Structural properties of RC plates damaged by fragmentation impact

This paper describes a second stage of a comprehensive experimental study of the fragment damage effect on the mechanical properties of reinforced concrete (RC) elements. In the first stage, RC elements were exposed to fragmentation impact in a field test series. These specimens were then brought to the laboratory together with reference undamaged specimens, to experimentally study their structural behavior in three-point bending static tests. All specimens exhibited a flexural failure mode and the characteristics of the resulting load-deflection curves are presented and analyzed. The effects of the fragmentation impact from the preceding field tests show differences between the behavior of the undamaged and damaged specimens with respect to their flexural moment capacity, stiffness, deflection capacity and structural ductility. Additionally, evaluation of an equivalent cross-section height is presented, which enables flexural analysis of RC elements under a combined loading of blast and fragments, in cases where the fragments reach the element before the blast (or at the same time). The quantitative results that have been obtained in this study emphasize the importance of considering the damage due to the fragmentation impact, which cannot be neglected, at least within a certain standoff distance.