Experimental analysis of punching shear strength of eccentrically loaded slab with the opening along the face of the internal column

•The eccentric load in the slab significantly reduces its punching shear.•The place of the opening in relation to the bending moment affects the punching shear.•The analyzed codes do not take into account the direction of the bending moment.•The punching force in accordance with Codes is notably lower than experimentally. The aim of this study is to discuss the punching shear strength of flat RC slabs supported directly on columns. Special attention is paid to slabs which, in addition to axial load, are loaded with an unbalanced bending moment caused by the eccentricity of the force in relation to the vertical axis of the column with the presence of an opening along the face of the internal column. The slabs with the opening are made in such a way that no additional reinforcement is placed around the openings themselves. The reason for this is an attempt to simulate the subsequent formation of an opening in the slab for the purpose of passing various types of installations in the existing structure. The experimental research included tests on seven RC slabs without shear reinforcement with a loading up to the punching shear failure. By varying the position of the opening in relation to the eccentrically loaded column, as well as the shape and dimensions of the column, the degree of reduction in punching shear strength caused by the eccentricity of the force and the position of the opening in the slab was determined. The measured forces due to which the punching shear failure occurred were compared with the calculated ones obtained in accordance with the design codes prescribed by the leading world standards (EC2, ACI 318 and MC 2010) as well as with existing experimental research from the published literature.