Blast resistance of ultra-high performance concrete slabs with multi-layer BFRP grids: Insights from experiments and numerical simulation

Combining fiber reinforced polymer (FRP) grid and ultra-high performance concrete (UHPC) offers a promising approach for developing cement-based composite materials for blast resistance. However, the effectiveness of different slab thicknesses and FRP grid configurations in dissipating energy under contact explosions remains uncertain. This study addressed the uncertainty by systematically exploring the role of multi-layer BFRP grids in enhancing the blast resistance of UHPC slabs. Experimental results indicated that BFRP grids reduced the crater and spall dimensions of the slabs under contact explosions and provided an additional path for blast energy dissipation. LS-DYNA was employed to simulate the damage modes, energy evolution, and destruction process of slabs with various parameters. The increasing slab thickness changed the damage modes from perforation to cratering and spalling. Adding grid layers helped redistribute tensile stresses and inhibit crack propagation on the rear surfaces. Moreover, the rotated grid configurations can make more grids participate in energy dissipation, leading to a significant increase in the internal energy of grids when the rotation angle changes from 0 to 45°. The findings clarify how design parameters govern the anti-blast performance of BFRP grid-reinforced UHPC slabs.