Strengthening and repair of circular RC slabs with openings using CFRP strips under repeated loading

• We test thirteen circular RC slabs which have a different shapes of openings.
• Strengthened slabs exhibit much stiffer responses than the unstrengthened slabs.
• The role of CFRP in repairing slabs is bigger than its role in strengthening slabs.
• Using CFRP lead to significant improvement in the flexural capacity of circular slabs.

The main purpose of this paper is to evaluate the effect of CFRP strips on the strengthening and repair of circular RC slabs with openings. Thirteen circular RC slabs with dimensions of (1200 mm in diameter and 75 mm in thickness) were tested under repeated loading through annular load subjected at the center of slabs. The slabs were simply supported on all edges. The experimental variables considered in this paper include the shape of openings (circle, square, and rectangular) and the strengthening schemes. The experimental results indicated that the use of CFRP strips to upgrade the circular RC slabs with openings has significant effect on ultimate load and deflection. Depending on the CFRP strengthening scheme used, the ultimate load capacity was increased by (27–52)%. The role of CFRP strips in repairing circular slabs was found to be bigger than its role in strengthening circular slabs.