In-Plane Shear Transfer between Thin Concrete Slabs with Concrete Shear Keys and Steel Shear Plate

In the present study, shear-friction tests were conducted under cyclic loading to investigate in-plane shear transfer across a thin and long interface between new and existing concrete slabs. For shear reinforcement across the interface, concrete shear keys and steel shear plates were used in combination with adhesive anchors (that is, post-installed reinforcing bars). Test results showed that the shear behavior of the thin slab interfaces was significantly affected by the types and details of interface reinforcements. The concrete shear keys and shear plate effectively restrained relative slip across the interface during the initial behavior and increased the peak strength, while the adhesive anchors contributed to the peak strength and post-peak residual strength. Failure modes were concrete failure around the concrete shear keys (that is, local crushing and shearing-off) and in the anchorage zone of the shear plate (that is, cracking and spalling-off). The nominal shear strengths of the thin slab interfaces were calculated by summing the shear-friction strength of adhesive anchors, local crushing strength around concrete shear keys, and shear yield strength of shear plates. The predicted strength agreed with the test results. Based on the results, design considerations of shear transfer across an interface between thin concrete slabs were discussed.