dc.contributor.author	Brodsky, Rachel Amanda	en
dc.contributor.committeechair	Roberts-Wollmann, Carin L.	en
dc.contributor.committeemember	Sarlo, Rodrigo	en
dc.contributor.committeemember	Koutromanos, Ioannis	en
dc.contributor.department	Civil and Environmental Engineering	en
dc.date.accessioned	2020-07-23T08:00:21Z	en
dc.date.available	2020-07-23T08:00:21Z	en
dc.date.issued	2020-07-22	en
dc.description.abstract	The Varina-Enon Bridge is a cable-stayed, precast, segmental, post-tensioned box girder bridge located in Richmond, Virginia. Inspectors noticed flexural cracking in July of 2012 that prompted concerns regarding long-term prestress losses in the structure. Prestress losses could impact the future performance, serviceability, and flexural strength of the bridge. Accurately quantifying prestress losses is critical for understanding and maintaining the structure during its remaining service life. Long-term prestress losses are estimated in the Varina-Enon Bridge using two methods. The first utilizes a time-dependent staged-construction analysis in a finite element model of the full structure to obtain predicted prestress losses using the CEB-FIP '90 code expressions for creep and shrinkage. The second method involves collecting data from instrumentation installed in the bridge that is used to back-calculate the effective prestress force. The prestress losses predicted by the finite element model were 44.9 ksi in Span 5, 47.8 ksi in Span 6, and 45.3 ksi in Span 9. The prestress losses estimated from field data were 50.0 ksi in Span 5, 48.0 ksi in Span 6, and 46.7 ksi in Span 9. The field data estimates were consistently greater than the finite element model predictions, but the discrepancies are relatively small. Therefore, the methods used to estimate the effective prestress from field data are validated. In addition, long-term prestress losses in the Varina-Enon Bridge are not significantly greater than expected.	en
dc.description.abstractgeneral	Post-tensioned concrete uses stressed steel strands to apply a precompression force to concrete structures. This popular building technology can be used to create lighter, stiffer structures. Over time, the steel strands experience a reduction in force known as prestress losses. Accurately quantifying prestress losses is critical for understanding and maintaining a structure during its remaining service life. The Varina-Enon Bridge is a cable-stayed, prestressed box girder bridge located in Richmond, Virginia. Inspectors noticed cracking in July of 2012 that prompted concerns regarding long-term prestress losses in the structure. Prestress losses were estimated using two methods. The first method utilized a computer model of the full bridge. The second method used data from sensors installed on the bridge to back calculate prestress losses. It was found that the prestress losses estimated from field data were slightly greater than, but closely aligned with, the computer model results. Therefore, it was concluded that the Varina-Enon Bridge has not experienced significantly more prestress losses than expected.	en
dc.description.degree	Master of Science	en
dc.format.medium	ETD	en
dc.identifier.other	vt_gsexam:26925	en
dc.identifier.uri	http://hdl.handle.net/10919/99398	en
dc.publisher	Virginia Tech	en
dc.rights	In Copyright	en
dc.rights.uri	http://rightsstatements.org/vocab/InC/1.0/	en
dc.subject	Post-tensioned concrete	en
dc.subject	Prestress loss	en
dc.subject	Varina-Enon Bridge	en
dc.subject	Finite element modeling	en
dc.subject	Creep	en
dc.subject	Shrinkage	en
dc.subject	Thermal gradient	en
dc.title	Effective Prestress Evaluation of the Varina-Enon Bridge Using a Long-Term Monitoring System and Finite Element Model	en
dc.type	Thesis	en
thesis.degree.discipline	Civil Engineering	en
thesis.degree.grantor	Virginia Polytechnic Institute and State University	en
thesis.degree.level	masters	en
thesis.degree.name	Master of Science	en

Effective Prestress Evaluation of the Varina-Enon Bridge Using a Long-Term Monitoring System and Finite Element Model

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