Type of Document	Thesis
Author	Spear, Herbert Houston
Author's Email Address	houston61184@aol.com
URN	etd-04122010-180407
Title	Exploration of Monostrand Use in Segmental Box Girder Bridges
Degree	Master of Science
Department	Civil and Environmental Engineering, Department of
Advisory Committee	Advisor Name Title Michelle Rambo-Roddenberry Committee Chair Kamal S. Tawfiq Committee Member Lisa K. Spainhour Committee Member
Keywords	Segmental Box girder Bridges Monostrand Post-Tensioning
Date of Defense	2010-04-02
Availability	unrestricted
Abstract For the past several decades the segmental box girder bridge has proven itself to be one of the more efficient bridge types. Using reusable form work, segments are match-cast, ensuring a more perfect connection during the construction phase. These benefits in conjunction with the fact that the costs of startup and form work are absorbed into the total cost of each segment mean that the longer the final bridge is, the less the cost is per segment, making the segmental box girder bridge one of the most popular long bridge types constructed in the U.S. To minimize cost, it is important to design each segment for efficiency in terms of quantity of longitudinal and transverse post-tensioning and reinforcing steel. The inclusion of post-tensioning technology results in an overall compressive state in the longitudinal and transverse directions of the segments, improving structure strength and service life. However, despite the benefits inherent in using post-tensioning technology, the webs still contain standard deformed reinforcement. The goal of this research is to fit a greased and sheathed monostrand within a segment in a way that both webs and bottom flange would be placed in a state of compression, thereby reducing the demand for standard web reinforcement and, hopefully, segment cost. The research objectives include analyzing principal stresses in the webs of the segment, modifying the segment so as to restrain the monostrand within the webs, designing any additional reinforcement that may be necessary, and finally comparing the estimated construction cost of the new design with that of a pre-existing structure. The results from this research have shown that it is indeed possible to place a greased and sheathed monostrand within the webs of a segment with beneficial results and that the demand for standard deformed reinforcement will thus be reduced.
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