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Browsing by Author "Stephen R. Sharp"

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    Acceptance Procedures for New and Quality Control Procedures for Existing Types of Corrosion-Resistant Reinforcing Steel
    Stephen R. Sharp; Larry J. Lundy; Harikrishnan Nair; Moen, Cristopher D.; Josiah B. Johnson; Sarver, Brian E. (Virginia Center for Transportation Innovation and Research, 2011-06-01)
    As the Virginia Department of Transportation (VDOT) continues to move forward with implementing the use of corrosion-resistant reinforcing (CRR) bars, it is important for VDOT to have a means of characterizing the candidate bars as well as ensuring that the quality of approved CRR bars is preserved. This is vital to ensure the bars respond physically in a manner that is consistent with VDOT's expectations. The purpose of this study was to provide VDOT's Materials Division with a method/specification for evaluating CRR bars. The study determined that visual assessment cannot be relied on to determine bar type. Further, steel fabricator markings cannot be relied on to identify the type of steel. However, when questions arise regarding the identification of bars, magnetic sorting provides a quick and easy method for differentiating between magnetic and nonmagnetic alloys. If more quantitative results are required, X-ray fluorescence provides a practical and much-needed method for positively identifying bars. Physically, the bars differ among producers. Relative rib area should be monitored as it also varies among producers. Further, alloying changes not only the corrosion resistance but also other important properties. The results of uniaxial tensile tests showed that the stress-strain behavior, elongation, and reduction in cross-section upon fracture could vary significantly for different CRR alloys. Therefore, mechanical testing, in addition to corrosion testing, of CRR is necessary to identify the most cost-effective bars with acceptable properties. Finally, the study determined that quality control measures need to be established to ensure VDOT receives the corrosion protection it needs. Further, care should be taken when relying upon international standards for acceptance criteria. The report recommends that VDOT's Materials Division implement the set of test methods provided in the appendices of this report as Virginia Test Methods for CRR acceptance criteria. To simplify the implementation of CRR in Virginia and elsewhere, VDOT's Materials Division should work with the American Association of State Highway and Transportation Officials to develop a single specification for the testing and acceptance of CRR. VDOT's Materials Division should also investigate retrofitting the uniaxial tensile test equipment with a non-contact extensometer to guarantee that stress vs. strain measurements of CRR can be made and ensure the yield strength is determined
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    Structural load testing and flexure analysis of the Route 701 Bridge in Louisa County, Virginia
    Cousins, Thomas E.; Lucas, Jeremy L.; Brown, Michael C.; Stephen R. Sharp; Lane, D. Stephen (Virginia Center for Transportation Innovation and Research, 2004-06-01)
    A continuous slab bridge in Louisa County, Virginia, on Route 701 developed a planar horizontal crack along the length of all three spans. This project was designed to determine if the current load rating of the bridge could be raised and to document the behavior and stiffness of the bridge to serve as a benchmark for possible future tests, which may determine if there is progressive damage attributable to crack growth. These objectives were accomplished through field tests performed in November 2003. One truck (loaded to three different weights) was used to perform static and dynamic tests on the bridge, and the truck was oriented in three test lanes. Vertical displacement gages (deflectometers) attached to the underside of the bridge slab were used to measure deflections during the truck passes. The recorded deflections were analyzed and normalized to document the behavior of the bridge. The values were also compared to estimated design values in accordance with the AASHTO Standard Specifications for Highway Bridges. Under the testing loads, the bridge behaved elastically, and thus raising the load rating of the bridge was considered safe. The deflections and process are presented to allow comparisons with future tests to determine if there is progressive damage to the bridge attributable to crack growth.