Precast Bent System for High Seismic Regions: Laboratory Tests of Column-to-Drilled Shaft Socket Connections
Publication No. FHWA-HIF-13-038
June 2013
TABLE OF CONTENTS
CHAPTER 2. DESIGN OF TEST SPECIMENS
- Configuration of Test Specimens
- Design of Prototype and Test Columns
- Design of Specimen Column-to-Drilled Shaft Connection
CHAPTER 3. EXPERIMENTAL PROGRAM
- Moment-Drift Response
- Effective Force
- Curvature
- Displacement
- Strains in Column Reinforcing Bars
- Strains in Shaft Reinforcing Bars
- Strains in Shaft Spirals
- Non-Contact Lap Splices Models
- Column Moment-Curvature Analysis
- The Strut-and-Tie Model and Shaft Spiral Design
CHAPTER 7. SUMMARY AND CONCLUSIONS
APPENDIX A: SPECIMEN CONSTRUCTION DRAWINGS
List of Figures
- Figure 1. Diagram. Precast bridge bent construction stages.
- Figure 2. Equation. Spacing of shaft spiral.
- Figure 3. Photos. Column reinforcement (left) and shaft-footing reinforcement (right).
- Figure 4. Photos. Specimen construction (left) and specimen test setup (right).
- Figure 5. Diagram. Test setup.
- Figure 6. Diagram. Locations of external instruments.
- Figure 7. Diagram. Top column displacement comparison for DS-1 (top) and DS-2 (bottom).
- Figure 8. Diagram. Locations of strain gauges.
- Figure 9. Graphs. Lateral loading displacement history.
- Figure 10. Chart. Comparison of specimens' drift ratios for the major damage states.
- Figure 11. Photo. Specimen DS-1 after testing.
- Figure 12. Photo. Specimen DS-2 after testing.
- Figure 13. Equation. Moment at the base of the column.
- Figure 14. Diagram. Displacements and forces on test specimen.
- Figure 15. Equation. Determination of axial load lateral displacement.
- Figure 16. Equation. Moment at the base of the column.
- Figure 17. Graphs. Moment vs. drift ratio response.
- Figure 18. Equation. Effective lateral force.
- Figure 19. Graph. Effective force-displacement response.
- Figure 20. Diagram. Detailed curvature rods setup.
- Figure 21. Equation. Calculating curvature.
- Figure 22. Graphs. Average column curvature (specimen DS-1 and DS-2).
- Figure 23. Graphs. Average column curvature (measured by Optotrak) in specimen DS-2.
- Figure 24. Graphs. Average shaft curvature for specimens DS-1 and DS-2.
- Figure 25. Illustration. Displacement types.
- Figure 26. Graph. Rotation comparison at 10 inches above the interface position (specimen DS-2).
- Figure 27. Graph. Rotation comparison at 18 inches above the interface position (specimen DS-2).
- Figure 28. Graph. Specimen DS-1 displacement profile.
- Figure 29. Graph. Specimen DS-2 displacement profile.
- Figure 30. Graphs. Displacement-drift response (specimens DS-1 and DS-2).
- Figure 31. Graphs. Displacement-drift response of shaft (specimens DS-1 and DS-2).
- Figure 32. Diagrams. Column strain gauge positions.
- Figure 33. Graphs. Strain profiles in reinforcing bars of the column (until 3 percent drift).
- Figure 34. Graphs. Strain profiles in reinforcing bars of column (after 3 percent drift).
- Figure 35. Graphs. Strain-effective force relationship of the column reinforcing bars.
- Figure 36. Diagrams. Strain gauge positions in the shaft.
- Figure 37. Graphs. Strain in shaft reinforcing bars in specimen DS-1.
- Figure 38. Graphs. Strain in shaft reinforcing bars in specimen DS-2.
- Figure 39. Graphs. Strain profiles in the shaft reinforcing bars.
- Figure 40. Graphs. Strain-Effective force relationship of the shaft reinforcing bars.
- Figure 41. Graphs. Strain in shaft spiral.
- Figure 42. Diagram. Two-dimensional behavioral model for non-contact lap splices.
- Figure 43. Equation. Shaft transverse reinforcement for rectangular columns.
- Figure 44. Equation. Shaft transverse reinforcement for rectangular columns with
- Figure 45. Equation. Volume of shaft reinforcement for rectangular columns.
- Figure 46. Equation. Volume of shaft reinforcement for rectangular columns - expanded equation.
- Figure 47. Equation. Minimum volume of shaft reinforcement for rectangular columns.
- Figure 48. Equation. Inclination angle of the concrete strut.
- Figure 49. Graph. Relationship between the total steel volume in a splice and the inclined angle of struts.
- Figure 50. Diagrams. Proposed three-dimensional behavioral model for non-contact lap splices.(18)
- Figure 51. Equation. Shaft transverse reinforcement for circular columns.
- Figure 52. Equation. Volume of shaft reinforcement for circular columns.
- Figure 53. Equation. Volume of shaft reinforcement for circular columns - expanded equation.
- Figure 54. Equation. Minimum volume of shaft reinforcement for circular columns.
- Figure 55. Equation. Inclination angle of the concrete strut.
- Figure 56. Equation. Shaft transverse reinforcement for circular columns under axial load and bending.
- Figure 57. Graph. Moment-curvature analysis (based on expected material properties).
- Figure 58. Graph. Moment-curvature analysis (based on measured material properties).
- Figure 59. Graph. Moment-extreme reinforcement tensile strain relationship for column (in specimen DS-1).
- Figure 60. Graph. Moment-extreme reinforcement tensile strain relationship for column (in specimen DS-2).
- Figure 61. Graph. Relationship of moment at the base and extreme reinforcement tensile strain for the shaft.
- Figure 62. Diagram. Strut-and-tie model proposed by Schlaich and Schäfer.(24)
- Figure 63. Diagrams. Elevation and plan of the strut-and-tie model for transmitting load from one column reinforcing bar to the three nearest shaft bundles bars.
- Figure 64. Diagram. Tension transfer from column to shaft longitudinal reinforcement.
- Figure 65. Equation. Distributed load determination.
- Figure 66. Equation. Distribution of tension in the shaft reinforcement.
- Figure 67. Diagram. Distributed load applied to shaft spirals.
- Figure 68. Equation. Distance of tensile forces from the neutral axis.
- Figure 69. Equation. Distribution of tension in the shaft longitudinal reinforcement.
- Figure 70. Equation. Distributed load applied to the shaft transverse reinforcement.
- Figure 71. Equation. Equilibrium equation.
- Figure 72. Equation. Distribution of tensile force in the shaft spirals.
- Figure 73. Diagram. Tensile force distribution in tie T2 in tension area.
- Figure 74. Equation. Maximum tensile force in the tie.
- Figure 75. Graph. Relationship of T2max vs. θ.
- Figure 76. Equation. Yield strength of a single spiral wire.
- Figure 77. Diagram. Column elevation.
- Figure 78. Diagram. Column sections.
- Figure 79. Diagram. Shaft and base - longitudinal section.
- Figure 80. Diagram. Shaft and base - transverse section.
- Figure 81. Diagram. Shaft and base reinforcement arrangement.
- Figure 82. Graph. Stress-strain curve for No. 3 bar.
- Figure 83. Graph. Stress-strain curve for No. 5 bar.
- Figure 84. Photo. Specimen DS-1 - significant horizontal crack in cycle 4-1 (0.56/-0.75 percent drift).
- Figure 85. Photo. Specimen DS-1 - first significant spalling occurred in the column in cycle 7-2 (3.00/-3.14 percent drift).
- Figure 86. Photo. Specimen DS-1 - plastic hinge formed in the column in cycle 8-3 (4.60/-4.68 percent drift).
- Figure 87. Photo. Specimen DS-1 - first noticeable bar buckling in the column in cycle 9-3 (6.90/-6.81 percent drift).
- Figure 88. Photo. Specimen DS-1 - first column spiral fractured in cycle 10-1 (8.43/-8.27 percent drift).
- Figure 89. Photos. Specimen DS-1 column damage after cyclic testing.
- Figure 90. Photo. Specimen DS-1 shaft damage after cyclic testing.
- Figure 91. Photo. Specimen DS-2 - significant horizontal crack in cycle 4-2 (0.73/-0.87 percent drift).
- Figure 92. Photo. Specimen DS-2 - first diagonal crack in the shaft in cycle 6-2 (1.87/-2.02 percent drift).
- Figure 93. Photo. Specimen DS-2 - shaft damage when first shaft spiral fractured in cycle 8-2 (4.59/-4.59 percent drift).
- Figure 94. Photo. Specimen DS-2 - first noticeable prying action in shaft in cycle 9-2 (6.72/-6.83 percent drift).
- Figure 95. Photos. Specimen DS-2 shaft damage after cyclic testing.
- Figure 96. Photo. Specimen DS-2 column damage after cyclic testing.
List of Tables
- Table 1. Prototype and specimen design dimensions.
- Table 2. Shaft reinforcement.
- Table 3. Target displacement history.
- Table 4. Damage state descriptions.
- Table 5. Damage milestones for all five specimens.
- Table 6. Moment and drift ratio at maximum and 80 percent of maximum resistance.
- Table 7. Effective force and displacement at maximum and 80 percent maximum of resistance.
- Table 8. Comparision of peak column moment.
- Table 9. Concrete strengths for specimen DS-1 and DS-2.
- Table 10. Tensile strength of spiral.
AASHTO | American Association of State Highway and Transportation Officials |
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ABC | Accelerated Bridge Construction |
BDM | Bridge Design Manual |
HSS | Hollow structural section |
LRFD | Load and Resistance Factor Design |
LVDT | Linear variable differential transformer |
MEF | Maximum effective force |
PTFE | Polytetraflouroethylene |
WSDOT | Washington State Department of Transportation |
Notice
This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The U.S. Government assumes no liability for the use of the information contained in this document.
The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document.
Quality Assurance Statement
The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.
1. Report No. FHWA-HIF-13-038 |
2. Government Accession No. N/A |
3. Recipient's Catalog No. N/A |
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4. Title and Subtitle PRECAST BENT SYSTEM FOR HIGH SEISMIC REGIONS: LABORATORY TESTS OF COLUMN-TO-DRILLED SHAFT SOCKET CONNECTIONS |
5. Report Date May 2013 |
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6. Performing Organization Code | |||
7. Author(s) Hung Viet Tran, John F. Stanton, and Marc O. Eberhard |
8. Performing Organization Report No. | ||
9. Performing Organization Name and Address BergerABAM, Inc. 33301 Ninth Ave South, Suite 300 Federal Way, WA 98003 University of Washington, Seattle, WA |
10. Work Unit No. (TRAIS) | ||
11. Contract or Grant No. DTFH61-09-G-00005 |
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12. Sponsoring Agency Name and Address Federal Highway Administration Highways for LIFE Program - HIHL-1 1200 New Jersey Avenue, SE Washington, D.C. 20590 |
13. Type of Report and Period Covered Final Report |
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14. Sponsoring Agency Code | |||
15. Supplementary Notes This is a companion report to the final project report, Precast Bent System for High Seismic Regions (FHWA-HIF-13-037). |
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16. Abstract This report provides detailed information from the laboratory investigation of two precast column-to-drilled shaft large-scale tests, including descriptions of the specimen design, testing, data reduction, and conclusions regarding the use of the connection with the precast bent system. The tests provide data regarding the performance of the precast column-to-drilled shaft connection. The results indicate that the connection, when used with a precast column, is sufficiently strong to resist plastic hinging in the column above the drilled shaft splice zone. The column reinforcing bars were anchored with headed bar ends to facilitate column strength development. The behavior is emulative of cast-in-place performance. The specimens tested were based on the minimum practical difference in diameters of the shaft relative to the column. When adequate confinement in the reinforcing cage of the shaft is included in the splice zone, the column can form a plastic hinging mechanism above the shaft without incurring damage in the shaft splice zone. If sufficient confinement is not included, then the resulting behavior is undesirable because the splice zone strength rapidly deteriorates. Recommendations for transverse reinforcement are provided to ensure desirable performance, and these result in more reinforcement in the upper portion of the splice zone than in the lower portion. |
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17. Key Words Bridges, earthquakes, accelerated bridge construction, precast bent, connections, drilled shaft foundations, prefabricated bridge elements and systems |
18. Distribution Statement No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161. |
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19. Security Classification (of this report) Unclassified |
20. Security Classification (of this page) Unclassified |
21. No. of Pages 125 |
22. Price |
APPROXIMATE CONVERSIONS TO SI UNITS | APPROXIMATE CONVERSIONS FROM SI UNITS | ||||||||
---|---|---|---|---|---|---|---|---|---|
Symbol | When You Know | Multiply By | To Find | Symbol | Symbol | When You Know | Multiply By | To Find | Symbol |
LENGTH | LENGTH | ||||||||
in | inches | 25.4 | millimeters | mm | mm | millimeters | 0.039 | inches | in |
ft | feet | 0.305 | meters | m | m | meters | 3.28 | feet | ft |
yd | yards | 0.914 | meters | m | m | meters | 1.09 | yards | yd |
mi | miles | 1.61 | kilometers | km | km | kilometers | 0.621 | miles | mi |
AREA | AREA | ||||||||
in2 | square inches | 645.2 | square millimeters | mm2 | mm2 | square millimeters | 0.0016 | square inches | in2 |
ft2 | square feet | 0.093 | square meters | m2 | m2 | square meters | 10.764 | square feet | ft2 |
yd2 | square yards | 0.836 | square meters | m2 | m2 | square meters | 1.195 | square yards | yd2 |
ac | acres | 0.405 | hectares | ha | ha | hectares | 2.47 | acres | ac2 |
mi2 | square miles | 2.59 | square kilometers | km2 | km2 | square kilometers | 0.386 | square miles | mi2 |
VOLUME | VOLUME | ||||||||
fl oz | fluid ounces | 29.57 | milliliters | ml | mL | milliliters | 0.034 | fluid ounces | fl oz |
gal | gallons | 3.785 | liters | L | L | liters | 0.264 | gallons | gal |
ft3 | cubic feet | 0.028 | cubic meters | m3 | m3 | cubic meters | 35.314 | cubic feet | ft3 |
yd3 | cubic yards | 0.765 | cubic meters | m3 | m3 | cubic meters | 1.307 | cubic yard | yd3 |
NOTE: Volumes greater than 1000 l shall be shown in m3 | |||||||||
MASS | MASS | ||||||||
oz | ounces | 28.35 | grams | g | g | grams | 0.035 | ounces | oz |
lb | pounds | 0.454 | kilograms | kg | kg | kilograms | 2.202 | pounds | lb |
T | short tons (2000 lb) | 0.907 | megagrams | Mg | Mg (or "t") | megagrams (or "metric ton") | 1.103 | short tons (2000 lb) | T |
TEMPERATURE (exact degrees) | TEMPERATURE (exact degrees) | ||||||||
°F | Fahrenheit | 5(F–32)/9 or (F–32)/1.8 | Celcius | °C | °C | Celsius | 1.8C +32 | Fahrenheit | °F |
ILLUMINATION | ILLUMINATION | ||||||||
fc | foot–candles | 10.76 | lux | lx | lx | lux | 0.0929 | foot–candles | fc |
fl | foot–Lamberts | 3.426 | candela/m2 | cd/m2 | cd/m2 | candela/m2 | 0.2919 | foot–Lamberts | fl |
FORCE and PRESSURE or STRESS | FORCE and PRESSURE or STRESS | ||||||||
lbf | pounds | 4.45 | newtons | N | N | newtons | 0.225 | poundforce | lbf |
lbf/in2 | pound per square inch | 6.89 | kilopascals | kPa | kPa | kilopascals | 0.145 | poundforce per square inch | lbf/in2 |
Notation
Atr | = | Area of shaft transverse reinforcement or spiral (in2) |
Al | = | Total area of longitudinal column reinforcement (in2) |
Alsh | = | Total area of longitudinal shaft reinforcement (in2) |
c | = | Depth to the neutral axis |
D | = | Diameter of shaft spiral (in.) |
d | = | Distance from the extreme compression fiber to the extreme tension longitudinal reinforcement |
e | = | Distance from the inner bar to the outer bar |
Ea | = | Modulus of elasticity of reinforcement (ksi) |
fr | = | Concrete modulus of rupture (ksi) |
fs | = | Tensile stress in reinforcement (ksi) |
fyt | = | Specified minimum yield strength of shaft transverse reinforcement (ksi) |
ful | = | Specified minimum tensile strength of column longitudinal reinforcement (ksi), 90 ksi for A615 and 80 ksi for A706 |
lns | = | Total noncontact lap splice length |
ld | = | Class C tension lap splice length of the column longitudinal reinforcement (in.) |
Ltr | = | Distance between the outer bars |
R | = | Radius of shaft spiral (in.) |
str | = | Spacing of shaft transverse reinforcement (in.) |
VOLs | = | Total volume of steel, including both longitudinal and transverse in the splice |
εs | = | Tensile strain in reinforcement (ksi) |
θ | = | Inclination angle of the strut (degree or rad) |
φ | = | Curvature (1/in.) |