Live-Load Moment-Distribution Factors for an Adjacent Precast Prestressed Concrete Box Beam Bridge with Reinforced UHPC Shear Key Connections

In this study, the live-load moment-distribution factors (LLMDFs) were evaluated for an adjacent precast prestressed concrete box beam bridge. The bridge used a new shear key configuration, which was grouted with ultrahigh performance concrete (UHPC) and contained noncontact lap-splice dowel bars. The bridge did not contain transverse tie rods, transverse posttensioning, intermediate diaphragms, or a composite deck. As newly developed shear key connections, the LLMDFs are not addressed in the current professional bridge design specifications. Therefore, the LLMDFs were evaluated using static truck load testing. A three-dimensional finite-element model was created and validated by using field results. After validation, the truck load designed by professional bridge standards was applied to the model, and the LLMDFs were evaluated. The results indicate that LLMDFs based on the professional bridge design specifications were conservative compared with the field results. Furthermore, the predicted LLMDFs by means of the professional bridge design specifications were also conservative when the finite-element model was loaded with a truck designed by these specifications and assuming full connectivity for the beams to act as a unit.