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Report
This report is an archived publication and may contain dated technical, contact, and link information
Publication Number: FHWA-RD-02-088
Date: May 2003

Evaluation of Joint and Crack Load Transfer Final Report

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Foreword

This report documents a study conducted to evaluate load transfer efficiency of cracks and joints for rigid pavements included in the Long-Term Pavement Performance (LTPP) program. Using deflection testing data, load transfer efficiency parameters were determined and joint stiffnesses were backcalculated. Trend analysis was performed to evaluate the effect of design features and side conditions on load transfer efficiency. The analysis was conducted for all General Pavement Studies (GPS), Special Pavement Studies (SPS), and Seasonal Monitoring Program (SMP) test sections.

This report will be of interest to highway agency engineers involved in the deflection data collection, processing, and analysis of data collected to improve on the design procedures, as well as future researchers who will improve structural models of rigid pavements.

T. Paul Teng, P.E.
Director, Office of Infrastructure
Research and Development



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 its contents or use thereof. This report does not constitute a standard, specification, or regulation.

The U.S. Government does not endorse products or manufacturers. Trade or manufacturers' names appear herein only because they are considered essential to the objective of this document.

Technical Report Documentation Page
1. Report No.
FHWA-RD-02-088		 2. Government Accession No. 3. Recipient's Catalog No.
4. Title and Subtitle
EVALUATION OF JOINT AND CRACK LOAD TRANSFER FINAL REPORT		 5. Report Date
6. Performing Organization
7. Author(s)
Lev Khazanovich and Alex Gotlif		 8. Performing Organization Report No.
9. Performing Organization Name and Address
ERES Consultants
A Division of Applied Research Associates, Inc.
505 W. University Avenue
Champaign, IL 61820		 10. Work Unit No.
C6B
11. Contract or Grant No.
DTFH61-960C-00003
12. Sponsoring Agency Name and Address
Office of Infrastructure R & D
Federal Highway Administration
6300 Georgetown Pike
McLean, Virginia 22101-2296		 13. Type of Report and Period Covered
Final Report March 2001 to January 2002
14. Sponsoring Agency Code
15. Supplementary Notes
Work was conducted as part of the LTPP Data Analysis Technical Support Contract.Contracting Officer's Technical Representative (COTR): Cheryl Allen Richter, HRDI-13
16. Abstract
This report documents an evaluation of load transfer efficiency (LTE) of cracks and joints for rigid pavements included in the Long-Term Pavement Performance (LTPP) program. LTE is an important parameter affecting pavement performance. This study presents the first systematic analysis of the deflection data collected under the LTPP program related to LTE. Representative LTE indexes and joint stiffnesses were calculated for all General Pavement Studies (GPS), Special Pavement Studies (SPS), and Seasonal Monitoring Program (SMP) rigid test sections. Data tables that include computed parameters were developed for inclusion in the LTPP Information Management System (IMS). Trend analysis was performed to evaluate the effect of design features and site conditions on LTE. Key findings from this study:
  1. Large amounts of high quality LTE data have been collected under the LTPP program. This data will be a valuable resource in improving understanding of load transfer effect and improving pavement design and rehabilitation procedures.
  2. LTE is a complex parameter, which depends on many factors, including falling weight deflectometer (FWD) load plate position, testing time (FWD LTE testing must be conducted in the early morning in cool weather to provide realistic estimation of LTE), season.
  3. LTE of CRCP cracks was found to be higher than LTE of joint in JCP pavements.
  4. LTE of doweled joints was found to be higher than LTE of nondoweled joints.
  5. Nondoweled sections with a high level of LTE are less likely to develop significant faulting than sections with low LTE.
  6. LTE from leave and approach side deflection testing data was found to be statistically different for a large number of JCP sections.
17. Key Words
Load transfer efficiency, joints, cracks, PCC, rigid pavements, joint opening		 18. Distribution Statement
No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161.
19. Security Classif. (of this report)
Unclassified		 20. Security Classif. (of this page)
Unclassified
 21. No. of Pages
118		 22. Price

 

SI* (Modern Metric) Conversion Factors

TABLE OF CONTENTS

  1. INTRODUCTION
    Research Objectives
    Scope of Work
    Report Organization

  2. SELECTION OF METHODOLOGY FOR PCC JOINT/CRACK LTE AND STIFFNESS EVALUATION
    Load Transfer Efficiency
    Mechanistic Modeling of LTE
    Joint Stiffness Backcalculation
    "True" versus "Measured" LTE

  3. FWD DEFLECTION DATA ASSESSMENT AND LTE CALCULATION METHODOLOGY
    Deflection Testing Details
    Deflection Data Assessment
    Load Transfer Index Calculation Procedures
    Results of LTE Analysis

  4. LTE TREND ANALYSIS
    LTE Data Assessment
    Effect of FWD Load Position
    Variability in Measured LTEs for Individual Cracks/Joints
    Load Level Dependency
    Effects of Design Features and Site Conditions on LTE
    Effects of LTE on Pavement Performance

  5. LTE ANALYSIS FOR SMP SECTIONS
    Effects of Time of Testing on Joint LTE
    Effects of Season of Testing on Joint LTE

  6. JOINT STIFFNESS BACKCALCULATION AND ANALYSIS
    Joint Stiffness Backcalculation Procedure
    Joint Stiffness Data Assessment
    Recommendation for Joint Stiffness Selection

  7. JOINT MOVEMENTS: CALCULATION METHODOLOGY, DATA ASSESSMENT, AND TREND ANALYSIS
    Joint Movement Measurements
    Assessment of Gage Measurement Data
    Joint Movement Calculation Procedures
    Daily Variation in Joint Opening
    Seasonal Variation in Joint Opening
    Effects of Joint Opening on LTE

  8. SUMMARY AND RECOMMENDATIONS FOR CONTINUED RESEARCH

REFERENCES

LIST OF FIGURES

  1. LTE versus nondimensional joint stiffness
  2. Finite element model for FWD loading simulation
  3. Comparison of LTE calculated from ISLAB2000 results with predictions using Crovetti's and Zollinger's models
  4. Comparison of true and measured LTEs
  5. Distribution of bending correction factors for approach slab testing based on O5 sensor configuration
  6. Distribution of bending correction factors for leave slab testing based on C6 sensor configuration
  7. Comparison of LTEs predicted using ISLAB2000 for the approach slab test (LTE1) and the leave slab test (LTE2) for pavements with voids
  8. Distribution of crack LTE mean values, CRCP sections
  9. Distribution of joint LTE mean values, JCP sections
  10. Effect of FWD load position on mean section crack LTE for CRCP
  11. Effect of FWD load position on mean section LTE for JCP
  12. Frequency distributions of standard deviations of LTEs for individual cracks/joints from different test types
  13. Frequency distributions of standard deviations of LTEs for nondoweled and doweled joints, approach test
  14. Frequency distributions of standard deviations of LTEs for nondoweled and doweled joints, leave test
  15. LTE for section 370201 on November 27, 1995, approach (J4) test
  16. LTE for section 370201 on November 27, 1995, leave (J5) test
  17. Coefficient of variation of LTE within a section
  18. Coefficient of variation versus mean LTE for approach tests
  19. Comparison of standard deviations of section LTE for doweled and nondoweled   JCP sections
    (approach tests)
  20. Comparison of standard deviations of section LTE for doweled and nondoweled JCP sections (leave tests)
  21. Distribution of section LTE mean value, nondoweled versus doweled, approach test (J4)
  22. Distribution of section LTE mean value, nondoweled versus doweled, leave test (J5)
  23. Distribution of joint LTE mean value, nondoweled versus doweled,   approach test (J4)
  24. Distribution of joint LTE mean value for different dowel diameters, approach test (J4)
  25. Distribution of joint LTE mean value, nondoweled versus doweled, leave test (J5)
  26. Distribution of joint LTE mean value for different dowel diameters, leave test (J5)
  27. Distribution of joint LTE mean values for different base types, doweled joints, approach test (J4)
  28. Distribution of joint LTE mean values for different base types, doweled joints, leave test (J5)
  29. Distribution of joint LTE mean values for different base types, nondoweled joints, approach test (J4)
  30. Distribution of joint LTE mean values for different base types, nondoweled joints, leave test (J5)
  31. Distribution of joint LTE mean values for different subgrade types, doweled joints, approach test (J4)
  32. Distribution of joint LTE mean values for different subgrade types, doweled joints, leave test (J5)
  33. Distribution of joint LTE mean values for different subgrade types, nondoweled joints, approach test (J4)
  34. Distribution of joint LTE mean values for different subgrade types, nondoweled joints, leave test (J5)
  35. PCC thickness versus LTE in CRCP sections
  36. PCC thickness versus LTE in JCP doweled sections
  37. PCC thickness versus LTE in JCP nondoweled sections
  38. PCC compressive strength versus LTE in CRCP sections
  39. PCC compressive strength versus LTE in JCP doweled sections
  40. PCC compressive strength versus LTE in nondoweled sections
  41. Steel content versus LTE in CRCP sections
  42. Mean joint spacing versus LTE in nondoweled JCP sections
  43. Mean crack spacing versus LTE in CRCP sections
  44. Joint skewness versus JCP LTE
  45. Annual precipitation versus LTE of doweled JCP
  46. Freezing index versus LTE of doweled JCP
  47. Annual number of freeze-thaw cycles versus LTE of nondoweled JCP
  48. Mean annual temperature versus LTE of CRCP
  49. Age versus LTE of nondoweled sections, approach test (J4)
  50. Age versus LTE of doweled sections, approach test (J4)
  51. Age versus LTE of CRCP sections, approach test (C4)
  52. Faulting versus. LTE of doweled JCP
  53. Faulting versus. LTE of nondoweled JCP
  54. Effect of LTE on faulting of nondoweled pavements
  55. Number of punchouts (all severity levels) versus LTE
  56. Daily variation in calculated approach LTE, section 163023 (September 1992)
  57. Daily variation in calculated leave LTE, section 163023 (October 1992)
  58. Daily variation in calculated approach LTE, section 4_0215 (March 1996))
  59. Daily variation in calculated leave LTE, section 4_0215 (March 1996)
  60. Comparison of mean LTEs for doweled SMP sections from different FWD passes on the same day of testing
  61. Comparison of mean LTEs for nondoweled SMP sections from different FWD passes on the same day of testing
  62. Seasonal variation in LTE and PCC surface temperature, section 63042
  63. Seasonal variation in LTE and PCC surface temperature, section 163023
  64. Seasonal variation in LTE and PCC surface temperature, section 204054
  65. Seasonal variation in LTE and PCC surface temperature, section 313018
  66. Seasonal variation in LTE and PCC surface temperature, section 493011
  67. Seasonal variation in LTE and PCC surface temperature, section 533813
  68. Seasonal variation in LTE and PCC surface temperature, section 833802
  69. Predicted versus actual ISLAB2000 nondimensional joint stiffness
  70. Frequency distribution of representative CRCP crack stiffness
  71. Frequency distributions of representative joint stiffnesses for joints of doweled and nondoweled JCP
  72. Comparison of backcalculated joint stiffness from two FWD passes on the same day of testing
  73. Flowchart of the overall process for joint movement calculation
  74. Relative changes in joint opening for section 274040 on May 6, 1997  compared to joint opening in October 1993
  75. Changes in joint opening from different measurement passes on the same day of measurements
  76. Change in joint opening versus change in PCC temperature, section 040215
  77. Change in joint opening versus change in PCC temperature, section 063042
  78. Change in joint opening versus change in PCC temperature, section 133019
  79. Change in joint opening versus change in PCC temperature, section 204054
  80. Change in joint opening versus change in PCC temperature, section 274040
  81. Change in joint opening versus change in PCC temperature, section 313018
  82. Change in joint opening versus change in PCC temperature, section 364018
  83. Change in joint opening versus change in PCC temperature, section 370201
  84. Change in joint opening versus change in PCC temperature, section 390204
  85. Change in joint opening versus change in PCC temperature, section 421606
  86. Change in joint opening versus change in PCC temperature, section 484142
  87. Change in joint opening versus change in PCC temperature, section 484143
  88. Change in joint opening versus change in PCC temperature, section 493011
  89. Change in joint opening versus change in PCC temperature, section 833802.
  90. Change in joint opening versus change in PCC temperature, section 893015
  91. Approach LTE versus joint opening, section 484142
  92. Leave LTE versus joint opening, section 484142
  93. Approach LTE versus joint opening, section 484143
  94. Leave LTE versus joint opening, section 484143
  95. Approach LTE versus joint opening, section 133019
  96. Leave LTE versus joint opening, section 133019
  97. Approach LTE versus joint opening, section 493011
  98. Leave LTE versus joint opening, section 493011
  99. Approach LTE versus joint opening, section 274040
  100. Leave LTE versus joint opening, section 274040
  101. Approach LTE versus joint opening, section 364018
  102. Leave LTE versus joint opening, section 364018
  103. Approach LTE versus joint opening, section 370201
  104. Leave LTE versus joint opening, section 370201
  105. Approach LTE versus joint opening, section 390204
  106. Leave LTE versus joint opening, section 390204
  107. Approach LTE versus joint opening, section 893015
  108. Leave LTE versus joint opening, section 893015

LIST OF TABLES

  1. Regression coefficients for bending correction factors
  2. Number of basins rejected because of high variability
  3. Availability of deflection data
  4. Deflections from ISLAB2000 near joints
  5. Comparison of statistical significance of LTEs from approach and leave deflection tests
  6. Comparison of practical difference between LTEs from approach and leave deflection tests
  7. Joint LTE load level dependence
  8. FWD pass LTE load level dependence
  9. Repeatability ratios for different LTE levels
  10. Results of t-test for the effects of LCB on mean section LTE
  11. Results of t-test for the effects of subgrade type on mean section LTE
  12. Coefficients of variation of the section mean LTEs from the same day of testing
  13. Seasonal variation of approach LTE (test J4) for doweled SMP sections
  14. Seasonal variation of leave LTE (test J5) for doweled SMP sections
  15. Seasonal variation of approach LTE (test J4) for nondoweled SMP sections
  16. Seasonal variation of leave LTE (test J5) for nondoweled SMP sections
  17. Recommended joint/crack stiffnesses for different types of pavements
  18. Changes in joint opening from different measurement passes on the same day of measurements
  19. PCC/Base friction factors for SMP LTPP sections

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