Performance evaluation of UHPC joints between composite slabs and shear walls for NPPs

Abstract Precast composite slab‐shear wall structures are advanced systems to accelerate the construction of nuclear power plants (NPPs). Nevertheless, the joints between slabs and shear walls constitute critical weak zones under vertical earthquakes. In this study, a composite slab‐shear wall joint (CSSWJ) with ultra‐high performance concrete (UHPC) and a short lap‐splice connection was proposed, and its performance was investigated through experiments and numerical simulations. Cyclic loading tests were performed on an RC joint and a UHPC CSSWJ. Subsequently, a numerical parametric study was conducted to evaluate the effects of the slab reinforcement ratio (SRR), height‐to‐thickness ratio (HTR), UHPC length (UL), and UHPC‐shear wall interface properties. Results indicate that the UHPC CSSWJ exhibits a superior mixed flexural‐sliding failure mode with higher bearing capacity and energy dissipation than the RC joint. To ensure optimal ductility, an SRR of 0.30%–1.20% and an HTR exceeding 4.0 are recommended. Additionally, increasing UL enhances strength without compromising ductility, while sufficient interface properties are critical for structural integrity. The proposed UHPC CSSWJ demonstrates promising potential for application in NPPs.