CFRP strengthening efficiency on enhancement punching shear resistance of RC bubbled slabs with openings

This paper focuses on investigating the influence of creating an opening in the vicinity of a column area on the punching shear resistance of reinforced concrete bubbled slabs and the effectiveness of their strengthening with (CFRP) sheets. The experimental program was intended to study the effect of dimensions, position, and distance of the opening relative to the column; the location of bubbles relative to the two-way critical shear section; and the effectiveness of strengthening with CFRP sheets on the punching shear resistance of the slab-column connection in bubbled slabs. Fourteen slab specimens of 2000×2000x230 mm dimensions were cast and tested up to failure. The test results demonstrated the negative effect of the creation of an opening in the vicinity of the loaded area and the reduction in the load-carrying capacity of the bubbled slabs compared to the reference solid slab. Meanwhile, there is an improvement in the service and ultimate load capacities of the bubbled slab specimens with opening due to the implementation of CFRP strengthening sheets. Also, the developed model by finite element software program ANSYS showed that the results of analysis have an acceptable convergence with the results of experimental tests.