Trunnion Rod Microcrack Detection

Abstract : Post-tensioned rods are used to anchor spillway gates and transfer the forces from the reservoir pool through the gates to the spillway structures. Large tensile loads are applied to these high-strength steel rods to compress the surrounding concrete and prevent it from experiencing excessive tensile forces, which are naturally problematic for concrete. These posttensioned trunnion anchor rods are used extensively for support of tainter gates and considered the standard for the US Army Corps of Engineers (USACE) and other government and nongovernment agencies within the United States and elsewhere. These rods are now experiencing ongoing failures. The Corps of Engineers needs reliable non-destructive testing (NDT) methods that are rapid, robust, and capable of detecting and quantifying defects, as well as methods for determining rod tensions. These methods are required to be rapid because of the large number of rods that exist at some installations. Robustness is required to handle the significant variations in design, construction, and field conditions that are known to exist. Defect detection and quantification provides tracking and monitoring data important for planning and prioritizing remediation efforts or operational practices.