Behaviour of Reinforced and Prestressed Concrete Slabs Under Multiple Impacts

In the present study, the performance of reinforced and prestressed concrete slabs was investigated against multiple drop impacts. The slab specimens were cast using two different concretes having 28 days strength of 48 and 68 N/mm2. The span length of the slabs and thickness were kept the same for all the slabs as 0.80 m and 100 mm, respectively. The level of prestressed in the slabs varied between 0 to 30%. A known mass of 242.8 kg was lifted to 1.0 and 0.5 m height and dropped freely to hit the target slabs multiple times. The deflection, impact force, reaction, progress of damage, energy, acceleration and strain were measured through different sensors and compared. Under the first impact, the magnitude of impact force and reaction increased in the prestressed concrete by 20 and 36%, respectively, compared to reinforced concrete. On the other hand, the deflection was reduced by 28% in prestressed concrete. Under multiple impacts, the impact force and reaction were noticed to have reduced and increased, respectively. The deflection increased under multiple impacts due to the accumulation of damage. A nominal influence on prestressed concrete was witnessed in the energy absorbed by the slabs. The energy was reduced by 10% with an increase in the strength of concrete. The reinforced concrete witnessed flexure–shear deformation, while prestressed concrete witnessed splitting–shear deformation under multiple impacts.