Analysis of bond-loss resistance models for pretensioned I-girders

Bond-loss failures have been observed in load tests of precast, pretensioned concrete I-girders. This type of failure is associated with shear cracking near the support that interrupts anchorage of the strands, leading to loss of bond and slipping of the strands relative to the concrete. This paper presents a database of bond-loss failures that are documented in the research literature and uses the database to create a bond-loss failure model. The database and model are expansions and refinements of the authors' previous work on the subject. The refined model is created through linear regression and least squares analyses and is demonstrated to have superior accuracy compared with the end-region model in section 5.8.3.5-2 of the American Association of State Highway and Transportation Officials' 2014 AASHTO LRFD Bridge Design Specifications. One of the key insights accounted for in the refined model is that stress in transverse reinforcement attendant with bond-loss failure is often less than yield stress. © 2018 Precast/Prestressed Concrete Institute. All rights reserved.