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

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.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Civil Engineering

Department dc:contributor.department

Civil and Environmental Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2020

Author dc:creator

• Brodsky, Rachel Amanda

Chair dc:contributor.committeechair

• Roberts-Wollmann, Carin L.

Committee members dc:contributor.committeemember

• Sarlo, Rodrigo
• Koutromanos, Ioannis

• Post-tensioned concrete
• Prestress loss
• Varina-Enon Bridge
• Finite element modeling
• Creep
• Shrinkage
• Thermal gradient

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

vt_gsexam:26925

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/99398