CFRP STRENGTHENING OF CIRCULAR CONCRETE SLAB WITH AND WITHOUT OPENINGS

This paper includes an investigation and experimental testing of R.C circular slabs with and without opening and strengthens with CFRP sheets, CFRP bare, and both. Normal concrete (NC) and self-compacted concrete (SCC) were used to cast the slabs. The experimental part includes testing of fourteen circular slabs divided into four groups having diameter of 1200mm and thickness of 80mm. Three types of strengthening used; the first type is CFRP sheets only, the second type is CFRP bar only, and the third type is the combination of the two types of strengthening (i.e. CFRP sheets and CFRP bar together). The use of CFRP sheets delays the appearance of the cracks by (14.75%-51.76%) compared with slabs without strengthening. The experimental results showed that the opening existence in the slabs without strengthening reduces the ultimate load carrying capacity by (24.98%-27.77%) compared with slab without opening, and the higher reduction in the ultimate load occurs in the slab (S2S2) by (30.55%) which is strengthen with CFRP sheets and contains two square opening. The increase in load carrying capacity of slab due to strengthening was (3.72%-26.18%) compared with the same slabs without strengthening. The optimum a result of strengthening was in the slabs strengthen by compensation of CFRP sheets and CFRP bar by increasing percentage (18.31%-26.18%) compared with unstrengthen slabs with openings. The numerical analyses present three-dimension nonlinear model by using computer program (ABAQUS 6.13).