Dynamic behaviour of sandwich panel-reinforced concrete composite slabs under low-velocity impact

This study investigated the low-velocity impact response of sandwich panel-reinforced concrete composite slabs through drop hammer tests and numerical simulations. The force-time history, displacement-time history, failure modes, and strain development were analysed to reveal the effects of the protective layer, impact energy, and reinforcement ratio on the dynamic behaviour of composite slabs. Test results revealed that the sandwich panel significantly mitigated shear failure in the reinforced concrete slab. Compared to the reinforced concrete slab, composite slabs developed reduced peak forces and deformations under impact of the same energy. A higher impact energy resulted in increased deformations and damage to the slabs, with the failure mode transforming from bending failure to a combination of bending and punching shear failures. Composite slabs with larger reinforcement ratios could develop greater impact resistances. Furthermore, finite element models were developed for composite slabs under impact. Numerical results show that the sandwich panel develops a cushioning effect and absorbs a large portion of the impact energy initially. Parametric studies reveal that compared to increasing the reinforcement diameter, increasing the reinforcement ratio by reducing the reinforcement spacing is more effective in improving the impact resistance of composite slabs. Besides, although higher-strength concrete can improve the impact resistance of composite slabs, it also increases the risk of punching failure as the concrete is more brittle. This study provides valuable results for designing sandwich panel-reinforced concrete slabs to resist impact loads.