Experimental and numerical studies on the drop impact resistance of prestressed concrete plates

The drop impact resistance and the resultant energy absorption capacity of prestressed concrete plates have been studied through detailed experimental and numerical investigations and the resultant outcome has been compared with the non-prestressed concrete plates. The concrete plates of span, 800 mm × 800 mm, have been pre-tensioned to 10 and 20% of the characteristic compressive strength of concrete (60 MPa), and these have been subsequently impacted by steel hammer (243 kg) falling at the center of span from 500 and 1000 mm height. The impact-force, support reaction, displacement and energy absorption have been obtained and compared with the non-prestressed concrete targets. A numerical study has been performed in ABAQUS/Explicit finite element code using Holmquist-Johnson-Cook (HJC) constitutive model for concrete, and metal-plasticity model for the reinforcement and the prestressing wires. Impact-force and the support reactions of the prestressed concrete plates (20% prestress) have been found to have enhanced up to 4.5 and 38% due to improved plate stiffness. The displacement of the plate, on the other hand, has reduced up to 28% in comparison with non-prestressed concrete. The impact-force and the support reactions have been reproduced numerically within 11.4 and 15.4% deviation, respectively. With the increase in drop height, the punching-effect became more pronounced in both the concretes. The reinforced and prestressed concrete plates have suffered flexure and tensile (splitting) dominant cracks, respectively, along with the shear cracks. The peak displacement and energy absorbed by the plate have also been obtained through analytical calculations and the results have been compared with the experiments.