Investigation of the Time-Dependent Longitudinal Flexural Behavior of the Varina-Enon Bridge

Post-tensioned concrete is a building technology which provides a compressive force to concrete via steel tendons. This combination of steel and concrete allows for the construction of lighter and stiffer structures. Post-tensioned concrete is widely utilized throughout the United States highway system and bridge construction. Over time, the force in the prestressing strands is reduced by delayed strains in the concrete. The accurate estimation of this prestress loss is vital for making good decisions about the remaining capacity of a structure and the infrastructure system at large.

The Varina-Enon Bridge is a post-tensioned concrete box-girder bridge in Richmond Virginia. Cracks in the bridge prompted an investigation into the magnitude of prestress loss experienced by the structure. To estimate prestress loss, a computer model of the structure was created. In addition, data from sensors previously installed on the bridge were used to back calculate prestress loss.

It was found that the estimation of losses from the field closely matched those estimated at the construction of the bridge. Additionally, more updated loss models estimated similar, or slightly smaller values for prestress loss.