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Load Testing Deteriorated Spans of the Hampton Roads Bridge-Tunnel for Load Rating RecommendationsReilly, James Joseph 12 January 2017 (has links)
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
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Evaluation and Structural Behavior of Deteriorated Precast, Prestressed Concrete Box BeamsRyan T Whelchel (7874897) 22 November 2019 (has links)
Adjacent precast,
prestressed box beam bridges have a history of poor performance and have been
observed to exhibit common types of deterioration including longitudinal
cracking, concrete spalling, and deterioration of the concrete top flange. The nature of these types of deterioration
leads to uncertainty of the extent and effect of deterioration on structural
behavior. Due to limitations in previous
research and understanding of the strength of deteriorated box beam bridges,
conservative assumptions are being made for the assessment and load rating of
these bridges. Furthermore, the design
of new box beam bridges, which can offer an efficient and economical solution,
is often discouraged due to poor past performance. Therefore, the objective of this research is
to develop improved recommendations for the inspection, load rating, and design
of adjacent box beam bridges. Through a
series of bridge inspections, deteriorated box beams were identified and
acquired for experimental testing. The
extent of corrosion was determined through visual inspection, non-destructive
evaluation, and destructive evaluation.
Non-destructive tests (NDT) included the use of connectionless
electrical pulse response analysis (CEPRA), ground penetrating radar (GPR), and
half-cell potentials. The deteriorated
capacity was determined through structural testing, and an analysis procedure
was developed to estimate deteriorated behavior. A rehabilitation procedure was also developed
to restore load transfer of adjacent beams in cases where shear key failures
are suspected. Based on the
understanding of deterioration developed through study of deteriorated adjacent
box beam bridges, improved inspection and load rating procedure are provided along
with design recommendations for the next generation of box beam bridges.
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