Investigation of the unusual deformations of external tendons in concrete highway bridges

During a regular inspection of a multi‐span highway bridge, an unusual deformations of external post‐tensioned tendons were observed. These deformations were not noticed or recorded during the previous main inspections. A detailed visual inspection of the condition of external tendons was performed on all bridges with external tendons by mapping the location and extent of unusual deformation. Based on this, several non‐destructive tests were performed, where deformations were first noticed, from magnetic‐flux leakage to radiographic screening. Some local destructive investigations were subsequently carried out at several locations in two bridges, i.e. opening the tendons. The result of the tendons opening showed the presence of foreign objects and non‐tensioned strands, the latter being a possible cause for the deformations of that tendon. In both locations, the injection mass was compact with only hairy transverse cracks, both on the undeformed part as well as on the moderately deformed part of the tendon. In this paper, the latest results from this study are presented in detail.