9634499 Sansalone Currently, evaluation of post-tensioned structures is performed predominantly by relying on invasive testing. The project will develop methods based on use of impact- generated stress waves. Preliminary studies on single ducts located in plate-like structures have shown that such methods have the potential to detect voids in grouted metal tendon ducts. However, a comprehensive and basic research study is still needed to (1) understand the propagation of transient stress waves in typical post-tensioned structural geometries, (2) to understand the interaction of stress waves with partial and full voids in ducts, as well as water- filled voids in ducts, (3) the effects caused by the use of plastic tendon ducts, (4) the interaction of stress waves with ducts closely spaced and ducts located two and three deep in a cross-section, and (5) to determine whether the extent of grouting in ducts can be determined during the grouting process. ***
