Researcher Namir Muhammad Jawad's master's thesis was discussed at the College of Engineering, Department of Civil Engineering, University of Basra, entitled EFFECT OF OPENING ON ONE-WAY CONTINUOUS RC SLAB

Openings in concrete slabs have become one of the basic requirements
that must be taken into account when designing buildings and concrete structures
in general, due to the urgent need for these openings for the purpose of passing
water, electricity, sewage services, and air conditioning ducts, etc... Many
previous studies have delt with the topic of openings in reinforced concrete slabs
of various types, but there are no sufficient studies that have focused on the effect
of openings in one-way continuous slabs. Therefore, for the importance of the
topic, this study focused on the effect of openings in continuous RC one-way
slabs.
This thesis presents an experimental study comprising fourteen
specimens, supported by an analytical study involving eleven specimens analyzed
using the finite element method in the ABAQUS program. This analytical study
is considered a complement to the experimental study to obtain sufficient results
that cover the topic of this thesis.
The variables of the experimental study and theoretical study were the
opening size, the opening location, the additional reinforcement diagonally
around the opening, the slab thickness, and the compressive strength of concrete.
The dimensions of specimens were 2200mm in length, 600mm in width, and the
thickness of 120mm and 150mm. To achieve the continuity of the slab, three
supports were supplied. One support at the middle of the slab and two supports at
the ends of the slab, and the clear span of each span was one meter. Two vertical
line loads were applied symmetrically at the center of each span. The initial
analysis of the control slab indicated that the highest stress zone was at the middle
of the slab and at the middle support zone. Therefore, openings of different
dimensions and locations around the central support of the slab were considered.
The results of both experimental and theoretical tests indicated that the
openings in the continuous RC slab have significantly affected the load capacity,
displacement, and ductility of the slab, which is the structure's ability to undergo
significant inelastic deformation without loss of strength, especially when the
opening is located close to the high-stress zone. All variables have negative effects
on the slab; however, the most influential was the location of the opening and the
closeness of this opening to the high stress zone. The maximum reduction of the
ultimate load and displacement caused by the opening of size 160mm*400mm,
which is located in the high stress zone, was 30% and 35% respectively. The
additional diagonal reinforcement in the corners of the opening significantly
enhanced the load capacity and the ductility of the slabs. The reduction of concrete
compressive strength highly decreases the load capacity, displacement, and
ductility of the slab.