete has been investigated by numerous authors (17, 18, 19, 20, 21, 22).
Chajes et al. (21) investigated the bond strength between FRP composites and concrete. They
considered such parameters as surface preparation, adhesive type and concrete strength. From their
experimentation, the following were determined:
• Surface preparation is paramount in achieving high bond strength.
• The value of concrete shear is proportional to ^ /^ .
• The strain distribution in the composite varies linearly along the bond length.
• After a certain development length, no increase in failure load can be achieved.
Bizindavyi et al. (22) investigated the bond length of composite-to-concrete bonded joints.
They tested 20 glass fiber reinforced plastic (GFRP) and 12 CFRP composite specimens bonded to
concrete blocks. The concrete block was fixed and an axial load was applied to the FRP monotonically
to failure. From these experiments the research concluded that a bilinear relationship exists for the
transfer length. After the cracking load, defined as the load at which the concrete or adhesive begins to
crack, the development length increases by a linearly increasing fiinction. They also derived an
expression for the development length of the FRP-to-concrete joint. This equation is based on the
maximum applied load and resultant shear stress, composite width and an experimental load level crack
initiation parameter.
• The development length of the CFRP depends upon the geometry and stiffness of the
connection.
• Surface preparation of the connection significantly influences the connection performance.
An equation for effective bond development length is presented in (16). It was derived using
fracture mechanics and depends upon the maximum tensile strain (e, ,) in the carbon, fiber direction
modulus (Ell) ' composite total thickness and peel-off shear strength of the concrete (f,~.,).
In addition to research done on structural subsystems, experimental investigations have been
carried out on individual connection components. The peel-off strength of FRP composites from
concrete has been investigated by numerous authors (17, 18, 19,20,21,22).
6
Chajes et al. (2 1) investigated the bond strength between FRP composites and concrete. They
considered such parameters as surface preparation, adhesive type and concrete strength. From their
experimentation, the following were determined :
• Surface preparation is paramount in achieving high bond strength.
• The value of concrete shear is proportional to .J1. . • The strain distribution in the composite varies linearly along the bond length.
• After a certain development length, no increase in failure load can be achieved.
Bizindavyi et al. (22) investigated the bond length of composite-to-concrete bonded joints.
They tested 20 glass fiber reinforced plastic (GFRP) and 12 CFRP composite specimens bonded to
concrete blocks. The concrete block was fixed and an axial load was applied to the FRP monotonically
to failure. From these experiments the research concluded that a bilinear relationship exists for the
transfer length. After the cracking load, defined as the load at which the concrete or adhesive begins to
crack, the development length increases by a linearly increasing function. They also derived an
expression for the development length of the FRP-to-concrete joint. This equation is based on the
maximum applied load and resultant shear stress, composite width and an experimental load level crack
initiation parameter.
ACI Committee 355 has developed guidelines for the use of anchors in concrete. The
Committees' state-of-the-art report on anchorage to concrete (23) gives design guidelines for shear and
tensile loading of anchors. It also discusses practical issues found in construction.
1.2 Objectives and Scope of Research
The objectives of this research are to:
• Develop a viable FRP composite connection for use in new and retrofit construction of precast
shear walls.
• Develop a design methodology for the FRP composite connection.
• Investigate the use of anchors to prolong delamination of the FRP from the concrete surface.
This research is primarily concerned with the FRP composite connection of in-plane precast
panel elements. The coimection is valid for both shear wall and horizontal diaphragm construction.
This thesis does not fully investigate the effect of different concrete compressive strengths or anchor
spacing.
1.3 Test Overview
Nine tests were carried out in the Structures Laboratory at the University of Utah. Two tests
were done on a three-panel shear wall assembly, and seven tests were done on a two-panel shear wall
assembly. Different connection sizes, FRP lay-ups, anchor bolt locations and FRP composite
connection locations were investigated. These different parameters are summarized in Table 1.1. A
conceptual CFRP fiber layout and a typical connection are shown in Figure 1.4 and Figure 1.5,
respectively.
Each test was instrumented with a variety of uniaxial, rectangular rosette and delta rosette
strain gages. Additionally, Celesco cable extension displacement transducers (CEDT or DT) were
placed at strategic locations to measure wall panel displacements. A Houston Scientific load cell was
used to measure the applied force.
7
ACI Committee 355 has developed guidelines for the use of anchors in concrete. The
Committees' state-of-the-art report on anchorage to concrete (23) gives design guidelines for shear and
tensile loading of anchors. It also discusses practical issues found in construction.
1.2 Objectives and Scope of Research
The objectives of this research are to:
• Develop a viable FRP composite connection for use in new and retrofit construction of precast
shear walls.
• Develop a design methodology for the FRP composite connection.
• Investigate the use of anchors to prolong delamination of the FRP from the concrete surface.
This research is primarily concerned with the FRP composite connection of in-plane precast
panel elements. The connection is valid for both shear wall and horizontal diaphragm construction.
This thesis does not fully investigate the effect of different concrete compressive strengths or anchor
spacing.
1.3 Test Overview
Nine tests were carried out in the Structures Laboratory at the University of Utah. Two tests
were done on a three-panel shear wall assembly, and seven tests were done on a two-panel shear wall
assembly. Different connection sizes, FRP lay-ups, anchor bolt locations and FRP composite
connection locations were investigated. These different parameters are summarized in Table I I. A
conceptual CFRP fiber layout and a typical connection are shown in Figure 1.4 and Figure 1.5,
respectively.
Each test was instrumented with a variety of uniaxial , rectangular rosette and delta rosette
strain gages. Additionally, Celesco cable extension displacement transducers (CEDT or DT) were
placed at strategic locations to measure wall panel displacements. A Houston Scientific load cell was
used to measure the applied force.
Table 1.1. Test No.
3C#1 3C#2 2C#1 2C#2 2C#3 2C#4 2C#5 2C#6 2C#7
Test overview Connection
Large Large Large Small Small Small Small Small Small
Shear Area** (sq. in.) 434.8 434.8 434.8 210 210 210 210 210 210
Number Layers
Joint Location
Number Anchors
Support Damage
Total None
* Large=24"widex37"tall, Small=18"widex24" tall. ** peel-off shear area=(connection width-gap between walls)/2 x connection depth *** High=High-pressure waterjet. Split=Half high and half low pressure waterjet.
HORIZ. LAYER FOR TEST 2C#4 TO 2C#7 ONLY
Figure 1.4. Direction of fiber layout in CFRP connection
Table 1.1. Test overview. Test Connection Number Joint Surface Number Support No. Size' Shear Layers Location Prep.*** Anchors Damage
Area** Used [sg. in.l
3C#1 Large 434.8 Four Middle Full Four Total 3C#2 Large 434.8 Four Middle Full None None 2C#1 Large 434.8 Four Middle Full Six Substantial 2C#2 Small 210 Four Middle Full Four None 2C#3 Small 210 Four T02 S2lit Four None 2C#4 Small 210 Five Bottom S21it Four None 2C#5 Small 210 Five T02 S21it Four None 2C#6 Small 210 Five Middle Full Four None 2C#7 Small 210 Five Bottom Selit Four None
• Large=24"widex37"tall. Small=I 8"widex24" tall. •• peel-off shear area=(connection width-gap between walls)12 x connection depth ••• High=High-pressure water jet. Split=Half high and half low pressure water jet.
HORIZ. LAYER FOR TEST 2C#4 TO 2C#7 ONLY
Figure 1.4. Direction of fiber layout in CFRP connection
8
9
10
Each test has a particular number that corresponds to different parameters. The first number
corresponds to the number of wall panels in the assembly. The letter represents the connection material
used. This is always ' C for this thesis, although other tests were done with steel imbeds. The last
number, after the pound sign, is the test sequence number. For the triple panel assemblies the highest
number corresponds to the first test done. But for the double panel assemblies the lowest number
corresponds to the first test done. For example, test 2C#3, was done on a double wall panel assembly
with a carbon connection. It was the third test done on the double wall panel assemblies.
The triple and double wall panel assemblies were tested in the fall of 1998 and fall of 1999,
respectively. Extensive notes can be found in the lab notebook for these tests (24). Raw data files from
these tests are currently stored at the University of Utah, Center for Composites in Construction (25).
1.3.1 Triple Wall Panel Assemblv
Two tests were performed on the triple wall panel assemblies as seen conceptually and
photographically in Figure 1.6 and T Figure 1.7, respectively. Large connections were used on these
tests and they were identical except that no anchor bolts were used for test 3C#2. The fiber orientation
used in the connection is shown conceptually in Figure 1.4.
1.3.2 Double Wall Panel Assemblv
A total of seven tests were conducted using the double wall panel assembly shown in Figure
1.8 and Figure 1.9. One large and six small connections were tested.
Because the concrete support on one side of the wall assembly failed prematurely during test
2C#1, the remaining supports were retrofitted with grout and CFRP. No damage occurred to the
retrofitted supports.
Static, finite element and composite analyses were conducted using hand calculations and
various computer programs. These models were derive fi-om Figure 1.6 and Figure 1.8. The static
analysis was only done for the double wall panel assembly. However, because it was only determinate
n the vertical direction, just the vertical shear component was determined. This is due to the presence
10
Each test has a particular number that corresponds to different parameters. The first number
corresponds to the number of wall panels in the assembly. The letter represents the connection material
used. This is always 'C' for this thesis, although other tests were done with steel imbeds. The last
number, after the pound sign, is the test sequence number. For the triple panel assemblies the highest
number corresponds to the first test done. But for the double panel assemblies the lowest number
corresponds to the first test done. For example, test 2C#3, was done on a double wall panel assembly
with a carbon connection. It was the third test done on the double wall panel assemblies.
The triple and double wall panel assemblies were tested in the fall of 1998 and fall of 1999.
respectively. Extensive notes can be found in the lab notebook for these tests (24). Raw data files from
these tests are currently stored at the University of Utah. Center for Composites in Construction (25).
1.3.1 Triple Wall Panel Assembly
Two tests were performed on the triple wall panel assemblies as seen conceptually and
photographically in Figure 1.6 and I' Figure I. 7, respectively. Large connections were used on these
tests and they were identical except that no anchor bolts were used for test 3C#2. The fiber orientation
used in the connection is shown conceptually in Figure 1.4.
1.3.2 Double Wall Panel Assembly
A total of seven tests were conducted using the double wall panel assembly shown in Figure
1.8 and Figure 1.9. One large and six small connections were tested.
Because the concrete support on one side of the wall assembly failed prematurely during test
2C#I, the remaining supports were retrofitted with grout and CFRP. No damage occurred to the
retrofitred supports.
Static, finite element and composite analyses were conducted using hand calculations and
various computer programs. These models were derive from Figure 1.6 and Figure 1.8. The static
analysis was only done for the double wall panel assembly. However, because it was only determinate
n the vertical direction, just the vertical shear component was determined. This is due to the presence
11
^
r £i^ l::^ il i i Figure 1.6. Triple wall panel assembly conceptual setup.
Figure 1.7. Triple wall panel assembly setup.
II
12
Figure 1.9. Double wall panel assembly setup.
12
n: ~
13
are given in Chapter 2). The shim shares the horizontal load with the composite connection. To
quantify the load path, a finite element analysis was carried out using SAP 2000 (26). The triple panel
assembly is statically indeterminate and necessitated the use of a finite element model to determine the
forces on the composite connection and support reactions. Composite analyses were executed using the
composite analysis program ABD (27). ABD calculates fiber du-ection strain and stress using material
property, layup and loading inputs and matrix algebra. Details and results for each of these analyses
can be found in Chapter 4 in their respective sections.
13
are given in Chapter 2). The shim shares the horizontal load with the composite connection. To
quantify the load path, a finite element analysis was carried out using SAP 2000 (26). The triple panel
assembly is statically indeterminate and necessitated the use of a finite element model to determine the
forces on the composite connection and support reactions. Composite analyses were executed using the
composite analysis program ABD (27). ABD calculates fiber direction strain and stress using material
property, layup and loading inputs and matrix algebra. Details and results for each of these analyses
can be found in Chapter 4 in their respective sections.
CHAPTER2
2.1 Hollow-Core Wall Panel Description
Monroe, Inc. (now Eagle Precast) in North Salt Lake City, Utah manufactured the precast wall
panels. The panels for the triple wall panel assembly were continuously poured on a bed eight feet
wide. They were prestressed parallel to the bed and smooth reinforcing steel was placed perpendicular
to the bed, approximately every three feet, at the top and bottom of the pour. After the bottom two
inches were placed, pouring gravel simultaneously with the top layer created hollow cores.
After curing, the continuous panel was cut in half and in lengths twelve feet long, parallel and
perpendicular to the bed, respectively. This resulted in panels that were four feet wide and twelve feet
long. A typical cross section of the panels is shown in Figure 2. 1.
Panels for the double wall assembly were salvaged from the triple wall tests by cutting off the
crushed concrete ends. Crushing occurred at the supports during testing. This resulted in panels, four
feet wide and eight and one half feet long. Enough panels were salvaged to make three sets of double
wall assemblies. Test 2C#1 was done on the first set. Tests 2C#2 through 2C#4 were done on the
second set. Tests 2C#5 through 2C#7 were done on the third set. The smaller connection size on the
last six tests allowed three tests to be carried out on a single set of panels.
2.2 CFRP Connection
The carbon fiber used was Zoltek, PANEX33-0048 48K unidirectional fabric. The matrix was
Shell 826 Epon resin and Shell 3379 Epicure hardener. Sikadur 31 Hi-Mod Gel was the adhesive used
to bond the saturated fiber to the wall.
CHAPTER 2
TEST SETUP
2.1 Hollow-Core Wall Panel Description
Monroc, Inc . (now Eagle Precast) in North Salt Lake City, Utah manufactured the precast wall
panels. The panels for the triple wall panel assembly were continuously poured on a bed eight feet
wide. They were prestressed parallel to the bed and smooth reinforcing steel was placed perpendicular
to the bed, approximately every three feet, at the top and bottom of the pour. After the bottom two
inches were placed, pouring gravel simultaneously with the top layer created hollow cores.
After curing, the continuous panel was cut in half and in lengths twelve feet long, parallel and
perpendicular to the bed, respectively. This resulted in panels that were four feet wide and twelve feet
long. A typical cross section of the panels is shown in Figure 2. 1.
Panels for the double wall assembly were salvaged from the triple wall tests by cutting off the
crushed concrete ends. Crushing occurred at the supports during testing. This resulted in panels, four
feet wide and eight and one half feet long. Enough panels were salvaged to make three sets of double
wall assemblies. Test 2C#1 was done on the first set. Tests 2C#2 through 2C#4 were done on the
second set. Tests 2C#5 through 2C#7 were done on the third set. The smaller connection size on the
last six tests allowed three tests to be carried out on a single set of panels.
2.2 CFRP Connection
The carbon fiber used was Zoltek, PANEX33-0048 48K unidirectional fabric . The matrix was
Shell 826 Epon resin and Shell 3379 Epicure hardener. Sikadur 31 Hi-Mod Gel was the adhesive used
to bond the saturated fiber to the wall.
15
y 4"
2.2.1 Material Properties
2.2.1.1 Composite
The CFRP matrix was combined at a ratio of 2:1 resin to hardener by weight.' It was then
mixed thoroughly by a paint paddle mounted on a drill press at a speed slow enough to minimize air
entrainment.
Tensile coupons of the CFRP were made per ASTM D3039.(28). Dr. Dan Adams of the
Mechanical Engineering Department at the University of Utah tested the coupons. From these tests the
fiber direction modulus (En) was determined. From this information and previous test results on the
same material (from ref 29), E22, G12 and Vn were determined. E22, G12 were scaled by the ratio of the
new and old modulus of elasticity. These values are summarized in Table 2.1.
' Themanufacturer recommends a mixing ratio of 2.5:1 by weight resin to hardener. The ratio of 2:1 was used by error, but kept constant for all connection tests and tensile coupons.
1'-,"± (TYP)
l' 42 " -16
:CXl_L..-_ L=-J-==H=O=LL:::;O;:W=t-)_O -+~ =H=O=L=L=O=W'j.)/.)~o~=:;~=+~o+-_(!)+- HIGH STRENGTH~ ~ ,~q
: N
CONCRETE 4" <-Y2¢ PRE-STRESS f' c= 7800 PSI STRAND (TYP)
LOCA nONS APPROXIMATE
2.2 .1 Material Properties
2.2.1.1 Composite
The CFRP matrix was combined at a ratio of 2: I resin to hardener by weight.' It was then
mixed thoroughly by a paint paddle mounted on a drill press at a speed slow enough to minimize air
entrainment.
Tensile coupons of the CFRP were made per ASTM 03039.(28). Dr. Dan Adams of the
15
Mechanical Engineering Department at the University of Utah tested the coupons. From these tests the
fiber direction modulus (E,,) was determined. From this information and previous test results on the
same material (from ref29), E", 0" and v" were determined. E22, 0" were scaled by the ratio of the
new and old modulus of elasticity. These values are summarized in Table 2.1.
'The manufacturer recommends a mixing ratio of2.5:1 by weight resin to hardener. The ratio of2:1 was used by error, but kept constant for all connection tests and tensile coupons.
16
2.2.1.2 Adhesive
The Sikadur 31 was combined at a ratio of 2:1 A to B by volume. It was then mixed with a
paint paddle.
2.2.1.3 Anchors
Hilti adhesive anchors were used to prestress the concrete, thereby prolonging delamination of
the CFRP from the concrete surface. Each anchor consisted of the following components:
• One Hilti adhesive anchor (HAS) 3/8"x5 1/8" long Hilti threaded rod insert.
• One HVU M10x90 Hilti epoxy insert.
• One 2" square x 1/8" thick Garlock high durometer, polyester scrim, neoprene washer with a
1/2" diameter hole in the center.
• 3/8"x2" diameter x 1/8" thick fender washers. One for Tests 3C#1 and 2C#1. Two for Tests
2C#2 through 2C#7.
• One 3/8" flat washer.
2.2.2 Concrete Surface Preparation
The concrete surface to which the CFRP connection was bonded was washed with a waterjet.
Two types of water jet were used: high pressure and low pressure. The high-pressure waterjet, shown
in Figure 2. 1, was done on all of the specimens. However, only half of the connection area for tests
2C#3, 2C#4, 2C#5 and 2C#7 were washed with the high-pressure waterjet. The other half was washed
with the low-pressure waterjet. Pressures and flow rates are shown in Table 2.2 for both the high and
low-pressure water jets. The high-pressure waterjet was done by Waterpoint. The low-pressure water
jet was done in the lab with the Equalizer 5300 pressure washer.
2.2.3 Composite Installation Procedure
Students in the Center for Composites in Construction installed the composite. Required time
for each procedure can be found in section 5.3.1. The following steps outline the actual procedure used:
16
2.2.1.2 Adhesive
The Sikadur 31 was combined at a ratio of2: I A to B by volume. It was then mixed with a
paint paddle.
2.2.1.3 Anchors
Hilti adhesive anchors were used to prestress the concrete, thereby prolonging delamination of
the CFRP from the concrete surface. Each anchor consisted of the following components:
• One Hilti adhesive anchor (HAS) 3/S"x5 liS" long Hilti threaded rod insert.
• One HVU MIOx90 Hilti epoxy insert.
• One 2" square x liS" thick Garlock high durometer, polyester scrim, neoprene washer with a
W' diameter hole in the center.
• 3/S"x2" diameter x liS" thick fender washers. One for Tests 3C#1 and 2C#I. Two for Tests
2C#2 through 2C#7.
• One 3/S" flat washer.
2.2.2 Concrete Surface Preparation
The concrete surface to which the CFRP connection was bonded was washed with a water jet.
Two types of water jet were used: high pressure and low pressure. The high-pressure water jet, shown
in Figure 2. I, was done on all of the specimens. However, only half of the connection area for tests
2C#3, 2C#4, 2C#5 and 2C#7 were washed with the high-pressure water jet. The other half was washed
with the low-pressure water jet. Pressures and flow rates are shown in Table 2.2 for both the high and
low-pressure water jets. The high-pressure water jet was done by Waterpoint. The low-pressure water
jet was done in the lab with the Equalizer 5300 pressure washer.
2.2.3 Composite Installation Procedure
Students in the Center for Composites in Construction installed the composite. Required time
for each procedure can be found in section 5.3.1. The following steps outline the actual procedure used:
17
0.36 * Data from new tensile coupons. ** Data fi-om ref (29).
Figure 2.2. High pressure waterjet of wall panel.
17
NEW' OLD" USED
. - .- -. ; .
Table 2.2. Water jet specifications and observations. Pressure Flow Rate Observations
i£si} (GPM) HIGH 40,000 8 Completely removed surface paste. Fine aggregate
visible. LOW 2,000* 5 Removed half of the paste. Surface rough, but no
aggregate visible. * The pressure gage shows 3000psi without any flow, but drops to 2000 psi with flow.
1) Clean off any accumulated dirt or dust after water jetting.
2) Cut the carbon fiber sheets to the proper size.
3) Mark the connection location on the specimen.
4) Place Styrofoam between the wall panels to prevent the CFRP from being pushed into the
gap-
5) Mix the Shell 826 Epon resin with the Shell 3379 Epicure hardener.
6) Thoroughly saturate the carbon fiber.
7) Mix the Sikadur 31 parts 'A' and 'B'.
8) Apply the Sikadur 31 onto the connection area approximately 2" past the edge where the
CFRP will be applied. Only a very thin layer (one molecule thick) is necessary.
9) Place the saturated carbon sheets in the correct orientation on the connection area.
Note! When placing the saturated sheets on vertical surfaces care must be taken to let the
epoxy become tacky enough so the saturated sheets do not slide down. This is why the sheets
are saturated before the Sikadur 31 is applied.
These steps should be modified as needed depending on the hardening time of the epoxies
used.
2.2.4 Anchor Installation Procedure
After the CFRP was cured, the anchors were installed. Each anchor was installed following
the documentation provided by Hilti in each epoxy insert box. The following steps outline the
installation procedure used:
2) Drill a 15/32" diameter hole to the proper depth.
Table 2.2. Water jet specifications and observations.
HIGH
LOW
40,000 8
2,000' 5
Completely removed surface paste. Fine aggregate visible. Removed half of the paste. Surface rough, but no aggregate visible .
• The pressure gage shows 3000psi without any flow, but drops to 2000 psi with flow.
I) Clean off any accumulated dirt or dust after water jetting.
2) Cut the carbon fiber sheets to the proper size.
3) Mark the connection location on the specimen.
18
4) Place Styrofoam between the wall panels to prevent the CFRP from being pushed into the
gap.
5) Mix the Shell 826 Epon resin with the Shell 3379 Epicure hardener.
6) Thoroughly saturate the carbon fiber.
7) Mix the Sikadur 31 parts 'A' and 'B' .
8) Apply the Sikadur 31 onto the connection area approximately 2" past the edge where the
CFRP will be applied. Only a very thin layer (one molecule thick) is necessary.
9) Place the saturated carbon sheets in the correct orientation on the connection area.
Note! When placing the saturated sheets on vertical surfaces care must be taken to let the
epoxy become tacky enough so the saturated sheets do not slide down. This is why the sheets
are saturated before the Sikadur 31 is applied.
These steps should be modified as needed depending on the hardening time of the epoxies
used.
2.2.4 Anchor Installation Procedure
After the CFRP was cured, the anchors were installed. Each anchor was installed following
the documentation provided by Hilti in each epoxy insert box. The following steps outline the
installation procedure used:
2) Drill a 15/32" diameter hole to the proper depth.
19
4) Insert the HVU epoxy insert into the hole.
5) Slowly screw the threaded rod into the hole until fully inserted into the hole.
After the epoxy insert had cured, the neoprene washer, fender washers, flat washer and nut
were installed. The nut was tightened until the washers were seated and flattened. Finally, the nut was
backed off, then turned one full rotation from the finger tight position. A photograph of the installed
anchor is shown in Figure 2.3. Figure 2.4 shows a cross sectional view of the installed anchor.
2.3 Specimen Installation and Instrumentation Layout
2.3.1 Fixture Material Properties
The fixture consisted of A36 steel structural shapes, a mixture of A325 and A490 high strength
bolts and high-density polyethylene (HDPE) shim plates. The shim plates were generally eight inches
square, varied in thickness from 1/8 to V", and had a compressive yield strength and elastic modulus of
69,650 psi and 155,900 psi, respectively. They were placed between any steel and concrete interfaces
to reduce localized concrete crushing.
2.3.2 Triple Wall Panel Assemblv
The triple wall panel assemblies were tested in the load frame using one, 150 kip, Hydro-Line
actuator. Various displacements were measured using cable extension displacement transducers
(CEDT). Strain on the CFRP was measured at various locations by uniaxial and rosette strain gages.
The following sections flirther describe the details of each test.
2.3.2.1 Fixture Layout
The fixture used for these tests was constructed for similar tests done during 1997 in the
Structures Laboratory. The general test setup is shown conceptually and photographically in Figure 1.6
and 1 Figure 1.7, respectively. Figure 2.5 shows the support layout in detail and the locations of the
CEDTs and connections. Photographs of the pin support, yoke and actuator can be seen in Figure 2.6 to
Figure 2.8. Further details of the test assembly are available in theses written by Hofheins (14) and
See Hilti documentation for temperature dependent cure times.
19
4) Insert the HVU epoxy insert into the hole.
5) Slowly screw the threaded rod into the hole until fully inserted into the hole.
After the epoxy insert had cured,' the neoprene washer, fender washers, flat washer and nut
were installed. The nut was tightened until the washers were seated and flattened. Finally, the nut was
backed off, then turned one full rotation from the finger tight position. A photograph of the installed
anchor is shown in Figure 2.3. Figure 2.4 shows a cross sectional view of the installed anchor.
2.3 Specimen Installation and Instrumentation Layout
2.3.1 Fixture Material Properties
The fixture consisted of A36 steel structural shapes, a mixture of A325 and A490 high strength
bolts and high-density polyethylene (HOPE) shim plates. The shim plates were generally eight inches
square, varied in thickness from 1/8 to y,", and had a compressive yield strength and elastic modulus of
69,650 psi and 155,900 psi, respectively. They were placed between any steel and concrete interfaces
to reduce localized concrete crushing.
2.3.2 Triple Wall Panel Assembly
The triple wall panel assemblies were tested in the load frame using one, 150 kip, Hydro-Line
(CEDT). Strain on the CFRP was measured at various locations by uniaxial and rosette strain gages.
The following sections further describe the details of each test.
The fixture used for these tests was constructed for similar tests done during 1997 in the
Structures Laboratory. The general test setup is shown conceptually and photographically in Figure 1.6
and I Figure 1.7, respectively. Figure 2.5 shows the support layout in detail and the locations of the
CEDTs and connections. Photographs of the pin support, yoke and actuator can be seen in Figure 2.6 to
Figure 2.8. Further details of the test assembly are available in theses written by Hofheins (14) and
, See Hilti documentation for temperature dependent cure times.
20
20
FRP COMPOSITE
^/e" 0 NUT
3/8x2x1/8 THICK FENDER WASHER (1) FOR TESTS 3C#1 THROUGH 2C#1 (2) FOR TESTS 2C#2 THROUGH 2C#7
2" SQ GARLOCK HIGH DURO NEOPRENE PAD
Figure 2.4. Cross-section at anchor.
8"
3/8x5V8 HAS HIL TI ANCHOR w / HVU M10x90 EPOXY INSERT
FRP COMPOSITE
3/8" ~ NUT
3/8X2x V8 THICK FENDER WASHER (1) FOR TESTS 3C#1 THROUGH 2C#1 (2) FOR TESTS 2C#2 THROUGH 2C#7
2" SO GARLOCK HIGH DURO NEOPRENE PAD
Figure 2.4. Cross-section at anchor.
22
... .J
L _
23
24
Figure 2.9. Hydro-line 150 kip hydraulic actuator (foreground). Figure 2.9. Hydro-line 150 kip hydraulic actuator (foreground).
\ \ \ i \ \
24
25
Volnyy (15). Note that the support conditions change depending on load direction (see Figure 1.6). For
example, when the assembly is being moved to the right, the steel plate at the left of the middle panel
does not touch the concrete, and vice-versa when moved to the left.
2.3.2.2 Test3C#l
The CFRP layup for the connection consisted of two layers in the plus and minus 45°
directions. Each layer was 0.074" thick, resulting in a total thickness of 0.30". Photographs and details
of the CFRP connections are shown in Figure 2.9 through Figure 2.12.
Test 3C#1 was the first test to use anchors to prolong the de-bonding failure of the CFRP from
the concrete. A total of four HAS anchors were placed near the edge of the wall panels as shown in
Figure 2.11 and Figure 2.12. Strain gages, as seen in these figures, were strategically placed to
investigate the strain variation in the CFRP near the anchors.
To prolong support failure the outside, bottom comers of the panels were retrofitted with
CFRP. Details of this retrofit can be found in the test laboratory book (24).
The CFRP size and layup and the location for the supports, CEDTs and connections were the
same as in test 3C#1 (see Figure 2.5). However, no anchors were used on test 3C#2. A connection
photograph and details are shown in Figure 2.13 and Figure 2.14, respectively.
2.3.2.4 Resistance Test
One resistance test, 3S#3RES, was done on the triple wall panel assembly to quantify the
system resistance. The test was carried out with the wall panels in place. Before the resistance test was
done, the yoke was well greased. The resistance value from this test applies to all triple wall panel tests
. The double wall panel assemblies were tested in the load frame using one, 150 kip Hydro-line
(CEDT). These displacement measurement locations are not the same for all of the double wall tests.
Strain gages measured micro displacements of the CFRP at various locations. The following sections
flirther describe the details of each test.
25
Volnyy (15). Note that the support conditions change depending on load direction (see Figure 1.6). For
example, when the assembly is being moved to the right, the steel plate at the left of the middle panel
does not touch the concrete, and vice-versa when moved to the left.
2.3.2.2 Test 3C#1
The CFRP layup for the connection consisted of two layers in the plus and minus 45°
directions. Each layer was 0.074" thick, resulting in a total thickness of 0.30". Photographs and details
of the CFRP connections are shown in Figure 2.9 through Figure 2.12.
Test 3C# I was the first test to use anchors to prolong the de-bonding failure of the CFRP from
the concrete. A total of four HAS anchors were placed near the edge of the wall panels as shown in
Figure 2.11 and Figure 2.12. Strain gages, as seen in these figures, were strategically placed to
investigate the strain variation in the CFRP near the anchors.
To prolong support failure the outside, bottom corners of the panels were retrofitted with
CFRP. Details of this retrofit can be found in the test laboratory book (24).
The CFRP size and layup and the location for the supports, CEDTs and connections were the
same as in test 3C#1 (see Figure 2.5). However, no anchors were used on test 3C#2. A connection
photograph and details are shown in Figure 2.13 and Figure 2.14, respectively.
2.3.2.4 Resistance Test
One resistance test, 3S#3RES, was done on the triple wall panel assembly to quantify the
system resistance. The test was carried out with the wall panels in place. Before the resistance test was
done, the yoke was well greased. The resistance value from this test applies to all triple wall panel tests
. The double wall panel assemblies were tested in the load frame using one, 150 kip Hydro-line
(CEDT). These displacement measurement locations are not the same for all of the double wall tests.
Strain gages measured micro displacements of the CFRP at various locations. The following sections
further describe the details of each test.
26
'-'"^m&
A
,\
/\ ,'" --~' ,
27
^8x51/8 HAS (TYP 4 PLC) WASHERS NOT SHOWN FOR CLARITY
T l
• CD
"., .. I
7'8x51,te HAS (TYP 4 PLC) WASHERS NOT SHOWN FOR CLARITY
II II II I
28
29
00
^ 8 X 5 V B HAS (TYP 4 PLC) WASHERS NOT SHOWN FOR CLARITY
RECTANGULAR ROSETTE CEA-06-125WT-120
SINGLE STRAIN GAGE EA-06-125BZ-350
Figure 2.12. Test 3C#1 right connection details. 2.3.2.3 Test 3C#2
• CSl ~
• ~ I
• III
7'8x51j8 HAS ~II (TYP 4 PLC) WASHERS NOT SHOWN FOR CLARITY
II I
SINGLE STRAIN GAGE EA-06-1258Z-350
Figure 2.12. Test 3C#1 right connection details. 2.3.2.3 Test 3C#2
29
30
30
31
TrPICAL FOR RIGHT AND LEFT CONNECnONS FOR TEST 3C#2 (U.N.)
RECTANGULAR ROSETTE CEA-06-125WT-120
• ~ I -,..,
TYPICAL FOR RIGHT AND LEFT CONNECTIONS FOR TEST 3CH2 (U.N.)
at
I
1/
31
32
The fixture layout for the double wall panel tests is shown in Figure 2.15. Photographic details
of the fixtures are shown in Figure 2.16 through Figure 2.19. This semp is the same for all the double
wall panel tests.
2.3.3.2 Test2C#l
The CFRP for test 2C#1 was 24" wide by 37" tall and can be seen in Figure 2.20. The layup
consisted of two layers each in the plus and minus 45° directions (four layers total). Six anchors were
installed on specimen 2C#1. They are located on the horizontal centerline and seven inches away from
the top and bottom edges of the connection as shown in Figure 2.21. Locations of the CEDTs can be
found in Figure 2.15.
To further investigate the effect of the anchors on the CFRP strain distribution, 76 strain gages
were placed on the connection. Rectangular rosettes, spaced 1.2" apart, were located along the entire
vertical centerline of the connection. Delta rosettes were placed on the vertical centerline between the
anchors and vertically halfway between anchors. Uniaxial strain gages were placed in the direction of
the top CFRP fiber sheet. A total of nine uniaxial gages were spaced 1.2" apart,

connection of precast shear wall panels using carbon fiber

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