Experimental study on direct shear resistance of horizontal grouted joints in PC shear walls under compression and in-plane bending moment

The upper and lower panels of the prefabricated concrete shear wall are usually connected via horizontal grouted joints to maintain structural integrity. The horizontal grouted joints are typically under compression and in-plane bending moment. In the current design practice, it is generally considered that the direct shear resistance of the horizontal grouted joint is identical to that of the new-old concrete joint, and not affected by the bending moment if no bending failure occurs. In fact, as far as the authors know, both considerations lack experimental evidences. In this study, eight horizontal joint specimens were tested, including four grouted joints and four new-old concrete joints, to investigate their direct shear performances under constant compression and different in-plane eccentricities. Test results indicated that the ultimate direct shear resistance of the grouted joints was averagely 15.9 % lower than that of the new-old concrete joints. For the joints under small eccentricities associated with full shear plane in compression, the ultimate direct shear resistances remained unchanged compared to the cases under no eccentricity. However, for the grouted joints under large eccentricities associated with partial shear plane in tension, the ultimate direct shear resistances reduced up to 27.8 % compared to the grouted joint under no eccentricity. In addition, the shear transfer mechanism was investigated with the aid of the extended shear-friction model. Finally, recommendations were proposed for direct shear design of the horizontal grouted joints.