Experimental study of reinforced UHDC-UHPC panels under close-in blast loading

Ultra-high ductile concrete (UHDC) has excellent tensile ductility, and ultra-high performance concrete (UHPC) possesses ultra-high compressive strength and hardness. It is expected that the combination of UHDC and UHPC should possess better blast-resisting capacity. This paper presents the dynamic performance of reinforced UHDC-UHPC panels under close-in explosion. Four reinforced UHDC-UHPC panels with different steel ratios were tested at scale distances ranging from 0.5 m/kg(1/3) to 0.8 m/kg(1/3). These panels show excellent resistance to local damage. Concrete cratering and punching failure on the UHPC surfaces are almost eliminated, and only multiple micro-cracks (no more than 100 mu m) occur on the UHDC surfaces. The numbers of micro cracks appeared on the UHDC faces decrease from 391 to 125 with the increase of scale distance. And with decreasing steel ratio, micro-crack number increases from 271 to 937. Moreover, maximum displacement and residual displacement decrease with increasing scale distance or steel ratio. The velocity and average acceleration in nonlinear state increase with decreasing scale distance, and the natural period and damping ratio in linear state reduce as damage level decreases.