Section loss in naturally corroded 7-wire steel strands in external tendons

Abstract

Naturally corroded seven-wire strands obtained from two in-service bridges were examined. All strand samples were cut into cross sections, and the corrosion depths and corroded areas were measured. Among various corrosion mechanisms, a majority of samples investigated were categorized as general corrosion. The trends in the section losses in the strands with respect to average corrosion depth were similar and showed a clear linearity. The average corrosion depth measured from the outside of strands showed an overall linear trend with section loss when the inside of strand cross-sections could not be observed and measured. In this study, a method to estimate section loss for general corrosion of a 7-wire strand is developed by using corrosion depth in the visible region. Although a limited number of samples were obtained from only two bridges, the section loss estimates were comparable to actual measurements. The study of strand samples corroded during service offers a rare opportunity and should distinguish this study from previous ones.