Punching shear strength of reinforced ultra-high performance concrete circular slabs with openings

This study investigates the punching shear behavior of reinforced ultra-high performance concrete (RUHPC) circular slabs with openings, focusing on the effects of perforation diameter, steel fiber volume fraction and shear reinforcement ratio on punching shear strength. Experimental results reveal a novel failure mechanism where energy dissipation during punching is partitioned into radial and circumferential yield line contributions, reflecting the combined ductile and brittle failure characteristics of RUHPC. A mechanical model is developed by integrating the yield line method with the rigid body displacement approach, thereby bridging plastic hinge rotations at the slab bottom and brittle fracture at the punching surface. Utilizing this model, the study further investigates the influence of the punching-to-span ratio, slab thickness, localized loading area and reinforcement ratio on the punching shear strength. The findings provide valuable insights into the design and performance optimization of RUHPC circular slabs under punching shear conditions.