Effect of voids in grouted, post-tensioned concrete bridge construction : volume 2--inspection, repair, materials, and risks.

Details

• Creators:
  Trejo, David
• Corporate Creators:
  Texas Transportation Institute
• Corporate Contributors:
  Texas. Dept. of Transportation. Research and Technology Implementation Office
• Subject/TRT Terms:
  Air Content Post-tensioned Prestressed Concrete Construction--Texas Concrete--Air Content--Texas Concrete Bridges Concrete Bridges--Inspection--Texas Concrete Bridges--Texas--Maintenance And Repair Prestressed Concrete Bridges
• Publication/ Report Number:
  FHWA/TX-09/0-4588-1 Vol. 2
• Resource Type:
  Tech Report
• Geographical Coverage:
  Texas
• Edition:
  Technical report; Sept. 2003-Aug. 2008.
• Abstract:
  Post-tensioned (PT) bridges are major structures that carry significant traffic. These bridges are designed and
  
  constructed because they are economical for spanning long distances. In Texas, there are several signature PT
  
  bridges. In the late 1990s and early 2000s, several state highway agencies identified challenges with the PT
  
  structures: mainly corrosion of the PT strands. The Texas Department of Transportation (TxDOT) performed some
  
  comprehensive inspections of their PT bridges. A consultant’s report recommended that all ducts be re-grouted.
  
  However, the environment in Texas is very different than the environments in which the corrosion of the PT strands
  
  were observed. The objective of this research was to evaluate the corrosion activity of strands for PT structures and to
  
  correlate this corrosion activity with general environmental and void conditions. To achieve this objective, timevariant
  
  probabilistic models were developed to predict the tension capacity of PT strands subjected to different
  
  environmental and void conditions. Using these probabilistic models, time-variant structural reliability models were
  
  developed. The probability of failure of a simplified PT structure subjected to HS20 and HL93 loading conditions
  
  was assessed. Both flexural failure and serviceability were assessed. Results indicate that the presence of water and
  
  chlorides can lead to significant corrosion rates and failure is dependent on this corrosion activity and the number of
  
  strands exposed to these conditions. These results are presented in Volume 1 of this report. To assist TxDOT with
  
  developing a plan to mitigate this corrosion, studies were performed to assess repair grout materials, inspection
  
  methods, and repair methods. In addition, a general methodology is presented on optimizing repairs. These topics are
  
  presented in Volume 2 of this report. An Inspection and Repair Manual was also developed from this research and is
  
  presented in a separate report. Results indicate that TxDOT should prevent water and chlorides from infiltrating the
  
  tendons — this can be achieved in part by repairing drain lines, ducts, and protecting anchor heads as these conditions
  
  can lead to early failure of PT bridges. Recommendations on inspections, repairs, and materials are provided,
  
  however, further research on the potential formation of galvanic coupling of strands embedded in both existing and
  
  new repair grouts need to be assessed.
  
  
• Format:
  PDF
• Funding:
  Project 0-4588
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:f48e84b3231815fe4550a83663a7f832c2f02ac1c071a2e9b99251053ca8de545bc655088b1f6cabda4ba2516d46ea4de69c8c0a1fb670bb28c4c11f0859fdb9
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/16990/dot_16990_DS1.pdf
• File Type:
  [PDF - 34.02 MB ]