Bursting forces in concrete panels resulting from in-plane concentrated loads

Abstract

The present state of practice for the design of bearing zones is mixed between solutions based on empirical equations, linear-elastic stress analyses and strut and tie models. If, however, the design requires large redistribution of stresses, the panel may perform poorly at service and/or overload. In this paper the results of a plane stress finite-element investigation of concentrated loads on reinforced concrete panels are presented. The numerical investigation suggests that the bursting force distribution is substantially different from that calculated using elastic design methods currently used in some codes ofpractice. The distribution of bursting stresses were found to be flatter and occur over a longer disturbed region than is predicted by the linear solution. The optimum solution for a uniformly reinforced bursting region was found to be with the reinforcement distributed from approximately 0·2 times the overall depth of the member (0·2D) to between 1·2D and 1·6D. A strut and tie model has been proposed based on the finite element analyses reported herein. The model has been shown to produce satisfactory transverse strain fields, for both strength and serviceability, when detailed in accordance with the static requirements proposed.