Mechanically Fastened FRP-Strengthened Two-Way Concrete Slabs with and without Cutouts

The feasibility of strengthening concrete slabs in flexure, with and without cutouts, using the mechanically fastened (MF) FRP technique is investigated. Two series of large-scale reinforced concrete slabs are tested. The first series is comprised of five slabs without a cutout, and measuring 2,600x2,600x120 mm; the second series consists of four slabs of the same dimensions with a central cutout measuring 800x800 mm. The mechanically fastened system is found to be a valid alternative to the externally bonded system resulting in a rapid, economic, and effective strengthening technique for two-way concrete slabs. The increases in ultimate capacities of the MF FRP-strengthened slabs range between 30 and 70% over those of the unstrengthened specimens. In addition, finite-element modeling of MF FRP-strengthened slabs is introduced in this study. The interfacial behavior between the MF FRPs and the concrete substrate is accounted for by using appropriate interfacial models. Very good agreement is obtained between the test results and the numerical predictions.