This paper describes an investigation into the collapse of a single-span, segmental post-tensioned concrete bridge. The structure consisted of precast units stressed together both longitudinally and transversely. It was built in 1953 and collapsed at approximately 7:00 a.m. on December 4, 1985. There had been no evidence of distress before failure, and there was no traffic on the bridge when it collapsed. The investigation showed that the bridge had deteriorated because of corrosion of the tendons where they passed through the segmental joints. Corrosion had occurred because the tendons had been inadequately protected at the joints, and this had enabled chlorides to enter the ducts. It is believed that deicing salts were the major source of chlorides, although it is possible that dune sand had been included in the mortar used to fill the transverse joints. The results cause concern about the condition of other post-tensioned concrete bridges in which tendons pass through joints.
Samenvatting