Corrosion induced failure mechanisms of prestressing steel

Rarely occurring fractures of prestressing steel in prestressed concrete structure can, as a rule. be attributed to corrosion induced influences. The mechanism of these failures often is not well understood. In this connection it is difficult to establish the necessary recommendation not only for design and execution but also for building materials and prestressing systems in order to avoid future problems. This paper gives a survey about corrosion induced failure mechanisms of prestressing steels with a particular emphasis on post-tensioning tendons. Depending on the prevailing corrosion situation and the load conditions as well as the prestressing steel properties the following possibilities of fracturing must be distinguished: Brittle fracture due to exceeding the residual load capacity. Brittle fracture is particularly promoted by local corrosion attack and hydrogen embrittlement. Fracture as a result of hydrogen induced stress-corrosion cracking. Fracture as a result of fatigue and corrosion influences, distinguishing between corrosion fatigue cracking and fretting corrosion/fretting fatigue.