Experimental and theoretical study on seismic behavior of precast exterior UHPC-HSC beam-column connections

This research evaluates the seismic behavior of precast ultra-high performance concrete (UHPC) and high-strength concrete (HSC) beam-column connections. Quasi-static test was performed on three UHPC-HSC connections and one cast-in-place connection. The UHPC-HSC connection features a composite beam featuring precast UHPC permanent formwork and post-cast beam core, in conjunction with precast HSC column and post-cast UHPC connection. Experimental results indicated that all four specimens experienced flexural ductile failure at the ends of the beams, with the UHPC-HSC connections exhibiting superior structural integrity and reduced damage. The seismic behaviors of the UHPC-HSC connections outperform those of the fully cast-in-place connection, demonstrating plump hysteresis curves and enhanced energy dissipation capacity. Compared to cast-in-place connection, the load-carrying capacity of the UHPC-HSC connections increases by 10.84–11.48 %. Additionally, the UHPC-HSC connections demonstrate satisfactory deformation capacity, higher stiffness, and improved integrity. The ductility coefficients for all specimens surpass 3.5. The novelty of this research lies in the adoption of UHPC permanent formwork and the development of a theoretical model for predicting the bending moment of precast UHPC-HSC beam-column connections, formulated based on the plane-section assumption and incorporating the tensile strength contribution of UHPC. The theoretical predictions show close agreement with the experimental results, accurately forecasting the bending moment values at both yielding and peak loading conditions.