Strengthening of RC one-way slabs including cut-out using different techniques

Often, it is essential to introduce a cut-out in an existing reinforced concrete slab for facility requirements. That cut-out poses a break in the continuity of the slab loading trajectories. Hence, a great attention has to be paid to the adopted strengthening approach in order to restore the flexural resistance of the slab included cut-out. To investigate the structural flexural performance of strengthened one-way reinforced concrete slab included cut-out, six slabs including cut-out adjacent to the central patch load in addition to one slab without cut-out as a reference slab were tested up to failure under incremental monotonic loading. The six slabs including cut-outs contained one control un-strengthened slab along with five strengthened slab. These slabs were strengthened using either Near Surface Mounted (NSM) steel bars or Externally Bonded Carbon Fiber Reinforced Polymer (EB-CFRP) at the tension side, while four out of them were strengthened by either NSM-steel bars (one slab) or an overlay of Engineered Cementitious Composites (ECC) material (three slabs) at the compression side. It can be concluded that end anchors for the EB-CFRP sheets along with the surface preparation before installing the ECC overlay are very important parameters in order to guarantee the optimum utilization for both the EB-CFRP sheets and the ECC overlay material. In addition, the test results showed that the hybrid strengthening technique incorporated NSM-steel bars in tension side along with ECC overlay in compression side showed its superiority among all proposed strengthening schemes. It is not only allowed the slab included cut-out to restore its flexural resistance, but also it enabled the slab to outperform its structural performance compared to that of the slab without cut-out.