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
  More +
• 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
• Description:
  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.
• 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