Time-Dependent Effects and Validation from Monitoring of Post-Tensioned Spliced Girders and Deck Joints

This project report summarizes the results of monitoring a post-tensioned spliced girder bridge in Salt Lake City. This report describes the monitoring of the 4500 South Bridge on Interstate 15. The north-bound bridge consists of eight post-tensioned, spliced, precast concrete girders, having three segments each, for a single clear span of 61.443 m (201 ft 7 in.). Four girders and portions of the bridge deck and parapet wall have been instrumented and monitored for approximately four years. Data recorded from the bridge included concrete strain at selected girder locations, as well as post-tensioned girder losses through eight load cells, and girder deflections for one of the girders through surveys. The actual losses at midspan in the girder being monitored, including time-dependent losses and anchorage sealing and friction losses, were on average 14.5% of the initial post-tensioning forces; the absolute upward midspan deflection was 0.15% of the clear span, and the two splice points were deflecting in an almost identical manner indicating excellent girder/splice performance. Analytical procedures are compared to experimental measurements of the losses of the post-tensioned spliced precast concrete girder being monitored. The assumed losses in design were very close to those observed and the design methodology for incorporating losses is found to be adequate. Shrinkage and creep tests, performed on concrete used in constructing the post-tensioned spliced, precast concrete girders, were used to obtain the ultimate creep coefficient and ultimate shrinkage strain. Linear Variable Differential Transducer (LVDT) measurements at the cold joints show that the cold joints are in good health. The abutment movements and rotations were found to be small. The vertical deflections of the post-tensioned girders were measured due to thermal gradients and were compared to American Association of State Highway and Transportation Officials (AASHTO) predicted deflections. General recommendations for using spliced-girder post-tensioned bridges in future projects are provided.

Language

  • English

Media Info

  • Media Type: Web
  • Edition: Final Report
  • Features: Figures; Photos; References; Tables;
  • Pagination: 70p

Subject/Index Terms

Filing Info

  • Accession Number: 01044131
  • Record Type: Publication
  • Report/Paper Numbers: UT-07-02, CVEEN-06/2
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: Mar 14 2007 9:25AM