Development of Precast Bridge Deck Overhang System

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Development of Precast Bridge Deck Overhang System

Author: Trejo, David Kim, Young Hoon | Size: 1.18 MB | Format: PDF | Quality: Original preprint | Publisher: Texas Transportation Institute | Year: 2010 | pages: 60

The implementation of full-depth, precast overhang panel systems has the potential to improve constructability, productivity, and make bridges more economical. Initial testing and analyses reported in the 0-6100-2 report resulted in a design that required a large number of shear pockets in the overhang panels. The general design methodology used in this report was to determine the number of connectors based on the shear capacity of a girder with conventional R-bars (not necessarily based on the required demand). The large number of shear pockets reduced the constructability and economy of the precast overhang system. Report 0-6100-1 (produced after 0-6100-2) used the American Association of State Highway Officials Load and Resistance Factor Design (AASHTO LRFD [2008]) demand requirements to design the number of shear pockets for a precast overhang panel system and reported that the number of pockets per panel could be reduced from the numbers reported in report 0-6100-2. However, this report only included an analysis for one beam type and one span length. In addition, the demand load used did not include all factors typically used by designers. Additional testing was required to assess different connector systems and further analyses were needed for the new Texas Department of Transportation (TxDOT) girders. The testing and analyses documented in this report (0-6100-3) provides a new equation for determining the number of shear pockets required for the various shear connector/coupler systems evaluated in this research. This equation was used to determine the number of shear pockets required for the newer TxDOT girders. Results from this research indicate that the roughened surface provides strong adhesion between the top girder surface and a precast panel. Steel reinforcing hoops placed in the shear pocket and shear reinforcing hoops placed in the overhang panel around the opening of the shear pocket provided limited or no improvement in capacity of the shear connector/coupler system. Hollow structural section (HSS) steel tubes placed around the perimeter of the shear pocket during fabrication did result in samples with higher shear capacities and could result in overhang panels with fewer shear pockets. This system could make constructing bridges with precast overhang systems more constructible, economical, and could reduce the construction time.

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