Cumulative damage of reinforced concrete subjected to repeated impact

Abstract This study was performed to develop methods of measuring the cumulative damage of steel reinforced concrete slabs subjected to repeated impact. Cumulative damage was monitored by measuring the crater depth and the reduction in ultrasonic pulse velocity across the impact region. Crater depth generally increased with increasing number of impacts and therefore was determined to be a reasonable indicator of cumulative damage. The percent reduction in velocity generally increased with increasing number of impacts up to about 40 percent or more of the total number of impacts to failure. Beyond that, interpretation of the ultrasonic results with respect to the failure mechanism appears necessary. The addition of steel fibers to the bar grid reinforcement resulted in substantial increases (about 2 to 7 times or more) in the total number of impacts to failure as compared to specimens with only bar grid or expanded metal placed at the midpoint of the slab thickness.