The Hampton Roads Bridge-Tunnel is one of the oldest prestressed concrete structures in the United States. The 3.5 mile long twin structure includes the world's first underwater tunnel between two man-made islands. Throughout its 60 years in service, the harsh environment along the Virginia coast has taken its toll on the main load carrying girders. Concrete spalling has exposed prestressing strands within the girders allowing corrosion to spread. Some of the more damaged girders have prestressing strands that have completely severed due to the extensive corrosion. The deterioration has caused select girders to fail the necessary load ratings. The structure acts as an evacuation route for the coast and is a main link for the local Norfolk Naval Base and surrounding industry. Because of these constraints, load posting is not a viable option.
Live load testing of five spans was performed to investigate the behavior of the damaged spans. Innovative techniques were used during the load test including a wireless system to measure strains. Two different deflection systems were implemented on the spans, which were located about one mile offshore. The deflection data was later compared head to head. From the load test results, live load distribution factors were developed for both damaged and undamaged girders. The data was also used by the local Department of Transportation to validate computer models in an effort to help pass the load rating. Overall, this research was at the forefront of the residual strength of prestressed concrete girders and the testing of in-service bridges. / Master of Science / According to Federal law, each bridge across the United States must be inspected by a licensed engineer on a biennial cycle – meaning every two years. Roughly every ten years, or when major work is performed such as a bridge widening, a load rating must be performed. During a load rating, licensed structural engineers analyze every structural component of a bridge under various loads. These loads include general traffic loads, heavy design loads, as well as special permit truck loads. For each of these loadings, it is proven whether each structural component has enough strength to withstand the load entering the member. Inspection reports are incorporated into the load rating analysis to account for any deterioration in the members which will lower its strength.
Recently, a load rating was performed on the Hampton Roads Bridge-Tunnel. The Bridge-Tunnel is a 3.5 mile long twin structure located in Southeastern Virginia. Throughout its 60 years in service, the harsh coastal environment has caused extensive deterioration to some of its main load carrying girders. The deterioration has caused the Bridge-Tunnel to fail its load ratings meaning load posting may have to be imposed. This means signs, and possibly security guards, would have to be implemented before the approach ramps preventing trucks over a certain weight limit from entering. The structure acts as an evacuation route for the coast and is a main link for the local Norfolk Naval Base and surrounding industry. Because of these constraints, load posting is not a viable option.
The Bridge-Tunnel is one of the oldest structures of its type so the effects of the deterioration are not well understood causing conservative assumptions to be used within the load rating. This research describes load testing that was performed on the structure to understand the performance and deterioration effects of the bridge. The results and recommendations from this research were used by the load rating engineers to justify assumptions made and help pass the load rating.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/74302 |
| Date | 12 January 2017 |
| Creators | Reilly, James Joseph |
| Contributors | Civil and Environmental Engineering, Hebdon, Matthew H., Koutromanos, Ioannis, Roberts-Wollmann, Carin L. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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