Conceptual Anchor Plate Perturbation Method to Determine Tension in Grouted Post-Tension Anchor Rods in Dams and Other Structures

Abstract

This study proposes a conceptual methodology to determine the axial load within a grouted post-tension anchor system via finite element analysis and calibration. The concept was built on the premise that a plate under axial load can develop a zone of fixity akin to a loaded free-free beam on an elastic foundation that develops nonzero subgrade reactions. The anchor plate, when perturbed, via moderate pulling on the edges, was found to deflect in a manner uniquely tied to the applied axial force. This study reviewed a range of axial loads to develop an empirical equation from the results of a nonlinear finite element model to create a force deflection plot for a plate of interest. The developed plot, to be useful for practitioners, was recommended to undergo a calibration exercise via a mockup of the actual anchor before being applied to in situ anchors to estimate post-tension force.