Corrosion Induced Loss of Capacity and Development of a Guided Wave Condition Assessment Method for Multistrand Anchor Systems Used in Corps Projects

: Over the past three decades, the US Army Corps of Engineers (USACE) has worked to upgrade its projects by installing high-capacity, post-tensioned foundation anchors. These stressed steel tendons have been used to strengthen hydraulic concrete structures and to improve their serviceability and structural stability. Substantial improvements to protect multistrand anchor systems from corrosion have been made since they were first used in Corps projects more than 50 years ago, but the corrosion of older multi-strand anchor systems is still a major concern. As a result of these needs, researchers at the US Army Engineer Research and Development Center (ERDC) are developing engineering procedures to estimate the current state of load-carrying capacity and to estimate the remaining service life of these tendons. These tools also aim to establish the rate of deterioration of anchorage capacity (with time), so costly replacement of ground anchorage can be delayed until absolutely needed. Analytical, laboratory, and field-testing efforts will be used to develop a methodology and analytical models to predict deterioration and loss of strength. Probabilistic procedures will be used to quantify uncertainties for the primary variable resulting in loss of strength of the post tensioned tendon. These uncertainty parameters will be carried into the risk-based analytical model. Procedures to extend the life of deteriorating multistrand tendons will be investigated.