Development of a Rebar Dowel Anchorage System for Attaching the California Type 25 Concrete Barrier to Existing Bridges

摘要

The objective of this research was to develop a satisfactory anchorage system for attaching New Jersey-shaped concrete bridge replacement barrier onto existing concrete decks. Initially dynamic pullout tests of rebar dowels bonded in shallow drilled holes in a reinforced concrete slab were conducted to develop methods which would maximize pullout strengths. Important test parameters included rebar diameter, hole depth, and type of bonding material. Ultimate pullout loads ranging from 25.0 kips to 34.8 kips were attained with individual no. 6 rebar dowels bonded in 6-inch-deep holes. Secondly, static load tests were performed on standard California Type 25 Concrete Barrier and replacement barriers constructed on a typical concrete bridge deck to determine maximum horizontal loads which could be resisted. In preliminary tests, two 3-foot lengths of replacement barrier, attached with grouted no. 6 rebar dowels, withstood higher horizontal loads than did the standard Type 25 Concrete Barrier. A 16-foot-long replacement barrier, tested subsequently and anchored using no. 6 grouted rebar dowels, withstood a maximum static horizontal load of 93 kips applied to a concentrated area about 26 inches above the deck surface. Recommendations are made to use a drill-and-bond procedure for attaching replacement barrier to existing bridge decks.