Technical Note: Failure Projection of Corroding Bridge Post-Tensioned Tendons Considering Partitioned Attack

Abstract

Post-tensioning (PT) has evolved to become an important technology for affecting integrity of large, increasingly sophisticated reinforced concrete structures. In the case of bridges, however, tendon failures resulting from wire/strand corrosion have been reported as early as two years post construction. In response to this, a recent study introduced, evaluated, and used an analytical modeling approach that projects timing of such failures, given statistics which characterize the distribution of wire corrosion rate. These efforts all considered that corrosion penetration is normally distributed across the entire population of wires comprising all tendons. However, it has been reported that corrosion, resultant wire and strand fractures, and tendon failures can be confined to a specific location on a bridge structure as a result of variations in material properties or construction improprieties (or both). Also, the distribution of corrosion rates can differ within individual tendons because of, first, variations in grout structure and composition and, second, presence of voids and free water. The present research extends these previous efforts and addresses such situations; that is, those where the corrosion rate distribution is spatially variable. The results are discussed within the context of better assuring structural integrity for PT bridges.