Concrete Roadside Barrier Anchorage Details for 5-inch Cast in Place Decks on Prestressed Beams

摘要

The Texas Department of Transportation (TxDOT) commonly builds bridge spans withadjacently framed prestressed box beams and slab beams and makes them composite with a 5-inch thickconcrete cast in place deck (CIPD). The presence of a cast in place concrete overlay allows use of morefavorable empirical live load distribution equations, resulting in more efficient bridge spans. This 5-inchthick CIPD offers limited depth for anchorage of rail reinforcement. AASHTO LRFD Bridge DesignSpecifications have a limiting hook development length of 6-inches for a #4 rail anchorage. With a 5-inch deck thickness and a 6-inch minimum required development length, the rail anchoragereinforcement must be cast in the pretensioned beams to meet Specification requirements for railanchorage strength. This has made ensuring adequate development of the rail anchorage reinforcementproblematic.Therefore, the objective of this study was to develop barrier anchorage details that would meetMASH (1) evaluation criteria while minimizing damage to the concrete barrier profile and CIPD, whilefocusing on preventing delamination of the CIPD from the precast beams witnessed in a previousresearch project performed at TTI (2).The anchorage modifications were successfully evaluated under MASH test 3-11 and areconsidered suitable for use on roadways that have traffic conditions appropriate for the use of TL-3safety hardware.