Axle Equivalent Transverse Loading on Segmental Bridge Decks.

摘要

For a prestressed concrete segmental box girder bridge, both design and load rating are determined by longitudinal and transverse analyses. A transverse analysis is performed for the top slab, typically by using Homberg charts (an engineers design tool), to account for transverse bending effects due to truck wheel loads. The FDOT Office of Maintenance issues thousands of permits annually for heavy trucks. These trucks may have different axle weights and spacings than the trucks that are analyzed in the engineers design or load rating. In this research, a Homberg-based tool was developed in Excel for analyzing vehicles for their effect on transverse bending moments in a prestressed concrete segmental box girder bridge. The tool allows the user to analyze vehicle loads quickly and provides a simple way to compare effects of different vehicles. For example, the effects of vehicles that were analyzed in the designers load rating could be compared to vehicles with axle weights and spacings that were not analyzed in the initial load rating. In addition, Finite Element Modeling (FEM) was performed to study the effect on transverse bending moment of elements such as barriers, barrier joints, diaphragms, supports, and expansion joints. The effect of axle load spacing was also studied to give insight into the Office of Maintenances formerlyused 8-foot rule. Calculated bending moments from Homberg analysis and FEM were compared for a few Blanket Permit Vehicles. Blanket Permit Vehicles are those vehicles permitted to travel an unrestricted number of times on unrestricted routes within one calendar year.