Study on punching performance of <scp>UHPC</scp> ‐ <scp>NC</scp> composite slab

Abstract In this study, a series of punching shear tests were conducted on eight concrete slabs, including one conventional C50 concrete slab and seven innovative ultra‐high performance concrete‐normal concrete (UHPC‐NC) composite slabs. The experimental program aimed to evaluate the structural behavior of composite slabs through comparative analyses of deflection characteristics, ultimate load‐bearing capacity, and overall serviceability. The results demonstrate that the UHPC‐NC composite slabs exhibit a 28.5%–42.3% enhancement in ultimate punching shear capacity compared to conventional slabs, accompanied by superior plastic deformation capability and crack control performance. To further elucidate the shear resistance of UHPC‐NC composite slabs under loading conditions, a detailed analysis was performed to assess the influence of UHPC thickness, reinforcement ratio, and slab thickness on the shear performance of these slabs. Additionally, based on the plastic limit theory, a computational formula was formulated to estimate the punching shear capacity of UHPC‐NC slabs.