Abstract: “Introducing openings in existing reinforced concrete slabs can severely weaken the slabs due to the cut out of both concrete and reinforcing steel which affects the overall behavior of the slab. This paper examines, experimentally, both the effect of openings either in column/field strips or in column/column strips and the effect of strengthening the opened flat slabs with sheets of Carbon Fiber Reinforced Polymers (CFRP) as a way of restoring the original load capacity of the flat slabs without openings. A total of five large scale reinforced concrete (RC) slabs were tested up to failure. It was found that the location of the opening is effective on the behavior as it affects the ductility, toughness and failure modes. Also, it was concluded that CFRP strengthening of slabs with openings affects both failure load and failure mode of slab. Due to presence of openings, the specimens showed a decrease in failure load capacity by about 25% with respect to the control slab S1. The use of C”

Keywords: Flat Slab, Openings, Strengthening, CFRP, Continuous, Debonding.