Document Type : Original Article


Structural Engineering Department, Faculty of Engineering, EL-Mansoura University, Egypt


The present paper presents an experimental investigation for the behaviour of flat plates provided
with drop parts formed by partially decreasing both top and bottom fibers of the plate. The
experimental study has been carried out on sixteen plate specimens one of them is kept flat without
any drop parts to be the control case, while the other specimens are provided with drop parts
having the same thickness of the plate, while they are located at different locations of the plate.
The locations of the drops parts, considered in the present study, are the intersections of; two
middle strips, two column strips, and one middle and one column strips. All plates had the same
thickness and the same aspect ratio of 1.0, while the main parameters in the study were the
dimensions of the drop part, the drop height and the location of the drop part. The plate specimens
were supported on four concrete short columns and subjected to uniformly-distributed flexural
loading where the cracking load, the overall cracking patterns in both sides after failure and the
ultimate load are reported. The steel strains at selected locations and the deflection at chosen
points are also measured. The stdy shows that the presence of drop paxts in flat plates has a
significant effect on the mode of failure of the plate while, this effect depends on the location and
the size of the drop part. The deflections of the plate specimens at various measuring points and
the strains developed in the reinforcing steel are also sensitive to the presence of such drop parts.
The study brings out the surprising result that the load carrying capacity of plates with drop parts is
relatively more than that of the flat plates without any drop parts.