Experimental Investigation of the Maximum Punching Resistance of Slab-Column Connections

Flat slabs represent a structural system with a typical concentration of shear forces near the vicinity of its local supports. A possible failure from punching is a dangerous phenomenon due to the brittleness and possible progressive collapse of a whole structure. An improvement in the structural behaviour of a slab-column connection provides transverse reinforcement. The amount of this reinforcement and thus its contribution to the resistance against punching has a limit, which is represented by the maximum punching capacity. This capacity can be assessed using the kmax factor or by direct verification of the strut capacity. The article deals with the results of a test campaign carried out on flat slab specimens with their transverse reinforcements designed in such a way that the crushing of the struts is the governing mode of any failure. The test results obtained allowed for an evaluation of the kmax factors and provide an answer as to whether it is possible to cover failures due to the crushing of struts by this factor.