Title: Fatigue of Diabolo-Deviated Unbonded Post-Tensioning Tendons
Author(s): Natassia Brenkus, Devon Skelton, and H. R. Hamilton
Publication: Structural Journal
Appears on pages(s): 27-36
Keywords: anchorage; fatigue; flexible filler; fretting; post-tensioning (PT); prestressing
An experimental investigation of post-tensioning (PT) tendons filled with flexible filler under cyclic loading was conducted to assess performance in fatigue conditions. Two post-tensioned specimens—with different duct profiles representing two angles of deviation—were cycled in a scenario modeled after the European Technical Approval Guideline (ETAG) 013 fatigue acceptance criteria for post-tensioning tendon systems. The tested post-tensioning systems included extreme tendon deviation angles and were cycled to produce high tendon stress ranges to mimic the ETAG 013 requirements; the chosen tendon angles and stress ranges, however, are more extreme than typical bridges in service. Following 2 million cycles of load application, the specimens were inspected for duct wear and evidence of fatigue. Both tested systems passed the ETAG 013 acceptance criteria, but some prestressing strand specimens exhibited reduced ultimate strength in subsequent strand-in-air tensile testing.