Seismic Performance of UHPC Post-Cast Precast Concrete Cruciform Beam-Column Joints

This paper proposes a staggered longitudinal reinforcement configuration suitable for UHPC post-cast precast joints， which significantly improves assembly tolerance during construction. The hysteretic performance， stiffness degradation， and energy dissipation capacity of the joints were evaluated through quasi-static loading tests and finite element simulations on four full-scale specimens. Parametric studies isolated key variables， overcoming the limitation of concurrent changes in tests and allowing targeted evaluation. The results indicated that the proposed joint configuration maintained a peak bearing capacity comparable to that of the specimen RC-A-2， with slight improvements in cumulative energy dissipation and ductility. All specimens exhibited a flexural failure mode at the beam ends， in accordance with the “strong joint-weak component” principle. Furthermore， tests demonstrated that the larger-diameter longitudinal rebar scheme substantially reduced the number of rebars and increased rebar spacing in the joint zone while maintaining essentially equivalent bearing capacity. This effectively reduced the risk of rebar collision during assembly， thereby showing potential for improving construction efficiency. The numerical analysis results showed good agreement with the experimental data， validating the model. This confirmed that the UHPC post-cast precast joint exhibits superior seismic performance and shear resistance compared to joints with conventional cast-in-place materials.