Use of Carbon Fiber Composite Wrap and External Post-Tensioning to Strengthen Prestressed Concrete I-Beams in the Hampton Roads Bridge Tunnel Approach Spans

The prestressed beams in the Hampton Roads Bridge Tunnel Approach Spans were fabricated in about 1960 (west bound lane) and 1970 (east bound lane). The spans are 50-ft and 75-ft, respectively. The brackish water environment caused corrosion and failure of the bottom strands and deterioration and spalling of the cover concrete in many beams. A project in 2018 strengthened 30 of the more deteriorated beams as an alternative to posting or replacing the bridges. Carbon fiber composite wrap (CFCW) and external post-tensioning (PT) were used to strengthen the beams. Prior to construction, a PT mockup was done with one 50-ft (flexible filler) and one 75-ft (grout) beam to demonstrate that the contractor had the materials, equipment and staff to successfully do the external PT. This presentation describes the project’s mockups and construction and the anticipated increase in strength to be obtained from application of the CFCW and external PT.

Learning Objectives:

1. Understand the mockups of two post-tensioned beams.
2. Understand construction to strengthen 30 beams.
3. Understand the increase in strength of beams through examples.
4. Learn cost benefits.