Secondary anchorage and residual prestressing force in locally corroded PT beams after strand fracture

Abstract

An experimental test with six specimens is designed to investigate the secondary anchorage and residual prestressing force in locally corroded post-tensioned concrete (PT) beams after strand fracture. The secondary anchorage of fractured strand is investigated, and the correlation between prestressing force generated by secondary anchorage and strand fracture positions is established. The flexural behavior of locally corroded PT beams after strand fracture is discussed. An analytical method is proposed to determine the damage control section of locally corroded PT beams after strand fracture for the flexural capacity evaluation, and the accuracy of proposed method is validated by experimental results. Results show that corrosion-induced strand fracture leads to the formation mechanism of prestressing force changing from the end anchorage transfer to the cement mortar bonded transfer. The secondary anchorage of fractured strand can form a new prestressing force for resisting the applied load, and the residual prestressing force in locally corroded PT beams depends on the strand fracture positions. The prestressing force generated by the secondary anchorage will decrease gradually when the strand fracture position moves from the end anchorage region to the mid-span region. The prestressing force loss is 16.7% when strand fractures in the end anchorage region. Once it occurs in the mid-span region, the prestressing force loss reaches to 83.4%.