Punching shear strengthening of two-way flat slabs using CFRP rods

The results of an experimental program on two-way reinforced concrete (RC) flat slabs under punching shear due to central loading are presented in this paper. All the six RC slabs were designed according to ACI 318-08 code provisions. Two slabs served as control without any modification while the other four were strengthened in different ways: one with M16 screws and nuts, and three with CFRP rods. For strengthening in each case, 8 and 24 strengtheners were used. A method is proposed for predicting maximum loading capacity of slabs strengthened with CFRP rods and with epoxy resin in drilled holes. The results of the experiments showed that the selected strengthening method was not only able to improve the maximum loading and deformation capacity of the slabs but also avoided brittle failures likely to occur under vertical point loadings.