Structural Repair of Prestressed Concrete Bridge Girders

It is common practice that aging and structurally damaged prestressed concrete bridge members are taken out of service and replaced. This, however, is not an efficient use of materials and resources since the member can often be repaired in situ. There are numerous repair techniques proposed by entrepreneurial and academic institutions which restore prestressed concrete girder flexural strength and save both material and economic resources. Of course, not all repair methods are applicable in every situation and thus each must be assessed based on girder geometry and the objectives of the repair scenario. This document focuses on the practical application of prestressed concrete bridge girder repair methods. In this document, repair methods are presented for three prototype prestressed concrete highway bridge girder shapes: adjacent boxes (AB), spread boxes (SB), and AASHTO-type I-girders (IB), having four different damage levels. A total of 22 prototype repair designs are presented. Although not applicable to all structure types or all damage levels, the repair techniques covered include the use of carbon fiber reinforced polymer (CFRP) strips, CFRP fabric, near-surface mounted (NSM) CFRP, prestressed CFRP, post-tensioned CFRP, strand splicing and external steel post-tensioning. It is the author's contention that each potential structural repair scenario should be assessed independently to determine which repair approach is best suited to the unique conditions of a specific project. Therefore, no broad classifications have been presented directly linking damage level (or a range of damage) to specific repair types. Nonetheless, it is concluded that when 25% of the strands in a girder no longer contribute to its capacity, girder replacement is a more appropriate solution.Guidance with respect to inspection and assessment of damage to prestressed concrete highway bridge girders and the selection of a repair method is presented. These methods are described through 22 detailed design examples. Based on these examples, review of existing projects and other available data, a detailed review of selection and performance criteria for prestressed concrete repair methods is provided