Title: Residual Tensile Capacity of Grouted Post-Tensioned Tendons

Author(s): Sharon L. Wood, Christopher A. McKinstry, and Jun Ki Lee

Publication: Structural Journal

Volume: 110

Issue: 6

Appears on pages(s): 1099-1108

Keywords: corrosion damage; damage detection; force redistribution; grout; natural frequencies; post-tensioned tendons; residual tensile capacity

DOI: 10.14359/51686164

Date: 11/1/2013

Abstract:
In the United States, segmental box-girder bridges are typically constructed with external post-tensioned (PT) tendons that are grouted for corrosion protection. The prestressing steel in these tendons often provides a significant portion of the load-carrying capacity of the bridge. Nondestructive methods, such as vibration-based techniques, have been used successfully in the field to estimate the tensile force in the tendons under service loads. Laboratory tests were conducted to understand how the tensile force and natural frequencies vary as localized damage accumulates in grouted tendons. Test results demonstrated that the service-level tensile force in the tendon decreased with increasing corrosion damage to the prestressing steel, but that significant tensile forces were transferred through the grout/duct. Redistribution of tensile forces is typically not considered when evaluating the behavior of grouted tendons, and use of standard approaches may significantly overestimate the residual tensile capacity of a damaged PT tendon.