Dynamic response of bidirectional bonded prestressed concrete slabs subject to low velocity impact: Impact energy and prestress degree

Abstract

Bidirectional bonded prestressed concrete (PS) structures have been widely used in energy engineering. However, the systematic studies on the failure mechanism and dynamic response of this structure suffering from impact load are still inadequate. This paper has carried out nine drop hammer impact tests and corresponding numerical models. The results reveal that overall flexure and local punching co-occur in the bidirectional PS slabs under the impact, with the local punching failure as the failure mode. The dynamic response of the slab includes: inertia loading stage, load holding stage and rebound unloading stage. Due to the influence of the membrane force enhancing effect and specimen damage weakening effect, the impact force in the load holding stage may present three conditions. The compressive prestress applied to concrete can provide in-plane constraint and limit the appearance and development of cracks, resulting in decreasing the plastic damage of the specimen and the drop hammer displacement, while improving the bearing capacity and stiffness of the specimen. For impact energy of 5.48 kJ, when the prestress degree increase from 0% to 11.6%, the equivalent impact force increases 95%, the peak drop hammer displacement, equivalent spalling and scabbing diameter decrease 40%, 22.6% and 8.6%, respectively.