Behavior of reinforced concrete pier caps under concentrated bearing loads.

Details

• Creators:
  Denio, R. J. ; Yura, Joseph A. ; Kreger, Michael E.
• Corporate Creators:
  University of Texas at Austin. Center for Transportation Research
• Corporate Contributors:
  Texas. Dept. of Transportation. Office of Research and Technology Transfer ; United States. Federal Highway Administration
• Subject/TRT Terms:
  • Pile caps
  • Bents
  • Piers (Supports)
  • Strut and tie method
  • Structural analysis
  • concrete piers
  • steel cap girders
  • shear strength
  • strut-and-tie method
  • connection detail
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• Publication/ Report Number:
  FHWA/TX-97IJ302-J
• Resource Type:
  Tech Report
• Geographical Coverage:
  Texas
• Corporate Publisher:
  Texas Department of Transportation. Research and Technology Implementation Office
• Abstract:
  At congested highway interchanges, the Texas Department of Transportation (TxDOT) uses narrow concrete piers and ; shallow depth steel cap girders. Research Project ()"1302 is concerned with the connection detail between these two ; elements. This report deals with the shear strength and reinforcement details at the top of the concrete pier in the vicinity of ; the bearings. Since no formal design procedure currently exists for determining the required amount and distribution of ; reinforcing steel in a pier cap, this research also had the purpose of providing design guidelines for the pier cap. To ; in'vestigate the behavior of the pier caps, six test specimens were constructed at a 30% scale. Five different reinforcing steel ; patterns were used in the six specimens to examine the contributions of different reinforcing types to the pier cap strength. ; Eleven static load tests were conducted to failure on the six pier caps. For all specimens, load on the pier cap was ; carried primarily by the action of a tied arch which transferred load from the base plates into the column. Overall, ; specimens that had a greater quantity of horizontal reinforcing steel and adequate development of horizontal reinforcing had ; a greater capacity. ; Three design methods were used to analyze the strength of the pier caps tested: (1) AASHTO (1992) Corbel Provisions; ; (2)ACI 318-89 Deep Beam Provisions; and (3) Strut-and-TIeMethod. The corbel and deep beam provisions were very ; conservative in predicting the capacity of the pier cap because they consider only concrete capacity in shear. On average, ; these two methods underestimated the pier strength by a factor of 3 to 4. Testing showed that the pier cap resisted loads ; through a tied arch, which is a much stronger load-carrying mechanism than concrete in shear. The strut-and-tie models ; used were much more accurate than conventional design methods in predicting the capacity of the pier caps because they ; model the compression arch action observed during testing. The strut-and-tie method is suggested for design because ; strut-and-tie analyses gave the best correlation with test results, modeled true behavior, and were still conservative. ; To detail the use of the strut-and-tie method, a design example using a proposed strut-and-tie model is presented. Also, ; recommendations are given for evaluating existing pier caps through field inspection.
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• Format:
  PDF
• Funding:
  Research Study 0-1302
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/31676/dot_31676_DS1.pdf
• File Type:
  [PDF - 3.79 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:5b4ec6718302aed2e624cbb232d66d9335d2bf0a54605ff45f4876978619f7be