Evaluation of longitudinal joint tie bar system.

Details

• Creators:
  Mallela, Jagannath ; Gotlif, Alex ; Littleton, Paul ; Sadasivam, Suri ; Darter, Michael I.
• Corporate Creators:
  Applied Research Associates, Inc.
• Corporate Contributors:
  Colorado. Dept. of Transportation. Research Branch ; United States. Federal Highway Administration
• Subject/TRT Terms:
  • Tie bars
  • Longitudinal joints
  • Portland cement concrete
  • Concrete pavements
  • Mechanistic design
  • Mechanistic-empirical tie bar design, Tie bar construction, Tie bar alignment, Portland cement concrete pavement, Subgrade drag theory
• Publication/ Report Number:
  CDOT-2011-12
• Resource Type:
  Tech Report
• Geographical Coverage:
  Colorado
• Corporate Publisher:
  Colorado. Dept. of Transportation. Research Branch
• Abstract:
  "An adequate longitudinal joint tie bar system is essential in the overall performance of concrete pavement. Excessive ; longitudinal joint openings are believed to be caused by either inadequate tie bar size or spacing or improper tie bar ; installation. If designed and installed properly, tie bars prevent the joints from opening and consequently improve load ; transfer efficiency between slabs and between slabs and shoulders, resulting in increased load carrying capacity. ; This study evaluated the longitudinal joint tie bar system currently used by CDOT, examining the criteria for proper ; use of tie bars and determining the maximum number of lanes that can be tied together without negatively impacting ; the concrete pavement structure. An improved mechanistic-empirical tie bar design method was developed. Tie bar ; design tables with recommended bar size and spacing were provided for each combination of pavement base types, ; CDOT concrete mixes, and weather stations. Field studies were conducted to investigate longitudinal joint ; performance and further evaluate the impact of factors related to design and construction practices. The experimental ; plan for this round of testing included the evaluation of tie bar alignment, measurement of joint load transfer, and ; measurement of relative slab movement at the joints. In addition, CDOT’s current specifications and practices related ; to longitudinal joint construction and tie bar design and placement were compared with those of other state agencies. ; Field testing results revealed that the measured joint openings at some tied longitudinal joints were in the typical range ; of non-tied slabs, implying that some tied joints performed as poorly as non-tied slabs. The results indicate the ; possibility of tie bar failure due to loss of concrete-steel bonding or yielding of tie bar steel. Another key finding was ; the possible impact of tie bar misalignment or misplacement on poor longitudinal joint performance. Testing indicated ; that the measured joint openings were wider when the tie bars did not connect to the other side of the joint, or when the ; embedment lengths were inadequate. On the other hand, tie bars with adequate embedment length on both sides of the ; joint, even when misaligned, appear to hold the joint tight. ; Implementation ; CDOT should adopt the mechanistic-empirical tie bar design procedure developed in this study. The research team ; recommends that CDOT conduct more rigorous experimental and field testing covering various base material types ; and concrete mixtures to obtain Colorado-specific model parameters for implementation."
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• Format:
  PDF
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/23400/dot_23400_DS1.pdf
• File Type:
  [PDF - 1.72 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:4e715e93029674b11c37fe3e58398832c92c75e80b93fd5bf0e8d468c7fa6e088629090756ff133b740d6c515511dcce3f778c2a72d777afb570d9fc2db047cd