Experimental study of moment redistribution in reinforced concrete slabs strengthened with CFRP sheets

Due to the elastic behaviour and brittle nature of CFRP composite materials, and also their tendency to debond from the surface of Reinforced Concrete (RC) members before their tensile capacity is reached, moment redistribution is often not permitted in design codes for FRP-strengthened RC flexural structures. In this study, the moment redistribution capacity of RC slabs is examined by testing seven two-span slabs with externally bonded CFRP sheets. The specimens were designed to have an upper-bound original 30% redistribution capacity before FRP strengthening. Various strengthening configurations and anchoring schemes for the CFRP fabric were used in the specimens. The experimental results showed that it is feasible to redistribute a high proportion of bending moment into FRP-strengthened zones. It was also found that the level of moment redistribution exhibited out of these FRP-strengthened zones can be significant, depending on the quantity and anchorage of the CFRP composite material used.