Redevelopment of Prestressing Force in Severed Prestressed Strands

摘要

The flexural capacity rating of prestressed girders having severed or corroded strands often progresses by simply neglecting the contribution of the affected strands from the girder section and assessing the capacity. While this is an adequate approach at the affected section, it is conservative elsewhere along the span, assuming that fully bonded strands are used. Once it reenters sound concrete, the severed or corroded strand continues to be bonded to the concrete; thus stress transfer between the concrete and strand is possible and the strand prestress force may be "redeveloped" (in the sense of transfer length) by bond transfer at a distance from the damage location. This paper reports an experimental study that clearly shows that prestress force is redeveloped at a distance from the location at which a strand is severed. Furthermore, American Association of State Highway and Transportation Officials (AASHTO) and American Concrete Institute (ACI) code-prescribed transfer-length calculations appear to remain valid for this redevelopment behavior.