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In this paper, the effect of cyclic loading on punching strength of flat slabs strengthened with Carbon Fiber Reinforced Polymer (CFRP) sheets is studied. Experimental results of ten slab specimens under monotonic and cyclic loading are analyzed. Eight specimens were strengthened with CFRP sheets on the tensile face of the slabs and the two other specimens were kept un-strengthened as control specimens. The width of CFRP sheets varied in different specimens. After the tests, the punching shear strength of specimens under cyclic loading was compared with those with monotonic loading. The comparison of results shows that cyclic loading decreases the effect of CFRP sheets on punching shear strengthening. This decrease was more for the specimens with a larger value of reinforcing steel ratio. Therefore, it can be concluded that for specimens with large reinforcing steel ratios, cyclic loading may completely eliminate the effect of CFRP sheets on shear strengthening of slabs.