under some circumstances, this practice can result in a weakened slab and decrease its ability to bear weight, as it
creates a discontinuity in the reinforcing bars. This research aims to examine the flexural behavior of two-way R.
C. slabs with an opening. The parameters of the study included the surface area, the number of layers of glass
fiber-reinforced polymer (GFRP) sheets, and the method of strengthening, which involved a combination of
externally bonded reinforcement (EBR) and near-surface mounted (NSM) strengthening techniques to effectively
control cracking. Additionally, examine the use of anchors with externally bonded fiber sheets to enhance
bonding efficiency. The design of this approach aims to reduce the risk of premature debonding, prevent
strengthening failure before rupture, and enhance the overall effectiveness of the strengthening process. A total
of ten reinforced concrete two-way slabs were fabricated and subjected to progressive static loading for testing
purposes. The examined slabs all have identical measurements: 100 mm for thickness, 1100 mm for width, and
1100 mm for span. All specimens were divided into two groups: Group I included two slabs, one of which was
solid without openings, and the other had a central square opening measuring 300 mm. Group II consisted of
eight slabs, all of which had a central square opening measuring 300 mm. In group I, the reference two-way slab
without openings was not strengthened, nor was the reference two-way slab with a central opening strengthened.
In group II, five two-way slabs were strengthened using externally bonded glass fiber-reinforced polymer (EB-
GFRP) sheets on the tension side. One two-way slab was internally strengthened by using reinforcing steel bars
around the opening. Additionally, two two-way slabs were strengthened using the near-surface-mounted tech-
nique (NSM). Specimens were loaded until failure occurred. Failure modes, cracking patterns, ultimate loads, and
load-deflection relationships of all slabs were computed and contrasted for both groups, where the different
strengthening techniques contributed to increasing the load capacity by 15–40 percent compared to the reference
slab with an opening. In this study, experimental testing, theoretical equations, and finite element modeling
using the ABAQUS program were used to evaluate the performance of RC two-way slabs with openings under
various strengthening configurations. The results of the experimental tests, theoretical equations, and finite
element modeling demonstrated a high degree of agreement, with the average ratio of theoretical to experi-
mental ultimate load (PThe/PExp) ranging from 0.92 to 1.03, and the average ratio of finite element to experi-
mental ultimate load (PFE/PExp) ranging from 1.00 to 1.09. |
