Investigation on the response of steel fiber reinforced lightweight aggregate concrete slab under sequential impact loading

The current study investigates the response of steel fiber-reinforced lightweight concrete slabs under sequential impact loading. The potential damages caused by impact loads which are a threat to many structures and the use of fiber to mitigate them was evaluated experimentally. Moreover, a comprehensive parametric study was conducted using the finite element method to evaluate the effect of influential factors such as fiber content, slab geometry, and energy of impact. The results show that impact loads can cause significant damage to lightweight aggregate concrete slabs, including cracking and spalling. The use of steel fibers in lightweight aggregate concrete can improve its stiffness, energy absorption, overall stability, and prevent crack propagation resulting in the reduction of the damage risk under impact loads, compared to specimen without fiber. The incorporation of fibers resulted in a significant rise in the number of impacts required for failure. In contrast to the control slab, which failed completely after three impacts, lightweight concrete slabs containing steel fibers at volume fraction of 0.5%, 1%, and 1.5% endured 87, 710, and 1213 impacts before failure, respectively. In addition, adding steel fibers causes a more consistent response in terms of stiffness as the frequencies of lightweight concrete slabs containing steel fibers at volume fraction of 0.5%, 1%, and 1.5% remained unchanged until 34%, 17%, and 40% of the total number of impacts resulting in failure. Moreover, the utilization of fibers preserves structural integrity and localizes crack formation. Overall, the current study provides valuable insights into the response of light weight aggregate concrete structures under impact loading and the potential benefits of using steel fiber and lightweight aggregate in concrete.