Improvement of the Method of Calculating Plates for Punching

Abstract

The article formulates proposals for improving the calculation methodology for punching. The methods in the current regulatory documents for assessing the tensile strength are based mainly on empirical dependencies obtained on the basis of numerous experimental studies. It should be noted that they give reliable results if certain design requirements are met (typical column sections). Along the interface line of the plate with a rectangular (square) column, supporting bending moments act in two orthogonal directions. The magnitude of these moments for the most common spans is large and, in an elastic setting, exceeds the span by two times. Taking into account the redistribution of forces and the most likely formation of cracks in the stretched zone, it can be argued that in the operational stage, the support sections of the plates have compressed and stretched zones. With such a stress-strain state, in the calculation scheme, when evaluating the tensile strength, the stretched part of the side surface of the “reduced” pyramid, bounded by the neutral axis along all faces, should be excluded. As a result, expressions are presented to determine the parameters of the reduced punching pyramid and the value of forces in concrete and reinforcement at the maximum bearing capacity stage.