Calibrated Finite Element Modeling of Creep Behavior of Prestressed Concrete Bridge Girders

A three-dimensional (3-D) finite element model capable of predicting the long-term behavior of prestressed concrete girder bridges is presented. A temperature-independent creep model was adopted and calibrated using early-age data from embedded sensors in a girder while stored in the casting yard. Additional sensors were installed when the girder was later erected to be part of a newly constructed bridge that was then monitored for over 2 years to evaluate the performance of a newly adopted continuity detail. The calibrated model was run for 1000 days considering the construction sequence from the casting yard to bridge completion. Good agreement was observed between model-predicted axial strains and field data. Creep-induced restraint moments were evaluated for different girder ages at the time of establishing continuity and were compared to results obtained from other analytical methods. Finally, conclusions are drawn and a recommendation regarding the creep coefficient for predicting the restraint moment in prestressed concrete girder bridges is given.