A current initiative by the Federal Highway Administration (FHWA), and the Innovative Bridge Research and Construction (IBRC) Program, focuses on new materials and technologies in bridge design and construction. Under this program, a recent project awarded to the North Carolina Department of Transportation (NCDOT) concentrates on a high performance concrete (HPC) deck girder system, comprising of a modified AASHTO Type III girder with an additional flange (deck) section, with the objectives to review the design and detailing information, monitor the deck girder fabrication and the bridge construction processes, load test the completed bridge, and to evaluate the embedded stud connection. The load testing of the deck girder bridge was performed using two tandem trucks. The bridge was instrumented using strain transducers, strain gages, and displacement transducers. The instrument layout was designed to experimentally determine the transverse distribution factors, impact factors, strain levels, and displacements of each girder due to different loading conditions.
A finite element (FE) model was also developed, for which, model calibration was performed by comparing vertical displacement and stress values using NCDOT, Larsa, and ANSYS results on a single deck girder. Once calibrated, the single-girder model was then copied to create five identical deck girders. The plate and diaphragm components were created and the appropriate loads were placed on the model. The results were then compared to the actual quasi-static load test performed on the finished bridge. Furthermore, using the working ANSYS model, a parametric study was then performed to investigate the influence of diaphragm and flange connection spacing.
The capacity and failure mechanism of the embedded stud connection used to join the adjacent deck girders is not accurately defined by current PCI specifications. Therefore, the shear and tension capacity of the connection was investigated through FE analysis, followed by laboratory testing of four specimens of each type. Only few of the calculations compared closely to the predicted values from the 6th Edition of the PCI Design Handbook. Hence, in order to accurately assess the capacity of nontraditional connections not resembling the standard headed stud details, experimental and/or FE studies should be performed.
