Failure Forecasting of Corroding Bridge Post-Tensioned Tendons

Abstract

Post-tensioning has evolved to become an important design and construction method for reinforced concrete bridges. However, corrosion-caused tendon failures on such structures have occurred and these, in turn, compromise integrity. In response to this, a previous research program developed an analytical methodology that projects the progression of wire and strand fractures and bridge tendon failures based upon corrosion rate statistics for wires. A remaining challenge, however, is to better understand the effectiveness and accuracy of existing technologies for in situ bridge tendon condition assessment, as well as the development of new and improved approaches. The present research builds upon this need by establishing quantitative relationships between the extent of corrosion damage to wires and strands and residual tendon strength. Most analyses are based upon a mean corrosion rate of 0.075 mmpy (3.0 mpy) with standard deviation 0.3, 0.4, or 0.5. As a forewarning of a pending tendon failure, the present study identifies the percentage of wire/strand section loss at 1 y and 5 y prior to failure. A recommendation is made regarding the establishment of a test facility for evaluating/qualifying existing and new technologies for nondestructive corrosion assessment of bridge tendons.