Load-bearing Capacity of Reinforcing Bars in the Zone of the Slab-column Connection Determined Experimentally and in the Result of Numerical Calculations

The destruction of the supporting zone of slab-column structures caused by punching pulls the upper reinforcement in the course of the dropping of the roof upwards. The only element which can deter a further catastrophe is the reinforcement at the bottom, which is not torn off, but even pressed against the concrete of the column and the slab. The paper presents the results of laboratory tests performed on a simplified model of a slab-column connection. The aim of investigations was to find out at which value of the load the destruction of such a connection occurs due to a rupture of the bars above the column. Basing on these investigations a numerical model was developed in the ANSYS program. In order to render the conditions of connecting the reinforced concrete element with the reinforcement bars in the case of considerable deformations, the model was divided into finite elements, applying the 20-node element SOLID186. In modelling the fragment of the connection of reinforcement bars with the concrete and anchoring, the contacting elements TARGE170 and CONTA174 were used. The obtained results of laboratory tests and the results of numerical calculations permitted to determine the relations between the exerted load and the displacement of the column in time and also to determine the values of the force at which the punching of the bars above the column had taken place.