Feasibility of Steel Fiber Concrete in End Zones of Posttensioned Bridge Girders: Results of Special Anchorage-Device Acceptance Test

The secondary spiral and skin reinforcement in the anchorage zone of prestressed, posttensioned girders cause congestion and pose difficulty in the placement of concrete. Also, it is labor intensive to produce and place the secondary anchorage reinforcement. A study was conducted to determine the feasibility of reducing or eliminating the secondary reinforcement and replacing with steel fibers for posttensioned anchor zones because of the expected improvement in mechanical properties of fiberreinforced concrete over nonfibrous concrete. The AASHTO special anchorage device acceptance test was performed. Variations of spiral and skin reinforcement, with concrete strengths ranging from 24 to 34.5 MPa (3,500 to 5,000 psi), were used to investigate the performance of the two types and various amounts of steel fibers. Experimental results indicated that 1% hooked-end steel fiber could reduce a maximum of 79% of the secondary reinforcement for a minimum concrete strength of 32.5 MPa (4,710 psi). Lower volumes of steel fibers may also result in reduction of secondary reinforcements.