Technical Reports, Biomedical Engineering and Mechanics
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Browsing Technical Reports, Biomedical Engineering and Mechanics by Author "Duke, John C. Jr."
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- Health monitoring of post-tension tendons in bridgesDuke, John C. Jr. (Virginia Center for Transportation Innovation and Research, 2003-02-01)Post-tensioned concrete has been used in a number of bridge structures and is expected to be used more in future construction in Virginia. This type of detail offers unique advantages for improving the performance of concrete members. Recent problems in the United Kingdom and Florida have increased concern over the condition of post-tensioned tendons in Virginia's bridges. There is a need for efficient, cost-effective methods of assessing and monitoring the condition of aging tendons in-situ. This study was carried out to survey the literature that addresses the condition of tendons to identify technology, perform a limited assessment of the feasibility of as many of the candidate technologies as possible, and consider follow-on efforts for development and application to post-tensioned tendons in Virginia in was described.
- Implementation and Non-Destructive Evaluation of Composite Structural Shapes in the Tom's Creek BridgeHayes, Michael David; Haramis, John Emmanuel II; Lesko, John J.; Cousins, Thomas E.; Duke, John C. Jr.; Weyers, Richard E. (Virginia Center for Transportation Innovation and Research, 2000-05-01)A bridge rehabilitation utilizing a hybrid fiber reinforced polymeric composite has been completed in Blacksburg, Virginia. This project involved replacing the superstructure in the Tom's Creek Bridge, a rural short-span traffic bridge with a timber deck and corroded steel girders, with a glue-laminated timber deck on composite girders. In order to verify the bridge design and to address construction issues prior to the rehabilitation, a full-scale mock-up of the bridge was built and tested in the laboratory. This set-up utilized the actual composite beams, glue-laminated timber deck panels, and geometry to be implemented in the rehabilitation. After the rehabilitation was completed, the bridge was field tested under a known truckload. Both tests examined service load deflections, girder strains, load distribution, the degree of composite action, inter-panel deck deflections, and impact factor. The field test results indicate a service load deflection of L/400 under moving loads and a factor of safety of over 7 using the projected A-allowable for beam flexural strength. The data from the field test serves as a baseline reference for future field durability assessments as part of a long-term performance and durability study.