Bond and re-anchoring tests of post-tensioned steel tendon in case of strand failure

Grouted tendons are commonly used in construction of bridges and other post-tensioned structures. The quality of grouting is essential to provide the durability, bond and robustness of the structure. In this study, the bond and re-anchoring of post-tensioned tendons in grout in case of tendon failure is assessed. A set of tests with beams of different lengths were conducted to
simulate the failure of a post-tensioned tendon in the structure. The results were compared with the theory of prestressing strand anchoring in concrete.
In the tests, the re-anchoring and bond lengths were measured in case of complete grout and incomplete grout simulated with a void. In the case of incomplete grout, the 60 % increase in re-anchoring length was observed. In the case of overlapping re-anchoring and bond length, the bond length and tendon slip increase significantly, which affects the force distribution between
tendons in structure. A limited re-anchoring length of tendon in incomplete grout increases the robustness of the structure, as the broken tendon can maintain its effectiveness outside of the failure region. Near failure region the forces transfer on tendons with better bond conditions and without breakage. In tests the observed re-anchoring lengths of broken 12-strand tendon
in grouting were 1.4 meters with complete grout and 2.3 meters in case of incomplete grout.The existing model in literature shows a good match with test results, and therefore it is suitable for the assessing of structures with broken tendons in grout.