Experimental investigation of prestressed and reinforced concrete plates under falling weight impactor

A detailed experimental investigation has been carried out for investigating the influence of induced initial stress on drop impact response of concrete plates. The square shaped (800 mm) concrete plates of 100 mm thickness have been induced an initial stress of 10% of unconfined compressive strength (48 N/mm2) through pre-tensioning of high strength steel wires. The plates were then impinged at the center point of span through a steel hammer of 243 kg falling freely from 500 and 1000 mm height under the action of gravity. The impact force-time response of falling weight impactor, reaction-time response at supports, displacement-time history, acceleration and force-displacement response of impacted plates were recorded and the post-test damage evaluation has been carried out. The behavior of the prestressed concrete plates thus studied with respect to two different drop heights has been compared and discussed. Further, in order to study the influence of the induced initial stress on the impact response, the results of the prestressed concrete plates have been directly compared with the reinforced concrete plates of equivalent thickness. Peak impact force observed in prestressed concrete plates were 12.2% and 5.4% higher for drop height 500 mm and 1000 mm, respectively. The energy loss in prestressed concrete plates has been found to have reduced to 3.71% compared to 10.57% in reinforced concrete plates with the increase in the drop height.