Experimental investigation on reinforced concrete slabs under high-mass low velocity repeated impact loads

Reinforced concrete slabs are among the most common structural elements. Despite the large number of slabs designed and constructed, the effect of their details on their behavior under impact loads is not always properly appreciated or taken into account. This paper describes a series of experimental studies to investigate the high-mass, low-velocity impact behavior of reinforced concrete slabs, and to provide high-quality input data and results to validate numerical modeling. The experimental scheme, which consisted of testing six sample two-way slabs with simply supported boundary conditions, was tested to failure under sequential high-mass, low-velocity impact loading conditions. The effects of different reinforcement ratios of slabs and the compressive strength of concrete on the dynamic response and behavior of reinforced concrete slabs were studied. The data indicated that the slab response is affected by the increase in the compressive strength of concrete, and it causes a clear increase in the load time history. But obviously, the load-time history is not affected noticeably by increasing the reinforcement ratio. The observed damage and crack development were found to be typical between the RC slabs. In the beginning, for slab group (1), which investigated the effect of increasing the steel reinforcement ratio, the slab with the largest reinforcing ratio was more resistant to local damage, and the cracking pattern on the bottom surface of the slab consisted of primarily discontinuous hairline cracks. The penetration and scabbing increased for the slab with one mesh S23 by ejecting the concrete around the reinforcing bars. For group (2), the decrease in the penetration and the scabbing area is observed because of the increase in the strength of concrete. For all slabs, the development of inertial forces under impact loading conditions led to observed responses and failure modes that were governed by shear.