Effects of fragments impact on reinforced concrete protective elements

A common type of extreme loading on structures includes combination of blast and fragments impact. Because of the complex nature of this combined load design and verification procedures of protective structures usually decouple the effects of overpressure and of the fragmentation impact. Although it has been shown that the simple addition of the separate actions of the fragments and the blast inflicts lower damage than that caused by their combined loading, the synergistic effect of blast and fragments has yet to be investigated. Studies of reinforced concrete (RC) protective structures have shown that the main cause of increased damage to a structure, which is exposed to blast and fragments, is the fragments penetration that in many cases occurs first. To investigate the combined effect of blast and fragments impact, field tests were performed, of full-scale RC T-walls, which were subjected to the action of a detonated cylindrical cased charge that produced blast and fragments impact. The impacted specimens were then sawed at their bases and the remaining damaged plates were tested in the laboratory under 3-point loading setups. The aim of these tests was to study the fragments penetration effects on the residual mechanical properties of a damaged wall. The paper presents initial results of these static tests of the damaged, as well as control, undamaged specimens.