超高性能混凝土连接装配式混凝土框架梁端节点抗震性能试验研究OA

To address the challenges of complex reinforcement detailing,stringent precision requirements,and susceptibility to cracking in the connection zone of precast concrete beam-column joints,this study proposed a confined anchorage lap splice using ultra-high performance concrete(CAL-UHPC).Low-cycle reversed loading tests were conducted on three CAL-UHPC joints with varying lap lengths and one cast-in-place(CIP)reference joint.The seismic performance of all joints,including failure modes,hysteretic behavior,stiffness degradation,and energy dissipation capacity,was analyzed.Meanwhile,the finite element model of the beam-column assembly was further developed in ABAQUS to explore the damage evolution behavior and transfer mechanism.The results demonstrate that CAL-UHPC beam-column joints exhibit a plastic hinge offset failure at the beam end,while the UHPC connection zone remains essentially undamaged,achieving the"strong connection"design objective.Insufficient or excessive lap lengths led to the slip or tensile fracture of the lapped rebars,respectively,compromising the mechanical performance and safety of the joint.At a lap length of 12d(where d is the rebar diameter),the strain curves of lapped rebars are essentially coincident and remain elastic.The synergistic interaction between UHPC and lapped rebars establishes a dynamic load-transfer mechanism progressing through"bonding-partial mutual anchoring-complete mutual anchor",enabling efficient stress transfer and full utilization of the superior properties of UHPC.Consequently,the CAL-UHPC connected joints demonstrate 34.36％,8.89％,and 21.83％enhancements in load-bearing capacity,ductility,and energy dissipation compared to the CIP joint,respectively,along with slower strength and stiffness degradation.Based on integrated analysis of the plastic hinge characteristics and seismic performance indicators,the recommended lap length for CAL-UHPC connections is 10d to 14d,with 12d proposed as the optimal design length.