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Mid-America Transportation Center

Performance Assessment of Deteriorated and Retrofitted Steel HP Piles

Final Report
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Researchers

  • Principal Investigator: Joshua Steelman (joshua.steelman@unl.edu (402) 472-1972)
  • Project Status
    Complete
    Sponsors & Partners
  • Nebraska Department of Roads
  • Abstract
    Steel piles are known to deteriorate at high rates in Nebraska, partially as a result of exposure to weathering, and partially due to corrosive soils. The Nebraska Department of Roads employs a reinforced concrete jacket to slow the progression of corrosion and also to restore capacity to deteriorated piles. The intent of this study was to assess the effectiveness of typical reinforced concrete encasement retrofits. The research included a literature review to collect information for current retrofit practices and research similar in nature to this study, followed by a series of experiments. The findings of the literature review showed that prescriptive concrete jackets were common, but fiber reinforced polymer wraps are gaining popularity. Analytical and experimental support for pile retrofits is limited, and recent research is focused on FRP applications, leaving a gap in knowledge for the expected performance of traditional concrete jackets. For the experiments described in this report, two pile scenarios were represented: abutments and pile bents. For each type there was a non-deteriorated, deteriorated, and retrofitted specimen. The capacity of each pile was assessed by applying axial and flexure-inducing shear loads. Deteriorated and retrofitted cases simulated corrosion loss by milling the flanges and cutting out portions of the web. The retrofitted case utilized a reinforced concrete encasement consistent with reference drawings provided by NDOR. The key findings of this study were that the standard retrofit is sufficient and likely more robust than necessary, concomitant with a greater than anticipated jacket-to-pile bond strength developed at the retrofitted section. Further investigation is recommended to determine the bond characteristics of steel fully encased by concrete, and whether simplifications to the typical detail can reliably provide capacity restoration.
    Project Amount
    $ 52,217