Tensile Behaviour of Corroded Strands in Prestressed Concrete Systems

摘要

Corrosion of strands can cause brittle failure of prestressed concrete bridge girders. The present study experimentally investigated the effect of chloride-induced corrosion on the tensile behaviour of 7-wire strands commonly used in prestressed concrete structures. Five prism specimens with embedded strands were subjected to impressed current corrosion in chloride environment. The corroded strands were extracted, and their section loss profiles were obtained using Computed Tomography (CT) scanning technique. Pitting factor was used to quantify the severity of corrosion in a strand. The strand specimens were tested under tension to generate the average stress versus average strain curves for the corroded regions. It was found that the ductility of a strand was completely lost even at an average section loss of about 12%. Analytical models for the mechanical properties of the tensile behaviour of a corroded strand were developed. An attempt was made to estimate the pitting factor from the average section loss, that can be used for field applications in the absence of section loss profile for a corroded strand. Finally, the developed models were substantiated by comparing with the results of the tension tests. They were also corroborated using test results and theoretical predictions available in the literature.