Author : F. Ali, Adnan
journal of kerbala university,
Volume 10, Issue 2, Pages 238-252
An experimental program to study the behavior of reinforced concrete slabs under impact loading was carried out through this work . Experimental work included testing of fifteen two-way reinforced concrete slabs , three of which were tested under central concentrated static loads while the others were tested under impact loading by means of a falling mass at the center of the slab .A steel ball of (90mm) diameter and (3 kg) weight was used as a falling mass for all the impact tests.
The main test variables in this study were: dimensions of the slabs , reinforcement ratio, height of fall of the striking object and support conditions of the slab. The maximum transient and residual central deflections were measured in each impact test using linear variable differential transformer(LVDT).It was found that the central deflections are proportional to the height of fall of the striker at low heights(less than 600 mm)for all tested slabs under impact loads. These deflections were found to be much larger with a slight increase in height of fall of the striker ( almost a double value of deflections was noticed at an increase in fall of less than 25 % beyond 600 mm height of fall ). Also ,it was found that , with the repetition of strikes and as the falling height of the striking object increases , cracks at the bottom faces of all slabs starts prior to those at the top face . However , cracks do not propagate longitudinally or widen with the increase of heights of falls but rather scabbing of the concrete starts to form with large pieces of concrete scabbs out at larger drop height .