Kazuhiko Naito
A Study on stress characteristics of concrete floor slab in steel bridge
Eiji Iwasaki
Floor slab in the highway bridge will receive a wheel load of passing vehicles directly, for the reason, generation bending moment is greatly influenced by loading the state of the wheel load and the restraint state of the slab by the support digit. For the reason, in the specifications for the highway bridge are defined design bending moment equation that it was floor slab span as a parameter. However, for this equation in the continuous version is approximately defined based on result of a simple version, actually there is a possibility that it has been overestimated, there is a possibility that it is able to expect a reduction of the design bending moment.
In addition, in recent years, few main girder bridge with a reduced main digit number from the viewpoint of the reduction of the construction cost is being built. In this situation, overseas has been adopted few main girder bridge that the main girder and the cross girder called ladder deck bridge, as rationalization countermeasures, consideration for the floor slab has already been several reports.
In this study, by performing the FEM analysis using a model of the steel bridge and ladder deck bridge considering the details of the digits that are not considered in previous studies, we grasped the characteristics of the stress generated in the floor slab, it was discussion of considerations relating to the calculation of the design bending moment equation. The results were the following.
In the middle fulcrum portion, the bending stress of the floor slab just above the upper flange is reduced, it was revealed that the maximum bending stress is generated in the upper flange edge from the haunch starting edge.
As a result of comparing results of FEM analysis of the slab which is supported by the main girder and the cross girder and the design bending moment expressions that are proposed in previous studies, it was found to be dangerous in the non-composite state.
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