Theoretical Method of Calculation to Determination the Change of Axial Force in a Reinforcing Bar During the Destruction of the Support Zone of the Central Column in the RC Structures

摘要

The behaviour of reinforced concrete slab-column structures under the impact of accidental loading is very significant due to safety reasons. The failure of the support zone by punching and lack of proper structural integrity reinforcement can lead to a progressive collapse. However, the instructions on how to prevent such situations are not very detailed. According to the guidelines of standard EC2, the structural integrity reinforcement should be continuous throughout the length and consist of at least two bars above the column in every perpendicular direction. EC2 does not state the amount of necessary reinforcement. The article presents a theoretical model of calculation that permits a more detailed analysis of internal forces in reinforcing bars located directly above the column. Adopting a solution in the form of exact equations makes it possible to take into account the influence of a non-linear change of the bar rigidity and considerable deflections. The calculation model was verified on the basis of the results of experimental investigations. It enables to estimate the tensile force of the bar at which it is ruptured during the destruction of the support zone.