Shear performance of concrete-grouting material-concrete connection joint under low cyclic loading

Polypropylene (PP) fiber grouting material is a high-performance cementitious composite material with high strength, crack-resistant and toughened characteristics, which can fully fill the gap between the component units and the cavity in the sleeve when prefabricated components are connected by grouted sleeve, and improve the interfacial connection performance. The shear performance of the double interface of concrete-grouting material-concrete (CGC) connection joint formed at the connection parts of components is the key to ensure the safety of the integral structure. Taking the keyway height, interfacial reinforcement ratio, axial compression ratio and grouting material fullness into consideration, the failure pattern, shear capacity, stiffness, energy dissipation and ductility of CGC connection joint under low cyclic loading were investigated. The results show that the failure pattern of CGC connection joint is dominated by horizontal penetration cracks at the interface, and the increase of axial pressure makes the keyway develop diagonal cracks while the joint shows “X”-type shear diagonal cracks; increasing the height of keyway and the axial pressure can improve the shear capacity, stiffness, and energy dissipation of the CGC connection joint, but reduces the ductility of the joint; among them, the increase of keyway height from 6 mm to 12 mm and 18 mm makes the shear capacity improve by 11% and 43%, makes the stiffness improve by 11% and 14%, but makes the ductility decrease by 10% and 21%; the increase of interfacial reinforcement ratio improves the seismic performance of the joint, while the lack of grouting material in the sleeve decreases the shear capacity and stiffness of the joint. According to the failure pattern of the CGC connection joint, the composition of the shear stress at double interface of the joint was analyzed, and the shear capacity calculation formula for the double interface of the CGC connection joint was established based on the superposition principle. tThe calculated values match well with the experimental values.