Numerical simulation on the dynamic response of bonded unidirectional prestressed concrete slabs subjected to low-velocity impact

In this study, the dynamic response of bonded unidirectional prestressed concrete slabs subjected to low-velocity drop hammer impact is numerically investigated by using finite element software LS-DYNA. The feasibility of the finite element models is verified using experimental results available in the literature. With the verified FE models, the dynamic response of bonded unidirectional prestressed concrete slabs is analyzed in terms of the impact force, displacement, energy dissipation, and failure modes by changing the parameters of prestressing degree, drop hammer weight, and impact velocity. The results show that the response of the prestressed concrete slab under the impact of the drop hammer can be divided into five stages, which are the initial impact stage, the inertial loading stage, the inertial unloading stage, the secondary loading stage, and the impact unloading stage. The deformations of the slabs consist of global deformation and local deformation. Impact kinetic energy is the key parameter that determines the dynamic response of the specimen, which could be used to derive the calculation formula of the specimen. With the increase of the impact kinetic energy, the main response of the specimen is changed from global response to local response. The concrete dissipates most of the impact energy under the impact of the drop hammer, which is above 67%, and the dissipation effect of the prestress bars is neglectable, which is less than 5%. The increase of unidirectional prestress can improve the impact stiffness and the penetration resistance of the slabs, and increase the proportion of local response in the specimen.