Retrofitting of reinforced concrete flat slabs with cut-out edge opening

Abstract

In existing buildings, it is common to create openings in slabs due to service supplies. In this case, the mechanical properties of slabs remarkably reduce, and strengthening must be applied. Therefore, this investigation proposed four methods to retrieve the lost mechanical characteristics of slabs owing to openings. Six reinforced concrete slabs were prepared with similar dimensions, 1300 × 1300 × 120 mm. One of them was reference without opening, whereas the others contained a square edge opening of 350 mm side. For slabs with openings, one specimen was the control left without strengthening, and the remaining four were strengthened utilizing various methods, which were Carbon Fiber Reinforced Polymer (CFRP), steel plates, steel bars, and near-surface mounted Engineered Cementations Composite (ECC) with steel mesh. The slabs were exposed to uniformly distributed load up to failure. The experimental tests showed that the opening reduced the mechanical properties of slabs remarkably, and the proposed strengthening methods, except for ECC, managed to restore a significant amount of these losses.