Design model for transferring longitudinal pipe forces using thrust rings

The load-carrying behaviour of thrust rings for the transfer of axial loads from the penstock to the bedrock was studied recently. Based on the laboratory tests of the pipes, finite element models (FEMs) were calibrated in order to investigate large-scale thrust ring configurations. A simple design model was developed based on a parametric study, considering practical dimensions. This design model covers the calculation of stiffness, ultimate load-carrying capacity and stress distributions in the elastic range, and is presented in this paper. In addition, complex load-carrying behaviour is demonstrated in an example and the background of the design model is shown in detail. Finally, the distribution of longitudinal force in the case of several thrust rings was investigated, leading to a simplified design rule for the most highly stressed thrust ring.