| Recently the Wisconsin Department of Transportation developed two new wide flange precast concrete girder (bulb tee) sections for highway bridges to improve span effectiveness compared to the AASHTO "I" girder sections. During recent construction projects with these girders, several doubts regarding the efficiency of construction procedures and overdesign of the concrete deck arose from the construction of pilot bridges and experimental research.;A new deck system is, therefore, desirable. The proposed deck system is to eliminate the need for conventional steel reinforcing, and the labor involved in placing, and to eliminate the need for temporary formwork during deck construction---thereby achieving more effective load carrying mechanism, more rapid construction and cost reduction. A new load carrying mechanism is introduced to eliminate the conventional steel reinforcements. The mechanism is a combination utilizing compressive membrane action in the deck by tying girders together with steel rods, introducing a polypropylene fiber reinforced concrete to control thermal and shrinkage cracks, and usage of fiber reinforced polymer stay-in-place panel with aggregates attached by epoxy as a formwork and also as a crack controlling device.;The results from the experimental research including testing of a half-scale bridge specimen, concrete beams cast on the aggregate-coated fiber reinforced polymer stay-in-place forms, restrained concrete deck element and the construction of a pilot bridge showed that the proposed system performs well.;A new design procedure using the modified strut and tie model including the material and geometrical nonlinearity is proposed as a design procedure for the proposed deck system. The design method is an alternative to a complex finite element analysis ensuring that the designed structure has sufficient ultimate capacity. The design procedure developed was verified by the experimental research, finite element analysis of the proposed deck system with various configurations and the construction of the pilot bridge showing that it provides simplicity to the design without losing accuracy. |
