Behaviour of Prestressed Concrete Under Drop Impact Loading

Structures are subjected to impacts loads of low to high intensity such as developed from falling of heavy object on floors, vehicle accident with bridge columns, missile attacks during war and terrorist blasts etc. The time duration under such incident is very low, an order of few milliseconds; therefore local and global deformation behavior of structures was of great importance in past research. Moreover, under impact loading the material behavior is entirely different than under static loading conditions. Therefore, in this study, impact tests have been carried out on prestressed concrete plates to identify their behavior when subjected to drop weight impact. The prestressed concrete plates of size 0.8 m x 0.8 m and thickness 100 mm were subjected to drop impact by 242.8 kg hammer. These plates having identical material and geometrical properties except prestressing force applied for initial stressing. The compressive strength of concrete used for casting of all plates was 40 N/mm2. The impact force, deflection and failure modes of the plate specimens have been studied. It was observed that with increase in applied prestressing force impact resistance capacity of plate has been increased and magnitude of peak deflection has been reduced.