Flat slabs that are supported directly on columns, without beams between the columns, generally transfer a significant concentrated load that affects a relatively small area. The critical element of this system is the slab to column connection because of the concentration of shear stress that is generated in the connection zone, and due to the slab punching risk. The term punching shear denotes slab failure in the zone where the concentrated load is applied, or in the support zone (column) due to shear stress. The punching shear strength is an extremely significant parameter for the design of flat slabs, i.e. the slabs supported directly on columns, without beams between columns. Slab punching design models are presented according to ACI Code