Performance improvement of precast, reinforced and prestressed concrete raft units (beam and slab) under impulsive loading

Abstract

In recent years, there has been an increasing use of concrete in various fields of construction activity. Not only is concrete being used for offshore structures, nuclear power plants and barges, but there is a growing possibility that it could also be used for structures in space [1]. Additionally, the application of high strength concrete and prestressed concrete is becoming increasingly common. The study of the behaviour of structures under impulsive loading is still in its infancy. There is a need to study quantitatively the mechanical behaviour of those structures, especially in the stages prior to failure. Furthermore, performance improvement indices and concepts of performance improvement have to be determined in order to design impact resisting structures. The design codes in most countries adopt an equivalent static load in representing impact loads [2, 3]. But even though it is effective up to the maximum stresses, it would not be able to withstand the effects of excitation of the higher modes of vibration, a change in failure mode due to propagating stress waves, scabbing at the rear face of the impacted structure, etc., which are peculiar to structures under impulsive loads. Therefore, there is a necessity for a dynamic approach in designing such structures.