The versatility of a flat slab system's design makes it popular. Openings might really be necessary to connect to public services like gas lines or deflation. In most cases, the designer has no control over where these openings must be placed in relation to or even directly next to the supporting column. In this case, the discontinuity between the concrete and reinforcing steel created by openings and flat slabs, particularly those with edge columns, is more susceptible to punching problems. The ability of a concrete slab's cross-section to withstand punching shear has an impact on that capacity. Openings that negatively affect flat slab punching shear behaviour are experimentally investigated on two specimens with different opening numbers in this research. Experimental results were used to determine the maximum load, deflection, energy absorption, and stiffness. The experimental results were compared with both the theoretical results using ANSYSV.21 software and the analytical results using Egyptian and American codes. The experimental results showed that holes in the critical perimeter surrounding columns reduce flat slabs' punching shear resistance. The decrease is inversely related to column face opening number and location. Punching capability diminishes with more openings, especially from one to two. In the slab with two openings, the ACI 318-19 code had higher maximum load values than the experimental values, but in the other cases, the maximum load values were lower. ANSYS V.21 numerical results match experimental results. The experimental results and the numerical findings produced using ANSYS V.21 agree rather well.