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The paper deals with the punching resistance of flat slabs with openings adjacent to a column. The results of an experimental campaign carried out at a laboratory of the Slovak University of Technology in Bratislava (STU) are presented in the paper. A total of eight slabs with a thickness of 250 mm and without transverse reinforcement were tested under axis‐symmetric conditions. The six slabs had two symmetrically placed openings with different distances measured from the column's periphery and two reference slabs did that not have any openings. The results obtained were compared with punching resistances assessed using the design equations introduced in Eurocode 2, Model Code 2010, ACI 318‐14, and the CSCT model expressed in a closed form. Significant differences in the values of the Vtest/VR,c ratio were observed for the different positions of the openings for each design model. In order to increase the accuracy of the models, some changes in estimating the reduced lengths of the control perimeter were proposed.

Flat slabs are commonly used structures in contemporary architecture. Although their common use there is still problem in design of these structures. The openings adjacent to a column are often used for plumbing and such a position of the openings increases shear stresses in the flat slab near the column. This paper deals with experimental work focused on the punching shear resistance of the flat slab specimens with openings adjacent to column compared to the flat slab specimens without openings. The opening influence is determined experimentally and by using models for the assessment of punching resistance from relevant standards and codes. The material properties of concrete and reinforcing steel were obtained from the laboratory tests.

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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.