Study on the mechanism of prestress loss caused by friction in the free segment of anchor cables

Significant prestress loss can substantially weaken or even eliminate prestressed anchor cables' support effectiveness. One of the major contributors to this loss is the free segment frictional resistance, the causes and mechanisms of which remain unclear. In this paper, a simplified steel strand-grout contact pressure relation is established. Using static analysis, a formula for calculating free segment frictional resistance is derived. Finite element analysis and on-site tensioning tests confirm the accuracy of this formula, emphasize the influence of isolation brackets on free segment frictional resistance, proposing that the formula can effectively predict the prestress loss caused by free segment friction.