Interface Shear Capacity of Concrete Surfaces Used in Strengthening Structures

Thirty-three push-off type specimens were subjected to cyclic shear loading to study the effects of such variables as interface surface preparation, amount and depth of embedment of the interface reinforcement, structural detailing of the concrete elements, and the compressive strength of both existing and newly cast concrete elements on the shear transfer capacity of reinforced concrete interfaces.

Test results consisted of load-deformation relationships, maximum shear capacities, stress-slip envelopes and an evaluation of the failure mechanisms of the specimens. The shear stress-slip relationship for each specimen was determined for slip levels up to 0.5 in., and their peak and residual shear transfer capacities were evaluated.

A comparison of the test results and ACI 318-83 design strengths is presented to determine the effect of the depth of dowel embedment as it relates to the shear friction provisions if ACI.