Investigation of Prefabricated Steel-Truss Bridge Deck Systems

As described in the final report, this research evaluated both a conventional cast in place deck system and an accelerated bridge deck system (cast integral with the truss) for the bolted/welded steel truss bridge. A 3D finite element model was used to more accurately calculate the distribution of lane and truck loads to the individual trusses. Truss members and connections for both construction alternatives were designed using loads from AASHTO Strength I, Fatigue I, and Service II load combinations. A comparison was made between the two truss configurations and a 205 ft. plate girder used in a previously designed bridge over the Swan River. Materials and fabrication estimates suggest the cost of the conventional and accelerated construction methods is 10% and 26% less, respectively, than the plate girders designed for the Swan River crossing.

The overall objective of this proposed research is to investigate, and develop as appropriate a prefabricated steel truss/deck system as an alternative to other accelerated bridge construction (ABC) systems available to MDT.

 

The Montana Department of Transportation has recently explored different accelerated bridge construction (ABC) systems and recognizes the advantages of these systems for certain bridge replacement and new construction projects in the state. In particular, a steel-truss girder system with an integrated concrete deck has the potential to increase the applicability of ABC projects for longer spans through a reduction in weight with more reliable deflection estimations, when compared to more conventional precast/prestressed concrete integrated deck systems. Results of this research would enable MDT to determine if a steel truss/integrated concrete deck bridge system is a viable bridge construction option for the state of Montana. Further, if deemed to be a viable option, this investigation will identify future research directions required to fully develop this new ABC methodology.

The research program will evaluate the potential of a proposed ABC system consisting of a prefabricated steel truss with integrated bridge deck. This evaluation will include a review of the state-of-the-practice in prefabricated bridge panels, an analytical assessment of the proposed system, and recommendations for future research required to fully develop this system.