Experimental Study of Reinforced Concrete Slabs under Different Loading Rates

Eighteen reinforced concrete (RC) slabs were manufactured and tested under static (0.0004 m/s [0.0013 ft/s]), medium (0.4 m/s [0.13 ft/s]), and high (2 m/s [6.6 ft/s]) rates of concentrated loading at slab center using a displacement-controlled rapid-loading machine. The data from the experiment were used to study the effects of loading rates and other parameters (such as slab depth and longitudinal and shear reinforcement ratios) on the performance of RC slabs. From test results, the load-carrying and energy absorption capacities of specimens, inertial force, and strain rate were found to increase with higher loading rates. Shear reinforcement was found to be more effective than longitudinal reinforcement in enhancing slab's performance under a high loading rate. The failure modes of specimens were governed by punching shear irrespective of loading rate. Additionally, another six slabs were made and tested under low-velocity (5.425 m/s [17.8 ft/s]) impact using a drop-weight machine. A comparison between the results from high loading rate and impact tests indicates similar damage process, failure mode, strain rate, and energy absorption capacity. This comparison well correlates a high-loading-rate test with impact testing, which suggests the possibility of using high load rate test to help understand slab's performance under low-velocity impact.