Cyclic behavior of a novel ear-shaped key for precast UHPC frame-shear wall structures

This study proposes a precast Ultra-High Performance Concrete (UHPC) frame-shear wall structure with embedded ear-shaped keys (ESKs). Its seismic performance was evaluated through quasi-static cyclic tests on three large-scale specimens and ABAQUS numerical simulations. The results indicate that the ESKs effectively transfer interface shear; compared to a bare frame, the ESK frame-wall system increased the peak load-carrying capacity and initial stiffness by approximately 5.0 and 6.0 times, respectively. The system exhibited a ductile failure mode characterized by relative sliding and corner cracking, maintaining a displacement ductility factor above 3.0 and an energy dissipation coefficient between 0.9 and 1.1 at the ultimate state. Parametric analyses demonstrated that joint geometry critically influences bearing capacity; the ESK configuration achieved a 124% higher load-bearing capacity than traditional straight keys. Furthermore, reducing the number of horizontal wall panels from 7 to 3 increased the ultimate capacity by 105%, whereas increasing the axial compression ratio from 0.1 to 0.5 yielded only a 7.6% capacity gain. These quantitative findings provide a solid mechanical foundation for designing prefabricated UHPC seismic structures.