Shear-Friction Behavior of Groove Interface in Concrete Bridge Rehabilitation

This study focuses on the shear-friction behavior of a groove interface with transverse reinforcement between existing concrete and newly poured concrete, which has been adopted in the rehabilitation project of three prestressed concrete box girder bridges in China. A series of push-off specimens with groove interfaces was tested with parameters of concrete strength, groove geometry, and reinforcement ratio. For comparison purposes, monolithic specimens and roughened specimens with or without transverse reinforcement were also tested to failure. Cracking loads, ultimate loads, residual strengths, cracking patterns, and failure modes were recorded. Load-slip curves, load-dilation behaviors, and load-strain relationships in steel reinforcement have been investigated. The groove on the surface of the existing concrete can significantly enhance shear-friction capacity of the interface between new and existing concrete. The transverse reinforcement can improve deformation capacity and residual resistance. The nonsimultaneous failure of concrete and steel reinforcement is revealed. Based on the shear-friction mechanism, the test results are compared with the existing design provisions. Design details on applying the proposed groove interface in the actual bridge rehabilitation are suggested.