Bridges, Tunnels and other Transportation Structures
Time-dependent losses due to corrosion can have catastrophic consequences in prestressed tension structures. In fact, the effectiveness of prestress concrete members depends on the structural soundness of prestressing steel to resist externally applied loads. Hence, metal loss caused by localized corrosion can be monitored by changes in strain and loss of prestressing force applied initially. Currently available non-destructive evaluation (NDE) techniques are still limited in their ability to quantify the time-dependent prestressing loss from corrosion. In this regard, an experimental study was conducted in full-scale, 46-ft, Florida I-beam (FIB-36) where pretensioned and post-tensioned behavior were investigated to identify prestress losses from corrosion in post-tensioned (PT) tendons with deficient grout. During the observation period, prestress losses, changes in top and bottom fiber strain and curvature at critical locations were measured using embedded vibrating wire gauges (VWG). At initial stages of corrosion, corrosion propensity in post-tensioned (PT) tendons with deficient grout was measured using localized corrosion sensor with the intent of detecting localized changes in strain behavior, and then to verify the localized damage due to corrosion, global behavior (i.e., longitudinal strain) of FIB-36 was measured using VWGs. In conjunction, finite element models have been developed to simulate the experimental behavior at critical locations and quantify the prestress loss. The finite element model provides a representative platform to differentiate prestress losses from the experimental short-and long-term data and in turn verify the numerical simulation with experimental data. Results obtained from prestress losses data would characterize the corrosion behavior of steel in the damaged bridge to assess grout deficiency and corrosion propensity.